MC5 jetting and gearing

[JNOYES]

I know jetting had been kicked around quite a bit, but I'm still confused.

My '76 MC5 with a Bing 54/36/102 has:

170 main
Needle ()
3.22 needle jet
45 pilot

Another '76 carb I have has a 190 main.


The John Penton article on Yahoo recommends:

#1 needle (is this the stock needle?)
165 or 170 main
2.83 needle jet
35 or 45 pilot

this is with a paper air filter

with the Twin air foam:

265 main (resp 170)
35 or 40 pilot
2.85 needle jet

What does resp 170 mean on the main jet?

Can I expect an increase in performance by changing to the 2.85 needle jet?

If so, do I need to order a #1 needle or is this stock?

I have a Unifilter oiled foam filter.

I am only looking for a starting point and realize I will have to optimize from there.

Second question

I had Mike Lenz modify my shift drum, so now I have second through sixth gears for MX. Where do I start with gearing? Stock is 14/52.
I'm thinking maybe 13/54???
Anyone out there racing a five speed?


Thanks

Jon Noyes

[Mike Lenz]

I run 13/52 for mx with the 5 speed. Ill check on the jetting.

[Mike Lenz]

Jon, I would start with a 170 main, 283 n jet, 4K2 needle and a 45 pilot. If anything you should be on the rich side.

[john durrill]

Jon,
 your needle should have some rings just below the clip slots. the # of groves ID's the needle. thats the needle # you would use if ordering one new from Bing. the carb # , type ( 54 , 84 etc) and
 the set of #'s stamped on the carb body plus the # of groves gives you the right needle for your bike if you were to order a new one from Bing.
 the Oil ratio, type of air filter and the altitude that your bike was used at would give you small changes in the needle jet, pilot jet, and main jet. the stock needle is usualy ok unless the pipe and ports have been changed
john d