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Cam chain tensioner or something worse?


nicksta43

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Anything over 20% would have me concerned enough to pull the head. Going in I was hoping for under 10%. The only air that I could hear seemed to be leaking past the rings down into the crankcase. I couldn't hear anything coming out of the exhaust or through the throttle bodies.
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@skippert @nicksta43 
I'm not that knowledgable about leak down tests...but isn't 17% high? What is acceptable? Were you able to hear the air leaking from any specific area?
 
 

 
17% is getting into the “cause for concern” range....
 
However: being that this engine hasn’t run for awhile, I would do exactly what Nic is undertaking: Adjust the valve lash back into spec, double check the timing with a new tensioner installed, and try firing it up and see how the engine sounds.
 
Air escaping during a leakdown test is always usually identifiable:
 
-rings/cyl/piston via the crankcase breather, timing hole covers or oil filler cap
 
-Ex valves, muffler outlet.
 
-In valves, airbox/intake/throttle body.
 
I’ve had engines that haven’t run in awhile have a higher leakdown percentage due to rings not sealing well, and be just fine after running for a short period. Similar to a compression test, you can also add a bit of oil to the cyl, rotate it a few times to distribute the oil onto the cyl walls and rings, and repeat the test to see if the numbers improve. Some times I’ve seen higher leakdown in all combustion areas due to carbon build-up as well.
 
Ring-free and/or a decarbon spray are great at removing carbon build-up. I’ve seen low (50-70 lbs) compression readings on inline 4 sportbike engines go back up to 150-180lbs after a decarbone treatment followed by ring-free. Unfortunately I don’t have leakdown numbers for those engines to compare....
 
-skip
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I really don't have any will to fight Yamaha on this. It's pretty clear from the way the conversation went with the service manager that they are not willing to go to bat for me in any way whatsoever with the mother ship.  
They have the records of every oil change, coolant flush, brake fluid flush, plugs and everything else that I've purchased from them since I bought the bike. And yet the salesman/owner that I dealt with when I bought the bike had to come over and make a little quip about my lack of maintenance. I'm assuming because I didn't have them do it even though I bought everything from them. I actually tried to have them sync the throttle bodies while it was in for the handlebar recall. They had it for a week, again it's my only vehicle, and when they told me it was ready and I went to pick it up they had not done it. They said I could leave it with them and they would get to it when they could.
 
Anyway the moral of that story is I'm over them. I have no desire to fight with them or Yamaha.
 
If it's a paperweight, it's a paperweight.
 
It was a terrific bike until Monday.
You don't live in Vancouver WA, do you?  Sounds like the smurf they pull at Pro Caliber.  With the three TERRIBLE experiences I had at that place, I wouldn't let them work on a lawnmower, never mind an actual motorcycle.  BTW, this thread is just packed full of good info.  Sorry this smurf happened to you, but so glad you are sharing.
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  • 2 weeks later...

Sorry guys, been busy. Haven't made any more progress as of yet. We're in a big end of the year rush at work so free time during the week is not a lot and we've had a lot going on during the weekends. 

We shut down the week in between Christmas and New year's. I hope to get a CCT in and put it back together enough for a test start during that week. If it does start or at least turn over without any bad noises then I'll take it back apart to adjust the valve clearances. 

My thinking is I don't want to go through the process of adjusting the valves only to find I do actually have an issue that's going to require pulling the head. 

That's the plan anyway.

Edited by nicksta43
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  • 2 weeks later...

We've got a running motorcycle!

Quite as it ever was! 

Let it idle up to Temp gave it some revs and it has no strange noises, revs freely and idles fine. 

Sounds a little soft on startup but settled into a normal idle. 

Nervously optimistic at this point. 

Have video will upload this evening. Going to wash it put it all the way back together and test ride.

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3 minutes ago, piotrek said:

Sounded like it needed some fuel and maybe had to work up compression at first. Sounded alright otherwise. Make sure your CCT isn't too tight (~9 threads out), and that your air box is seated on the throttle body (no leaks). That whistling-like pitch could just be an audio/microphone thing (or an intake air leak). Sounds pretty good. Let it cool down fully and give it a go again. If compression is good, should fire easily.

What a good ear you have. 

Took it for a test ride around the block. Smelled fuel, looked down and saw it pouring out from under the tank. Pushed it home and an getting ready to pull the tank back off. Hoping I just didn't have the hose connected securely and that I didn't break anything. Didn't smell any fuel when it was running in the driveway.

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