Topic: '77 Cb550 early ring wear

[kerryb]

Cant tell if they are upside down or not, any markings on the rings face upwards.
Wrong possition or orientation would wear ringsquickly and loose compression

According to the machine shop rep, ( if I heard it right) the compression ring should have it's wear at the top, and the oil scraper ring should have it's wear at the bottom.  He said something about the ring not being perfectly square under load, but I couldn't repeat it. I pulled one ring off and there were no markings on it at all.  I pulled a new set of oem honda rings from my stash and the very faint marks were tough to find, but there.

Going for a ride now to the machine shop to see if there are any results yet.  Sure, I could call them, but then there is no need to go for a ride!

[dave500]

the mark should be near the gap,old rings its hard to spot,i wouldnt imagine yours have worn away with such little use already?maybe they had none?cheap arse set?

[kerryb]

the mark should be near the gap,old rings its hard to spot,i wouldnt imagine yours have worn away with such little use already?maybe they had none?cheap arse set?

I only took one ring off for fear of breaking it without the right tools ( have them now)  there were no markins on it at all. I used my best magnifying  glass to be sure.  My guess is the pistons and rings came from a low buget place.

[kerryb]

Seeking suggestions for new pistons and rings.  Current bore size (from the machinist) is 2.235". After pistons are delivered he will rebore for .001 clearance and fit rings.

[bryanj]

David Silver sells oversize piston kits for the 550, all models are the same, i would go 0.5mm oversize

[jonda500]

Cant tell if they are upside down or not, any markings on the rings face upwards.
Wrong possition or orientation would wear ringsquickly and loose compression

According to the machine shop rep, ( if I heard it right) the compression ring should have it's wear at the top, and the oil scraper ring should have it's wear at the bottom.  He said something about the ring not being perfectly square under load, but I couldn't repeat it. I pulled one ring off and there were no markings on it at all.  I pulled a new set of oem honda rings from my stash and the very faint marks were tough to find, but there.

Going for a ride now to the machine shop to see if there are any results yet.  Sure, I could call them, but then there is no need to go for a ride!

Not going to argue about it, however I will say what I believe to be true.
The compression rings are not perfectly square when not under load. They are very slightly curved upwards and straighten out under combustion pressure. This means that on the way back up only the bottom of the outside ring surface touches the bore carrying a little oil up with it (trapped above where the surface contacts the bore).
-So I think the wear is always on the bottom side of the ring! (I have observed this on new rings installed with markings to the top)
John

[maxheadflow]

The Oil control rings are on in the right direction but having them in the wrong position ain't helping anything. Cylinder surface finish looks like crap. Bore job will fix it. 

[PeWe]

Cruzinimage has cheap piston kits.
My CB750 have it, +0.5mm.
Their 836 kit very popular with own thread here.
So I guess the kits for CB550 will work too.
+0.5 mm, + 1.0 mm available too.
They have spare rings too which can be good idea for sure if one of the rings will fail during assembly.

Tight bore clearance.
https://www.cruzinimage.net/2017/08/17/74-78-honda-cb550k-0-5mm-oversize-pistons-set/

[dave500]

ive been thrashing a david silvers 550 oversize set for years,you must find a place that does the job properly,each bore is done for each piston exclusively.

[kerryb]

So far we have an expert machine shop that will bore to correct size for each piston. Now we have to choose pistons (59mm) and which rings to use.  Are the cruzinimage rings gererally reliable or are oem honda rings preferred?  I was pleased to see you can buy an extra ring set from "crusin" to allow for minor catastrophes.

[RAFster122s]

Cruzin has a weird rep for having blocked customers from buying replacement rings when they report they broke a ring on install... no explanation...just silence and blocked. Weird behavior indeed. The shipping time also stopping the project until new rings arrive being another reason to have spare sets...

[HondaMan]

So far we have an expert machine shop that will bore to correct size for each piston. Now we have to choose pistons (59mm) and which rings to use.  Are the cruzinimage rings gererally reliable or are oem honda rings preferred?  I was pleased to see you can buy an extra ring set from "crusin" to allow for minor catastrophes.

