Engine running problem when leaning bike to the right

[XSFrank]

Here's a question for all engine guys, see if you can help me.
After not using my bike for a few weeks I've now got a very peculiar problem I've not heard of before and my bike mechanic friend is lost on too.
The bike starts first time and idles perfect when on it it's side stand (leaning over to the left). I can raise the RPM's slow or fast all the way to the red line if I want to. All fine.

Problem is, as soon as I put the bike upright and then lean it over to the right, it starts playing up and won't respond to the throttle being opened.
If I just hold it upright on idle, the RPM's slightly increase, but it'll just sit and idle fine.
If I leave it on idle and tilt it further over to the right (as if going round a right hand bend), the RPM's drop and it starts running lumpy until it eventually dies after a minute or a bit longer. This is without touching the throttle at all.
If I try to open the throttle with the bike upright or leaning over to the right, it just sounds completely flat (lean), won't rev up and will eventually die.


The bike is modified with an XS750 tank but has a stock '81 SH engine with stock electronic ignition, which as I said, was running absolutely fine until I parked it about 4 weeks ago. I don't think it's ignition related, but have hit a dead end with the fuel side of things.

I've checked both petcocks and the diaphragms are working fine, checked the float level, again, both even, cleaned out the main, idle and air jets with carb cleaner just in case the fuel was old or dirty, put new fuel in the tank and checked the plugs, which are fine. Pulling the choke out doesn't help either, even though it sound flat/lean. Is it fuel starvation?

So, the bike idles and runs fine on it's side stand or leaning over to the left, but runs rough and won't pick up RPM's when standing upright or leaning over to the right.

Any ideas???

Frank

 

[TwoManyXS1Bs]

Well, wild guess here, the crank could be shifting slightly to the right, opening up the gap between the ignition sensor coil and trigger magnet (which may be weak).

Try the forum's google search (upper left box) using "rare earth magnet"...

 

[pamcopete]

The right side carb float is too high allowing the bowl to overfill when you lean it to the right. However, this will not happen when you are riding and lean into a turn because centrifugal force keeps the fuel level level.

 

[XSFrank]

Thanks for your ideas guys. I've triple checked the float levels, crank play and gap between the pick up and sensor. No luck, plugs not fouled, nothing. So thought it's got to be ignition related and carried on.
Now I feel like a real idiot!!!!
The reason why the bike wouldn't run when leaning over to the right was that I had water in the ignition box

As I hadn't used the bike for a while, I took the seat off to keep the battery on charge. In the summer I keep it outside just under a bike cover, which I guess is not as water tight as I thought and since I fitted the ignition unit under the seat, it was right there to collect the water coming through. When I popped the lid off, the box had enough water in it to just touch the circuit board, so every time I leaned the bike over, it caused a shortage.
Unbolted the box and tipped the water out, dried it in the sunshine and hey presto, it worked again

Please send all comments to xsfrank@worldsdummestmechanics.com

 

[TwoManyXS1Bs]

Haha, another good one to add to the list of "well, have you tried this. ?.?".

 

[Brian902]

Frank, you missed a step, drill 1/8" hole in one front and one rear corner diagonally to each other.

Drainage man, you need drainage. ha ha