uneven running

[arnaud]

Hi, today i found some time to install the engine and primary drive.
i was excited that the engine, after revision and a long time waiting, started with the recently tested injector.
however,, the engine is running uneven, although i do not give any throttle, the engine is revving high, stays there for a fe seconds, back to almost idling, and this repeats untill i mangae to shut it down.
i am afraid that i did something wrong with the governer system, although it did not seem complicated.
i hope this can be solved without getting the engine out of the frame etc.
Anyone a clue??

[IgorVigor]

I cant remember what engine you have

sounds as though the engine is running away in bursts...

is the engine smoking excessively?

[TimppaX]

lubrication leaks inside engine to cylinder/injectionpump causes symtomps just like that. More common with turboed diesels whee turbo´s seals broke and it sucks oil to intake.

There might also be poor/blocked breathing hoses.

[IgorVigor]

or one of your valve stem seals is damaged (and oil is being pulled into cylinder)...

either way, you may have to remove the engine again (depending on how much room you have in the bike)

[arnaud]

it has no valve stems (it is a yanclone)
i've reassebled everything with new seals and gaskets..
it is smoking, but i installed the piston with new rings with a lot of oil./

[IgorVigor]

it could be just burning off all the oil then

does using the throttle change how its running at all?

[albertaphil]

Air leaks in your fuel system can cause some weirdness. Make sure all your hoses are sealed well.

[arnaud]

Thanks all for the info.
when i've got some time and not riding my jawa, i will take out the fuel pump. i may have done something wrong wih the governer..
At least i've herad the engine again..
Will a dB killer in the baffler cost any power??

[IgorVigor]

yes, most likely...

but higher back pressure (caused by the DB killer) should increase torque a little...

[arnaud]

Yes, got it solved..
the governer thingy did nog grasp the fuel pump thingy..
anyway, although i got a thicker shim in the injector (+0.25mm) it is hammering harder then ever!
Maybe because of the new piston rings??
If i didn't change the big end bearings, i would guess the bearings were absent!
Anyway, to put another gasket under the fuel pump cover, i need to get the engine out again..
So, i think i will mix with salad oil fist, look how things settle in.