I strongly recommend using 0.0004"-0.0008" piston clearance, NO MORE, on these engines. I used 0.0006" on my own 750, stellar results. I build the smaller ones tighter, as did Honda. I go even tighter on the little ones (350F/400F), never more than 0.0006" on those.

The very best (non-Honda) rings I can recommend in this engine are the ones from RIK. They come in both 1-piece and 3-piece oil ring designs, your choice.

There are some decent non-marked (omnidirectional) rings in the 750, haven't seen those yet for the 500/550, though. They had chrome top rings and cast 2nd rings, and 3-piece oil rings in those kits. They were simple 'square' rings, no features on the 2nd ring to indicate a direction, either.

[PeWe]

If order from Cruzinimage, forget eBay, use their website.
They usually refund on shipping, especially when irdet several items.

[TheHulk]

The very best (non-Honda) rings I can recommend in this engine are the ones from RIK. They come in both 1-piece and 3-piece oil ring designs, your choice.

Hey HondaMan, I'm the dude KerryB is helping with the rebuild. I haven't had any luck sourcing any RIK rings on ebay so far. Any other ideas where I should be looking?

I did find a couple decent options on Cruzinimage, I'll link them below with some thoughts/questions.

1. Cruzinimage 600cc "big bore" kit. This item is labeled as a 550f/550k kit. Part of me is thinking since I'm going to have to bore the cylinders anyway, might as well add a little more room for displacement? I'm curious what your thoughts are on big boring in general. Will this cause any issues or concerns? https://www.cruzinimage.net/2017/08/25/honda-cb550k-cb550f-600cc-bigbore-pistons-kit-61-50mm/

2. Cruzinimage 500k/500f "big bore kit". This kit is labeled for the cb500. Correct me if I'm wrong, but the 500 engine is the same as the 550, just with smaller cylinders correct? This kit equates to the 550's +.5mm overbore, matching the 59.mm piston diameter I would need anyway. Would this work just as well? https://www.cruzinimage.net/2017/08/17/honda-cb500k-cb500f-553cc-bigbore-pistons-kit-59mm-w-head-gasket/

Each of these comes with a new head gasket as well. I'm assuming because the pistons will be larger, a larger gasket will be needed correct?

Thanks!

[RAFster122s]

CruzinImage Big Bore I believe is a 61.5mm bore size. It is ss large as you can safely bore a 550 and leaves you with some pretty thin liners.
Overboring a 550 that large is fine but expect many machine shops to charge quite a bit for such an overbore. I know one guy who paid a shop $400 to overbore to that size.
Going to +2 overbore from stock gives you room for future motor rebuilds. An overbore to big bore size rarely gives you any kind of noticeable boost in power UNLESS you also boost compression. The CruzinImage kits are not high compression solutions. Dynoman kits are...

[TheHulk]

Going to +2 overbore from stock gives you room for future motor rebuilds. An overbore to big bore size rarely gives you any kind of noticeable boost in power UNLESS you also boost compression. The CruzinImage kits are not high compression solutions. Dynoman kits are...

Got it. So, even though I would be increasing displacement it might not create a noticeable increase in power?

[dave500]

itll be refreshed,dont baby the break in just ride it properly once warm but avoid heavy downshifts.

any oversize with the same flat top pistons results in slightly more compression,higher compression pistons are used to compensate for wild cams with long overlap that waste compression so to speak,using high compression pistons only without a hotter cam limits your power due to detonation as youll need to watch ignition timing,hot cams need a higher degree of initial advance.

[kerryb]

itll be refreshed,dont baby the break in just ride it properly once warm but avoid heavy downshifts.

any oversize with the same flat top pistons results in slightly more compression,higher compression pistons are used to compensate for wild cams with long overlap that waste compression so to speak,using high compression pistons only without a hotter cam limits your power due to detonation as youll need to watch ignition timing,hot cams need a higher degree of initial advance.

This stuff is all so fascinating, complex, and interconnected....and to think they learned by experimentation and testing on Sunday at the dragstrip, (or on sat night on the street!)   I'm hooked!