Nytro Engine Timing

[jaydaniels]

Anyone have any tips on setting the timing on a 08 Nytor motor. I have the manual and am following it but cannot get things lined up. Manual shows to set the cams with the gears at a certain point where referance points line up, then install the chain. I've done this but the cams will not stay at this point in order to install the chain as the valve spring pressure rotates them back enough so I'm off just a bit. Any tips? I tried putting eveything in place without bolting the gears to the camshaft and then rotated the motor until the bolt holes in the gears lined up with cams. This seemed to get things perfect but when I tried turning the motor over with the flywheel, the exhaust camshaft seemed to jump ahead at certain points and put it out again. It like the intake camshaft gear is pulling the exhaust camshaft gear but at a certain point, the exhaust camshaft quickly rotates forward faster than the intake and puts slack in the chain.

 

[Roadrider]

tie raps

 

[jaydaniels]

Not quite sure what you mean. What do I tie wrap?

 

[Roadrider]

Tie wrap the chain to each cam gear so they can't
jump off. You can also clamp a bar across the cam gears if you care to take the time to fab one up.

 

[jaydaniels]

Okay I see. Is it normal for the gears to want to jump like this. I think part of the issue is that there is no tension applied by the tensioner until the chain pushes and releases it. Thanks for the advice.

 

[Roadrider]

valve springs are pushing on the cams and trying to
rotate them to the closest closed position.

 

[grizztracks]

this is for replacing the chain tensioner on a RS sled but the procedure is similar for the Nytro: http://www.ty4stroke.com/viewtopic.php?t=90826

 

[jw3210]

valve springs are pushing on the cams and trying to
rotate them to the closest closed position.

Thanks for post and excellent solution of tiewraps.

grizztracks thanks for url and great picture.

 

[jaydaniels]

That's awesome, thanks for the good advice. Looks like I'm going at things correctly just need the tie wraps. Is there anyway to trip the tensioner before rotating the motor over?

 

[jaydaniels]

Well figured out how to release tensioner but still cant keep chain from skipping. Used tie straps and did one complete revolution, then tried without tie straps and it skipped. Something is just not right. I did notice the manual says to set timing while cyl 3 is at tdc. Seems to me it would be at tdc during the intake.

 

[Roadrider]

Right after the intake valve closes on Number three it will come up to tdc. How could you turn it over with it
tie wrapped? If the tensioner is the same as the vector
it should have released when you pulled the screw driver out after installing it.

 

[jaydaniels]

Based on the diagram above for timing and the position of the intake cam, it's just about to open the intake valve ande the exhaust just closed. Seems to me it's just ready to complete the intake stroke. Different style tensioner than the vector. No place for a screw driver. I turned it over by repositioning the tie wraps. Just as the chain was ready to come of the gear I would remove the wrap and place where the chain is just coming onto the gear. I continued this process for one complete revolution hoping the tensioner would tension enough to keep things from holding. As soon
as I turned motor over by hand without the wrap the exhaust cam would skip ahead one tooth every revolution. I'll see if I can upload a video tonight.

 

[jaydaniels]

Well, I think I may have figured this out. I noticed that the valve cover has a chain quide on the inside between the 2 gears. It seems to me like this helps keep the chain tight. I'm thinking that you can't turn these motors over without the valve cover in place. Going to try this tonight.

 

[Srxspec]

Line up all the marks, turn it over one revolution by hand using zip ties and if the marks all line up again then install the motor and start it. You will be fine.

 

[Roadrider]

If the exhaust just closed it's on the exhaust stroke. And Don't think so much, read the manual. You should be able to turn it over fine without the cover. New gears,chain and guides? Did you measure the old ones if you are using them?