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Valve check?


Long time since I posted here, dealing with my father’s 14 viper, it has just shy of 20,000 km’s. This sled never started right from day one in my opinion but you get to learn the tricks. Anyways, last year on his last trip he started having cold starting issues that were way worse than before. Won’t stay running without throttle when cold and when coming to a stop it was stalling. A few people I have talked to have said to check the valves, a few dealers have said to check the valves, Yamaha Canada said to check the valves. Background, I’m an automotive service technician. I pulled the valve cover tonight to check clearances, with the minimum exhaust spec. Being 0.083” I can put a 0.008” feeler gauge on all 12 buckets and they fit, with resistance as they should, but they fit. I can spin the buckets on the valve so they are not tight. Any ideas?? Seems like an idle air control problem to me, I don’t feel like dropping $1400 plus tax on a complete throttle body (can’t buy IAC separate) on an educated guess.
 
DVW said:
View attachment 142490
I can now share the details on how Lighthouse Motor Sports made sure the tensioner did not move when removing the cams. I first had to ask them permission out of respect for them. They opposed the tensioner spring by wiring up the cam sprocket (see photo). In the middle of the two strand wire loop was a long bolt that they used to twist the wire. The twisted wire acted as a turnbuckle. This retaining method allowed them to remove the cam without moving the tensioner or the sprocket. All this is detail compared to the idea of making sure the tensioner did not move when removing cams. That idea came from a member of this forum after being spurred on by me saying it was possible. This all happened last night but then again I said it was possible seven months ago.
Click to expand...

Small question, got my valves measured and Cam Tensioner out. Manual says to compress tensioner and then put clip over pin to hold it compressed. Do I install it that way? What make the clip release from pin?
 
I did my nytro before winter. 24k mi and all ex were 1/2 clearance. intakes were fine. I did cheat by rigging the sprocket and not touching tenssioner. sucked leaving apart for a week waiting on shims. dealer "never heard of it" and thought I was an idiot for doing valve maintenance. 6 shims were like $150
 
Barry said:
Small question, got my valves measured and Cam Tensioner out. Manual says to compress tensioner and then put clip over pin to hold it compressed. Do I install it that way? What make the clip release from pin?
Click to expand...
Not sure what year your Viper is but the Viper I did was a 2016 and when the engine starts the oil pump pressurizes the tensioner and if there is any pressure or movement from the camshaft guide this will help to release the tensioner thereby freeing up the clip. I rolled mine over 2-3 times with the kill switch off to build oil pressure and hopefully release the clip which seemed to go according to plan. Ran 3000km this year with no problems.
 
Well I just put final bolt in after Spring project of a valve adjustment. All the intakes were fine, and all exhaust valves needed attention. Two of which I couldn't even measure, smallest feeler gauge was .002". So I ordered all exhaust shims from Yamaha ($9 each) I guess -.010" for the tight valves and I guessed correctly. I bought a few extra shims that were -.012" from what was in there. Well cranked sled over with switch off to get oil pressure to tensioner. Then hit kill switch and started like a charm. No leaks or missing bolts. Still not sure if this will fix my cold start issue, since its 60 degrees here. O 'well i'll wait until October. At least I can eliminate that valves need adjusting. All valves are perfect now. Big thanks to cannondale27 for advice. No special tools needed except Service Manual. Not sure time it took, worked on it few hours here and there after dinner. Anyone need advise on doing this job, hit me up. (did it with motor in sled)
 
Barry said:
Well I just put final bolt in after Spring project of a valve adjustment. All the intakes were fine, and all exhaust valves needed attention. Two of which I couldn't even measure, smallest feeler gauge was .002". So I ordered all exhaust shims from Yamaha ($9 each) I guess -.010" for the tight valves and I guessed correctly. I bought a few extra shims that were -.012" from what was in there. Well cranked sled over with switch off to get oil pressure to tensioner. Then hit kill switch and started like a charm. No leaks or missing bolts. Still not sure if this will fix my cold start issue, since its 60 degrees here. O 'well i'll wait until October. At least I can eliminate that valves need adjusting. All valves are perfect now. Big thanks to cannondale27 for advice. No special tools needed except Service Manual. Not sure time it took, worked on it few hours here and there after dinner. Anyone need advise on doing this job, hit me up. (did it with motor in sled)
Click to expand...
Nice Job! Is intimidating time consuming job but well worth piece of mind. Now lets hope our valves stay where WE adjusted them on our sleds!
 
pretty obvious that the vipers burn/wear valves twice as much as the nytro, must be the front exhaust
 
rbell14 said:
What mileage are you guys starting to adjust the valves at?
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Started showing symptoms at 6500 miles. Hard cold start, shot gun blast through exhaust while attempting, very low idle to point of stalling, not idling at all without throttle until warmed up, stalling at stop signs, etc.
My friends was at 11,000 and again at 19,000. He tolerated the symptoms much longer than I.
 
FrozenTows4 said:
Started showing symptoms at 6500 miles. Hard cold start, shot gun blast through exhaust while attempting, very low idle to point of stalling, not idling at all without throttle until warmed up, stalling at stop signs, etc.
My friends was at 11,000 and again at 19,000. He tolerated the symptoms much longer than I.
Click to expand...
so shimming cured it? I never had a viper, but read about them forever. remember yellowknife ? I wondered about burned valves since then. My nytro was at 25000 miles and had for a few years needed a touch of throttle to start when warm. The exhaust were 1/2 clearance and the intakes were perfect. I would have to believe that mine still leak even with new shims, because it starts the same. runs perfect otherwise and always has. the vipers I read about were tight by 10kmi, I am sure shimming helps prolong, but a burned valve is a burned valve. most running engines have leaking valves, nature of the beast.
 
I know for a fact there are some with tight valves the minute they are started. What makes me suspect mine being out of tolerance from factory is that the one and only exhaust valve that was in spec also had the smallest shim in it right from factory. No doubt running it as long as I did with tighter than spec valves may have burned them but it's almost 5000 mi since I adjusted them and stills runs same. So hoping to make 20000mi before checking again.
 
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