Setting up 34mm carb do i rejet black spark plug

[Birdylegs]

I need help setting up a dellorto vhsb34ld carb my bike as it just spluttors at 5000 rpm is it a mixing problem or do i rejet ? It came with a 160 main should i try diffrent mixture turns or lower main jet at £5 a jet im after any help i can get looked at diffrent forms but doing plug chops would be a pain anyone with any tips apart from just use old carb. Thanks for your support.

[WR6133]

If the plugs are new you can get a decent (ish) colour reading without actually chopping them (Here's a colour chart http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html ). Does opening the choke half/full lessen or increase the splutter? (this can give you an idea of if you are rich or lean).

[Birdylegs]

Never seen that link befor im no.2 lower jet as mix is to high even with screw inbut 1 turn would a 140 jet be to high still ?

[WR6133]

I'd try the 140 lower than that sounds too small though I've never fiddled with 2 strokes (I run 100's on my 28mm carbs (4 stroke twin)). A lot of it is trial and error so it's a good idea to have a few sets of jets of neighbouring sizes. It took me a lot of fiddling (and hours of cursing) to get mine right when I replaced the airbox with a pair of proper cones, infact the thought of having to go through it again is the reason I'm no longer planning on getting better pipes.

[Jon_W]

It could be several things. do you have a setup manual??? They are £6.99 on line from dellorto. Or look here for the basics.

http://www.scribd.com/doc/9641108/Dellorto-Manual

Is it the correct jets for the bike or a guess??

What you describe sounds like not enough cutaway, ignition timing or too rich on the needle. It depends on the throttle position and load on the engine.

Choppling isn't hard, I do it but it can be time consuming. I get the bike right by feel to start with then chop as a check.

The Amal system is to set the main jet, set the pilot jet, set the cutaway, set the needle jet and position then recheck the pilot and set tickover. This is done purely by feel and not by chopping. They give tips as to what to look for.

[Birdylegs]

Thanks for the comments carb was sold with a 160 main as just a bolt on upgrade needle only has one setting dont know how to do ignition timming going phone seller see about a set of main jets hope bike ant off the road for more then 1 week or ill see if i can pay a garage to fix it thanks again for info.

[db]

Sounds to me like the needles too rich, drop the needle one slot and see if it improves, will it clean up on WOT ?(wide open throttle),I like playing with 2 strokes.....eurocarb in reading are very helpful and carry every jet in stock for delorto's, I have some delorto mains floating about.....

[Birdylegs]

Asked sales company ( pj motorcycles) for advice who said i should try a 155 or 150 im sure it needs a lot smaller but i cant move circlip up or down on needle as its a flat slide reading is a bit far out from me if you got some mains you dont need pm me with sizes and a price if your not to far away pop around for a play ill put kettle on lol

[Brizzer]

http://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf this mite help you I know its says its for Keihin carbs but there all generally the same don't be scared to try different jets and buy a few spark plugs , have fun

[db]

Asked sales company ( pj motorcycles) for advice who said i should try a 155 or 150 im sure it needs a lot smaller but i cant move circlip up or down on needle as its a flat slide reading is a bit far out from me if you got some mains you dont need pm me with sizes and a price if your not to far away pop around for a play ill put kettle on lol

I've mucked about with vhsb's before and you can adjust the needles......I ll have a dig in my tin of jets and see what I've got.155 is the stock jet for a full power mito/supercity with the 34mm

[db]

Just had a look......got 155, 132 and a 130 yours if you want them....

[Birdylegs]

Just had a look......got 155, 132 and a 130 yours if you want them....

Iv ordered a 155 they might send me a 150 free of charge a 130 or 132 would help to try see if it runs lean as there far from 150s as i was just watching carb. Being fitted i never seen any needle settings it was first time iv changed a carb. And used this type so when stripping to put new jets in ill lower it if i can but thats a bugger to fit cable back on.

[alanTDM]

I would check if the float height is correct aswell before changing jets if thats out it could give you a rich or lean mixture.

[db]

found this topic on ww.125ccsportsbikes.com ,
http://www.125ccsportsbikes.com/forums/index.php?showtopic=103063&st=0&p=1479121&hl=+34mm%20+carb%20+jetting&fromsearch=1&#entry1479121
looks like a good base setting to me,there's alot of information to be found on there

[Birdylegs]

Float hight was not even on list thanks ill google it..

[Birdylegs]

found this topic on ww.125ccsportsbikes.com ,
http://www.125ccsportsbikes.com/forums/index.php?showtopic=103063&st=0&p=1479121&hl=+34mm%20+carb%20+jetting&fromsearch=1&#entry1479121
looks like a good base setting to me,there's alot of information to be found on there

He gets top end i only get 5000 rpm just have to use gears to get 40mph tops but im a member of there form ty

[db]

but it gives you a good base setting for the needle and mains,the needle will clean the midrange up

[Birdylegs]

Last time i moved a needle hight the bike never even started so ill look at that first as its less work to do. Thanks
Seen link which shows me where circlip is for needle hight and feel like thats best bet to try thanks again.

