Scott carburetor - needle jet length

This topic has 4 replies, 2 voices, and was last updated 5 years, 8 months ago by Martin27.

Viewing 5 posts - 1 through 5 (of 5 total)

Author

Posts
27th November 2020 at 7:08 am #31622

Martin27
Participant

Hello,

I have a question, what is the influence of the length of the needle jet length? I got new one from Richard Blackburn which is for 276 pre-monobloc. Old one that was originally fitted to my brass carb (of course, there is question, if it’s really original or was already changed) is a bit longer. Length of the hexagon part (without the main jet) is 29 mm, total length of the needle jet (without the main jet) is 47,6 mm.

What influence has the length of the jet? Which one is better to use? I have blind head long stroke engine, don’t know if the setting was different for the long stroke/short stroke engines?

Thanks a lot, all the best,

Martin

28th November 2020 at 1:17 pm #31623

Deleted User
Participant

Your jet seems to be too long,should be a Stnd.jet (no markings),& the lengths should be 24 mm & 42.30 mm .Should be in good condition as 95% of all running is done on the needle jet.These are available from dealers. ——-Potty——

29th November 2020 at 12:33 am #31625

Martin27
Participant

Dear Potty,

ok, thanks a lot. So the jet from Richard is correct, this longer one was probably fitter later.

What actually does it with the performance of the engine if the longer one is fitted? Could it have some reason why someone did it?

Thanks, Martin

29th November 2020 at 3:05 pm #31626

Deleted User
Participant

Martin, — the longer one is for a different carburetter,not a type 6 series,probably a type 29 ?. check if the carb has any other wrong parts fitted.The type 6 carb has different primary air holes to a type 276,the air holes must line up with the jet block & the jet block must be stamped 51 on the top in both cases.The throttle valve needs to be a No.3 (a 3 1/2 tiger cub one will probably be OK) Potty.

1st December 2020 at 5:27 pm #31628

Martin27
Participant

Dear Potty,

thanks for all informations. I’ll check it. Needle jet should be Ok, I will see how the other parts.

Thanks, al the best,

Martin
Author

Posts

Viewing 5 posts - 1 through 5 (of 5 total)

The forum ‘General Scott topics’ is closed to new topics and replies.