Bike Stalling

[brainbug007]

Hoping someone can offer some advice on this one. My bike has started stalling on me alot. Especially when I come to a stop? After a stall it's a right git to get started again and makes alot of poping noises which sound like they're coming from the carb/airbox. I've tried giving it a bit more fuel with the mixture screw which didn't make any difference (difficult to adjust as the carb has to be removed, currently set at 2.25 turns out which is the max they haynes manual recommends). I've also tried putting the idle higher but that doesn't seem to want to go any higher. The haynes manual recommends 1500rpm and mine sits at 2000rpm and sounds like it's gonna die any second. I've tried putting it up towards 2500 & 3000 but then when you blip the trottle the engine just keeps going and takes 5-10 secs to then fall back down to idle?

[motomaniac]

what is it?... how long since the carbs were cleaned?... could be a blocked jet or even a hole in the diaphram .... sounds like fuel starvation, but i could be wrong....

did it start after filling with juice?.. could be water in the fuel.... you have an inline filter?... could be blocked....

now someone elses turn for advice...

[robo]

Does sound like its drawing air on the induction side. Does it have those rubber inlet manifolds? They can perish with time.

Bob

[brainbug007]

It's a honda cbr 125 clone which has a honda cg 125 engine in a nutshell. So it's an OHV setup if that makes sense. It's about 3 months old now and done just over 2k miles. Hard to say when it started but it was definately round about when the weather got colder and wetter so water could be a possiblitity. I have refilled the tank a good few times though in between. There's no inline fuel filter..

The manifolds are rubber but looked to be in good shape and a decent seal when I last tried adjusting the carb. If it is an air leak somewhere, wouldn't that be noticeable at speed though? I've tried driving it on 0-75% choke and it doesn't stop it stalling. There not difference in performance either really at speed which I thought would have ruled out running to lean?

[wylliezx9r]

If it's a chinease copy, the carbs are absolute sh1t. My mates son had a pw50 clone, the carb was un-tuneable. You may have the same issue.

[ozzy1]

I would take the carb apart and give the jets a clean and then set it back up to the specs listed in the manual to start with.

[dogwood]

Originally Posted by wylliezx9r

If it's a chinease copy, the carbs are absolute sh1t. .

Absolutely agree.
My GY6 seems to demolish carbs

[brainbug007]

Great... I'll try cleanin the carb out 1st then. I'm guessing it's likely to be the pilot needle that's the problem as the mid & wot are fine. It's a pz26 carb clone i've got i think so anyone know what the original would be (eg klien or mikuni?) and what bike would have it that I could nick a used on off?

[robo]

Originally Posted by brainbug007

It's a honda cbr 125 clone which has a honda cg 125 engine in a nutshell. So it's an OHV setup if that makes sense. It's about 3 months old now and done just over 2k miles. Hard to say when it started but it was definately round about when the weather got colder and wetter so water could be a possiblitity. I have refilled the tank a good few times though in between. There's no inline fuel filter..

The manifolds are rubber but looked to be in good shape and a decent seal when I last tried adjusting the carb. If it is an air leak somewhere, wouldn't that be noticeable at speed though? I've tried driving it on 0-75% choke and it doesn't stop it stalling. There not difference in performance either really at speed which I thought would have ruled out running to lean?

If its only three months old why touch it launch the thing back at the dealer, it must be under warranty. I though we were talking about a bike that was a few years old.

Bob

[brainbug007]

The dealer(s) are a bit of a joke really with these bikes. They charge from £100-£200 for a service on a bike that costs £1k to buy... They didn't fix quite a few problems when I put the bike in for it's first service and just dismissed them as the bike is working as intended :S Considering most of the parts for them can be bought from ebay fairly cheap I figured it was easier, cheaper, and less hassle to just keep it running myself.

I had another go at trying to correct the stalling and turning the mixture screw out to 3 turns seems to have resolved it for the most part. I checked all of the seals with some wd40 while the engine was running and didn't find any leaks. I did notice though that it only really cuts out when I stop quickly compared to a gradual stop. This made me think perhaps its something with the float stopping fuel to the engine as it could be doing something like sloshing around? The other thing that occured to me is the mechanical fuel pump that runs off the inlet vacum is crap and won't handle a sudden change?