Author Topic: Anyone tried the $120 CB550 big bore kit yet? (Read 41357 times)

HondaMan · « **Reply #25 on:** September 09, 2012, 09:04:08 PM »

One day, I'm gonna find a 550 somewhere and make a "Gentleman's Express" out of it, just to see..

In the meantime, if anyone wants some 750 pistons for their GE, I've got about 10 sets of 61mm 750 pistons in a box...hate to take them to the scrap dealer...also one set of used 61.25 1st oversize pistons.

RAFster122s · « **Reply #26 on:** September 09, 2012, 09:56:14 PM »

There were specific pistons this could be done to and they were pretty flat topped if I remember correctly. The problem several people reported who tried this in the last couple years was finding a shop that would touch modifying a set of pistons.
Soos was the only guy on the forums who would do a set. He apparently lost his wife (died) or someone very significant in his life and things turned severely upside down. Gotta understand that if you've ever had that happen in your life.
There are several steps to modifing the pistons and the quench band to fit the smaller dome is only one of them. I didn't think the dome of the piston intruded into the 550 head, but, it has been a while since I read the article and threads here.

Quote from: d9canada on September 09, 2012, 09:02:09 PM

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.

d9canada · « **Reply #27 on:** September 09, 2012, 10:12:09 PM »

Thanks for that info. According to the article, they used modified 750 slugs because they wanted really high compression (actual value not stated) and they said that they had to do custom mods to the dome and valve reliefs.

They also said that Poweroll made off-the-shelf pistons for this application that required no mods. I've emailed them to see if they can still provide them, and if so, how much. Betcha it'll be a bit more than 120! But then again, how many guys can accurately file a thou out of a ring groove on four pistons? Maybe stock is better.

FunJimmy · « **Reply #28 on:** September 09, 2012, 10:17:58 PM »

Although not cheap, Dynoman sells a sweet looking set of forged 592cc pistons.
I might just give them a ty too.

FJ

RAFster122s · « **Reply #29 on:** September 09, 2012, 10:23:54 PM »

Meant to say, smaller head opening...not dome. I really need to proofread my post better. I guess there had to be some dome into the head because of the mods. Valve pockets of course being one of the mods.

Only recall ring grooves needing modified on the henry abe kits, to run honda oem or good quality rings, as they grenaded w/stock one piece oil ring.

I really need to reread the threads and GE article, just not tonight...

Flying J · « **Reply #30 on:** September 09, 2012, 10:28:53 PM »

Quote from: FunJimmy on September 09, 2012, 10:17:58 PM

Although not cheap, Dynoman sells a sweet looking set of forged 592cc pistons.
I might just give them a ty too.

FJ

Ill let you know how they work hopefully by the end of this year. "Fingers crossed"
They sure are pretty!

From what i understand ( and thats not much) you cant just chuck up a piston in the lathe and have at it. You have to make a fixture of some sort to hold the piston square. Like i said i dont know really how that works but maybe someday. Im keeping my eyes out for a decent lathe and then im going to learn how to use it.
\
Also if you want to read the gentlmans express i have it hosted on my blog page
http://flyingjcustoms.blogspot.com/2012/03/gentlemans-express.html

Greggo · « **Reply #31 on:** September 15, 2012, 07:38:24 AM »

I think the consensus has been spot on with these kits. They look great for a ~$100 kit, and while I wouldn't go racing with them, I think they'll do well on the street. They WILL need a little work...not ready to throw right in...but what would you expect for $100 I received my 500/4 +1mm kit within a week, but did have to go to my post office to pick them up...restricted mail apparently

Dimitri13 · « **Reply #32 on:** September 18, 2012, 09:08:05 PM »

So the general consensus is to get the 500 61mm kit for a 550, as opposed to the 550 61.5mm kit? Or is it worth the risk to use the 61.5mm kit without resleeving?

RAFster122s · « **Reply #33 on:** September 19, 2012, 12:00:14 AM »

61 is recommended but you can most likely safely stretch it to 61.5 is the advice I heard back to this thread. The 500 cannot go to 61mm without resleeving the cylinder, easier to pick up a 550 cylinder and have it align bored to sized.

FastCB550 · « **Reply #34 on:** November 02, 2012, 04:54:01 AM »

Quote from: Dimitri13 on September 18, 2012, 09:08:05 PM

So the general consensus is to get the 500 61mm kit for a 550, as opposed to the 550 61.5mm kit? Or is it worth the risk to use the 61.5mm kit without resleeving?

Giving this topic a bump. Has anyone installed and ran these 61.5mm in their 550 yet?

I'm in need of a rebore and new pistons. This set seems like a interesting alternative to paying 3x for the same OEM items.

dave500 · « **Reply #35 on:** November 02, 2012, 05:03:31 AM »

if your engine just needs a rebore go with the first or what ever oversize it needs,,you wont gain much power or torque in these over bores anyway!if your engine was worn out the refurb will be better than new anyway!,these old bikes already have nearly enough power,,unless your just a straight line rider?

