sticking throttle

[skid jackson]

06 300

My bike has the following disconcerting habit .....

If you ride through water deep enough to hear a change in the sound made by the air box ..... Shortly thereafter the throttle starts to hang up/stick. My bike does this any time I cross deep water. Fortunately its not that often. the last time was a few weeks back in the middle of an enduro. The lower carb vent lines are run down by the linkage,have a 45 degree slash cut and are slit. The upper carb vents go to the air box. I'm curious if anyone else has this issue when dealing with deep water?? Actually its not really that deep but evidently deep enough. The throttle will hang if you run it up onto pipe. When you lift off the throttle it won't snap back. Assuming you get the clutch in you can then work the throttle and it will come back down. If you keep off the pipe the throttle usually won't do anythign crazy but you might get a neat mid throttle cruise control thing going on sometimes. Whats really interesting is if you go through some whoops at a good clip shortly after the water crossing it will go wfo in a big way!! Something about the way the bike goes up and down really seems to set it off!!!

My first theory was some gunk was getting sucked in through the air box ... but the air filter should stop any debris. The other thought was water coming up the lower carb vent lines ... but that isn't suppose to happen if your running the others up to the air box right?? Not only that but is feels like the slide is getting hung up which would indicate grit .. which I doubt would make it through the jets. Or is it just water in the gas going thorugh the system causing alean wind it out conditions which make the slide hang? The other thought was gunk coming down the throttle cable into the slide area. However I can't say I have ever really found anything in the slide area.
The solution to the problem is to pull the carb and clean it. After that it usually runs fine.

My last cleaning I did find debris inside the float bowl drain catch thing. I did not really see anything in the slide area. The carb was such a bitch coming out that what debris I found in the venturi area probably came from removal. I checked the float height and it was about 8mm which I believe is about right. Ordered a new throttle cable.

anyone else have this problem. It is almost garaunteed that the throttle will start hanging if you run it through deep water. You can run all day in wet sloopy conditions and it won't miss a beat. But if its dry as a bone and you hit one semi deep crossing you better be fast with the clutch fingers for the rest of the ride.

[TNT Cycle]

check needle for burrs, scratches, nicks, etc. they flop a bit in the slide and if not smooth will hang on needle jet....if sand is in the bowl it will usually be a problem at some point....

[GMP]

Skid,

This is a classic case of exactly what happens when dirty water is sucked up the carb vent lines. Dirt and especially sand (larger) sit in the bowl and when you gas it hard are drawn up between the needle and nozzle, jamming it. I guarantee you have vertical scratches on the needle.

Now since you split the vents, why? Logical answer is the upper lines or the "T" passage in the carb body casting are blocked, so the only vent is the lower lines. These lines are always pulling air so when its dry they will pull fine dust/dirt as well. Run the small filters on the ends of the upper lines, or make one up from a film container and some filter foam. If your in really deep water (at or over the carb) long enough then the water will try to seek its level and flow up the lower lines into the carb. It mosty depends on how long your in the water. There are kits available with check valves and small filters if you ride in these conditions.

I think the sound change you hear is the pipe vibration being damped by the water allowing you to hear the airbox more, I notice this on a small river crossing we do fairly regularly.

[motorhead]

My 05' 300 does the exact same thing skid. My dealer told me to look for scratched needle and dirty air filter/poor air filter cleaning technique. Kinda weird no other bike I've owned over the years exhibited same behaviour,and I still clean filters same way I have for 31 years. Can be kinda nerve wracking at times,tryin' to kick out the jams on the trail with a digit or two on clutch lever waiting for her to lunge the wrong way from ya if and when. I do ride some sandy areas though,how bout you skid? Maybe sands gets sucked up vent hoses???

[GMP]

I figured this out years ago on KTMs, same carb. Any PWK equipped bike will do the same thing with unmodified vents, it has nothing to do with the bike. I've been running split and filtered vent lines since on three GGs and never a problem. Clean the carb body, vent lines, and add the filters and you guys should be fine.

[skid jackson]

motorhead not alot of sand .. but the water I was running through was pretty churned up. I got a chance to look at my needle it does seem to have an area with some wear on it and a few scratches. I'll have to get some filters and one way vents for those hoses.

[motorhead]

Sounds like I'd better inspect my needle and look into a filter kit although since I've never ran one,none come to mind. Any suggestions on brand or style to search for gmp? I wanted to replace my dull original vent hoses with shiny new ones this winter so might as well get'em all done at once. Thanks

[stainlesscycle]

i run this one:
http://pcracingusa.com/store/product...roducts_id=113
it was less expensive than the film cannister style ones (7602 and uptite)
it would be simple to diy one, but for me, it was quicker and easier to spend the $20.00

[GMP]

I got mine here:

http://www.kevinscycleracing.com

I have not seen the need for the "T"s on the PWK carbs as there is a "T" in the casting where the tubes connect. I have had both the check valve type and just the small filters (what I have now) and both worked well, never any dirt in the carb. I just just occasionally flush the filters out backwards with a shot of contact cleaner.