Author Topic: Cheap 836 kits back on ebay...$110! *Update!  (Read 109864 times)

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Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #150 on: December 05, 2011, 02:03:35 PM »
I got my kit today, shipped right from Japan. The kit looks pretty good in general. The only thing that bothers me is the exhaust valve pockets are kinda heart shaped, so it looks like they will have to be machined slightly to clear the valves. Other than that it looks pretty good.
« Last Edit: December 05, 2011, 04:52:12 PM by KJ790 »
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Offline jaguar

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #151 on: December 05, 2011, 03:12:10 PM »
I think the pockets are so that the pistons can be used in any cylinder

Offline Duke McDukiedook

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Re: Cheap 836 kits back on ebay...$110!
« Reply #152 on: December 05, 2011, 03:18:39 PM »
heh...hard to beat an endorsement like that. Thanks Hondaman!!

I wouldn't exactly call it an endorsement, he only said he installed a set on a bike.
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Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #153 on: December 05, 2011, 04:49:52 PM »
I think the pockets are so that the pistons can be used in any cylinder

That could be true. I'm going to measure it up once I get my engine apart and see what the valve to piston clearance is anyways to make sure that everything fits right.
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Offline Grnrngr

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Re: Cheap 836 kits back on ebay...$110!
« Reply #154 on: December 05, 2011, 07:13:16 PM »
heh...hard to beat an endorsement like that. Thanks Hondaman!!

I wouldn't exactly call it an endorsement, he only said he installed a set on a bike.

Well, yeah, he's prolly not getting paid by "Cheap 836 Kits" to say he uses their product exclusively and put their stickers all over everthing...but "he" is Hondaman, I think he probably enjoys his reputation and wouldn't chance it by installing random crap on a friend/customer's bike, so just using it is endorsement enough, for me anyway. I think if he thought it was crap he'd say so...so yeah, you're right, maybe I should have said "positive affirmation" instead... :D
So...it is kinda hard to endorse a new product without field reports..anyone got any kind of miles on one yet? Do they go faster? 
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Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #155 on: December 08, 2011, 12:24:46 AM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?
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Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #156 on: December 08, 2011, 12:31:36 AM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?

Sorry for pointing it out Matt but you have already been told in your other thread. The F2-F3 bikes have a totally different head and pistons, these pistons are for the Earlier K and maybe the F0- F1 engines.  F2-3 pistons are totally different with a much higher dome, you put K pistons in your F2 and it will have the compression of a Turbo bike without the turbo  = no good... ;)
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Offline classic bike tuner

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #157 on: December 08, 2011, 02:56:13 AM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?

i think you end up with about the same compression ratio as stock
you gain in cappacitie but combustion chamber becomes bigger
i have built a f2 with boldor pistons [64,5mm] and that runs great
 
about MPG  get an electronic ignition with boldor coils

Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #158 on: December 08, 2011, 03:54:01 AM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?

i think you end up with about the same compression ratio as stock
you gain in cappacitie but combustion chamber becomes bigger
i have built a f2 with boldor pistons [64,5mm] and that runs great
 
about MPG  get an electronic ignition with boldor coils

How can you end up with the same compression as stock when you have increased the overall volume of the combustion chamber....
Lower compression will be the result of using K model pistons in an F2....
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Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #159 on: December 08, 2011, 08:22:58 AM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?

i think you end up with about the same compression ratio as stock
you gain in cappacitie but combustion chamber becomes bigger
i have built a f2 with boldor pistons [64,5mm] and that runs great
 
about MPG  get an electronic ignition with boldor coils

How can you end up with the same compression as stock when you have increased the overall volume of the combustion chamber....
Lower compression will be the result of using K model pistons in an F2....

Because you increased the displacement while increasing the combustion chamber size proportionally. The K model has a combustion chamber of about 22-23cc, which gives around a 9:1 compression ratio with the stock 736cc displacement. When the cylinders are bored out to 836cc and the combustion chamber is kept the same size the compression ratio goes up to around 10.25:1 (hence why the wiseco 836 kit has this compression ratio on the K model). If you put an 836 piston meant for a K model with the F2/3 head you get a combustion chamber of around 27cc, so your final compression ratio ends up being around 8.8:1, so almost identical to stock. If you go with a thinner MLS head gasket you can get it up to 9.5:1 compression. If you keep the same compression ratio as stock but increase the displacement then you will see a power increase. Those Ebay pistons will work fine in the F model as long as the valve relief pockets are correct, they may need to be machined slightly to clear the valves.