[Birdylegs]

Droped needlie and raised it but sill bogs out at high revs could be power cable snaped or needs lower jets just need socket set spaners are killing me thay dont ave same the reach or ease to turn with out scratching anything ... fun to fix but more fun when finnished fixxing with good job ..

[db]

Where was the clip to start with?, where did you raise it too?, when you say high revs...what is it?, what throttle position ?

[Birdylegs]

Where was the clip to start with?, where did you raise it too?, when you say high revs...what is it?, what throttle position ?

Second from top moved it to bottom it ran better but only got to seven rpm with two in second gear only done six k. than spluttored and at that point my brake pads and jets turned up my stepdad with socket set busy never looked at plug but turned down mixture screw and it idiles same as befor sun should be out to day to have a look.

[Brizzer]

your bike used to run ok before didn't it ? perhaps its your reeds that are the problem or a air leek

[Birdylegs]

your bike used to run ok before didn't it ? perhaps its your reeds that are the problem or a air leek

Bike would stall and be jumpy at slow speeds so had to get bigger carb to make it predictable in traffic

[Birdylegs]

Needile on top clip 150 jet fitted still black plug ill have to keep reading links about clip on needle rasing and lowering fitting new manifold might have broke a reed as it never went past 8000 rpm when i drove it. Even when i worked in a work shop boss said he'd take car to someone alse to fix as of problems so booked it in tomorow see what they say.Thanks for help sorry its not much use to anyone alse but iv got a lot more expearence now working on my bike better will come later.

[db]

Bike would stall and be jumpy at slow speeds so had to get bigger carb to make it predictable in traffic

A bigger carb wont make the bike more predictable in traffic, bigger carbs are for more top end with the sacrifice of bottom end torque......

[Birdylegs]

It would pull of but i had to pull in clutch and feed it if i over rev it stalled i road my lf 125 for a year without stalling but this bike could cut out when clutch was out and power on. Tighten clutch cable ran a leaner mixture that helped but uninspected stalls could have killed me on crossroads bike also droped speed 5th at 80 mph then in 6th droped down to 60mph never pulled up when in 6th at 60 very fast hoped new carb would stop me putting every one at risk behind me. I do drive slowly and safely but would also like to pass trucks not have lines of them build up behind me blasting past my 55mph on a419 on way to mums

[Brizzer]

feck sake don't ride the bike then, sounds like a death trap

[db]

i think you have more issues than just the carb,find someone with a compression tester to start with.....

[Birdylegs]

i think you have more issues than just the carb,find someone with a compression tester to start with.....

Piston rings are due for a change thats all iv been told to do for a top end rebuild would have got piston and cylinder but should do bottom end at same time to keep it even on servie will do com. Test thanks forgot about asking for one of them.

[Birdylegs]

feck sake don't ride the bike then, sounds like a death trap

Wizzed past a biker to have engine cut out on me in i switched to res. Fuel but slowed down a lot he was thinking same thing.

[Birdylegs]

feck sake don't ride the bike then, sounds like a death trap

Iv been getting v power fuel from shell ever sence you told me to thats helped exept the lorry with no brake lights that stoped infront of me and the fact my brake pads was reduced to metal a mounth after getting a machanic to look at them and as it aug he could't work on it till sep as he orders parts from them im lucky to be alive with pro help id dredd to own a diary (my girlfreind needs meds ten tablets a day i needed transport to bring her stuff when she gets kept in over night or i have to go pill chasing my bike has saved her life ) mine gets pushed of road by cars over takeing then when they see theres no room as on coming car they just switch lanes and push me off road even a amblance tryed it a seat over taked a jag behind then jag over powered had to brake hard and nearly drove strate in to back of it in need a go pro cam to recored the accidents that nearly happen i belong in muppet form lol

[Brizzer]

sounds like you have had the run around of your mechanics you use, take it to gary vardy in Swindon he a top mechanic and ask him to sort it I would also take the old carb with you aswell

[Birdylegs]

Hes busy for few weeks but bikes running and just needs a fine tune Thanks for support just a bit over fussed on bike sorry to have wasted your time if anyone has any jets can you let me know so i can fine tune it a bit more :eek:

[db]

i'm on evenings this week,i go to work at 1 pm,if you want to pop over to stratton st margret, i could have a look quickly and you can collect those jets

[Birdylegs]

i'm on evenings this week,i go to work at 1 pm,if you want to pop over to stratton st margret, i could have a look quickly and you can collect those jets

I read this earlyer this morrning been thinking about it all day i got to take it to steve lynham wensday might just need moving circlip and mixture or idle screw about thanks anyway

[db]

im just up the road from him !

[Birdylegs]

im just up the road from him !

I can pop around any time you want if you dont mind mate .