Running Rough

[chaser]

Not used the bike for a couple of weeks, when it ran fine. Laid it up while I tended to the rear wheel bearing issue. Fixed that and thought I would just give it a lap or two round the garden.

Started on the third kick then coughed and died.......Aha ! No fuel. Topped up with fresh fuel and tried to start but no joy. Took plug out, which was a bit sooty but not wet. After many kicks I got it to fire but it wouldn`t catch and rev. Eventually got it to run but sounded rough and like it was misfiring. It cleaned up a bit when it warmed up but still feels lumpy and won`t tick over.

The only other thing that changed was I added 50ml of gear oil to bring it up to 400ml as mentioned in another thread.

 

Any ideas welcome.

[breagh]

This may be rubbish but here's what happened to my 300.

 

After last years 6 days I was riding a club trial and the last 2 sections it suddenly started running like a carb bike with the choke on.

 

Changed the plug which was sooty made no difference so local dealer put it on the computer but when I tried it  ran way rich.

 

So I had a go at the sensor that you're really not supposed to touch that I'm not really sure what it does?

 

Anyway, I loosened it slightly and moved it minutely while listening to the motor and how it took throttle. 

 

As soon as it sounded right I stopped.

 

Has run perfect since plug looks the right colour and just got round another 6 days.

 

Not exactly scientific.

 

Be brave, mark the position and have a fiddle, what could possibly go wrong?i

[chaser]

Is that the screw on the throttle position sensor ? Mine still has the factory  (I assume) paint blob on it.

 

I am quite brave (foolish) when it comes to stuff like that but being a long way, and a ferry fare, away from a dealer that may have the diagnostics kit, I haven`t yet been that brave

[breagh]

Yes the one with the paint blob though mine had seen previous fiddling at some point by others unknown.

 

I wouldn't be totally cavalier about it maybe I was lucky but it runs like it's electric.

 

Fingers crossed

[lotus54]

For me, I need to reset the TPS about every 100 hours.

[tsiklonaut]

Yes, TPS needs to be re-set quite often (running rough or poor idle is a good sign), also cleaned from the inside every 100 hours or so. The original Bing throttle body is plastic, it deforms in time, also in time the 2T oil mounts up on the butterfly and surfaces of the bypass hole drilled into the butterfly (this is how it get's most of the idle air) hence giving slowed and poor idle.

 

I had Btwice metal throttle body but not having time to fiddle with it I sold it, makes me think I shouldn't have. It's made from metal and is superior to plastic, also has a bypass screw which is neater design. But the buyer said it couldn't get the idle to slow down with the Btwice so not sure.

 

I have the diagnostics cable so I can set the idle, but needs quite often with stock Bing TB.

Edited May 10, 2016 by tsiklonaut

[chaser]

Update : Had a fiddle today, moved the tps back and forth but didn`t seem to make much difference. Checked everything I could, wiring plugs etc. Eventually put a new plug in and it ran sweet as. Plug was only replaced a couple of weeks ago. Duff plug maybe ?

When it was running clean I went back to the tps setting and altered it slightly, it seems to run cleaner and the pickup is smoother. It always felt a bit like a carb engine with the choke not fully off.

Have to wait another 2 weeks before the next trial to see if it is cured unless I can get out for a practice somewhere beforehand.

 

Thanks for advise.