This Post Got Me Banned From "2 Stroke Research & Development Forum"

[jaguar]

Tuning Question: Which replaceable carburetor part has the biggest influence on jetting thru the whole throttle range?
1. idle jet, 2. main jet, 3 needle jet, 4. slide cutaway, 5. needle

ANSWER
The needle jet edges out the main jet by just a little as the one replaceable part that has the greatest overall effect on jetting thru the whole throttle range. Surprisingly, if a carb is jetted right, then the needle jet clearance to the needle contributes more than 60% of the gasoline at slightly above idle. But of course this depends on carburetor sizing. The bigger the carb, the less vacuum there is at the needle jet when the slide is very low.
So overall I would say the needle jet is the most important "adjustable" part in the carburetor. But ask your riding buddies if they even know what that is. In Keihin carbs the needle jet size is fixed and the "adjustment" comes by selecting different needles of different widths. The clearance between the needle jet and the needle determines the effective needle jet area. That is strictly controlled by that clearance until over 1/4 slide open. After that the needle taper allows more clearance the more the slide is opened. In Mikuni and Dellorto carbs you can select needle jets with different hole diameters.
Keep in mind also that you can assume the needle jet hole is wallowed out to be too big in a carb over 15 years old, the carbs in big engines being the worse due to the extra vibration if the engine doesn't have a balance shaft.
When that happens you have to put in an extra small idle jet for a good idle mix. When you need a smaller idle jet then often the slide opening for a smooth idle is over 10% of the carb bore.
If you want to inquire about getting a new needle jet you should email chadt@sudco.com and he'll help you out.
The graph below shows the % control that the 3 jets have thru the whole throttle range. This is from my VM18 and varies from carb to carb, especially due to sizing.

 

[jaguar]

A moderator deleted the post, then I posted it again, then it was deleted and then talking to him he started making weak excuses that made no sense and I told him (Alfio) to stop lying and tell me the truth but he never would. Then when complaining to the admin he let it slip that they thought poorly of me because I had insulted one of their idols, a famous tuner. I said "well yeah I did call him an asshole but he totally is". Then I posted a poll and asked the members to vote whether I should leave the forum or Alfio, and everyoe voted that he leave. Then Davd Bristow banned me from the forum.

 

[jaguar]

my response; "Whatever, that's less work for me now"

 

[RM_guy]

They sound like a bunch of egotistical poopy heads...better off with out them!
I thought your answer was well thought out and stated!

 

[jaguar]

thanks RM_Guy. Yeah they didn't contribute to me any, it was the other way around. I feel sorry for all the beginners there that don't get very good advice when they have a problem with their engine. The majority of advice given there isn't any good at all.

 

[jaguar]

So now the total is 3 forums that cater to the cavemen of motorcycling: Thumpertalk, 2 Stroke Tuning (on facebook), 2 Stroke Research & Development (on facebook).

After my mistreatment on 2 Stroke R&D I tried to make the same post on 2 Stroke Tuning and they wouldn't even post it. WTF!? A post about carb tuning and the 2 Stroke Tuning forum won't post it! They are also run by Europeans and so they are probably friends and share hatred of honest Americans.
On Thumpertalk I posted an introduction to the topic of How Engine Oils Affect Needed Ignition Timing and one of their cavemen members called the topic "retarded" and so I flagged it as abusive and the admin just removed my post! I'm telling you, it's obvious that they love and protect their cavemen members, you know, those redneck drunkards that think it's fun to kill brain cells with alcohol.