I am going to be putting one of the Ebay kits in an F3 engine soon, so I will check and see how much room there is for the valves and if any machining needs to be done.
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Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #160 on: December 08, 2011, 02:52:32 PM »
Thanks for the info, sounds like this is exactly what I need.

I was planning on upgrading to the Cycle-X optical ignition. I've got one on my F1 and it works great, mileage and HP improved dramatically but my old points were shot so it's hard to say definitively if the Cycle-X is much better than stock. I'm not finding much info on the boldor(baldor?) coils. Looks like they manufacture a variety of electrical products, could they be what Cycle-X is using?

KJ, can't wait to see how you're build goes.
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Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #161 on: December 08, 2011, 03:36:57 PM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?

i think you end up with about the same compression ratio as stock
you gain in cappacitie but combustion chamber becomes bigger
i have built a f2 with boldor pistons [64,5mm] and that runs great
 
about MPG  get an electronic ignition with boldor coils

How can you end up with the same compression as stock when you have increased the overall volume of the combustion chamber....
Lower compression will be the result of using K model pistons in an F2....

Because you increased the displacement while increasing the combustion chamber size proportionally. The K model has a combustion chamber of about 22-23cc, which gives around a 9:1 compression ratio with the stock 736cc displacement. When the cylinders are bored out to 836cc and the combustion chamber is kept the same size the compression ratio goes up to around 10.25:1 (hence why the wiseco 836 kit has this compression ratio on the K model). If you put an 836 piston meant for a K model with the F2/3 head you get a combustion chamber of around 27cc, so your final compression ratio ends up being around 8.8:1, so almost identical to stock. If you go with a thinner MLS head gasket you can get it up to 9.5:1 compression. If you keep the same compression ratio as stock but increase the displacement then you will see a power increase. Those Ebay pistons will work fine in the F model as long as the valve relief pockets are correct, they may need to be machined slightly to clear the valves.

I am going to be putting one of the Ebay kits in an F3 engine soon, so I will check and see how much room there is for the valves and if any machining needs to be done.

KJ 790, have you used these in an F engine before.?

Well that goes against everything i have been told about the F2-F3 engines and K model pistons. If i were putting a kit in an F2, i would be using the F2 pistons {like everyone else does}, yes sure the K pistons will "fit", but it defeats the whole purpose of using an 836 kit in the first place.
If this was such a simple conversion then why would companies like CycleX have  the F2-F3 specific piston kits made with the much higher domed pistons?. I also think when telling someone that they will fit you should also tell them that the Kit will NOT perform like it was designed to do in an F2-F3 engine. Overall that kit will add to displacement and not much at all to the power side of the equation....
I know you probably bought these pistons without knowing the differences but, If you really want to know Matt, give Jay a ring at APE {CBR zone} , Ken at CycleX or resident Head Guru Mike Rieck.........
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Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #162 on: December 08, 2011, 05:00:05 PM »
I'm planning on using this kit on my 1977 CB750F2. The bike is used primarily for loaded (sport) touring and has taller than stock gearing. Mileage is about 26,000. I also plan on having the head rebuilt. I hope to increase torque without diminishing fuel efficiency. Will this "flat topped" piston be appropriate for my "domed" F2 head? Does anyone have any other recommendations about building a touring motor? Cam selection? MPG improvements? Other mods?

i think you end up with about the same compression ratio as stock
you gain in cappacitie but combustion chamber becomes bigger
i have built a f2 with boldor pistons [64,5mm] and that runs great
 
about MPG  get an electronic ignition with boldor coils

How can you end up with the same compression as stock when you have increased the overall volume of the combustion chamber....
Lower compression will be the result of using K model pistons in an F2....

Because you increased the displacement while increasing the combustion chamber size proportionally. The K model has a combustion chamber of about 22-23cc, which gives around a 9:1 compression ratio with the stock 736cc displacement. When the cylinders are bored out to 836cc and the combustion chamber is kept the same size the compression ratio goes up to around 10.25:1 (hence why the wiseco 836 kit has this compression ratio on the K model). If you put an 836 piston meant for a K model with the F2/3 head you get a combustion chamber of around 27cc, so your final compression ratio ends up being around 8.8:1, so almost identical to stock. If you go with a thinner MLS head gasket you can get it up to 9.5:1 compression. If you keep the same compression ratio as stock but increase the displacement then you will see a power increase. Those Ebay pistons will work fine in the F model as long as the valve relief pockets are correct, they may need to be machined slightly to clear the valves.