RAFster122s · « **Reply #36 on:** November 06, 2012, 01:46:34 AM »

Need to go faster, drop some weight and attend a rider's school where they can teach how to do so... After you rebuild if needed. These overbores take away any future boring jobs on the head/cylinders..

alancop · « **Reply #37 on:** November 06, 2012, 09:01:33 AM »

I purchased this kit and my machinist said they were better quality than the OEM ones that came out of the bike and they had the 2 piece oil ring.

FastCB550 · « **Reply #38 on:** November 06, 2012, 09:48:49 PM »

Quote from: alancop on November 06, 2012, 09:01:33 AM

I purchased this kit and my machinist said they were better quality than the OEM ones that came out of the bike and they had the 2 piece oil ring.

Thats good news! I ordered my set a few days ago and am looking forward to receiving them. Im wondering if Ill have to do any jet changes for the rise in displacement. Does anyone have a favorite place to send their cylinders to get bored? My local guy quoted me $100 a hole!!!!

Retro Rocket · « **Reply #39 on:** November 06, 2012, 09:51:33 PM »

Quote

My local guy quoted me $100 a hole!!!!

Your local guy is a thief....

Flying J · « **Reply #40 on:** November 06, 2012, 10:08:06 PM »

I have 2 different places. one is $100 a hole for over bore and the other is $80. If it is just 1 or 2 sizes over bore its half that price. Thats why i wouldn't use these, the benefit doesnt justify the cost. Unless your buddies with a machinist, then why not.

FastCB550 · « **Reply #41 on:** November 06, 2012, 10:18:45 PM »

Yeah I didn't realize that the machine shops charge by how big you are going. I was thinking a bore job is a bore job. Guess not!

Since this set is 61.5mm and stock is 58.5mm (CB550) this is 3mm over which falls into the overbore pricing. I failed to add this to my calculations.

Hasenkopf · « **Reply #42 on:** November 06, 2012, 10:59:54 PM »

I'm still waiting for mine to come back from ape.......

FastCB550 · « **Reply #43 on:** November 07, 2012, 08:50:43 AM »

Quote from: GSX69bun on November 06, 2012, 10:59:54 PM

I'm still waiting for mine to come back from ape.......

What are they charging per cylinder?

Hasenkopf · « **Reply #44 on:** November 07, 2012, 09:55:43 AM »

too much......but I couldn't get anyone else to do it.

HondaMan · « **Reply #45 on:** November 10, 2012, 04:52:20 PM »

Heck, at $100 per hole, I could buy a boring bar and do them myself! I have 8 engines to rebuild...

Flying J · « **Reply #46 on:** November 10, 2012, 05:04:37 PM »

trust me i thought long and hard about that. I was watching craigslist for them but decided that if i bought a boring bar it might end up costing me a few cylinders to learn on and unlike you i am not sure how many times i would use it. So i bit the bullet and paid up. TWICE! but thats a whole different story. Did you know the cylinder can flex when they are clamped down to be surfaced? Anyway I am going to avoid bike with 4 cylinders when i plan to do big bore stuff.

HondaMan · « **Reply #47 on:** November 10, 2012, 05:21:01 PM »

Quote from: ffJMoore on November 10, 2012, 05:04:37 PM

trust me i thought long and hard about that. I was watching craigslist for them but decided that if i bought a boring bar it might end up costing me a few cylinders to learn on and unlike you i am not sure how many times i would use it. So i bit the bullet and paid up. TWICE! but thats a whole different story. Did you know the cylinder can flex when they are clamped down to be surfaced? Anyway I am going to avoid bike with 4 cylinders when i plan to do big bore stuff.

Boy, they flex like they were made of rubber! But, that's part of why they last so long (and have steel liners) and leak so little over time.

To bore them, you must make a steel tooling plate that mounts them flat and true. I did that last year, made one that can fit up to 900cc bore for the 750. Next, you need either the boring head (which I have) or the boring bar that can be installed to bore thru the plate (don't have) with regular tooling bits. Or, you need a professional one where the block (cylinders or car engines) must be bolted to it: my garage isn't even big enough to hold one of those!

I am aiming at opening a small engine repair shop as my 'retirement plan', so bit by bit, gathering the pieces...

FastCB550 · « **Reply #48 on:** November 10, 2012, 05:58:23 PM »

I just got my set in yesterday and thought Id share some images. They seem to be the exact same height as the OEM stock ones and they also seem to have the same height from the wrist pin center to the top of the piston. From what I can tell the only difference is in the diameter.

FastCB550 · « **Reply #49 on:** November 10, 2012, 06:03:44 PM »

On the ring set I cant tell which one of the top two rings go where. One seems square and one has a bevel on the top and bottom edge. Both seem to be of the same material and there is not a chrome one.

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Author Topic: Anyone tried the $120 CB550 big bore kit yet? (Read 41357 times)