bog / rub through

[destey]

Don't want to hijack this thread but this comment about the tors has me curious. My sled has a quirk where once in a great while at the end of a good healthy lake/top speed run it will do exactly that... just plain quit right as I back out of it and as soon as I roll to almost a stop and burp the throttle the thing comes back to life and runs great. Now for the million dollar question... how would the tors cause that to happen?

Could be like this: cruising along at 110mph, let off throttle. The throttle sensor detects the thumb throttle to be at 0%, same time the carb sensor is (in our hypothetical) is misadjusted and TORS thinks the blades aren't closed and kills the spark.

Although the problem should be reproducable. Does it sound like the killswitch was hit (no spark at all)? Or is it running cruddy?

Possible things I might consider:

*needle valve/float bowl adjustment - though this would surface during the WOT (unless the needle valve wasn't shutting fuel off and it overflowed into the intake)
*stator - as it gets hotter maybe its function is reduced
*wire rub through - decelleration shifts the motor slightly in the mounts moving some wires that are already rubbed through against each other
*air screw(s) misadjusted - won't let it idle?

 

[thunder66]

Could be like this: cruising along at 110mph, let off throttle. The throttle sensor detects the thumb throttle to be at 0%, same time the carb sensor is (in our hypothetical) is misadjusted and TORS thinks the blades aren't closed and kills the spark.

Although the problem should be reproducable. Does it sound like the killswitch was hit (no spark at all)? Or is it running cruddy?

Possible things I might consider:

*needle valve/float bowl adjustment - though this would surface during the WOT (unless the needle valve wasn't shutting fuel off and it overflowed into the intake)
*stator - as it gets hotter maybe its function is reduced
*wire rub through - decelleration shifts the motor slightly in the mounts moving some wires that are already rubbed through against each other
*air screw(s) misadjusted - won't let it idle?

I would rule out the carb issues in my case because I just went through them but the stator and wire rub through issues could be possibillities. It does act as though I hit the kill switch though when it has happened and acts like it takes a few seconds for the switch signals to get back in sync.

 

[destey]

I took the recoil cover off, the flywheel looks like it was spraypainted with rust, a light coat covering it. Would this be the problem?

 

[tyler66665]

Did you rule out the TORS by bypassing them? I would give that a try. Unplug the two TORS wires and plug them back into themselves.

If the flywheel is all rusty that could be your problem. Possibly not sending our the correct charge but that is just a guess from myself... can say for sure.

 

[destey]

Did you rule out the TORS by bypassing them? I would give that a try. Unplug the two TORS wires and plug them back into themselves.

If the flywheel is all rusty that could be your problem. Possibly not sending our the correct charge but that is just a guess from myself... can say for sure.

It doesn't really seem like a TORS issue. TORS would cause it to cut out completely. The motor seems to have intermittent spark above 6000rpm judging from the strobing of the timing light. I have the recoil cover off and flywheel will come off tonight. When it all goes back together and if the stator isn't the issue I'll try bypassing the tors.

I'm 90% sure its the stator at this point but I'm batting 0 for 10 so far

 

[tyler66665]

Let us know how you make out?

 

[destey]

Stuck at the step of getting the flywheel off. I can't seem to get the allen bolts out. It feels like if I give the wrench any more torque it'll just round off the head. I have an acetylene torch but the sled is out in a field a good 500 feet from where I can get to it with the tanks. A little propane didn't seem to get the bolt hot enough. Any tips? I tried grabbing on to the outside of the head with vice grips while turning with the allen, but the vice can't get a good grip (usually works with stuck phillips screws). I'd rather not use an impact driver as I'm rebuilding my 250r because of ruining the crankshaft bearings from getting that flywheel off.

edit:

anyone know if yamaha used loctite on these bolts? Would it come loose with a longer application of heat from the propane? Or maybe a cylinder of mapp gas?

 

[destey]

Put on a stator from ebay, it now runs good as new.

The 3 allen screws came right off when I brought the sled into the garage and heated them with oxy-acetylene. Then I thought the 3 bolt puller was going to strip or break or the 3 bolts would strip out the flywheel, but with a little acetylene it popped off. The flywheel had a thick black grime all on the inner bore. The stator had a gooey resin and black substance.

2 of the stator screws came right off without any problem. The third needed an impact driver. The two screws holding the guide plate were tougher. I couldn't get a good hammer swing on the impact driver inside the cowel so I grabbed the head of the screw with vice grips and turned them. Sometimes works better than an impact driver.

And the thick coating of grime on the walls. Rust in the keyway made it difficult to remove. Almost couldn't get the flywheel off.