Morning everyone,

I recently took my bike apart to try and solve an issue I was having regarding the engine sounding rough and running at different speeds when the throttle was held in a certain position. I quickly realised that 1 of the spark plug leads was not pushed down firmly and this is what the issue was, I figured that having come this far I should go on and replace the spark plugs.

After doing this and cleaning out the air filter (with the correct cleaner and thoroughly drying after) I put the bike back together and started her up, she sounded the best she has ever sounded and idled at 1200RPM and would redline like a dream. BUT..... once you jump on her and put her under load the acceleration in pretty much the same as my Peugeot 206 1 litre, with the throttle open completely you are barely moving.

What could have caused this? I don’t understand what I could have touched to cause this problem. Ive checked the engine vacuum, fuel pipes, coil order and anything else I can think of.

Please help me, I am well beyond my own knowledge and I am hoping you guys have an idea.


Many thanks

 

Hi, your problem seemed to start with the cleaning of the air filter, did you use compressed air or just cleaned with solvent and did you take the airbox off to do it, could be that your idle jets has somehow got blocked, did you clean the carb jets

 

They were cleaned with a air filter cleaning solution my father in law had in his garage, you covered the filtered with this liquid and worked it with a paintbrush, left it 15 mins then cleaned it through with warm water. Then used conpressed air to force excess water out and a dryer to evaporate any left over moisture.

I have bot not touched the carbs yet, as I didn’t know if I could be creating a new problem.

 

Hi Dan , have you tried running without the air filter in, what type air filter do you have bey the way

 

Yes and it was exactly the same. It made absolutely no difference at all.

 

Right Dan, so as it is ,it will idle and rev up to the red line, but nothing under power when in gear, is that right, for some reason the carbs aren't supplying enough fuel when asked for ,take another look at the tank and fuel connections to the carbs ,could be a kinked pipe when you put the tank back

 

Same problem I’m having with my F3, it’s driving me mad, took it out today and it’s exactly the same symptoms, as soon as it’s under load at lower revs it splutters and holds back, as soon as you hit 7,000 rpm it’s fine.

I agree with your diagnosis that it’s probably fuel starvation, I’m wondering if mine could be a faulty fuel pump or petcock

 

Definitely not a kinked pipe. You can still get to them once the tank is down and they are completely free.

Yeah when pulling the throttle conpletely open from 0 you pull away and 0-60 would take about 15 seconds

 

Hi Gunk maybe a removal of the air solenoid could give you an idea if it still runs the same with it missing

Have you tried switching to reserve on the petrol tank, taking it for a run, if still the same try cleaning tank vent pipe

 

I’ve now sourced a spare, so that’s the next job, just lots of trial and error!