88 XR600 Issues

Just bought a 88 XR600 and it had 2 bent intake valves...

timing chain was wore..So I tore motor apart,replaced the valves (lapped them)

put new valves seals,piston and rings seemed tight to me..(never took cylinder off,walls of cylinder looked real good..bike has drilled air box with super trapp exhaust,I know I need to rejet carb,I can pull choke up about half way and it runs fairly well...choke off it bogs...

but my main issure right now is that it smokes....yes oil smoke..

I was told to take valve caps off one at a time and pour oil in each one then crank bike,and see if (or) what valve is leaking around the seal..??

is there a better way...it may be the rings(not sure)I guess I should have checked them before I put the motor back together..

and advice would help///

Pull the exhaust off and carb and intake.........if you see oil on the valve guides that means seals/guides.......if not...you need to do a compression test......possible oil rings.

B

Oil smoke on startup that disappears when the engine warms up = leaky valve stem seals/guides. Oil smoke that gets worse as the engine warms up = worn piston/rings/bore.

I got the head off and the cylinder..the cylinder looks good..the rings had a huge gap in them,no way of checking the limits on the cylinder..

the piston looked very good.I put 2 new intake valves and all new seals and new T chain...never checked the cylinder..untill now..

I was hoping I could get away with just new rings ?

did the nikasil cylinders wear alot on these bigbores?

the valves and seals were done a week ago when I got the bike...

the chain had jumped...was the way I got the bike cheap....

If the Nikasil plating is not scratched up or peeling, a new piston & rings should fix you up. Don't go by " the piston looks good", measure it and check the ring grooves for damage/wear. Honing the Nikasil is a touchy thing, Google the procedure. Check your PM box.

If the cam chain was THAT worn the bottom sprocket will be trashed. If not replaced with the new chain it will wear the new chain shorty. And be noisy also if not replaced..

If the cam chain was THAT worn the bottom sprocket will be trashed. If not replaced with the new chain it will wear the new chain shorty. And be noisy also if not replaced..

Dead right..No way would I reuse that bottom Cam Chain sprocket. In actual fact any sort of jumping of that chain would lead me to not be satisfied unless I'd replaced both top and bottom cogs,,both tensioner guides, the chain and also the Tensioner mechanism and spring..Anything else and you can never be sure that one of those parts may not be faulty,,, It'll be expensive if it jumps again at any sort of pace..Do it once do it properly..

Is the bottom gear pressed on?I know on a xr200 it gave me a fit getting it off

No it's not pressed on. You'll need to remove just about all the Clutch cover side internal stuff to get it off. It's also kinda tricky to put back on as it only fits the splines if it's orientated in one way..it can however be put on backwards..Make sure you get it right..At the very least a new Cam chain and bottom sprocket are in order and possibly the tensioner mechanism itself..Chains don't just jump that Sprocket for no reason...You'll also be needing a rattle gun or a clutch holder or penny to lock the movement to get those clutch and other associated large nuts off..They are torqued to about 60ft/lbs so they take some moving and some sort of energy re-torqueing....

it was pretty wore out,,,the new chain was very quiet..the gears looked good but now I have it back off I will replace it,,,,

any ideas of a good set of new rings...

the ring gap was terrible...the nikasil looked great...still had hatch marks on the cylinder....I think I will replace the rings and be done...

its a 88 model..I just posted pictures of it the process of restoration...

have new tank decals ready to go on and new fork boots and I will be replacing the seat cover...even though its in good shape...

its a tractor for sure....

the 1/2 impact got it right off.....

so the lower gear goes on same as the outer 2 gears?they only go on 1 way...for the pickup.....

If you see cross hatch marks, the previous owner may have just honed the cylinder and threw a set of rings in. If the cylinder is out of spec, you can't just re-ring it. Take it to a machine shop and have the cylinder checked with a bore gauge, and then decide. Might as well take the piston and have it checked as well.

the 1/2 impact got it right off.....

so the lower gear goes on same as the outer 2 gears?they only go on 1 way...for the pickup.....

They all only fit on the shaft if orientated in the correct way..I'm fairly sure they can all be put on backwards with the orientation correct so you need direction and orientation right....Study what was there or study a picture in a manual to make sure you have things the correct way around...the final small Sprockets always the trickiest because there's virtually no shaft left when you go to put it on so it's not easy to tell if you have it slotted onto the shaft and correct....Check..double check,,triple check..

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