carburettor stutter

[RogueCarl]

Hey all, I'm back with my CG125 from 1980...
Okay so after the previous carb's butterfly valve snapped in half i bought a new one (save myself some hassle). I've fitted it fine, and set it up mostly alright, but no matter how much i fiddle i can't seem to get rid of the stutter it has when accelerating! If i accelerate slowly then i can control it, but then i'm just a hazard so that's not best.
The amount of stuttering also varies with the amount of fuel in the tank - more fuel= less stuttering.
Can anyone share their thoughts as to what i should do to eliminate this problem?
I've had a quick look online for the specific settings but to no avail (all parts are standard), and the old one went straight in the bin so i can't refer back to it
Thanks guys, Carl

[Matt B]

Well it sounds like fuel starvation.

Is the new carb NEW? Have you checked the fuel filter, jets, floats, needle etc? Have you stripped it and given it a blast of carb cleaner?
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stinkwheel: He had an animated .gif of a cat performing fellatio. It's not socially acceptable. It can have real life adverse effects on other people.

[RogueCarl]

[temeluchus]

fuel tap clagged up?
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Some shite cruiser. Now with guns and FREEDOM!

[RogueCarl]

nope, the fuel tap is just fine :/

[tomh]

Check what size jets are in the new carb compared to your original carb? There's been quite a few jet size changes over the years.

Also does both of the carbs have the extra fuel pump (Can't think of the name of it) on the side of the carb

[Srengam]

I had this recently, between 6k-7k revs bike would stutter, more noticable in higher gears.

In my case it was crap in the fuel tank blocking up the bottom section of the fuel filter. More fuel equals more surface area of the filter for fuel to pass through, less fuel equals less surface area for fuel to pass through. Not enough fuel to pass over the top of the crap blocking the filter and the bike stops as if it's run out of petrol (in my case my bike needed more than 5 litres to run at all).

I took the tank off, steam cleaned it in work, cleaned the filter and the tap with wd40 and then compressed air (hold the filter to your mouth and blow through it afterwards to check, I found that wd-40 actually sealed the filter up like a clear gum, so give it a good blast with air, then check with your mouth).

Put it back together and bike was fine. A couple of hours and no cost other than car petrol to take the tank to work solved it (you may want to use local garage with a jet wash, but if possible try and pick one with a variable pressure dial so you can lower the pressure a bit).

It might not be the case for your bike, but it won't do any harm, it certainly sounds similar to my problem.
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Suzuki GSX600F Katana (1997)

[RogueCarl]

TomH - it's exactly the same model of carburetor, just this one is new, they both have dual inputs too.

Srengam - definitely sounds like a positive move even if it doesn't work for me! do you think the steam cleaning is totally necessary? as i don't really have access to one :/ but the rest sounds easy enough, i'll have to give that a shot! thanks!

*to do - clean filter and tap thoroughly*

[Casper]

[RogueCarl]

awesome, cheers!


anything else i might need to check if that's not the problem? thanks!

[Casper]

[Lord Percy]

I have the exact same problem. I thought it was to do with the carb but it seems to come and go, no matter what settings I stick it on.

But fuck I can't just go and clean my fuel tank, it's fucking full of rust and even has two big wads of hard plastic in it (WTF?!). Special thanks to Vince Candelin, E two Motorcycles, Vincan Motorcycles (or whatever the hell he's changed his trade name now), who sold me the bike.

SEEMINGLY NICE GUY, AWFUL BIKES. Spread the word.

So for me it's looking to be new fuel tank time.... £80 for a hollow metal lump, yaaaaay. And if that doesn't fix it.... well... I've tried EVERYTHING!

[tomh]

[Lord Percy]

[abc123321]

What goes around comes around mate he/they will get it back.

I got my bike and was running ok for 2 days then kick start broke of then well the list goes on to eventualy cracking the case open to find bearings and conrod going.

So at least I know what I have changed has made it a refurbed engine.

In this day and age you cant trust many people with what they say cos most sput bullshit as everyday language.

Roll on my bike back on the road
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You get what you give in life.

[RogueCarl]

Hey all, over the weekend i did as instructed: cleared out the tank and cleaned the fuel filter (although it wasn't actually clogged up at all?).
So after taking it to work and back in the same condition as before, i've concluded that that wasn't the problem - it was all for a good cause anyway though.
so does that just leave it down to the Carburetor settings?
Carl

[Matt-]

[RogueCarl]

yeah the spark is fine, i don't believe there's anything wrong with the air intakes at all, so Carburetor here i come.
Also, i have to start it with the choke (i can turn it off immediately though), so does this mean i'll need to take it off and adjust the main jet? or can i do it all from the Pilot Jet (the one on the bottom, i may have named it wrongly)
Carl