I've got problems (piston ring source?)
 

Short version: I need a set of piston rings for a stock 1989 CBR600F motor.

Long version: I'm a Harley mechanic so I have quite a bit of experience. Don't work on Hondas, other than this one, which belongs to me.

Installing a new head gasket. I have the ring compressors so I carefully install the cylinder over pistons number 2 and 3. Slide the cylinder down a bit, rotate the motor to raise pistons 1 and 4 and clamp the rings down. Slide the cylinder on and I can't get the right side compressor clamp off. The frame is in the way. (Book shows the engine out of frame, by the way). Slide the cylinder back off pistons 1 and 4, move the clamp around so that it is sticking out to the right rear instead of right front on piston 4, slide cylinder back onto the two pistons and remove the clamps.

Here is where the problem starts. The number 4 piston cocks. I wiggle the whole assembly around a bit to try to uncock it, move the whole thing up and down a bit by rotating the motor, but it won't uncock so I slide the cylinder up and off pistons 1 and 4. The second oil ring is bent, probably because it popped out as I was sliding the cylinder down. Just a little bend, right at the end of the ring, but enough that it won't move freely in the groove.

Frustrating, but not a big deal EXCEPT that there appear to be no replacement piston rings available for a stock sized motor from any source. I can buy .025 and .050 overbore rings, I can buy sets of pistons to overbore the motor, but I can't buy a replacement ring (or set). I really don't want to overbore the motor and spend the money on new pistons since there is only 13k kilometers on this bike. The only reason I was replacing the base gasket is because I pulled the head to check the valves and it broke the base gasket seal.

Anyone know of a source for a set of stock rings, or a set that is not designed specifically for that motor but will work? All I really need is a single second oil ring (middle groove) but I'm happy to buy a full set if anyone knows of one.

Thanks.

If Honda can't order you a set, contact the aftermarket ring manufacturers directly with the dimensions you need. They may be able to point you to a set that fits.

I sent you a PM before I read your post because you messaged me.


I outlined the issues with trying to replace stock sized rings.


I've done more research and found that what I told you wasn't correct. It came from my recollection but may be newer engine than F1.


Stock rings will be difficult to find because when an engine needs rings they are usually oversized and matched to new pistons because the engine is worn. I did a little more research and you can overbore the engine it has steel sleeves. There is a coating but not critical to rebuild. Honda service manual shows specs for over boring so it is possible.


There are a lot of issues with trying to put stock rings in without rebuilding. You need to ream the ridges because if left in the top of the cylinder they can crack the new rings.


Really not sure about other issues with stock rings in a used engine. I've never done it. Wear patterns, possible out of round bores, all kinds of things come to mind that could rear their heads after you get it together. I would measure everything carefully. Normally an engine is bored and new pistons and rings fitted. I'm doing a Triumph engine as we speak. It was serviceable but made no sense to me to not bore it and put new parts in.

Thanks for the advice. I don't know if I agree on the "don't replace stock sized rings" although I am a Harley mechanic and there may be differences. Given the low mileage of this bike and the fact that there was no failure in the engine (just on the part of the mechanic, me) I doubt that there is significant wear or ridging in the cylinders.

Either way, all I really want to do is get a bike back on the road that has sentimental value (I had a new one in 1989 and this one was my sister in laws that she gave to me). I already have nearly a thousand bucks into it with new chain and sprockets, tires, carb work, fork seals, engine gaskets, etc and since it isn't worth much more than $1500 putting much more than this into it is seeming like less and less of a good deal. Especially $4/500 for an overbore including new pistons and rings.

I'll have to do a little more digging and see if I can match a ring through one of the manufacturers. I guess I'll also keep my eyes open on ebay.

Thanks.

I totally understand the financial issues. These are not money making bikes. Sometimes they feel like a money pit.


The advice I gave you applies to Harley engines as well as any engine. 13K may be low mileage, but how many times have the pistons gone up and down in those miles. Wear patterns can result in problems with new rings. A ridge even if it's microscopic can break new rings. Cheap repairs usually end up costing a lot more in the end. Personally I can't put a motor back together if there is any question there might be a problem. Remember, a Harley spends most of it's life running at low RPM compared to a CBR. You might get away with wear in a Harley, but a high reving sport bike engine will spit the parts out.


I would at the very least do some proper bore measurements with a bore gauge. It's your choice but I would be concerned putting the motor together without measurements and cleaning the ridge if necessary.


You might consider my other suggestion and look for a short block on Ebay. Might not cost much more than new rings.

These people list std Honda CBR600 piston rings: Bunbury City Motorcycles - Honda RING SET PISTON ( (13011-MN4-305).
I've not had much to do with them, but the little I have had indicates good customer service. Hope this helps.

Thanks, Gearloose. I went to the link and realized they are in Australia. That made me wonder if maybe Honda Canada could also get the rings. Gave Carter Honda in Vancouver a ring (about half an hour away from me) and sure enough, they will be in on Tuesday.

I remain unimpressed with Honda Motorcycle USA as a company. They refused to give me an EPA compliance letter for an older Honda I wanted to buy (exactly the same as the one sold here in the US), and now I discover that they don't sell parts that everyone else in the world still sells.

Anyway, I have new rings coming, I will probably run a light ball hone through the cylinders and re-ring all four while I am there, then back to reassembly with only a couple weeks of stress before "problem solved time".

Thanks again for all the help.

That's fantastic news. Yes, parts availability seems to vary around the planet. D'you mind saying how much the rings were from Carter Honda? (and whether per piston or full set?) excluding shipping? Thanks!