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View Full Version : Bogging problem (detailed description)



Uncaged
04-22-2004, 10:02 PM
Went to Hatfield the other week... You know the week where it rained the whole week? Ya, that's the one. Despite that, had a blast. Anyway, onto the question.

The 300ex developed this very elusive bogging problem. Of course at first I thought it was related to going through the huge puddles, but it would do it when there hadn't been a puddle in sight, the airbox was drained:rolleyes: , and doing a hillclimb or going along on relatively dry trail where water wasn't splashing on anything.

Description of problem:
Going along, 1/4-1/2 throttle or so, any terrain, suddenly bog (boooooowwaaaahhhhh) and pumping the throttle didn't help. Back off the throttle and it would idle very low (chug). Touching the throttle would produce bog. Sometimes pumping (feathering) it from here would spring it back to life, sometimes it would just stall out. A few seconds later it would be running fine.

At one point, it started to bog while I was rolling along at a good clip and found that if I held it at right about 3/4 throttle, it would run, no less or more than that or it'd bog. I ran for a little while holding it at 3/4 throttle, but you can't do that forever. Other times when it'd start to bog I'd try to go back to that 3/4 spot, but it wan't having anything of it and would still bog there too. A few seconds later, it'd run fine.

When running WFO it never happened.

Took the carb off the first night, sprayed the *whole thing* down with carb cleaner paying special attention to the float and float needle/seat (thinking it was sticking).

Next day it did the same thing. :confused:

Stumped, I am. Who knows what the heck I'm talkin about? Help!

mikeminyard
04-24-2004, 05:38 PM
No idea, free bump.

TheFontMaster
04-24-2004, 06:07 PM
I've ocasionaly had that problen too, and i have no idea what would cause it. Altho thats only happend to me about 4 times, and it hasn't been a constant problem, but I know what yer talkin about.

TheFontMaster
04-24-2004, 06:09 PM
It kinda feels like the engine is sudenly running lean.

KY Woods Rider
04-24-2004, 07:25 PM
Sounds like it could be an air leak, so do a good inspection of the air boots if you haven't done it already. Also, it could be something momentarily messing with the fuel flow, so other things to check would be the gas cap vent, the carb overflow line, and the carb vent lines.

Uncaged
04-26-2004, 02:04 PM
I checked the air boots when I took the carb off (to clean the insides) and then when I put it back on, so I don't think there's anything going on there.

Good idea about checking the gas cap, I wouldn't have thought of that. As far as the vents go, I'll look at the bowl vent, but I don't remember seeing any other carb vents besides that one. Is there another one that vents the top of the carb that I didn't see?

Thanks for the suggestions. :)

hondarider2006
04-26-2004, 03:34 PM
This sorta happened to me. Ended up earlier that day I was messing with my needle, and the little screws that hold that plate over the needle to hold it in had fallen out....it would idle, and run at WFO....but nothing in between. Have you checked that out??

04'400ex'er
04-27-2004, 06:44 PM
Check the spark plug and see if it is fouled.check to see if your air filter is clogged with dirt. Check to see if your fuel lines are clogged.otherwise, i dunno. its in the carb.

H_W
04-27-2004, 08:33 PM
I just recently had the exact same problem with my 400. I found the cause yesterday and fixed it today, with the help of a friend of mine. We took my carb apart and found out the clip on the needle was worn out. It would not stay in the groove. It was just sliding up and down the needle. I put a new clip on the needle and the problem is gone.

Uncaged
05-19-2004, 02:05 PM
Just wanted to post the followup to this problem.

The cause was a black rubbery substance that was in the carb bowl vent tube. It was soft and was layered, like it didn't get in there all at once in one big blob, but rather a little at a time and built up on itself. Not really sure what it was.

So it looks like it was built up enough to let a tiny bit of air past it, but could plug up easily and prevent gas from pouring in the bowl and venting out past the clog.

Took it for a spin, and no more bogging.

Thanks for all the suggestions! :D :macho

hondarider2006
05-20-2004, 02:13 AM
glad you got it fixed:cool: