Bike loading up when fuel turned on.

[Mick D]

yeah mick that vent issue has got me twice before (im a slow learner). It usually makes them starve for fuel but depending on the temp of the tank they can build up pressure too. worth as you say, Popping the cap to eliminate that possibility.  that fuel usage as one of the guys mentioned is of a concern as it does seem excessive. This is going to be an interesting thread i think.

Yeah Pokey, I think a non vented cap on a non vented tank getting the shit shaken out of it with the kick start action, might be like every Jerry can I have every opened

[evo550]

What about the little plate doovy that goes under the big throttle slide return spring and holds the slide needle in position?
Is it there doing its thing?

My money is on this or something to do with needle/slide.

[TT5 Matt]

did you try the 430 carb on the good running 400 to be sure it's ok?you can make a bike running level gauge out of the bowl drain cap and tap it for a 90 degree bend.when I rebored my ts185A I put a yz125 32mm carb on it to match the port job I gave it and it ran like crap loading up no matter where I adjusted the float level and it only ran good when the bowl was nearly empty and upon checking the needle/needle jet I could see the wear and why it wouldnt seal off when on the pilot jet.when I put the std carb back on the bike idled like it did before

[Paulos]

What about the little plate doovy that goes under the big throttle slide return spring and holds the slide needle in position?
Is it there doing its thing?

My money is on this or something to do with needle/slide.

Me three. Was the whole carb swapped or just the bottom half with the cap, slide, needle etc from the original carb used?

[80-85 husky]

my nephew had a wr400 yammie that used to run for 30 mins then stop...just enough time for him to get out to the "back country" on the property he was working at. it would not start for 20 - 30 mins then it would do the same... it was stripped to the crankshaft twice with no result over a year. he bought it home and I took it for a spin. no probs...rode it for an hour without a hiccup. then....decided to slip home via the road...15 mins and bwuaaaaahahh it stopped?? ( just near a mates place) so had a coffee and came out and kicked it and it went?? so riding home quietly I noticed it was not giving me "main jet flow" skidded to a stop, opened the tank cap and swoooosh...sucked whole lot of air in. checked the breather ... ball bearing jammed in it.

Apparently some ones chookshed was burned down later that nite...

wait! moral...blocked cap seemed to reduce flow more than push it but I can see how fresh fuel in a sealed tank could load the needle and seat.

[crossedup2]

This might sound stupid but pull the head off and see if the piston is in the right way.

A mate had an '80's model CR125 that sounded similar in many ways. Turns out that he did the simplest mistake in a rush. It ran but loaded up. Had us all scratching our head until in pure frustration he pulled it down only to fine the piston in the wrong way.

Peter B

[bigk]

All good thoughts thanks, however I have checked all of that including if the piton is in backwards (it's not), it's doing my head in. The bike has great spark, the timing is correct, it starts from the kicker (albeit with the throttle held wide open), so it doesn't seem electrical, but could it be an ignition issue?
K

[Lozza]

Need some ideas from the brains trust please.
I have a WR430 Husky which has had a complete engine build (rod, bearings, seal, piston etc), done may & nothing is different to any of the others. The bike loads up & won't run with the fuel tap turned on. Turn the fuel tap off & as it leans out it runs clean until it runs out of fuel. If I crack the fuel tap (even 1/4 open), the bike immediately begins to load up again. It used a litre of fuel in about 5 mins of static running, most of it out of the exhaust pipe. Standard 38mm Mikuni with standard jetting for the model.
I have checked, the needle & seat, floats, reeds, air cleaner with nothing out of the ordinary or obvious. I have tried a second carby which I know for certain is good with the same result. So the bike gets too much fuel or not enough air, but I can't see why either should be happening. Anyone experienced this or have any ideas on what is happening?
Cheers,
K

Sounds very much like float valve as your doing the job of the float valve with the fuel tap. It may look ok but the head pressure from the fuel is too much for it. It could be too big a size for it also.

[Mick D]

If you want to rule out ignition from the equation?
Strobe light it to check its consistency whilst running.

[Mick D]

Other than that. Matt's idea about the hose from that threaded bung in the bottom is sound. At least you will know wether a varying fuel level is in or out.

[John Orchard]

When you swapped the carbs, did you also change the needle & slide?  I think someone mentioned the needle sliding up in the slide (not secured down).

Failing that, have you run it with the airfilter element out?  Maybe the pores are not flowing enough air from being cleaned in wrong solvent?

[Curtis]

You didnt answer if the fuel tap was standard? Iv had an issue before with a oversize fuel tap. The standard carb couldnt stop the extra pressure.

[evo550]

Take the carb off but keep attached to fuel line, turn fuel on and see what happens..

[shelpi]

you have my attention;
can you run the carbs on another bike just to cross check
place another tank onto it ( I use an old lawn mower tank for bench testing stuff )
maybe a bit of this and a bit of that ie slightly high float level with needle and seat sticking mid drift, needle jet, jet needle is all that ok as in is it locked down with washer, clip, spring (but on both carbs)
good luck

[ITDOG]

Check the reeds out?