Good Morning,

I'm after some help with my 315r 2003 Montesa. I just wanted to know what the carburettor settings were for the two screws on the outside.

There is a small screw on the left hand side and then the other one is a larger screw centre of the Carb. Would anyone know how many complete

turns it is for each one, and could someone explain what each one does.

Thanks in advance.

T

Edited September 17, 200817 yr by Triage

Hi and welcome to TC. The central screw on your carb is the tickover adjuster. If you screw it in it lifts the throttle slide a bit to give you a faster tickover. Vice versa for unscrewing it. Screw it in until the revs rise and then back it out slowly until you've got the tickover speed you like. The other screw is the fuel/air (mixture) screw that allows you to get the mixture just right for a smooth pick-up from low revs. The earlier Dellorto carbs, and most older carbs this adjusts the air in the fuel/air ratio. On your carb this screw adjusts the fuel in the fuel/air ratio and is normally set at around 3 to 4 turns out from fully in. Screw it in a bit to get less fuel so the mixture will be a bit weaker, out will give more fuel and a richer mixture. When you adjust the mixture screw the tickover will probably change so you balance that out with the tickover screw. You're looking for a slow, smooth tickover with a nice clean, instant pick-up from tickover to part-throttle. I like mine a bit richer (more fuel, or less air on the earlier carb) off the bottom than some people so I would try it at 4 turns out and then go back in 1/4 turn at a time until I was happy with it.

Hi and welcome to TC. The central screw on your carb is the tickover adjuster. If you screw it in it lifts the throttle slide a bit to give you a faster tickover. Vice versa for unscrewing it. Screw it in until the revs rise and then back it out slowly until you've got the tickover speed you like. The other screw is the fuel/air (mixture) screw that allows you to get the mixture just right for a smooth pick-up from low revs. The earlier Dellorto carbs, and most older carbs this adjusts the air in the fuel/air ratio. On your carb this screw adjusts the fuel in the fuel/air ratio and is normally set at around 3 to 4 turns out from fully in. Screw it in a bit to get less fuel so the mixture will be a bit weaker, out will give more fuel and a richer mixture. When you adjust the mixture screw the tickover will probably change so you balance that out with the tickover screw. You're looking for a slow, smooth tickover with a nice clean, instant pick-up from tickover to part-throttle. I like mine a bit richer (more fuel, or less air on the earlier carb) off the bottom than some people so I would try it at 4 turns out and then go back in 1/4 turn at a time until I was happy with it.

Cheers for the info. I will try it tommorow and let you know how I get on. Thanks

Cheers for the info. I will try it tommorow and let you know how I get on. Thanks

Thanks for the PM. Will be giving it a run around tommorow. Shall keep you posted.