dangum carb question - 85 BR 250es

[rally4x4racer]

I hate to ask a simple carby question - but I am having a hard time figuring this out. I know some of you guys on here would have it tuned up in a second so I give up - I figured I would post and hope for the best.

85 250ES and 350X - brought them both to FL from the Ozark Mountains a while back.. and just got around to getting them running again. Neither gave me probs while I was in the mountains - but both are acting up now.

250ES - everything seems fine - but if you go from no throttle to WOT super fast it cuts out. I figured this was due to the pilot jet being lean so I found a 42 that was in an old 350X carb and replaced the 38 that was in it. No luck. Still the same.. I have fooled with the pilot screw etc.. cant make it better.. machine is pretty much stock other than the silencer being rotted out.. any ideas?

350X is similar - but it has a 400es carb and a DG pipe - it rips, but ever since I got it down here it seems to backfire on decal a lot, it also has the zero to WOT loss and the last time I rode it I noticed it choking in the intake a bit.


well - while I am at it.. I am also looking into a B80 issue - when you hold the BW80 at WOT it never cleans out... kinda bogs on WOT indicating its too rich - but it has an oil can and I have never had to adjust it.. I see a bolt - maybe it adjusts the oil input? can I just add some fuel to the oil? LOL.. man that's lazy.. but time is precious.

Many thanks..

[Flyingw]

That problem you are having is very common with the QA series carb. I have rebuilt dozens of the QA carbs this past year and more than half have that same problem. I have changed the slide, butterfly, shaft seals, messed with the pilot jetting, adjustment screw, and noting seemed to change the problem. The problem only shows itself if you stab the throttle hard right off idle. The fuel source right off of idle is the pilot circuit so it has something to do with that. I have run out of ideas so all I can offer is don't stab the throttle off idle.

[rally4x4racer]

"don't stab the throttle off idle" lolololol that might work for my girls big red - but I def. have figure out the issue with the X!

[DohcBikes]

Try a few different slide/jet needles if you have access to some. Needle position should be experimented with as well.

[rally4x4racer]

I have a few various needles somewhere, but I will have to order some screws for the choke plate beforehand since these are about toast.In any case, maybe I can fool with the needle without completely pulling the carb and save some work. Has anyone ever noticed the rubber boots on the big reds shrink up after about 30 years?

gave up on the bw80 btw.. I think it needs a new set of rings. ... it wasn't a bog after al more like a flat spots that seem like compression over powering rings stuck to the piston.

[tri again]

See if you can get FW to send you a good carb?
The QA 1 carbs are trouble unless completely redone.
I do have an aftermarket carb on an 85 sx that works perfectly.
Flip hand choke and accel pump.
I'll go look at the numbers if you want.

[rally4x4racer]

thanks... hopefully I wont have to go as far as replacing the carb completely. I do have a stock 250sx carb somewhere that I may rebuild and try later.

I went to order some new screws for the choke plate (no idea what this piece is actually called, but its the disc in the middle that opens with throttle) and I do not see the choke plate or the screws listed on servicehonda microfiche.. I see the tiny little screws in the slide (attached to the arm link set) are listed - but not these.

Any idea on how to get these little screws? Maybe the slide screws are the same as the plate screws? Carbs suck

[Flyingw]

I have many scrap carbs so I have the screws.

[Jmoozy27]

I go to a hardware store and match them with stainless.