The Curse of Odot

[Fred W]

Franks is out. Rough guestimate is he still had 3/4 of his travel to go (changing oil real often may have unseen benefits). An Idea Follows.

In the XS650 Yammi, of which I had several, and built several motors for, a screw assembly tensioned a strong spring which acted against the plunger that pressed the chain guide for chain tension. The chain was correctly tensioned when you could see the right end of that plunger, which was exposed when a cap was removed, just barely moving in and out of the housing. In other words, some slack/no slack was the best. The spring would allow for this, while keeping it to a minimum. I notice that the FJR's allows no movement other than forward and against the guide, constantly tightening, but never slacking. Not sure about all this, but I'm thinking that rather than a solid tension against the guide, a stiff compression spring acting against it would be better, and allow for the tight/loose action that naturally occurs with a chain. Note, however, a XS650 cam is single, and acting on 2 cylinders, while the FJR's is a double, and working 4 cylinders worth of valves.

I'm gonna work on an idea, since 4" of snow has Frank sittin on his dead ass anyways.

The problem with doing this on a timing chain tensioner is that the spring is free to compress and allow the chain to develop slack at high rpms. To prevent that you would either have to have a very stout spring, which would probably put too much tension on the chain causing the guides to wear prematurely, or use a relatively weak compression spring with a ratcheting mechanism to prevent retraction. This is a proven technique in autos and other bikes.

I think the trick to finding a better automatic tensioner will be to try and find one from some other application that can be adapted to fit in the FJR. Or just go straight manual adjuster and make adjustments at every other oil change? If it was easy enough to do, it would be no big deal.

 

[radman]

The FJR's tensioner can be manual, just go in and turn it. The spring is an advancing mechanism, not a tensioner per se. And the assembly shown in my earlier post is a tensioner-one which worked on thousands of XS650's for years, still does, and will until the last one rusts to dust. It did allow slacking, but only a miniscule amount. A cam chain is like any other-it has tight spots and slack spots. Adjusting the XS650's chain involved watching the tip of the plunger protruding from the assembly on the back of the motor-tighten until the tip just barely moves in and out of the assembly as the engine idles. And some slacking isn't a bad thing-like I said, too tight and you eat the guides, a problem on high perf, high revving hydraulic tensioners. Of course, the XS650's tensioner didn't have to deal with as long a run as the FJR's does.

 

[Toecutter]

I would suggest that a replacement every 50k schedule become S.O.P for any owner who abhors noisy, expensive surprises.

But isn't the sloppy 50K chain gonna put the new CCT in the same position, almost used up? Shouldn't we be talking CCT AND chain replacement interval?

 

[radman]

But isn't the sloppy 50K chain gonna put the new CCT in the same position, almost used up? Shouldn't we be talking CCT AND chain replacement interval?

If the chain is indeed worn, yes. I have no indication Franks is-he's using, at 56K, less than half the travel available, which leaves a lot. Don't know though what the new combo uses for turns out. Ultimately, replacing both would be the safest procedure. But without any real indication that there is a big problem, Franks getting a tensioner now, a chain next winter.

 

[ionbeam]

But isn't the sloppy 50K chain gonna put the new CCT in the same position, almost used up? Shouldn't we be talking CCT AND chain replacement interval?

If the chain is indeed worn, yes. I have no indication Franks is-he's using, at 56K, less than half the travel available, which leaves a lot. Don't know though what the new combo uses for turns out. Ultimately, replacing both would be the safest procedure. But without any real indication that there is a big problem, Franks getting a tensioner now, a chain next winter.

From a post earlier in this thread, the empirical service length of the CCT

 

[7xray]

Radiohowie, radman, and others. Thank you for the great discussion and all the information. As a newbie to this whole motorcycle gig, I appreciate all the teaching points you guys give. I'm not a wrench by any means but I did change my oil before putting it (I don't have a name for him, her, ...) for the winter, and I did once stay in a Holiday Inn Express.

You guys are great :fan_1:

 

[RadioHowie]

"In for a penny, in for a pound" as the old saying goes.

I'm going to yank the head off this week for inspection. Apparently it IS possble to remove the head with the motor in the frame and from reading around the forum, it's about a 2 hour job.

HERE

BTW, I fully expect my valves to look just like KeithB's.

It's my time, so it's free. Gonna need a new catch basin for coolant....the wife took her big mixing bowl back.

Assuming there's no horrible piston damage, I may attempt a valve replacement myself. Only tool I'd need to acquire is a valve spring compresser.

But that's only speculation until I know more.

 

[Allnight]

Man, I really hope this works out for you. As someone who knows what a lot of the parts are, but not so much what they're for, this thread has been kinda scary.

Have to keep in mind some of your summary when you thought it was totally dead: you and Ionbeam have the only two catastrophic failures that have been reported here. Out of the rather large number of fjrs accounted for here, my odds are pretty good.

But, I really wanna know what that chain rattle sounds like...anybody got a video of it on youtube, best would be before cct replace and then after as well, to see the comparison and difference.

I don't push my bike very hard, it's a commuter vehicle, but I'm hoping that can change after the kids get out of the house and life can restart.

 

[radman]

Tick is left, CCT is right. Noise on both sides of motor-go out and pound the shit out of it till it kablooies, ain't gonna matter anymore.

 

[Unicycle52]

I wouldn't pull the head until you have confirmed with a leakdown test that you have bent valves. I agree with Tim05FJR on this one. I'm don't believe that spinning the motor without the cams in is confirming anything!!

