Hi all,
I'm looking into doing a top end rebuild on my '87 cane. The bike ran fine all last year, but I can tell it's a little tired. It has an unknown amount of miles on it, smokes a little on startup, the cam chain rattles around and it has low compression. I've rebuilt a number of 2 strokes, but never a 4 stroke so valves are all new to me.

Cylinders 1, 3, and 4 have around 100psi, cylinder #2 has 80psi. I dumped some oil in the cyliders and 1, 3, and 4 jumped up to 120psi, #2 stayed at 80. Obviously I need new rings, but what about the 2nd cylinder? Burnt valve? Broken/weak springs? Lifter issues? Valves out of adjustment? Cracked head? What would be the most likely culprit with this bike?

Anyone here rebuild an F1? Any info you can give me would be appreciated, Thanks.

 

my first step would be to check the valve clearences, most likely they could be too tight. i dynoed mine and it was low on power, leak down was good but compression was alittle low. my valve cleareances were way off. set intake side to .18 and exhaust to .22 if they arent in spec.

 

Thanks for the reply f1cbr,
I talked to the local Honda dealer and they said the same thing, that may just need a valve adjustment. I'll give that a shot some time this week.

A valve adjustment probably won't help cylinders 1, 3, and 5 correct? It's my understanding that if oil in the cylinders brings up compression then the issue is worn rings. Is 100psi low enough to be concerned about?

 

yea its possible..but i would do a leak down test too. if you hear air escaping from the crankcase/oil filler cap, your rings may be the issue. but i would try the valve adjustment first

 

Can a leakdown test be performed on a cold motor? I have the motor out of the frame so there's no way for me to actually start it. I'll adjust the valves as soon as I get myself a decent set of feeler gauges. Thanks again for your help.

 

yea you can do a leak down test on a cold engine, just make sure your on tdcc. set cyl #1 on tdc then do 2..4..then cyl 3. tdc comes in that order so for me it makes it easier.
hopefully the leakdown test is roughly 5%. but do the valve adjustment first

 

My 89 is also burning oil number 2 cylinder has 45 thousand miles 3rd owner. Engine is still solid, except for the cylinder head has a rattle at certain rpms. I was going to rebuild it but part wise was scarce hard to find or discontinued. I just ride mine till it stops running. I was thinking getting a used motor for parts on Ebay, right now tight budget. I just add oil when needed. Keep us posted CSXfan let us know the outcome. For parts i checked Bike Bandit.

 

it would be cool to plan a nice rebuild on your engine once its on its last leg.. weisco pistons/rings, web cams, replace the valve guides, headgasket, clutch.....keep running for another 50k+ miles

 

That sounds like something I would like to do in the future. I have 23k on my bike but I like it when an engine purs when it runs

 

It'd be nice to do a full rebuild, but for me it's not really reasonable. I stopped at the dealer and was quoted $360 for a gasket kit and a full set of rings...No thanks. That is, IF they can even get me the rings, they came up as discontinued and unavailable.

I did a valve adjustment last night, some of them were WAY out of whack. Should've done it a long time ago, it was a lot easier than I was expecting. I still have to do a compression test to see if it helped. I should be able to do that tonight.