Bike trouble

[Chris Polariski]

Twice now Ive gone out and tried to see what the top speed is on my bike. Both times Ive peaked out at about 160k or 100mph. The problem is that as soon as I reach this speed, the bike starts to sputter and continues to run rough at any speed until I shut it off, if it doesnt stall. If I leave it for a bit, it will run fine for around town. Any ideas

[Snow]

Perhaps fuel starvation? Numerous things to check such as fuel cap vent, petcock filters, fuel lines, fuel filters in the carbs, main jets, float level.

Being that it runs rough until you let it sit for a little bit, I would lean more towards the fuel vent being clogged or the float level.

Of course, I am definately no carb guru.

[Chris Polariski]

Im going to see if I can figure out the coil test, a search for a sputtering engine seemed to indicate a coil problem.

[TheDjost]

Overheating coils can provoke the symptoms you have, but like Snow said, I'd be more inclined to think that it is fuel related. It's also easier to troubleshoot since you will have to overheat the coils to check them as they will check fine when cold since they work fine on a cold engine. Don't be too quick to blame something electrical. Check fuel first.

Easiest to check is the fuel cap vent. Just run it until it runs rough, then open the gas cap and keep going. The problem should gradually go away if the vent is plugged.

You can also try running the bike on prime for a while. If you have a small vacuum leak and have an octopus or vacuum petcocks, on a full throttle run the low vacuum situation can keep the vacuum valves closed long enough to keep the bowls full.

Check fuel lines to make sure that they don't loop up and trap air bubbles that will keep fuel from flowing fast enough to keep the bows full.

Clogged filters or screens can also lead to fuel starvation. The next time your tank is almost empty, take it off and unbolt the petcocks from the tank to check the screens. Replace any fuel filters on the bike if you have any doubt as for age and condition.

I don't know for sure how much fuel per minute is needed in top speed runs, but you can check the fuel system by taking the fuel lines off and redirecting them into suitable containers. You should get a good flow out of the petcocks.

Good luck, and keep us posted.

-Justin

[Chris Polariski]

Thanks for the advice. If it doesnt start storming right away, Im going to test your theory.

[mitch]

octypuss

My buddys xj was starving for fuel and it was the octpuss malfunctioning, removed it and run a line from the front taps to each carb bank then run a line an the back tubes from one side to the other to shut off the prime mode . his bike hauls a** now hth .....................MITCH