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Rattle following shim change -- #2 not firing

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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Ladies and Gentlemen:

I've been working on the bike for the last 6 hours. Tonight was supposed to be the night it all came together.

I have a GS850GL. I took her for a test drive two weeks ago. Before I put the fairing on I decided to check some things I had forgot to do. I checked that the timing chain was set as it should be with respect to TDC per the book. Some adjustment was needed -- I had more than 20 chain pins between the #2 mark and the #3 mark ... and the EX sprocket was not lined up as it should have been. I set everthing to the book specs. (Prior to this, the bike sounded pretty good considering the exhaust is rotted).

Several shims were out of spec. I was unable to find a .03mm feeler gauge and set everything to between .038 and .08 mm.

I expected the bike to purr when I cranked her up. She purred a little bit, but she mostly rattled.

I checked the forum for possible causes. I checked the cam chain tensioner -- it seems to be working. I pulled it out and reinstalled it anyway.

I let the bike run long enough for the header pipes to get warm, not hot. #1, 3 and 4 warm up like I expect. #2 does not. It could be that I didn't let the bike run long enough, but in light of the noise I thought it would be unwise.

I have not done a compression test yet. I'm going to bed, I'll do it tomorrow.

My questions -- finally:

Could I have bent a valve when I was setting the timing. I may have cranked past the timing mark and then cranked the engine backwards to come back to it. I read, after I'd done that, that cranking backwards was not good. I can't believe I woud've cranked the engine too much -- but I really can't recall. I'm certain I never had to put too much pressure on the ratchet to get anything to move -- wouldn't it take an above normal amount of pressure to bend something while hand cranking.

What else could it be? I rechecked the timing by the marks tonight. I've rechecked the shims over and over. I've looked at the cam chain tensioner. I've checked the nut that is part of the bolt assembly that I use to hand crank the engine (I hand crank using the larger bolt.)

The bike rattles with the clutch in. I did not let it out while it was running so I don't know if it rattles then ... I suspect it will. The rattling increases as the engine revs. It was idling at 1000 rpm while this was going on. I was unable to determine if the noise was coming from the chain or #2 cylinder.



As always, thank you.
 
try using a "long screwdriver " put the handle to your ear and see if you can locate the rattle..
 
i would take the valve cover off again and check what you have done a shim might not be in properly or incorrectly measured ..it is near impossable to bend a valve etc when winding by hand,yes use the large nut not the smaller one.. most people bend valves not winding by hand to check they hit the starter button wham bam dollars down the drain good luck ozman
 
yes its very hard to bend a valve with hand tools and the engine would lock up , to tell you something was wrong!, recheck all the valve adjustments as suggested .
 
Thanks for the replies guys.

It is good to hear that trashing a motor would be hard work cranking by hand.

I've had the cam cover off three times. I, too, thought that maybe I'd left a shim unseated. I've checked clearances each time. I checked the last time just to make sure everything was seated well.

I believe I read that a valve that is adjusted too tight or too loose will cause problems. And, when I was buying my shims, and wondering which size to buy, the Suzuki guy asked me if I wanted to "hear or smell" them (the "them" I believe is my valves). If, in fact, I have something out of whack enough to just be 'hearing' them what is that?

Is there too much gap between the lobe and shim? Too little gap between the lobe and shim. As I said, everything is within spec between .038 and .08mm. Am I better off to be nearer the lower or higher value.

Again, it was working, though shims/lobes were not within spec and the cam chain was not set properly. I took it apart and found almost all the cam/shim gaps were too small (less than .038 mm). I pulled the tensioner out when I moved the cam sprockets back and forth. I reinstalled the tensioner (I've done this many times). I put it all together and it rattles. I have certainly caused this. (Confession is supposed to be good for the soul. Strangely, I don't feel any better.)
 
was your oil-fill open when you noticed this? the clutch basket makes a bunch of noise normally, if the filler is open, it sounds like ww3
 
daveo said:
was your oil-fill open when you noticed this? the clutch basket makes a bunch of noise normally, if the filler is open, it sounds like ww3
Click to expand...

That wouldn't stop it firing on No2 cylinder. A slightly bent valve wouldn't stop it firing either - it wouldn't run very well but it would run (eventually burning the valve & seat).
But if No 2 wasn't firing it would make a rattling noise, as well as other noises!
Have you replaced spark plug caps correctly? replaced fuel lines to the carb feeding No2 (or dislodged it whilst working?)
 
I can't get past the fact that the cam timing was "incorrect" and it ran good. Now the cam timing is correct and engine, no so good. I would back up and see what i did there. Did u do the compresion check on all cylinders. That may hint towards a cam timing error also if compression is low across the board.
 
nert has a point if it ran ok before go back to that setting . you never know with older bikes people change cams etc might be something altered that you don't know about ozman
 
Thanks everybody for the replies. I've gone from having the sick-to-my-stomach worries about how I trashed the engine to having a general sense of just "what the he** have I done wrong."

I'll recheck everything again tonight and see what I come up with.

Thanks again.
 
And the winner is ....

"Go back and check your work again."

When I set everything up to the timing mark I set it to the F and not the T for 1-4.

When I rechecked my work the previous times it would seem my several quick glances were not enough to find the mistake. It wasn't until I had the cams and everything else off that I found the it.

If you've noticed the glasses in my avitar, try to imagine them getting thicker ... much like my noggin.

The bike is now purring.

With any luck I'll have the fairing on tonight.

Thanks again everybody.
 
well done the moral to the story. look for simple problem first .don't imagine the worst case senario. happy riding 8) 8) 8) ozman
 
Yea, big difference between F and T marks!

When in doubt, go back and check the basics. I shattered a shim not doing this, but no harm seems to have been done. At the time I was rather emotional..but one I got myself together things were ok :)

Now I have some o rings gone in the carbs I think....time to just get logical again and fix it :)
 
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