Low power on load but well at idle

[zoufris]

Hello there,

First I'm from France so sorry for my bad english

I have owned one of these 80cc 2 stroke engine and I have a little problem and I need your advises.


My engine is fitted with a HP carb (dellorto clone) and I bought new jets because the original one doesn’t work.

It work well and the engine is very responsive when it is at neutral gear / idle (or when I put the bike on the crutch) but when I ride it, when I engage the clutch, it don’t have any power and it seems restrained .

I can get high rpm and my top speed is around 23 km/h (14 mph)...


You can check my youtube video here:

I reach the top speed at 17 sec... I have tested lots of jets ( .52 to .70) and my problem is still here.


My ideas: Maybe a compression problem ? Or a CDI problem ?


Do you know the cause of this dysfonctionement ?

Thank you for your answers

 

[FurryOnTheInside]

Find leaks around the intake manifold by spraying with water and listening for a change in engine sound/speed.

You may have more than one problem; but the intake must be sealed first, before any other adjustments to the fuel/air mixture can be made.

 

[zoufris]

Hey ! thanks for your answer. I looked closely the engine, specialy the "top gasket" and I saw this incorrect assembly (check my picture). Do you think I'm on the right track ?

 

[crassius]

they often look like that because the sealing of the gasket happens more toward the center - if there is no oil stain around that gasket, then it usually is good

can you get a pic of how your carb is mounted, the manifold seems upside down

 

[zoufris]

There is a pic of my carb, can you confirm that I put it upside down ? Could it reduce the efficiency ?

 

[FurryOnTheInside]

There is a pic of my carb, can you confirm that I put it upside down ? Could it reduce the efficiency ?

I would want to get the carb closer to level than that is, so yes I'd say the intake is upside down. You may need to make a new intake gasket as you have had the engine running already so it'll probably tear the gasket when you remove the intake.

 

[crassius]

yep, that's upside down and carb will never work right that way

on another note, what do you have stuck in your motor mounts and why is there a flat plate outside of front mount (should be a curved strap there) please look at some pics of bikes to see where you went wrong - as it is, your motor will start shaking and fail again very soon

 

[Spare_Parts]

Looks like burlap.

 

[FurryOnTheInside]

Looks like burlap.

Nah, not jute, too coarse. That looks like coconut coir.

 

[zoufris]

Hey,

I put yesterday evening the carb right but it changed nothing and the problem is still here. The engine has no power... After I tried to find leaks around the intake manifold with water but I didn't see anything.

Actually I don't know what to do except open the engine and check the gasket (it's my last chance I think).

My setup seems OK, what do you think ?

And yeah I stucked coconut fiber coir in the motor mounts to reduce vibrations. I ordered the motor in china and I only have a flat metal plate to stuck the engine on the bike.

Thank you for your help