I am going to be putting one of the Ebay kits in an F3 engine soon, so I will check and see how much room there is for the valves and if any machining needs to be done.

KJ 790, have you used these in an F engine before.?

Well that goes against everything i have been told about the F2-F3 engines and K model pistons. If i were putting a kit in an F2, i would be using the F2 pistons {like everyone else does}, yes sure the K pistons will "fit", but it defeats the whole purpose of using an 836 kit in the first place.
If this was such a simple conversion then why would companies like CycleX have  the F2-F3 specific piston kits made with the much higher domed pistons?. I also think when telling someone that they will fit you should also tell them that the Kit will NOT perform like it was designed to do in an F2-F3 engine. Overall that kit will add to displacement and not much at all to the power side of the equation....
I know you probably bought these pistons without knowing the differences but, If you really want to know Matt, give Jay a ring at APE {CBR zone} , Ken at CycleX or resident Head Guru Mike Rieck.........

Did you even read my post? I have built many race engines over the years, I'm not new to this. I wanted these pistons b/c I didn't want 10.25:1 compression on a street motor. For the price, these kits are one of the best bang for your buck that you can buy.

CycleX makes the 836 kit for the F2-F3 for people that want 10.25:1 compression (like the wiseco or ebay kit equate to on the K model). As I said, the ebay kit works out to almost exactly equal to stock compression ratio in the F2-F3 engine. With a thinner MLS head gasket you can get above stock compression ratio. From your response I can tell that you do not have much if any experience with the effects of compression ratios on engines. The difference between 9.5:1 compression and 10.25:1 compression ratios is almost unnoticeable, especially if you are running a stock cam.

A properly setup engine (appropriate squish and deshrouded valves) with 9.5:1 compression will out run an engine that is just slapped together with 10.25:1 compression pistons any day. That's not even adding a little porting into the mix. You seem to have this notion that going to an 836 big bore and keeping the same compression ratio will perform worse than stock. Like the old saying goes, there is no replacement for displacement.

For anyone that is interested, here is a picture of an F2-F3 stock piston next to an ebay piston:



You can see the dome difference, it is about 4cc of combustion chamber displacement. The biggest downside to the ebay pistons are their weight. The stock F2-F3 piston with wristpin, rings, and c-clips is 207g, the ebay pistons with all hardware is 232g, but it can be modified to save a little weight.
« Last Edit: December 08, 2011, 05:02:43 PM by KJ790 »
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Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #163 on: December 08, 2011, 05:04:08 PM »
As I'm seeing it putting a STOCK K piston into a STOCK F motor would give unacceptably low compression. However, increasing displacement creates a larger volume of air/fuel mixture to be compressed into the same area at TDC which means higher compression ratios. I don't necessarily want a higher compression ratio in a bike I will be riding fully loaded w/ gear at high speeds for days on end in areas far from civilization. I have absolutely no hands on experience w/ this but I am assuming that increased displacement/stock carbs/stock compression ratio will result in a motor w/ modest hp/torque increases while maintaining relatively low head temps.

Here is the quote from Hondaman that I based my decision to order these on. -
Quote
Quote from: gschuld on June 05, 2011, 08:44:36 pm

    Could someone give me an idea as to what compression ratio I would end up with if I used this kit(which I just ordered ;)) in a 76 cb750f engine?  It doesn't seem like it would be very high.  Any idea as to how much I can reasonably increase the CR with head milling, etc?

    Thanks


They come in at about 9.5:1 compression if you do not modify the head to add a quench band. If you add the quench band, it drops to about 9.25:1, depending on how much you taper the edges of the chamber. Don't forget: you are increasing the displacement by about 14% with these pistons, while the chamber remains the same as for the 736 engine.

The Wiseco pistons, with their domes, come in at an advertised 10.5:1 at 836cc, but that number presumes an untouched chamber. It makes for a lot of extra heat and a tendency to knock at low octanes, so the lower CR of these pistons is a good bet for trouble-free riding. ;)
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Offline ekpent

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #164 on: December 08, 2011, 05:13:13 PM »
In that quote Matt, Hondaman was comparing with a 1976 F model which has different pistons than the 77-78 F's for whatever thats worth.

Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #165 on: December 08, 2011, 05:17:58 PM »
Quote
The biggest downside to the ebay pistons are their weight. The stock F2-F3 piston with wristpin, rings, and c-clips is 207g, the ebay pistons with all hardware is 232g, but it can be modified to save a little weight.

How does this weight difference affect performance? More energy required to move the extra 100 grams around = more heat produced/minor hp loss? Any benefits to the added weight?
I assume you're talking about taking a dremel to the inside of the pistons to hog out some weight like I've seen recommended to do when balancing a piston set? I'd love to see some before and after pics if you do this.
Is the added weight simply because it's a larger piston or are there other factors?
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Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #166 on: December 08, 2011, 05:24:11 PM »
In that quote Matt, Hondaman was comparing with a 1976 F model which has different pistons than the 77-78 F's for whatever thats worth.

Yup. Hence the different compression ratios he's quoting compared to KJ(8.8 vs. 9.5 to 1). I may go w/ the thinner head gasket that he recommends to get the compression back to exactly stock. Any reason to just stick w/ the slightly decreased compression ratio(8.8) versus bumping it back up?
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Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #167 on: December 08, 2011, 05:42:21 PM »
Quote
A properly setup engine (appropriate squish and deshrouded valves) with 9.5:1 compression will out run an engine that is just slapped together with 10.25:1 compression pistons any day.

What a stupid comparison coming from an engine builder, thats goes without saying with any engine, who mentioned "slapping together" anything? And you assume that Matt is going to deshroud the valves and do everything you mentioned as well, all this costs money and i am sure thats not what Matt had in mind, budget pistons for a budget build, what you have said is correct but adds substantial cost to his build.  Most all people that go for the 836 kits and larger WANT PERFORMANCE, which is what i have been referring to, you won't get that with these pistons, for a stock style rebuild, go for your life but without doing everything mentioned you will have lower compression.... And by the way, these bikes go just fine on the street with 10.25 to 1 compression.... You also didn't mention that the MLS gaskets will cost almost as much as these kits....

Quote
From your response I can tell that you do not have much if any experience with the effects of compression ratios on engines. The difference between 9.5:1 compression and 10.25:1 compression ratios is almost unnoticeable, especially if you are running a stock cam.

Nice assumption dude, He will only get those numbers if he does all the things you mentioned. {added costs} I am no engine guru but have had over 20 of these bikes {over 40 bikes of different makes} , all kitted bar 1 and currently have 2 bikes being built, one 1000cc with big ported head, forged pistons,  billet aluminium block and tons of awesome parts, the other is a 970cc, with RC crank and rods and everything else as well.... Why put in an 836 kit if all you want is stock like performance..Matt may as well save his dollars and just re ring it ? Considering that all the HP in these old bikes is found in the heads, cam and carbs, pistons alone do sweet FA...   Anyway i'm out of here, If Matt wants relatively stock performance while he still has to get the engine bored, gaskets and everything else then thats great, i would buy the correct pistons and get the added HP that comes with that...
« Last Edit: December 08, 2011, 05:44:30 PM by Retro Rocket »
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Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #168 on: December 08, 2011, 06:04:32 PM »
Quote
The biggest downside to the ebay pistons are their weight. The stock F2-F3 piston with wristpin, rings, and c-clips is 207g, the ebay pistons with all hardware is 232g, but it can be modified to save a little weight.

How does this weight difference affect performance? More energy required to move the extra 100 grams around = more heat produced/minor hp loss? Any benefits to the added weight?
I assume you're talking about taking a dremel to the inside of the pistons to hog out some weight like I've seen recommended to do when balancing a piston set? I'd love to see some before and after pics if you do this.
Is the added weight simply because it's a larger piston or are there other factors?

