Carb guru's required

[mellow]

just been out on the 125 for a good thrashin and its still not perfect!
Goes really well once i have pulled away but its pulling away where the problem lies.i've read all the carb info and know its the pilot circuit.so i again stripped the carb and cleaned all the pilot circuit so it was spotless and got sprays through all jets and passageways there should be.also triple checked float height.the symptons are just as i initially touch the throttle it kinda bogs like its gonna stall so i have to blip throttle to get revs upto 4k then pull away.also when stoppin for a junction etc sometimes it doesnt drop to tickover immidiately.it sits about 2k.
So if anyone has any ideas for me id really appreciate the advice.
Cheers

[elsie1411]

mellow do you have an air leak any where?

[mellow]

i've squirted wd40 round rubbers while its running with no noticeable effects m8

[elsie1411]

crank seal? it's just that if the carb is spotless it kind of points you to the mixture weakening . does it die if you pull out the choke when its hot?

[elsie1411]

Gary's answere is better than mine so i would go with him first

[mellow]

yep dies straight away if i turn choke on when ticking over

yeah gaz i know.got the service manual.pilots bigger but the main is smaller than the english model

[mellow]

yeah?i got a 10w carb here i can rob the pilot out of but not sure if that will sort it other differences in carb.Throttle valve cutaway and main air jets different.here's the specs of carbs below;

1985 1GU-SE1 Model
..................................EXCEPT FOR ENGLAND.................FOR ENGLAND

CARB...........................VM26SS MIKUNI......................VM24SS MIKUNI
I.D MARK..............................1GU-00.....................................12A-01
MAIN JET...............................190............................................195
MAIN AIR JET.........................1.2.............................................2.5
JET NEEDLE/CLIP POSITION..406/4......................................5GN36/4
NEEDLE JET............................P-2............................................O-2
CUTAWAY...............................2.0............................................1.5
PILOT JET...............................25..............................................20
PILOT AIR SCREW.................1 1/2 Turns out..........................<-
VALVE SEAT SIZE....................2.5............................................<-
STARTER JET...........................25.............................................<-
FLOAT HEIGHT........................21.0+/-1.0mm...........................<-
FUEL LEVEL............................0.5+/-1.0mm.............................<-
IDLE SPEED...........................1300+/-50r/min..........................<-

1987 2HK-SE1Model
CARB..................................VM26SS MIKUNI
I.D MARK................................1GU-00
MAIN JET................................190
MAIN AIR JET..........................1.2
JET NEEDLE/CLIP POSITION...406/4
NEEDLE JET............................P-2
CUTAWAY...............................2.0
PILOT JET...............................25
PILOT AIR SCREW..................1 1/2 Turns Out
VALVE SEAT SIZE....................2.5
STARTER JET...........................25
FLOAT HEIGHT........................20.0~22.0mm
FUEL LEVEL............................ZERO~0.5mm
IDLE SPEED............................1300~1400r/min

Ieven considered the correction factor for altitude etc but it was such a tiny amount (we're talkin .3 difference on pilot) didnt think that was worth changing

[mellow]

Jul 30, 2011 23:53:20 GMT 1 garyrdrobbo said:

but the uk was restricted so hence the 24 mm carb

But the 2HK is uk mk3 isnt it that has exactly the same carb.26mm
Doin my tits in too.R1 was fine today though ;D
And i saw a black f2,2 rd 400's and a rd 250air cooled

[mellow]

its up there m8^^^^^^^ 2HK 1987 VM26SS

[mellow]

yeah im currently building a pyre for mine if it dont run right soon the fuel in the tank will be used for its own celebration of a short life
f**king motorbikes

[mellow]

thats it! i give up!
Adjusted fuel level, set tickover and it sits there ticking over fine.
still splutters on pullaway just as throttle starts to move slide.Have to rev to about 4k to pull away. Once goin its perfect until i stop.sits there ticking over about 2k. If i leave it there its same as before,if i turn throttle screw down next time i stop it nearly dies
Really doin my tits in now.aint got a clue

[Norbo]

mells some times i fined no matter what you do changing jets cleaning carbs etc nothing will make the bike run correct . so just swop the compleat carb and like magic its running fine . let me see if i have a 125 carb i can send you to try out .

