Help with intermittent starting on Motorbike

[wolverine]

Hi All,

I was wondering if anyone can point me in the right direction. I have a Pulse Adrenaline 125, last night I changed the speedo drive.

Afterwards when I tried to start the bike its doesn't start. The strange think is, when I put the bike on a uphill angle it started, downhill angle it doesn't. When it does start, as soon as pull off it stops. I was suspecting maybe it was a vacuum issue, but when it does start it will stay on. I have had it running for 5 minutes, but as soon as I set off it cuts out. I have checked for spark on a uphill angle and there is one single spark when I first turn the engine over, but its doesn't repeat. A friend said this is normal, can anyone confirm this?

I did drain the front brake fluid when putting the front break disk back on, do you think this would have anything to do with it? I'm thinking is there possible a sensor inside the brake fluid reservoir.

I did have a slight "mini-drop" when I was putting the front wheel back on, The toolbox the bike was resting on collapsed, the bike didn't fall on the floor but it dropped rapidly for about a foot, no visible damage was done and I really didn't think much of it. I have been suggested I may have disturbed something in the carb and need to dis-assemble, clean and check the floats, does this sound correct?

Can any suggest what steps I should be looking at in order to resolve this.

Few points.....

This bike doesn't have a side, so its not a faulty switch.

I have checked the fuel flow to the Carb and that seems fine.

The vacuum pipes all look OK

[jape]

Sounds like carby, float sticking or crap stuck under something. Should be easy enough to check. But also look at killswitch wiring in case there is a short at one angle where a wire has come loose but not fully dislodged. Time for a general strip back and check of all you can get to I would say ...

[slabo]

An amateur mechanic doing his own work and breaking something ... Well, well... this post deserves an answer. Unfortunately, I don't have an exact answer.

Sensor inside the brake fluid? Nop, never heard of such a thing.
Further trouble shooting steps:: If the bike is on the center-stand, front wheel in contact with the ground, rear above ground, can you start it, put it in gear? Does the rear wheel spin freely? Also, does the front wheel turn freely? Are the brakes locked even your not pulling the brake lever? It's possible the bike is stalling because the wheels can't turn?? My chain was stuck the other day, bike was starting fine. As soon as I put it in gear, and start to go forward, I feel something locks and then the bike stalls..
I took the cover off and looked... Turns out the front sprocket was off the spindle!! I'm very lucky I found this while still parked.. phew :D

[papadad]

I suspect it is an electrical issue given the bike runs only at certain "angles", like a wire is loose and at one angle the wire is not contacting the chassis but at another angle the wire is dangling and comes in contact with the chassis shorting to ground and killing the motor.

can you START the bike at any angle?

[wolverine]

Thanks for your help. I have taken the carb apart and the floats moves fine, has no leaks and looks parallel to the bowl. The jets look fine and can see daylight through them. There was a small bit of gunk at the bottom of the bowl which I have removed. It's now re-assembled, I'm just waiting for the battery to charge to retest. If that doesn't work, ill get my multimeter out.

[wolverine]

Hi All, the problem is still there. I think Ive checked all the fuel related stuff, which leads me to suspect it may be something to do with the electrics. Can anyone confirm if when turning over the engine, the spark plug is supposed to spark multiple times and not just once. I am reading in the Haynes manual "If the system is good condition a regular, fat blue spark should be evident at the plug electrodes" which its not because I only get 1 single spark each time I try to start it. The engine keeps on turning though. I have tried a new plug and it does the same. I had a freind tell me that some bikes only have a single spark from which it starts and it will then produce more, is he fibbing to me?

Once again, thanks again for your help

EDIT: Update, I have just started it again and the spark happened multiple time, put the plug cap on the plug and it started! Its not only doingit a single time again now though so Im guessing it must be electrics.

[MJH]

It sounds like a connection not the starter but the connection that feeds the spark after your already running. The starter will spark until it gets running then another circuit takes over the starter uses the battery the running bike uses a stator…it’s like an alternator.

You may have worked something loose.

It should spark as long as you are holding the starter switch and ignition has not occurred.

[wolverine]

Bought new igition coil, same problem, same problem. One of my firends said, "have you tried with the speedocable unplugged", it then fired first time! I think its earthing through the speedo cable somehow, I think it might there might be something wrong with the way the speed / Rev meter / Igntion is wired.

[jape]

Glad you fixed it.
Well that was the thing you were playing with! Your mate deserves a beer.