Carb problems

[JonnyB]

Have cleaned the carbs on the gs450, but i can't keep the dam thing running. It will start on choke and run, but when i put the choke in it starts to back fire the dies.

any ideas

[mick]

fuel starvation?, weak mixture? blocked jets? cheers Mick.

[SteveD CB500K0]

As Mick says, your symptoms point to lean running which can only be attributed to fuel starvation, either through blocked jets or an air leak.

[Bryanj]

the 2 bikes that gave mechanics nightmare with carbs were the Suzuki GS and the Honda CB250/400N(or T). We used to strip down and send for ultrasonic cleaning with the proviso to the owner that we only stripped down 3 times and if it still didnt run right it was up to them to get replacement carbs.

It seems that crud sets like concrete in the jetways

[JonnyB]

  Typical  I have managed to get it running better, I can now put the choke in without it dying but idle running is still a bitch. I have an ultrasonic cleaner - What fluid did you use to use?

[Bryanj]

Jonny this was a long time ago and we didnt have a cleaner, we sent them out to an engineering firm that had one.

Alternatively strip absolutely everything out (ESPECIALY Rubber bits) and submerg the bodies in closed tins of cellulose thinners NOT GUNWASH. i dis this with 500 bodies and left them in the bed of the pickup for a week whilst i drove round----came out like new

[OLIVER1GEORGE]

HI mate i had the same problem with my carbs on my 400/4 it took 3 strips to get them right i never had them ultra sonic cleaned just did it my self took every jet out, idle jets main jets checked all the orings ,replaced them with some i bought from halfords but i will say the first few times of me putting carbs back on it would run only on two sometimes and back fire then i stripped again and found 2 jets that were blocked i soaked them over night and blew them through with compressed air and when i put them back on it seemed to do the trick it ran like a dream even better now there balanced
goodluck

[JonnyB]

Got this carb problem mostly sorted now, except if i blip the trottle if doesn't come back down, it must be air gewtting in but where from?

I've stripped and cleaned the carbs a dozen time or more now, so i'm convinced there are ok.

Any ideas???

[Bryanj]

Carb balance will give you the same symptom mate as will "sticky" slides

[Yoshi823]

For air leaks testing I spray WD40 around the inlet rubbers while the engine is running.If there is a leak the engine will pick up the revs slightly.

On CV carbs I use a bit of Brasso wadding to polish the slide and the inside of the slide bore of the carb.This removes the residue of petrol off the surfaces without damaging them.

I had a problem with the carbs on my wifes CB550F2 when I came to sell the bike.The engine would not start after a 6 year layoff...and I hadn't drained the carbs when I took it off the road and stored it in the back of the garage.It took a good 3 hours of cleaning to get them ready.Once they were back on the bike and recharged with fresh petrol the bike started up first time.As has been said,balancing the carbs makes a big differance,but only when everything else has been done.

[Yoshi823]

Got this carb problem mostly sorted now, except if i blip the trottle if doesn't come back down, it must be air gewtting in but where from?

I've stripped and cleaned the carbs a dozen time or more now, so i'm convinced there are ok.

Any ideas???

There is a trick for seating the diaphragms correctly. Lift the slide...by holding it up then lowering the carb top down onto the seated diaphragm, making sure that the small 'O' ring is in place, then screw the cover in place.

You can actually run a CV carb without the slide in place, so it wouldn't have any effect on tickover. I've tried this in an attempt to find a problem on a friends bike.