How's this for a theory?

[EARTHWALKER]

Some may have seen my post a few weeks ago, but for those that didn't, here is a short summary.

Basically, as long as you stay below 70mph, the bike runs like a dream. If it's pushed beyond that, it will cough, splutter and eventually die.
I recently had it in the garage for some back pads, but the mechanic said they are fine and didn't need changing. I left there and got about 1 mile away and the bike died while doing 40 (it had been raining hard). He diagnosed the problem being the carb having water in it.

My theory is this:-

1) If my petrol cap seal is gone, water would be getting into the tank when it rains; causing what I am experiencing? I'm quite certain of this one.
2) The more speed, the more air will be sucked through the broken tank seal, stopping the bike.

Good or bad theory? I just thought of it while in bed...lol
I've recently changed the HT's, Coils and CDI with no change in problems.


Try not to laugh...I don;t know much in the way of mechanics. Give me a PC, printer, notebook, netbook, digicam and I can strip, change, repair, look smug, but bikes...oooh, scary
____________________
Insanes Numquam Moriuntur

[.]

Theory seems fine providing you actually find some water in the carb.

[EARTHWALKER]

[The Artist]

All fuel caps should have a vent to allow air in to replace fuel you use up.

To be honest it would splutter and die before 70 if that was your main problem. The cutting out at 40 could be the water though.

[robocog]

I would say part 2 is the opposite of what I have read

Leaving the filler cap off would not cause running issues, just a tad dangerous

If the seal was too good on the tank it would create a vaccum in there (because you are using fuel in a sealed tank, and it needs to be replaced by something) and could cause fuel starvation and behave like there is a blockage (filler caps need to allow air in and usually have a small drilling ...maybe yours is clogged?)
As you are running carbs it may pay to crack the float bowl drain screws open when it has done the dying thing...if they are empty then it would be fuel related

I could imagine that this is not such an easy task though if they are not easy to get to

If next time it dies you crack the filler cap open with your ear next to it and you hear it suck air in then you have found a possible cause and could be done fairly immediately after the event without having to strip the bike down


Regards
Rob

[el_oso]

i doubt it

but possible.


what bike is it?
____________________
Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[EARTHWALKER]

It's a GSXR-1100 WP. I like the ear thing as it made me smile.

I am deaf btw
____________________
Insanes Numquam Moriuntur

[Kickstart]

Hi

If there is no vent to the tank then it will cause problems. No air in means no fuel can leave the tank. Tends to get worse at higher speeds (and could be the problem you are having).

Water in the fuel would probably stop the engine with barely any throttle. Water sinks to the bottom of the carb and the main jet is down there, so as soon as you move off the idle circuit the main jet will probably draw in the water. Takes VERY little water to cause a problem.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[karoshi]

[el_oso]

have you checked your air filter/passages for holes/blockages etc
____________________
Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L