Weird stuff

[BA80]

Greg, I had exactly the same problem some time ago with my SF.
Turned out to be the fuel tank cap vent. I asked the nearly identical question of why, on the Aussie forum. Check the reply I got, which explains the "why" simply

[IMG][/IMG]

It fixed my problem immediately, and it hasn't happened since.

Greg
You say all four carbs so it has to be something common to all 4. If you have your lines tied together it could be an air bubble trapped as I have had that issue before with a filter but only on one group of carbs for me as mine are separated. The only thing I could see is the vent in the tank as far as fuel goes. If it was electrical it would need to be supply of voltage to the coils or bad connection to the ignition. The only reason I even think it could be electronics is you say it sounded flooded and its very doubtful all carbs had a float problem at the same time but an ignition problem would act the same]after it starts to fire.

Never thought of the vent. The cap is/was new in 09. I'll check that.

My fuel lines run down under then back up to the carbs so it's pretty impossible for bubbles to form in the lines

[TopCatGr58]

Hey Greg,

Well, the most common problems have already been eliminated by no octy and the gravity feed petcocks. That leaves a possible air lock in the in line filters, OR...when was the last time you checked the gas cap vent??? It might have gotten gummed up and you developed the dreaded vac. lock in the tank once it got just so low! JAT!?

T.C.

Hmmm, gas tank cap vent...where have I heard that idea before....oh yeah....in my FIRST reply a few days ago....guess that speed reading doesn't always pay off eh Greg!

T.C.

[BA80]

You got me there TC. I did miss that but I did check it and it's still shiny new and clean.

[jetmechmarty]

You got me there TC. I did miss that but I did check it and it's still shiny new and clean.

Where did you source the cap? How long was it sitting on the shelf before you bought it? The filter in the cap is a piece of sponge in the OEM version and it rots over time. I expect the aftermarket version won't last half as long. I replaced mine with a tiny piece of Scotch-Brite. I don't know how good a filter it is, or how long it will last, but I have three Yamaha Special caps running that way and have been for some time.

[BA80]

I know what the inside of the cap looks like Marty, I've had a couple 3 apart.

I don't really remember where I got this cap from since it's been 6 - 7 years since I put it on there. I'm thinking parts-n-more.

It's EXACTLY like an OEM cap, I just swapped the lock out when I got it so my key fit.

[jetmechmarty]

I don't really remember where I got this cap from since it's been 6 - 7 years since I put it on there. I'm thinking parts-n-more.

That may be just long enough for it to rot. I think it's worth a look.

[BA80]

OK, here's pics. This cap doesn't have a filter, it has a baffle.



This is the first time I've taken this aftermarket cap apart but as you can see, there is no filter. Just a baffle and everything is perfectly clear and clean.

[jetmechmarty]

Well....Now we know.

[BA80]

Well....Now we know.

Everything but WHY the damn thing did what it did.

I would have been happy to find a problem.

[ViperRon]

Well you unfortunately have one direction to go Greg. As you said it was all cylinders and you have eliminated the gas flow issues so the only other direction is electrical and I know you have checked that but a bad crimped wire going to supply the ignition fuse give me a fit 3 years ago because of how it acted. I only had the bike cut off twice but it developed start problems related to the self hold path that drove me nuts and I just had to jumper around to find it because a meter would not find it. Good luck hope your issue does not act like mine did in the end.

[motoman]

Well you unfortunately have one direction to go Greg. As you said it was all cylinders and you have eliminated the gas flow issues so the only other direction is electrical and I know you have checked that but a bad crimped wire going to supply the ignition fuse give me a fit 3 years ago because of how it acted. I only had the bike cut off twice but it developed start problems related to the self hold path that drove me nuts and I just had to jumper around to find it because a meter would not find it. Good luck hope your issue does not act like mine did in the end.

Old school theory works here majority of time a I and Ron have stated......."electrical before fueling". In this case from what you initially stated........secondary ignition, not primary.

[BA80]

Switching from main to reserve fuel must have completed the broken circuit..

[motoman]

Switching from main to reserve fuel must have completed the broken circuit..

There ya' go..........whatever works.

[BA80]

Well Brant, I checked and rechecked every electrical circuit on the bike when my exhaust was having an electrical issue. Pretty sure it hasn't changed in 3 months since all the electrics are working fine.

[motoman]

Well, even tho you replaced all that under timing vcover at some point, those wires flexing and breaking internally sure can cause sporatic ignition issues.......all works and checks out fine, then for an unknown reason doesn't while running. That advance mechanism sure can raise TEMPORARY havoc with that constant wire movement when bike is running. IMO, still would be worth removing that cover and trying to separate every inch of those wires,...... just for peace of mind if nothing else.