The weight is mostly due to the piston. The wristpin is about 1g heavier and the rings are a couple grams heavier since they have to be larger for the larger bore. These pistons will probably never be as light as stock since they are physically bigger, but you can save a couple grams. The biggest down side to heavier pistons is the added stress on the rods and big end bolts at high RPMs. I definitely wouldn't suggest revving it to 11,000 RPM with the stock bottom end.
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Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #169 on: December 08, 2011, 06:24:08 PM »

What a stupid comparison coming from an engine builder, thats goes without saying with any engine, who mentioned "slapping together" anything? And you assume that Matt is going to deshroud the valves and do everything you mentioned as well, all this costs money and i am sure thats not what Matt had in mind, budget pistons for a budget build, what you have said is correct but adds substantial cost to his build.  Most all people that go for the 836 kits and larger WANT PERFORMANCE, which is what i have been referring to, you won't get that with these pistons, for a stock style rebuild, go for your life but without doing everything mentioned you will have lower compression.... And by the way, these bikes go just fine on the street with 10.25 to 1 compression.... You also didn't mention that the MLS gaskets will cost almost as much as these kits....

Not a stupid comparison at all, you were coming off as if you feel that there is no way an ebey kit could outperform stock, let alone a cyclex 836 kit. I was merely stating that it is very easy to do. Deshrouding the valves can be done by anyone, it doesn't cost anything other than time and a little research. There are plenty of people on here, myself included, that are more than happy to lend guidance to someone that is willing to learn. I never said that these bikes won't go on the street with 10.25:1 compression, I said that I did not want that compression ratio in my street engine.

You seem to get hung up on the static compression ratio. This number in reality tells you little to nothing about the engine's performance, as the dynamic compression ratio is what is important. The dynamic compression ratio is almost exclusively controlled by the cam profile and timing.

An MLS head gasket is $80, so for a total of $190 you can have an 836 kit that will run with the $450 cyclex kit.


Nice assumption dude, He will only get those numbers if he does all the things you mentioned. {added costs} I am no engine guru but have had over 20 of these bikes {over 40 bikes of different makes} , all kitted bar 1 and currently have 2 bikes being built, one 1000cc with big ported head, forged pistons,  billet aluminium block and tons of awesome parts, the other is a 970cc, with RC crank and rods and everything else as well.... Why put in an 836 kit if all you want is stock like performance..Matt may as well save his dollars and just re ring it ? Considering that all the HP in these old bikes is found in the heads, cam and carbs, pistons alone do sweet FA...   Anyway i'm out of here, If Matt wants relatively stock performance while he still has to get the engine bored, gaskets and everything else then thats great, i would buy the correct pistons and get the added HP that comes with that...

An 836 kit with stock compression will still make significant power over stock, even without touching anything else on the head. By simply putting these pistons in and slapping it together you will see 90% of the gains that you would with the 10.25:1 compression pistons. Basically instead of seeing a 10hp gain you will see a 9hp gain but save $250.

Reringing an F2-F3 is pretty hard, the rings for the stock pistons are pretty expensive. You can buy the ebay 836 kit for less than a set of rings for and F2-F3, and you will end up with a better performing engine.

Sounds like you buy all the trick parts you can and then pay someone to bolt them onto your bike for you. You can throw all of the most expensive, trickest parts in a motor and make less power, I've seen it a million times. It is fun to see their faces when they see their dyno run after spending all that money on trick parts. A bunch of bolt-ons thrown at a bike will not necessarily make it fast. Getting the porting to match the cam timing, ignition timing, and the exhaust design is how you make power. Everything in an engine has to work together.
« Last Edit: December 08, 2011, 06:28:41 PM by KJ790 »
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Offline fatmatt650

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #170 on: December 08, 2011, 06:53:51 PM »
Quote
Pistons alone do Sweet F.A. - RetroRocket

I assume you're referencing the song "Motorcycle" from the Love and Rockets album "Sweet F.A." If that's the case then, thank you, this is exactly what I want my new pistons to do for me. 

Me and the Motorcycle 
Me and the motorbike 
We just running around 
My feet are off the ground 
She's not gonna let me down 
She's not gonna let me down 
 
Me and this motorcycle 
Me and this motorbike 
You don't go too fast 
You just set me free 
It don't go too fast 
Just let me out 
Let me out 

AHHHH - Motorcycle 
AHHHH - We are free 
 
I feel warm inside 
On the motorbike 
The wind is all around 
On the motorbike 
We are free 
The motorcycle and me 
The motorcycle and me 
The motorcycle and me 



So much to do, so little time.

Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #171 on: December 09, 2011, 09:15:12 PM »
Quote
Sounds like you buy all the trick parts you can and then pay someone to bolt them onto your bike for you. You can throw all of the most expensive, trickest parts in a motor and make less power, I've seen it a million times. It is fun to see their faces when they see their dyno run after spending all that money on trick parts. A bunch of bolt-ons thrown at a bike will not necessarily make it fast. Getting the porting to match the cam timing, ignition timing, and the exhaust design is how you make power. Everything in an engine has to work together.

