Topic: Anyone tried the $120 CB550 big bore kit yet?

[Scott S]

 Anyone pulled the trigger on this one yet? Results? Quality?

http://www.ebay.com/itm/Honda-CB550F-CB550K-600cc-Bigbore-Piston-Kits-with-Head-Gasket-CB550FBB-/160775419335?pt=Motorcycles_Parts_Accessories&hash=item256ef635c7&vxp=mtr

[Greggo]

I just pulled the trigger on the +1mm CB500 kit.  There was a thread about a few guys who had tried them and had good results, both 550 and 750's.  HondaMan has used the 836 kits from him with success in some of his motor rebuilds.  They're solid, at a great price.

[Reid Irwin]

Just bought the 836 kit for my CB750 from the same company.  Ordered the kit on a Sat. and received it from Japan on the following Thursday.  Total $110.00 Canadian with free postage.  Just waiting to remove the motor and start the project.  Go for it, good luck

[FunJimmy]

These are 61.5mm pistons.
I thought 61mm was the max a 550 could be bored.

[RAFster122s]

Henry Abe kit provided liners for cb500s but cb550 could go to 61mm with stock sleeves. I don't know about 61.5mm.

[Tews19]

Depending on my cam tensioner status, If it breaks, I am definately interested. What kind of gains would oen look to acheive with this?

[Scott S]

These are 61.5mm pistons.
I thought 61mm was the max a 550 could be bored.

 Hmmm....that's definitely food for thought. I'd like to hear some definitive answers about this, or from someone who's actually used this particular kit.

[Scott S]

 Bumping this one up in hopes of getting some answers about the max overbore size. 61mm vs. 61.5mm.

[Flying J]

alread done a thread on this.
http://forums.sohc4.net/index.php?topic=111587.0

Bumping this one up in hopes of getting some answers about the max overbore size. 61mm vs. 61.5mm.

you could bore the cylinder out to 63 im sure there is plenty of metal. Its just when it get to thin the cylinders can warp from heat. so i think 61 has always been said to be the max to leave the correct amount of cylinder wall but another .5 is possible. How long the cylinders will last? who knows. I doubt any body has installed one and put enough miles on it to know for sure.

[BAchvytrk]

i used to own a 2000 zx9r. with 3k on it I installed a muzzy big bore kit which took it from 899cc to 998cc.  the kit came complete with plated cylinder. I was told from the tech guys at muzzy that with this kit, the cylinder wall where a little thin, and when machined they left the tolerances a little looser than normal( i don't remember the exact specs) to accomadate for expansion. they told me that on cold starts a little piston slap was normal until operating temperature was reached. I was careful to let the bike warm up everytime before i rode it and put 30k miles on it, some easy, many not so easy. I'm sure with this kit for the 550, as long as the cylinders are machined right, there should be no problems.

[dave500]

just use the offered normal over sizes,you cant rebore again if you go way over,the zx9r has no business here as its a totally different thing with forged pistons maybe and probably a nikasil bore?

get the machine shop to final hone each piston to a bore and number them.

[Brantley]

Scott, I'm installing an cruzinimage 836 kit right now.  Can't help you with the .5mm dilemma. I will say they are decent quality, but what you save in $ you'll make up for in time filing rings, removing flash, etc.

[d9canada]

I emailed these guys to get more info on boring, recommendations for carb changes (jetting or whatever).  I got a cryptic reply from a guy who clearly spoke and wrote English as a second language.  Basically he could not answer anything. 

I am tempted but frankly unless I had a complete engine plan, head porting, cam, carbs, ignition.. why bother?  So - my first 550K is a stocker, nearly running, stock is good.  On the other one - I'm tinkering to marry 750 Katana forks, wheels & brakes to it - maybe even the swingarm.  I've got a line on a 650 cam and tach drive - a modest start and a reasonable price but a Dynoman would be better.. not sure about carbs.  I need someone to do the head, any suggestions (in the Pacific Northwest preferably!).  Of course, dumping the rotor and going to some sort of mag would add more Zoom than probably any other change.. what mag would that be?  Hmm..

Brantley - obviously you have some experience, could you give a little more detail?

[Brantley]

Well, the only details I can add pertain to the 836 kit. I'm willing to guess that these are manufactured in the same place. My point was these don't come completely ready to install- Hondaman pointed this out in the "cheap ebay 836 kit" thread. Mine came with flash on the inside of the skirts that needed smoothing. Some oil holes needed to be deburred. All accessible ones needed chamfering. The top and second ring end gaps were close but needed to be matched (by .001"). ALL the oil rings were super tight. Measure EVERYTHING before assembling. Mine are decent quality, but require several more hours of diligence than, say, buying a 1st over set from Honda.

I wish one of you 550 cats would pull a "Gentleman's Express" on standard 61mm 750 pistons and post the results. If you haven't seen that article: http://forums.sohc4.net/index.php?topic=20601.0

[Flying J]

I emailed these guys to get more info on boring, recommendations for carb changes (jetting or whatever).  I got a cryptic reply from a guy who clearly spoke and wrote English as a second language.  Basically he could not answer anything. 

