monty carb settings.

[rpm-bert]

hi folks, anybody got any insight into carb settings for Monty 500 ? currently running 140 mains/55 pilot jet/float height 18mm std,seems to like pilot screw at 3 turns out think this might suggest bigger pilot might help ??, any form of tick over seems to be out of the question !, ign timing correct,valve clearance OK, never really liked anything less than 2000rpm, any ideas ? that don't include scrapping  std Dellortos and std, Bosch ign, system ?? cheers , Bert.... Lol       

 

[paul-haggis]

Hi Bert.

Starting with the mixture.... Are the idle and transition circuits clean and clear?  Sometimes if you drum your finger over the pilot screw hole (with the pilot screw completely taken out and the engine running) you can cause pressure pulses to flush out the channels. Or you can splat your palm over the carb mouth, to cause a huge draw and rush of fuel through the circuits and clear things out.

Float levels OK?

Anyone buggered about with the slides? (includes modification of the with a file - not just different slides fitted).

PH

 

[bob]

Bert, I'd go back to basics and give the carbs a very thorough overhaul replacing anything that is slightly suspect. To select the correct pilots open the throttle to a quarter turn. If the revs rise unevenly and the engine doesn't seem to hold a steady throttle then the pilots are too small. If instead it sounds deep and you can see evidence of smoke in the exhaust then they're too rich.
I don't think that you current settings would create any problems although the mains might be a wee bit too large. The reluctance to tick over might be caused by cam timing. Monty's have a very aggressive cam timing as standard and if it's moved for whatever reason [ such as an incorrectly fitted cam chain] then it will be hard to start and reluctant to tick over.
Contrary to popular belief and Monty/ F500 will happily tick over if everything is as it should be.
If you changing jets etc I'd suggest going for big increments so that you can detect what difference is being made, once you know that excessive richness or leaness is causing the problem then you can move in whatever direction you want in smaller increments .
Bob

 

[KERMIT1200]

Hi Bert,
Can't confirm whether the pilot jet is right or wrong because I'm at work,hopefully someone can.

In terms of getting a Monty to idle,set up vacum gauges for both carbs.Set the mixture skrews rich say two and half/two and three quaters out.Set the bike to run/idle at say 2000rpm or the lowest rpm that can be achieved without to much trouble.
While its idling synchronize the carbs.
Start to turn the idle skrews to lower the rpm,but try and keep both carbs synchronized,while you do it!.
Once you start approching 1200 (approx) rpm you can start adjusting the mixture skrews.Its all about listening for the change in the exhurst note.The lower you can get the rpm the easier it becomes in setting the mixture and helping to achieve a fairly low tickover.

Might take a few attempts,and don't let the engine over heat.
Once your satisfied,I'd set the tickover at say 1100 rpm(or slightly higher),just make sure carbs are still
synchronized by checking guages.


Andy