NEED HELP no top end!

[BIG BOBBY]

So i tried posting a thread and it disappeared because I didn't have an account, well I'm back and I will use copy and paste until it works.
Its a lot to read but if u can help me It'd be great!


So I'm having trouble with my 66/80cc China 2 stroke. I recently built a new bike because my frame broke, It was running great before putting it on new frame. Easy 35mph+
New frame is BBR Tuning gas tank frame, (which eliminates the need for chain tensioner) basic HP Carb carb and HP magneto

The problem is not noticeable when going slow ( 1- 20mph ) but as soon as 25 hits it will not go faster. It just sounds like sh*t. Like the engine is maxing out, but it's not over revving, it's just gets louder with no speed change. Slow down a bit and it runs good again. Speed back up and-- you know.

I RAN OUT of gas. Right before it ran out, it had full power, it got up to 31mph and would have kept going but,, it ran out of fuel... hmm??

I have tried adjdusting idle screw/cable stays, cleaned the carb ( float is not level with carb? also, found green liquid on air filter? Why is this here?? ) , tighten head bolts, check spark, ride without gas cap, checked fuel flow from tank... ALL made no difference to performance.

I heard about jet size? I guess I have 77 but they sell 60, 66, 70, 77, and so fourth... What what are these numbers and what do I need?

My stock exhaust broke in half but when it did, the bike got a lot faster so I don't see how this would slow it down. New exhaust coming tomorrow!

I may have missed mentioning some things. Please ask question if you have them but more importantly help me solve this!

Thanks

the part im having trouble grasping in your post is: how exactly does the BBR tuning tank frame eliminate the need for a tensioner????

 

[dparenti13]

the part im having trouble grasping in your post is: how exactly does the BBR tuning tank frame eliminate the need for a tensioner????

Horizontal rear dropouts, so you can move the rear wheel back to remove slack from the chain.

 

[BIG BOBBY]

ohhhhh. hmmmm. maybe i'll experiment with taking my tensioner off and dropping a few links. my chain is old anyway. I always thought that it helped guide the chain onto the rear sprocket,... and prevented the derailment/lockup/ICU visit. I haven't had a chain remain tight enough to prevent slop,..ever,... for more than 2, 3 rides. some slop happens,...and then it stops increasing. completely. but there is usually always enough slop to cause a disaster if I lean REALLY far. you can hear the thing start chattering against the tooth tips in a deep lean. im talking,...1-1/2 inches of play on the top run with the bike in gear and pushing forward against the compression slightly to reveal the top run's true amount of slop.

 

[Rjb13]

the part im having trouble grasping in your post is: how exactly does the BBR tuning tank frame eliminate the need for a tensioner????

Also the motor is lifted a bit because of the motor mount,,, and a short rear end

 

[BIG BOBBY]

tyvm.

 

[Rjb13]

ohhhhh. hmmmm. maybe i'll experiment with taking my tensioner off and dropping a few links. my chain is old anyway. I always thought that it helped guide the chain onto the rear sprocket,... and prevented the derailment/lockup/ICU visit. I haven't had a chain remain tight enough to prevent slop,..ever,... for more than 2, 3 rides. some slop happens,...and then it stops increasing. completely. but there is usually always enough slop to cause a disaster if I lean REALLY far. you can hear the thing start chattering against the tooth tips in a deep lean. im talking,...1-1/2 inches of play on the top run with the bike in gear and pushing forward against the compression slightly to reveal the top run's true amount of slop.

It is good to have about a half inch of play in your chain

 

[BIG BOBBY]

why would the play increase to about 1-1/2 inches,..and then stop completely? once I get that much,... it STOPS increasing. weird. if my sprocket was off-center,... it would never stop increasing. head-scratcher.

 

[Rjb13]

why would the play increase to about 1-1/2 inches,..and then stop completely? once I get that much,... it STOPS increasing. weird. if my sprocket was off-center,... it would never stop increasing. head-scratcher.

I'm lost on that one

 

[Rjb13]

UPDATE: I put NT carb back on, a little adjustment and it works pretty perfect now. needle is on center notch and I am at 300ft oboe sea level. Also switched out CDI and added more oil to my gas. 36mph top speed. wheels feel a little weak, probably going to but buy the solid aluminum ones they make for these bikes!

 

[gary55]

why would the play increase to about 1-1/2 inches,..and then stop completely? once I get that much,... it STOPS increasing. weird. if my sprocket was off-center,... it would never stop increasing. head-scratcher.

The myth of chain stretch - MRO Magazine