[mellow]

u got any 1GU-00 Carbs then m8
I know what ur sayin.its gotta be the carb.cant think of anything else causing the pulling away issue

[mellow]

apparently not m8 a friend has a few and says they run fine
its the same with standard pipe and nikon.And yeah mine revs quite high,although i like to change about 9 1/2k ;D im sure i had 60 in third out of it.shame about the pulling away

[kennyroberts]

i have gone through all this on my gpx 600, exactly the same problem x 4 carbs,
it took over 2 months in a garage for them to draw a blank , and me and a mate of mine with determination to sort it out did so after 2 hours,, did my head in big time ...2 sets of carbs, multiple strip downs and clean ups.....arrrgh, and to think, when i get closer to completing my 350, ill have it all over again

[mellow]

wot was it then m8
;D

[wiseric]

I'm no expert and no doubt you have already tried this but I had a similar problem on my bike with it bogging down at low revs and then when it did pick up it would not drop back to idle but sit at 2k for a while, it had that sound like it was running out of fuel at low revs. Anyway after checking everything twice I eventually solved it by raising the needles to one notch from top(circlip one notch from the bottom) and adjusting the air screws 3/4 turns out instead of 1.5.
Picks up sweetly now and drops straight back to idle again. Wish I had done that first instead of cleaning the carbs AGAIN
Sounds like your best bet would be to test it with another carb, easier said than done I know.
Hope you solve it soon.

[mellow]

Another question.
When setting FLOAT level......are you supposed to leave the gasket in place and measure from that or remove the gasket and measure from the carb body where gasket normally sits
I ask this because haynes book of lies says to remove the gasket then measure

[mellow]

Im waiting for a new one to arrive m8.next size down to

[blue2smoke]

mells , try all the above, i had the same issue years ago.

I phoned "ALLENS" carb parts guys and described the symptom , told them the carb model& size and they sent me a different needle.

Fitted new needle and fark me couldn't believe it spot on , got back on the phone and kissed his arse lol......

worth a try

phil

[mellow]

yeah thanks m8.will try the pilot first,its gotta be that well thats wot gaz n i think
failing that il ring allens.
Cheers

[mellow]

i have FINALLY sorted the bike out!!!
BITCHING f**kING BIKE!!!!
After checking float height countless times i decided to check the fuel level with the carb off the bike. With the float height set to 21mm the fuel level was wrong so i adjusted it so the fuel level was correct. I changed the pilot down to 22.5 from 25 as all the other uk 125's had a 20 pilot jet.This made a "slight" difference but still not anywhere near perfect. Today i was going to bite the bullet and try my 10W carb but i thought i will check the reeds while i was there as i was getting really fed up with checking carb. Well....guess what.......the reed petals were sitting up from the block and the stopper plate was way out of spec!!So off i went to my hoard of spares to find my spare reed block.checked it,all looked fine so fitted it to my barrel. PROBLEM SORTED!!
It now pulls away much better and the revs actually drop to tickover pretty much straight away. Been for a ride on it.had 90ish out of it )
I can now put this project to rest.Took a couple of pics.will add them to my rebuild post soon.
Thanks to all for advice given

[blue2smoke]

well done mate... quick aren't they when running good

[mellow]

well.....yeah not bad has to be worked to overtake cars...but i am comparing it with a 350 ypvs and an R1 ;D
Did a flat out run and had 70mph in 3rd n 90 ish in top with a bit to go
just glad its running.now i just gotta sort out my squeling speedo and broken mirror

[drew1967]

How do you check fuel level Mellow?

[mellow]

set the carb up somewhere where its dead level then remove the drain screw......wedge a bit of clear hose in there.....then add fuel to the carb(i use old washing up bottle of fuel into carb fuel pipe)
the clear pipe should be routed up the side of the carb and the fuel in the clear pipe should be 0.5mm below the line where the bowl meets the carb

[drew1967]

Aaaaahhhhh clever!

[drew1967]

I assume you have to then block off the overflow output pipe.

[mellow]

If you wedge the pipe far enough in it covers the outlet hole

[drew1967]

Finally got bike running and ticking over.
Float levels were way out by the measuring technique (2-3mm) which makes loads of difference to fuel level.
Did fuel level check instead loads better and more accurate.
Loads of crap came out of the exhausts at first.
I'm assuming it was a build up of fuel with it flooding so much.