I am tempted but frankly unless I had a complete engine plan, head porting, cam, carbs, ignition.. why bother?  So - my first 550K is a stocker, nearly running, stock is good.  On the other one - I'm tinkering to marry 750 Katana forks, wheels & brakes to it - maybe even the swingarm.  I've got a line on a 650 cam and tach drive - a modest start and a reasonable price but a Dynoman would be better.. not sure about carbs.  I need someone to do the head, any suggestions (in the Pacific Northwest preferably!).  Of course, dumping the rotor and going to some sort of mag would add more Zoom than probably any other change.. what mag would that be?  Hmm..

Brantley - obviously you have some experience, could you give a little more detail?

If your going to spend the time to do head work put in a cam and upgrade the ignition why waste your time on a set of bigbores that dont increase compression?

[FunJimmy]

If your going to spend the time to do head work put in a cam and upgrade the ignition why waste your time on a set of bigbores that dont increase compression?

Unless the big bore pistons have a dish top (negative dome) then the CR will increase due to larger cylinder volume vs combustion chamber volume. 

[d9canada]

FunJimmy - yeah that!

ffjMoore - I neglected to mention that I'd plane the head to bring it up to about 10:1 along with the porting, along with exhaust considerations and more.  Of course it would be best to first check the volume and valve clearances after getting the piston & cylinder combination finalized first.  There's also practical considerations because much over 10.2:1 is dicey on pump gas.  An increase in displacement and a general increase in flow efficiency is will provide a modest performance boost without sacrificing reliability.  It's a great idea if you're rebuilding an old bird.  If you want HOT, throwing money at a 35 year old Honda is a lost cause.

Brantley, thanks for the links.  I did request a pdf of the article.  I'd certainly consider it instead of a kit of poorly finished parts.

[Scott S]

I wish one of you 550 cats would pull a "Gentleman's Express" on standard 61mm 750 pistons and post the results. If you haven't seen that article: http://forums.sohc4.net/index.php?topic=20601.0

 I tried to do this but the forum member that modified the pistons has gone M.I.A. I went with OEM style 1.00mm over, ported/polished head and a CB650 cam. This was on my '78 550K. It runbs great, but I have a leaking head gasket. I was considering the cheap kit for my '71 w/ a 550 engine.

[Retro Rocket]

FunJimmy - yeah that!

ffjMoore - I neglected to mention that I'd plane the head to bring it up to about 10:1 along with the porting, along with exhaust considerations and more.  Of course it would be best to first check the volume and valve clearances after getting the piston & cylinder combination finalized first.  There's also practical considerations because much over 10.2:1 is dicey on pump gas.  An increase in displacement and a general increase in flow efficiency is will provide a modest performance boost without sacrificing reliability.  It's a great idea if you're rebuilding an old bird.  If you want HOT, throwing money at a 35 year old Honda is a lost cause.

Brantley, thanks for the links.  I did request a pdf of the article.  I'd certainly consider it instead of a kit of poorly finished parts.

Terry {TIA} runs 12.5 to 1 on the street with no problems at all....

[d9canada]

Scott,

I just got the PDF.  Surely one guy going missing shouldn't cause the world to stop turning.  If you're interested I'll get back to you when I've had time to check it out.

[Flying J]

I have a set of pistons from said missing person. I was not impressed. Im not sure they were machined evenly and the skirts  hit the crank on the bottom side. I still have them if anybody is interested in them.

[Brantley]

If your going to spend the time to do head work put in a cam and upgrade the ignition why waste your time on a set of bigbores that dont increase compression?

Because your bores are worn and these are 1/4 of the cost of 1st over Honda pistons and rings? Because you gotta go to the machine shop anyway, why not add a lil HP for the same labor cost? Because you don't live within 50 miles of the only station in your state that has ethanol free 93 octane and you find spark knock embarrassing?

d9- I didn't mean they are poorly finished, they just need a little more finishing.

Mick- You and Terry have the luxury of dinosaurs that haven't been force fed corn...

Scott- I remember that head now...

[d9canada]

Scott - finished reading.. the spec for the modification to the 750 pistons is right there in the article, complete with picture, any good speed shop machinist should be able to do that.  Hell I could just about do that on my rickety old lathe.. or maybe I should buy the new lathe and discount the cost by the money I 'save' doing my own pistons!  yeah!

Brantley - yeah 'because' and 'poorly vs more' - 'po tA to - po tat o!'  And thanks again for pointing me to that article.  I raced MX for years, hoping in vain to finally escape the confines of Vancouver Island for road racing and flat tracks.  Jess Thomas and Gordon Jennings gave great advice even helped a kid desperately trying to race on a meagre budget.  Wow what trip!

ffjMoore - if there's already issues??  PM me and we'll talk.

[Retro Rocket]

Mick- You and Terry have the luxury of dinosaurs that haven't been force fed corn...

 

[d9canada]

Whoa up there Youze guys!  A retired engine builder and 550 devotee friend of mine quickly introduced some doubt on the modified 750 piston idea.  As he pointed out, that dome will intrude into the chamber far higher than the original flat top. 

Despite what some might say, it's pretty commonly accepted that our current pump gas will knock holes in pistons if your compression ratio is much higher than 10.2 to 1.  This CR would have been just peachy back in the days before ethanol.  Those domes will probably take you up into the 12:1 range.  I'll try to get some confirmation on the CR.  Stock CR is 9:1 and that dome is pretty big.  And as my buddy was quick to mention, you can't cut much off the crown because you'll have nothing left.