None of us know since only sleds that for sure had tight valves were fixed by dealers and issue was fixed by replacing everything. We who suspect tight valves don't even know that they are yet. It could also just be a coincidence that a crappy tune which was updated this year has the same symptoms of tight valves. I am hoping it's just the tune.
I was thinking about this statement. Not saying you aren't right and am comparing a Dirtbike to a snowmobile. Buddy had CRF450 he could not start it in morning. Adjusted the valves started bike and ran 2hr race. Shut bike off and it then would not start again. Tight valves effect starting much more than anything else.
I don’t know man.....
Tight valves cause strange drivability issues for sure. I deal with the bucket shin design issues all day long with the Subaru wrx/sti/ Fb engines.
I’m trying to put together the pieces to this mystery like everybody else.
14 mapping started better but had kick back and had extended crank issues. Then we’re flashed with the lastest and greatest and are all f&ck &up.
15 mapping has rolling idle issues, inconsistent crisp startup’s, minor kick backs, flashed with the latest and greatest and all f&ck &up.( describing my 15).
-10 and up it would start without backfire so if my experience was just tight valves I would have starting issues north of 0 degrees.
I will say crappy fuel mapping being to rich or lean or inconsistent will deteriorate a valve train eventually.
What we need to know....
Vacuum readings from startup to operating temperature.
Cylinder leakage / hot/cold
Compression hot/cold
Valve clearance specs cold/hot.
Just a technician’s opinion.
Tight valves cause strange drivability issues for sure. I deal with the bucket shin design issues all day long with the Subaru wrx/sti/ Fb engines.
I’m trying to put together the pieces to this mystery like everybody else.
14 mapping started better but had kick back and had extended crank issues. Then we’re flashed with the lastest and greatest and are all f&ck &up.
15 mapping has rolling idle issues, inconsistent crisp startup’s, minor kick backs, flashed with the latest and greatest and all f&ck &up.( describing my 15).
-10 and up it would start without backfire so if my experience was just tight valves I would have starting issues north of 0 degrees.
I will say crappy fuel mapping being to rich or lean or inconsistent will deteriorate a valve train eventually.
What we need to know....
Vacuum readings from startup to operating temperature.
Cylinder leakage / hot/cold
Compression hot/cold
Valve clearance specs cold/hot.
Just a technician’s opinion.
Alsim
Expert
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- LTX SE 2018
I have EVO flash and after I ran it, I experience crappy idle when the engine is hot. If I don't put a little throttle in a cold start they would stall if. Sometime I had thinking maybe is because of my mbrp header but seems I have the same valves issue at 8,000 miles
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Yea. I will do a cold valve check and go from there. I know I can tune mine decent enough at least with the can on it. The stall thing really bothers me though. It’s almost like a ignition cut off. Idling normal then out like a light. Buddies same thing.
Maybe not valves. What tune did Evo base yours on? There was options. Heck I have even seen issue like that from too tight belt deflection. Have to check everything else before condemning the motor itself.
Always had a start up stall but once running it never just shut off. That’s interesting. Curious to know if you find that issue!!!
Did the nytro with Japan elections have any valve clearance issues causing havoc?
Did the nytro with Japan elections have any valve clearance issues causing havoc?
Alsim
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It's EVO flash 4. I just checked my belt deflection and it is ok. It's seems a little bit worse this year when I started it in a cold day. In the firts minutes I have to put a little throttle. I had never touch it before this year
Janne339
TY 4 Stroke Junkie
I know car guys works a lot with cams-/valve timing. Maybe we should check that on our sleds too? What happens if the camshafts chain is loose?
Some pics to Illustrate
Some pics to Illustrate
Janne339
TY 4 Stroke Junkie
DVW
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Similar running issues can have different causes. The first time I had warmup issues we checked out cam chain tension because it seemed likely to be the cause. We continued to try this and that with no luck. The factory sent out a new clutch shaft/coupling with the thought that it was effecting the sensing of the crankshaft position. I checked out the the operation of the idle speed control with the thought that it was not doing its job. Finally in my case tight valves was found to be the root cause. For all those concerned I am hoping that tight valves was caused by the way I drive my but I am starting to think not. More than the way I drive is how much I drive year after year. In my case adjusting the valves to eliminate tight valves immediately got rid of all symptoms on both occurrences. The second time around Lighthouse Motorsports in Rosemount MN figured out a way to adjust the valves with minimal disturbance of the engine. For those that think they have tight valves hopefully they are wrong but if not I would recommend Lighthouse Motorsports.
edc
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- 2014 viper xtx
I have my sled apart 4000 miles so i measured my valve clearances at room temp. picture show results, don't think spec written on sheet is right. What are the specs ?????
Allan
TY 4 Stroke Junkie
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- Sidewinder, SR Viper XTX, SR Viper XTX, 2016 Apex XTX and Pro-Line Pro Stock 1000
Allen,
Think the upper dimension on intake is .0087
Think the upper dimension on intake is .0087
Allan
TY 4 Stroke Junkie
mis print from me, pic below show correct
