Timing chain problems after new head.

[Dudewith4x4]

I think I posted this in the wrong section before so I will post it here if that's alright with the mods.


Timing Chain after new head.
Hey guys I'm new to the miniJ bike scene but about a week ago I found a little dayang pit bike in the side of a heap of scrap and bought it for 15$. It was complete just looked like it had been sitting for awhile. I took it apart and fixed a few wires and got a good spark. Next rebuilt the carb and cleaned the gas tank. Couldnt get it to fire still so me and my freind took the head apart and of course the intake valve was bent. So I ended up picking up and new bigger head and and 48cc cylinder bored to around 118 today and me and my freind got it all togeather but went the timing chain on there and it was about 3/8"s to short... Where do I go from here?

 

[rotn50]

are you sure the timing chain wasnt bunched up one link, did you release the timing chain tensioner on the bottom of the crankcase(on the opposite side of the sump plug) need more info, is this a china 50 were talkin about?

 

[Dudewith4x4]

Thanks for the reply man. Yes we cycled the chain through to make sure it wasn't bunched. We also released the tensioner hoping to give us the little more room. The tensioner on this bike is more of a roller to tell you the truth. This is a dayang pit bike so I assume it's china and it looks like around a 90cc motor stock.

 

[Dudewith4x4]

Anyone? Loo

 

[sean01]

are you using the same cam sprocket? there are a couple of different sizes which have different diameters. compare against the original sprocket as you cant change the diameter..

also there is a plunger in the engine which is oil feed to keep the cam chain tight, 14mm bolt under the engine... undo it a couple of threads and see if the cam sprocket and chain goes on easier...