Piston rings

[teck_mountain]

Hello

Questio for the day. I have my bike broken down to the Cylinder boars. I've had a bunch of work done on the cylider head and valves. very, very, carboned up. My bike was using oil. Didn't seem to be burning, or blowing blue. The valves were in bad shape but that problem in fixed. I have to remove the cylider boar to replace the lower gasket. (it leaking a bit)..

Should I change the rings?? I have no compression test prior to break down. What should I look for?

any tricks to keep in mind?

[Ken Talbot]

Now that you're down that far, especially witout a compression test, you might as well go ahead and do the rings.

Chances are the leak you thought you had at the base gasket was in fact oil dribbling down from much higher. I'll bet you were seeing a bit of oil on top of the crankcase on the rearside of the cylinders, right?

Your oil consumption was also probably mainly from the valve stem seals, but again, without a compression test, you won't have a good read on general ring condition and whether or not the oil rings might still be okay.

It would be pointless not to button it all up, do a compression test and find it below spec, and have top tear it all down again. I would say proceed with the ring job.

[TopCatGr58]

Ring Job.

Hey Ken,

Since he can't get standard oversized pistons anymore, unless he has the cylinders "miked", about the only ring job he can do is HONE them and then get a set of OEM sized rings, new!! I can't remember how many miles he had on this engine, but most engines tend to wear out in an out of round oval pattern, and if they are already out of spec, then a Honing won't be enough or do any good, don't you think!?

If he finds his cylinder 'bores' too far out of round/spec, then he'll need to invest in a big bore kit and get the cylinders bored out to fit the new pistons and rings won't he!?
T.C.

[teck_mountain]

Cylinder removal

Hi Ken

Thanks for the imput. I decided to keep going. However, I am having a #$@@ of a time getting the cylinder off. I've tapped, pulled and ready to find tnt. any suggestions

Tim

[ratbyk]

Cylinder removal

Looking at the front of the engine, in the crankcase area there are two large ears/tabs. The ones that the long front engine mounting bolt passes through. At their base where the cylinders mate to the crankcase are two pry points. Use a lever type pry bar or large screw driver to try and lift the cylinders off of the crankcase.
If it still will not move take a fairly sharp screw driver, using a small (1/2 lb) hammer and try and enter the screw driver into the gasket between the cylinder and the crankcase. Tap lightly to break the seal between the cylinder/crankcase. As soon as the seal is broken stop hammering and go back to the lever. Once the cylinders are removed examine the area that the screw driver entered and dress off any damage or marks that you may have inflicted with the screw driver.
Ken/Sooke
78E Ratbvyk
82 FT500 'lilRat"

[Ken Talbot]

Have you got the cylinders moving at all? Seems to me that when I did the top end on Tsunami a few years back, I got the cylinders loosened okay with a few good whacks with a rubber mallet. But then I still couldn't get them to come up more than a little bit. Turns out there was a lot of nasty gunk built up around a couple of the studs. The studs are narrower in the middle than towards the ends where the threads are. The cylinders would move up a bit, then the larger part of the studs jammed up against the gunk buildup and would go no farther. It took a bit of soaking with WD40 and some work with picks to get rid of the gunk before things would finally move.

Hmm, let me see now, did that happen while I was trying to lift the cylinders, or did it happen earlier whan I was still trying to get the head off...

[TonimusMaximus]

Even if the cylinders are out of round, you can still hone them a little with no problems. The way those pistons were designed, when they heat up to operational temp, they are ovals anyway, not circular. So as long as you don't hone much, nor try to clean up the actual surface of the piston (polishing and the like) you shouldn't have any problems once she warms up. Much like an old Buick I had. Burned oil until she warmed up, then ran like a champ.

[teck_mountain]

Cylinder removal

Thanks all

Was able to get the cylinder off with a combo of suggestions. What a mess. When I pulled the cylinder off there was a bunch of what looked like sand round all the posts. It's not sand but a very fine dust of some sort.

Further exam observed this stull has fallen in to the crank case. What should I do? continue to break the bike down until it all apart and clean it up good or is there any other tricks?

[xssiveone]

I don't think this was sand, but rather plastic. The studs were covered with a plastic tube of some sort that breaks down over time. Remove the drain plug, or better still the oil pan. Flush the crank case good with diesel fuel or kerosene and you should be OK.