reason for engine to loos its cam timing.

[Jona$]

This is a weird one even for me.

At last the engine was in and all ready for launch, didnt fire up because of forgot to put the Cylinder identification sensor together, also the 1-4 ignition coil timing backwards, fixed this and fired up, sounded weird and got code 34 went on 3cyl and died off, nr2 coil had lost its contact so fixed it but then it sounded like it didnt have any compression, and yep there wasnt, atleast at nr 1 that i checked.

teared down the sled to find out that the intake camshaft was off but the out and timing on crankshaft was was dead on, what could cause the chain to jump? it was dead on before firing up

could
1.putting the wires for 1-4cyl backwards making it fire in wrong order do this?
2.a stuck starter do this? how to test it?

gonna lift off the head and check valves etc before assemble again,,,but what caused it

 

[Jona$]

Well anyways, on cyl2 the middle valve at the intake got hit so bad that it cracked the lifter and bent all 3 valves. luckely the piston have non marks. tearing it down on saturday and fixing it and rechecking shims.

 

[Bluebullet]

no clue, way above my knowlege, good luck with this one. I am waiting to hear from the experts as I am sure you are.

 

[givemeaboost]

Are you sure that you got the chain on right. It has to be put on in one certain order. It tells you in the factory service manual.


Ken...............

 

[Jona$]

The chain was newer off, the engine was out because of a leaking hoose behind it, checked valves shim and cam timing before installing and dead on, stumbled over this one... Maybee mcx screwed up when they had it in, they made several once..for example i found a extra washer when taking out the nuts inside the motor, guessing they missed there already was one there,,, o well, on saturday im going home to a newer friend of mine to get it right, a real great fabricator

 

[Some_Boost]

Check your chain tensioner , I have had one jump on me over a bad tensioner. I now run a manual one for the r1 motor and know it won't fail on me , hope your head is ok still, good luck

 

[Jona$]

Well i feel haunted, fired up the sled today,ran like a champ but no shutdown code 30 oilpressure , and started up again to check feedback on oil, there was none, gave it a little throttle and I could hear it jump the timing, safe to say my first time having it jumped was the fucking pump, so gonna tear down the whole motor, what parts should I replace when having the chance ....damn it

or after reading now its a common thing that you need to prime the pump, not mentioned in the manual.. still doesnt explain if so why my chain jumped again... no marks on gears or sloppy chain and the tensioner jumps right out.... or does it not work without oil pressure... im going crazy.. do i pull or not

put timing back, prime for oil and start again?

 

[maim]

I would suggest a new tensioner as it sounds like that one is not holding under load anymore. from what I remember of the bike ones (been a few years) they are supposed to lock in some fashion to prevent it from backing off tension under load.

 

[Jona$]

been checking this now because i dont buy that the tensioner just half way gives up after a engine build, what i found that its hydraulic, the spring only keeps it intact on idle without oil pressure, and when oil comes along the hydraulic part takes over.

http://www.ty4stroke.com/threads/nytro-engine-timing.111413/page-3

And yes it dont back down.

 

[Some_Boost]

Get a manual one and be done with it

 

[givemeaboost]

When you put the timing chain on it has to be tight between the intake and exhaust cams and tight from the exhaust side down to the lower gear. Then you put the tensioner in and tighten the two bolts. Then you take a small screwdriver and loosen the tensioner up so thw spring pressure takes the slack out of the intake side of the chain. Did you do it this way ?


Ken............

 

[Jona$]

yes did it that way, i know the procedure Ken

Some Boost, its in my mind, see its the same as in the r1, my thoughts is how hard it needs to be tighten and how often, i guess once a season and perhaps finger tight? cant find any threads about the manual ones.

 

[Jona$]

Ordering å Manuel cam tensioner today, also how do you prime the oil pump I plugged all but one and blew with compressor but no return, I poured into the return tube to it was filled and turned the engine and it pushed the oil out, does this mean the pump works but haven't just got any pressure to get it going ? I'm confused

 

[Some_Boost]

Tighten the Manuel tensioner finger tight and lock it . I check it every oil change . has not needed any adjustment as of yet . and I have been using it for about 2 years now .

 

[machzrobbie]

Make sure you check your cams as they will seize very quickly without oil pressure and make the chain jump