I don't think it is hydraulic. The oil dampens the load.
The spring should hold it. If it were me I would talk to
a Yamaha tech before taking the chance. Little slow around here as season is over with.
The spring should hold it. If it were me I would talk to
a Yamaha tech before taking the chance. Little slow around here as season is over with.
09nytro
TY 4 Stroke God
You should. Be able to turn it over several times clockwise and the tensioner will hold it...I think the spring is bad or the whole tensioner needs tobe replaced
grizztracks
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09nytro said:
If it was me I'd be replacing the tensioner just to make sure. The tensioner looks like it has oil entering it but it is spring loaded and I also don't believe it's hydraulic.
jaydaniels
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I will try replacing the tensioner but believe me, it's design is so simple that I don't see how it could go bad. Also, I have 2 tensioners, one from the original motor that only had 2800 miles on it, and both do the same thing. These tensioners have a locking spring that keeps the tensioner from coming loose but for some reason have a certain amount of free play built in and it's this free play that's allowing the tensioner to loosen off just enough that the chain comes off the gears. Think I'll take it to a dealer to see if they can figure it out.
grizztracks
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keep us informed!
jaydaniels
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Well, turns out they are hydraulic. The spring is only to keep the tensioner in place when there is no oil pressure. Once the motor is running the hydrualic takes over. There seems to be a fair amount of play with the spring system which allows the chain to push away from the gear under load from the cams. Seems to be the 'nature of the beast'. Not a great system in my opinion.
09nytro
TY 4 Stroke God
That's good to know...the manual doesn't say anything about that..
found this today: http://www.snowestonline.com/forum/arch ... 19191.html
Whhhaaattss up Loui. Once he pulls the motor down to work on it the head will be off and timing done etc so it's the best time to put in the manual tensioner. The benefit to the manual tensioner is that you set the tension with the motor on the bench. At start up there is ZERO chance that you could skip a tooth. I have seen it 3 times and heard of it many other times happening with the stock hydraulic tensioner. The issue is with the TDC on the Nytro and where the cam lobes sit when the crank is at TDC. To be blunt, it is in a f**ked up position. Once you have the timing set with the crank at TDC, the timing chain on the intake cam sprocket, looks like it wants to come off (it is actually lifting up off the sprocket a little bit). I don't know this for sure but I think that is why Yamaha puts the timing chain guard stopper on the roof of the valve cover as a way to hold the chain down while the motor is started. I have done 5 of these my self and no matter what you do you cannot get that timing chain to sit tight over the sprockets. The hydraulic tensioner works by the oil running through it. That in itself is a problem. That crank is gonna be spinning over multiple times before oil even gets to the tensioner to release it to tighten down all the way. The way the stock tensioner initially releases is by turning the crank over by hand. It will release and tighten but not all the way. You can actually have a buddy turn the crank over and you can put your ear up to the motor where the tensioner is and you can hear it releasing. Problem is that it does not fully release and tighten until the motor is started. You can avoid all these issues by just putting in the manual tensioner. Most of the time the stock one will work but when it doesn't it will cost you mega bucks to rebuild that motor. At a minimum your valves are toast, if it jappens at high rpms your head could be killed and worse yet your rod bearings go and you lose a case because your rod poked out the block. Cheap insurance boys.
pylon
Whhhaaattss up Loui. Once he pulls the motor down to work on it the head will be off and timing done etc so it's the best time to put in the manual tensioner. The benefit to the manual tensioner is that you set the tension with the motor on the bench. At start up there is ZERO chance that you could skip a tooth. I have seen it 3 times and heard of it many other times happening with the stock hydraulic tensioner. The issue is with the TDC on the Nytro and where the cam lobes sit when the crank is at TDC. To be blunt, it is in a f**ked up position. Once you have the timing set with the crank at TDC, the timing chain on the intake cam sprocket, looks like it wants to come off (it is actually lifting up off the sprocket a little bit). I don't know this for sure but I think that is why Yamaha puts the timing chain guard stopper on the roof of the valve cover as a way to hold the chain down while the motor is started. I have done 5 of these my self and no matter what you do you cannot get that timing chain to sit tight over the sprockets. The hydraulic tensioner works by the oil running through it. That in itself is a problem. That crank is gonna be spinning over multiple times before oil even gets to the tensioner to release it to tighten down all the way. The way the stock tensioner initially releases is by turning the crank over by hand. It will release and tighten but not all the way. You can actually have a buddy turn the crank over and you can put your ear up to the motor where the tensioner is and you can hear it releasing. Problem is that it does not fully release and tighten until the motor is started. You can avoid all these issues by just putting in the manual tensioner. Most of the time the stock one will work but when it doesn't it will cost you mega bucks to rebuild that motor. At a minimum your valves are toast, if it jappens at high rpms your head could be killed and worse yet your rod bearings go and you lose a case because your rod poked out the block. Cheap insurance boys.
pylon
jaydaniels
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Interesting. Good find. Atleast I have some piece of mind knowing this is not from something I'm doing incorrectly. One bit of advice given to me was to back of the bolts on the tensioner once it has been activated to allow the tensioner to extend to the next locking position. Just have to be careful that this won't place too much pressure on the chain and guide once the tensioner bolts are re-torqued.
Hmm this was interesting!
I will soon be putting together a Nytro motor for the first time and I am glad a came across this thread.
I have been doing valve jobs on motorcycles (removing cams to change shims), changed cam chain tensioners and and also installed manual ones.
But I have never had problems with the timing, I guess the Nytro motor is special.
I am rebuilding a friends motor and I really dont want the cam chain to skip when starting it for the first time.
We are replacing the tensioner but not the guides or chain. (engine has 12.000km on it).
On the other hand I guess there is no other way of installing the cams/chain/tensioner then what the manual sais and I guess this is how they do it at the factory? But with the hydraulic tensioner getting no oil pressure on the first startup I must say I am worried.. .
Hmm
I will soon be putting together a Nytro motor for the first time and I am glad a came across this thread.
I have been doing valve jobs on motorcycles (removing cams to change shims), changed cam chain tensioners and and also installed manual ones.
But I have never had problems with the timing, I guess the Nytro motor is special.
I am rebuilding a friends motor and I really dont want the cam chain to skip when starting it for the first time.
We are replacing the tensioner but not the guides or chain. (engine has 12.000km on it).
On the other hand I guess there is no other way of installing the cams/chain/tensioner then what the manual sais and I guess this is how they do it at the factory? But with the hydraulic tensioner getting no oil pressure on the first startup I must say I am worried.. .
Hmm