Unicycle52

Good luck

 

[Unicycle52]

"In for a penny, in for a pound" as the old saying goes.
I'm going to yank the head off this week for inspection. Apparently it IS possble to remove the head with the motor in the frame and from reading around the forum, it's about a 2 hour job.

HERE

BTW, I fully expect my valves to look just like KeithB's.

It's my time, so it's free. Gonna need a new catch basin for coolant....the wife took her big mixing bowl back.

Assuming there's no horrible piston damage, I may attempt a valve replacement myself. Only tool I'd need to acquire is a valve spring compresser.

But that's only speculation until I know more.

 

[ionbeam]

I wouldn't pull the head until you have confirmed with a leakdown test that you have bent valves. I agree with Tim05FJR on this one. I'm don't believe that spinning the motor without the cams in is confirming anything!!
Unicycle52

Good luck

Radio H say:

Pulled the plugs so air can be drawn in and forced out with piston movement. Lightly place finger in plug hole to allow air in, but feel compression out.
Cylinder #1 is a dead hole. Cylinder #2 will jackhammer your finger in and out of the plug hole like a meat-piston. Cylinder #3 & #4 also dead holes.

NO vacuum or compression on 1, 3 & 4 using this method.

Plus, the intake lifters on 1, 3 & 4 are noticeably lower in their holes than on 2.

The only way this can happen is the bad way. The valve stems are bent and stuck in the valve guides. I know what hat looks like...

 

[Unicycle52]

Leak down test, leak down test!! Don't pull the head just yet. I'm with Tim05FJR on this one. I'm not convinced that your test of cranking the engine with no cams and getting a "free spin" confirms anything. A leakdown test is the only way to confirm the condition of your valves. If they are bent you'll know right away and "dig in" if not then you have saved yourself a boatload of time,money and aggravation.

Good luck.

Bill Hamilton

P.S. I tried to post this earlier and think I screwed up but if I didn't I apologize for any duplicate posts.

 

[RadioHowie]

Leak down test, leak down test!! Don't pull the head just yet. I'm with Tim05FJR on this one. I'm not convinced that your test of cranking the engine with no cams and getting a "free spin" confirms anything. A leakdown test is the only way to confirm the condition of your valves. If they are bent you'll know right away and "dig in" if not then you have saved yourself a boatload of time,money and aggravation. Good luck.

Bill Hamilton

P.S. I tried to post this earlier and think I screwed up but if I didn't I apologize for any duplicate posts.

Unfortunately, as Ionbeam points out between your last two posts, further details HERE.

You must have missed this post earlier. Lots of people nodding off reading this thread. Can't blame 'em.

 

[radman]

I had suggested any valve buckets that appeared to sit in the head differently than the others meant problems-don't need to leak test or compression test beyond that if it is indeed the case. It is, and he doesn't.

 

[charismaticmegafauna]

"In for a penny, in for a pound" as the old saying goes.I'm going to yank the head off this week for inspection. Apparently it IS possble to remove the head with the motor in the frame and from reading around the forum, it's about a 2 hour job.

Assuming there's no horrible piston damage, I may attempt a valve replacement myself. Only tool I'd need to acquire is a valve spring compresser.

But that's only speculation until I know more.

RH, keep an eye out for cracks in the exposed end of any valve-guide that has had a bent valve-stem. If a valve-guide/s needs replacement...? That's pretty-much a (good) machine-shop operation.

Also, sometimes?, the valve-seat (when a bent-valve event occurs) needs re-dressing. This also may necessitate valve stem length re-dressing (ginding the follower end of the stem) to compensate -- in order to keep you in the same relative area of shim sizes. Not absolutely necessary as long as a wide range of adjustment pads (shims) are available -- but, more-often-than-not, they tend to run (and be readily available at m/c shops) in a common range of sizes.

You certainly can have a good/sound cylinder-head again for your FJR -- but, it make take a little more than just replacing parts.....

Good luck

 

[nofreeride]

Personally I find it nearly incomprehensible that the life of the engine is left in the hands of ONE tiny little spring.

That's what she said.

Seriously, sorry to hear of your latest woes. This thread (and others previous) has been an emotional roller coaster. Please keep us up to date with the continuing saga (new bike, new engine, etc.).

I recently had everything apart and also checked the CCT. All seemed well, but the bike has 65K. Should I be worried?

 

[ionbeam]

...If a valve-guide/s needs replacement...? That's pretty-much a (good) machine-shop operation...

Some Yamaha shops like the one in Hudson, NH that did my repair have the machine shop equipment on site to be able to do valve guide repair, some valve grinding and valve seat work. In any case, it is a very good bet that RH is going to need to have at least a few valve guides replaced.

 

[charismaticmegafauna]

Personally I find it nearly incomprehensible that the life of the engine is left in the hands of ONE tiny little spring.

That's what she said.

Yea, kind'a reminds one of all that can enuse (in a relationship) from a simple "wardrobe malfunction"....

I recently had everything apart and also checked the CCT. All seemed well, but the bike has 65K. Should I be worried?

Well, you may be worried un-necessarily? All machinery (once put into service) runs on used-parts. Unless or until we know the definitive problem with that little spring -- we don't know the answer.

It would be good to know what MamaYama did when they up-dated/superceded the cam-chain-tensioner part #. :huh:

 

[radman]

It would be good to know what MamaYama did when they up-dated/superceded the cam-chain-tensioner part #. :huh:

I'll let ya know when mine comes. McCoy is sending it my way, I'll see if anything is different. Gary is keeping 2 in stock due to info coming from here-I told him this latest episode may give him a few more orders. Cost is $66 by the way.