I have seen it all before mate.
one of the heads i have  was on a 10 second 750/4 at only 776cc's, Bigger valves, big ports , titanium retainers, heavier springs and beautiful ports, If you knew anything about the Aussie performance scene you would probably know the fastest gas engined 750 Honda's are built right here. My bike is being built by one of the best performance Honda mechanics  {modern} there is, period, last time i spoke to him he had a 140 HP SOHC bike with him, i expect around 100HP out of this engine and it will last, nothing has been overlooked. I have had some very fast performance cars as well my friend, i know exactly what is needed to get big HP gains out of any engine, I may not have the opportunity to do it all myself but i know exactly what is needed, in fact, when i was young and stupid {not young any more, still stupid  ;D} i was the only guy around that had his engines flowed properly {in my neighbor hood anyway}, my Father raced cars so i was quite familiar with how to get good gains out of my engines, i never had the shop or space to build my engines but knew plenty of people that could do an excellent job, still do. Its nice to make assumptions but you couldn't be further from reality. I don't have lots of money, thats why it has taken me so long to get the parts i have, most have been custom made and i haven't finished yet. Suspension is covered as well, 43mm cartridge forks with progressive springs {off a race bike} Huge boxed swingarm, heavily braced frame, and better 18 inch front and rear, alloy{wider}wheels {With custom billet hubs}and tyres.  After run in ,  fuel injection is next... Make no mistake, this bike WILL BE FAST.... ;D ;D ;)
« Last Edit: December 10, 2011, 06:19:57 PM by Retro Rocket »
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #172 on: December 10, 2011, 06:40:36 PM »
Ok, so these cheap cast ebay pistons are stock or close to stock compression, not 10.25 to 1,  so putting them in an F2 is going to give very low compression, Now i know 790 is going to come back and refute this because he builds his own engines.... ::) But i was just told by another experienced engine builder, that has had a couple of sets on these pistons, that in an F2, they would only be good for turbo application, which is what i said in the first place.....
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline KJ790

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #173 on: December 10, 2011, 08:53:42 PM »
Ok, so these cheap cast ebay pistons are stock or close to stock compression, not 10.25 to 1,  so putting them in an F2 is going to give very low compression, Now i know 790 is going to come back and refute this because he builds his own engines.... ::) But i was just told by another experienced engine builder, that has had a couple of sets on these pistons, that in an F2, they would only be good for turbo application, which is what i said in the first place.....

That is not correct, the ebay pistons are flat top pistons machined to the same deck height as stock K model pistons. They are not the same compression ratio as stock in a K model engine. I already gave you real combustion chamber volume numbers measured for these pistons in an F2-F3 head, I don't know what more you want. I don't know how you can even argue about this since you have never even seen these pistons, let alone measured them. Have you ever even seen an F2-F3 head?
The most dangerous part of a motorcycle is the nut that connects the handlebars to the footpegs.

Offline Retro Rocket

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Re: Cheap 836 kits back on ebay...$110! *Update!
« Reply #174 on: December 10, 2011, 11:54:31 PM »
Ok, so these cheap cast ebay pistons are stock or close to stock compression, not 10.25 to 1,  so putting them in an F2 is going to give very low compression, Now i know 790 is going to come back and refute this because he builds his own engines.... ::) But i was just told by another experienced engine builder, that has had a couple of sets on these pistons, that in an F2, they would only be good for turbo application, which is what i said in the first place.....

That is not correct, the ebay pistons are flat top pistons machined to the same deck height as stock K model pistons. They are not the same compression ratio as stock in a K model engine. I already gave you real combustion chamber volume numbers measured for these pistons in an F2-F3 head, I don't know what more you want. I don't know how you can even argue about this since you have never even seen these pistons, let alone measured them. Have you ever even seen an F2-F3 head?

Quote
i was just told by another experienced engine builder, that has had a couple of sets on these pistons, that in an F2, they would only be good for turbo application,

Did you not see this, i sent a copy of the reply to Matt.. I'll happily get my info from guys i trust and respect.  You are the only guy i have seen on the forum that endorses the use of K model pistons in a late model F bike...
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.