Big Bore kit and the pipe don't go along well

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
R

rctrucker

Active Member
Messages
33
Reaction score
0
Location
New England
Installed the big bore kit last night. My last task is to put on the Jetpro pipe and the screws just wouldn't go all the way in, only like half way. Am I not supposed to use the Jetpro screws and use a smaller screws or something?

Thanks.
 
If you are using the supplied screws. Or something.
Try cleaning the threads in the head maybe their is some dibber in their.
It is best to check all screws before instillation. Just hand tit them in and make sure the threads is ok. It will be easer to fix if it is not fixed all together.
 
While searching around, I found a tutorial for a different brand BB kit and the guy was drilling, creating more thread inside the exhaust mounting holes. Is this required with the Chung Yang BB kit? The threads seem clean when I inspected.

I can also get the shorter screws instead of the ones shipped with the Jetpro pipe.
 
Shiny,

It goes about 5mm inside. Is this too short? There are 3 mounting position, so it's really not that bad, is it? The original screw length is like 17mm. Do people usually buy new shorter screws or make the thread deeper?
 
Fueled air from the cylinder - leaking?

Hello all,

I borrowed a tap and die kit from my friend and I can now put the screws all the way inside of the mounting holes (whew!) Just when I think my FG MT5 is good and ready for normal break-in, I think I find a new problem:

After running for a few minutes, I find residue of fuel on the gas tank and surrounding area below the pipe. The pipe itself is not leaking, but when I put my hands around to inspect when the engine is running, I feel some air pressure with some light amount of fuel coming out of the side of the cylinder right above the exhaust port (not the exhaust port itself where the pipe is connected to.)

I haven't run full throttle to test the power of the pipe yet, but this means I'll have to do some big clean up job at the end. Any suggestion/input is appreciated.
 

Attachments

  • mt5-fueled-1.webp
    mt5-fueled-1.webp
    22.6 KB · Views: 16
  • mt5-fueled-2.webp
    mt5-fueled-2.webp
    23.1 KB · Views: 12
The spark plug was re-tightened. I will re-tighten the engine screws tonight.

One thing I noticed is that the engine screws were not shipped with any lock washer, not with the CY or the Zenoah engines either. Is it recommended to have lock washer on these?
 
No I haven’t heard of any one recommending washers of any kind. You can use locktite but if the screws are not loosening prefer not to.
Never hade any problems either these screws. But after removing them I retighten them after running the engine for 10 minuets.
 
its always good to keep checking the exhaust and cylinder bolts. they do loosen up occasionally. i made access holes in the cooling shroud to get to the cylinder bolts easily.

as far as the air, its likly just the air from teh flywheel. if it Feels PUFFY! like it being forced out in big quanities, it may be a leak in the exhaust flange or cylinder gasket, but if its even and smooth feeling, then its likely just the air from teh flywheel.

no washers on the cylinder bolts, but if you can get them on the exhaust bolts and still have room for them, then i would say ok there.

best idea for exhaust is to just stud it and use nuts on the pipe. again if there is room for nuts on the studs Next to the pipe (some pipes just don't have the clearance area in the flange for them).
 
Make sure the oil is not coming from the underneath of the pipe flange. Funny thing about those gaskets, they look fine and leak if not tight. Make sure to torque your bolts to the proper torque or you will have problem after problem. You can find the torque specs in the engine area here.
Good luck looks like you have some good fun ahead of you.:cool2:
 
Back
Top