Not Monster - but HELP!

[Paranoid Dave]

I know there's a load of techno heads out there so I call on you to help me here, I have posted similar on another forum but with little help.

My Lilac friend has had a new carb and exhaust this weekend, i'm trying to set it up as at the moment she has trouble idling and riding - so a bit poo.
I have an air idle speed screw, a main jet screw and little else. I know the needle has a few notches so can be adjusted but my problem is i have no clue what is the best way to set up the system. Where do i start??

I have ridden it a mile or so but i can hear it starting to backfire if i open it up for too long and if i downshift coming to stop, so i know its too rich. The can is a supertarp jobbie and i know that the venturi effect of the plates actually helps remove unburnt fuel so it must be really over fuelled. I unscrewed the idle air a 1/2 and then another 1/2 and still not working right. I was told it becomes of little effect after that much unscrewing.

I've turned the main jet needle screw thing in 1/8 of a tun and i'ts starting to idle better but once i changed the air screw it's back to square one.

So can anyone help me with a step by step guide to how to figure out the right set up or diagnose any problems. I'm open to all suggestions as until sorted i can't play on her and i want to hear that pipe again. I'm guessing i have to move the needle a notch but i haven't a clue??

Anyone there able to help?

Thanks
Dave.

[Pedro]

PD

is the motor not one from a C90 or similar? I know you've made some change but if the carb is similar, I'd start with similar settings.

Have you done a plug chop? Run at a steady 50mph then cut the ignition and coast to a holt then whip the plug out - the colour should tell you a lot about the mixture (decent plug colour pics in the back of the haynes books).

Failing that, have you tried one of the Monkey bike specialists for a bit of guidance?

Ped

[Paranoid Dave]

i spoke to a monkey expert and got some good tips, but its still not ideal set up. The engine is a jap 110cc but 40mph is the easy target, 50mph is achievable with a long open road. I was thinking of doing the plug thing but forst of all i need to get a setting that allows me to comfortably get a mile away from home and on to a decnt road to do these things.

[Shauns4]

Std setting is usually middle notch on the needle and air screw ~ 1 1/2 turns out.

If it runs really lumpy after this and gets worse when it warms up drop the needle a notch (raise the clip), conversly if it needs lots of choke lift the needle a notch, when you have this something like fine tune the tickover by obtaining the highest idle speed by slowing moving the air screw +/- 1/2 turn, its better to do this with the tick over set high, find the optimum and then back it off.

Shaun

[Gilps]

I had something similar with a Honda 750 engine . I always understood backfire on overrun to mean that the engine is running too lean. Either an air mixture problem or holed exhaust leading to reigniting unburnt fuel. I would suggest the former. I adjusted my tickover first. Get the engine ticking over then slowly wind in the idle screw, when the engine starts to die or sound rough take it back out 1/4 turn then that shoukd be it. Then the main mixture screw. I wound mine in all the way then back out about 2 turns. It then was a case of suck it and see. keep checking the plugs for colour.
Screw in is weaker mixture and out is richer.

[slob]

http://www.ukmonster.co.uk/monster/showthread.php?t=13783
post #12

[Fosse Foxfight]

I have ridden it a mile or so but i can hear it starting to backfire if i open it up for too long and if i downshift coming to stop, so i know its too rich.
This may be a tad of flawed logic, have you checked the state of the head n valves?