Call all XR600R!!!

[EggspurtSpellar]

Originally Posted by mcma111

Eggspurt,

Just for kicks find TDC with that dowel and check through the hole on the stator cover and see if the timing mark is where it is supposed to be. Could be you have had the cam/ cam chain jump time.

Bingo! Although checking it with the dowel did no good as the timing mark travels with the piston. After removing the v-cover I found the cam gear way off. Cam lobes were well with in spec for a stock cam and all in good shape. Vales and guides all mic out fine so I think the PO at least had the good sense to back off the adjusters before it tore up the motor. How the thing ever ran is a mystery I won't worry about. The tensioner looks good and is tight. there is an oddball mark on the cam gear that was lined up so I think maybe the PO used that. I do know he was in the engine. anyhow thanks for the responds, hopefully I can get in a few good rides before the major tear down rebuild.

Dave

[EggspurtSpellar]

Originally Posted by Zombie_Stomp

Ah yes. I failed to realize this possibility too, but if it ran when you got it and it was that far out of spec to enable it to run, someone may have put the chain on wrong. If it slipped and jumped time, odds are high that a valve would have been bent in the process. Not ruling that out, but if you are on this parts order still, order a cam chain tensioner spring and do a compression test to check out the valves' condition.

It seems even though I thought the valve was not hitting the piston because it was on the down stroke the cam must have been "catching up" with it. I don't think the chain slipped it all fits nice and snug and the tensioner looks good. Thanks for your timely posts and insight, now to tackle the kick starter... .

Dave

[mcma111]

Eggspurt,

Is/was the bolt in the cam chain tensioner shaft? If not then the tensioner was not doing it's job.

[Tim in Belgium]

As I had a free afternoon I thought I'd make a start on the XR engine swap after it gave out on me just outside of Helmsley at the end of October.
One XR up on its newly purchased stand.



One replacement engine from a breaker, with guarantee fast running out, must get it in!



Remove side panels:





Remove tank and seat:



Undo front sprocket stuff, and various control cables:



The complicated wiring 4 of the 5 connections that had to be undone:



Carb removed and strapped to frame:



Exhaust removed too:



Drain the metal flake effect oil, not good:





Remove all engine mounts:



Then lift out engine:





Next jobs are to flush out the frame/headstock oil tank, clean the screen filter, clean the replacement engine, touch up a few bits of the frame with paint, mount the new motor, get a front sprocket that matches the splines on the output shaft, connect 5 wires, oil lines and control cables, change oil and filter on new motor, fit bodywork, start the beast up.

One thing is that the output shaft on the replacement engine has fewer splines on it than the dead one , any idea what year front sprocket I therefore need to get?

[endocrantz]

I once had a finger on a shift fork pop off, hit the oil pipe in there which put some restriction on oil delivery, almost a crimp. Still shifted but would have done some damage sooner or later to the top end, luck to get 50% flow through it looking at the pipe - and it is small already.

Originally Posted by mrfixit54016

Yep. That chunk lead to a tooth shearing off the crankshaft gear and counterbalancer gear. Oh, and a little trouble shifting as well.

[MortimerSickle]

Originally Posted by Tim in Belgium

g
One thing is that the output shaft on the replacement engine has fewer splines on it than the dead one , any idea what year front sprocket I therefore need to get?

My 1988 has this spline. It is the same as my 1979 XL500, and probably every model between. I don't know what year they went to the finer spline.

Also, if you don't want your shaft to end up looking like the pic below, you might want to use only OEM front sprockets.

[veetwo _tls]

while its stripped to a rolling chase grab some CT-18 truck wash & kerosene mix 30% ct-18 to 70% kero in a pump spray (garden weed sprayer) from the local hardware store. give the rolling chase a good spray down let soak for 10min then pressure wash. it'll look new again & money permitting get the frame powder coated while its stripped another option too.

happy building

[mcma111]

Fewer splines = an older model engine. Sorry. I don't know what years.

[HeadTrauma]

I think the change from a six-spline countershaft to a 13-spline happened about the time XR600s were given a rear disc brake, so roughly 1991.

[Dino3310]

Originally Posted by MortimerSickle

Also, if you don't want your shaft to end up looking like the pic below, you might want to use only OEM front sprockets.

still quite a few thousand miles left on there matey

people throw on a hardend sprockets so the sprocket lasts longer, without thinking of the concequences of doing so

[MortimerSickle]

Originally Posted by Dino3310

still quite a few thousand miles left on there matey

people throw on a hardend sprockets so the sprocket lasts longer, without thinking of the concequences of doing so

Sprocket hardness may have been the problem, I don't know. But, the sprocket I put on was not supposed to be harder than standard.

[Blakebird]

The discussion I remember was that people using the hardened JT sprockets were having problems with the splines being buggered.
Not a huge sample size, but enough to cause alarm....I had two JT's in rotation (a 13t and a 14t), and promptly removed them and went with oem for the stock size, and I believe an AFAM or Sprocket Specialist for the 13t.

There was no sign of any damage to the splines, but I'd just put a new 628 in and didn't want to damage the countershaft on a motor I'd just spent money on. The JT's were on there a while with the first motor and no wear.
It's quite possible they would have worked fine....internet hysteria and all

[MortimerSickle]

Originally Posted by Blakebird

The discussion I remember was that people using the hardened JT sprockets were having problems with the splines being buggered.

Funny you should mention that; JT was the brand of my sprocket. I emailed them, and at first they sounded concerned; they had me send them the sprocket for testing. But, once tested all they said was that it tested within their tolerance, and pretty much told me: "Too bad, so sad."

At no point, from purchase at the dealer, through the test results did anyone mention anything about the sprocket being harder than OEM. I hadn't suspected it might have been, because I had been using aftermarket sprockets on my 1979 XL500 since the first replacement, and had never had any problems.

[screwit]

Has anyone put a Keihin 39 FCR on a XR600? If so how hard and was it worth the trouble? As always, any help is appreciated.

[Tim in Belgium]

Thanks for the front sprocket info all.