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/sp...s_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/TechCent...arbJetting.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