setting up a 58 G3LS (350)

hamiltia · Post by **hamiltia** » Mon Jan 03, 2011 9:12 pm

Hi
Wondering if anyone has a formula that has worked for their 58 G3LS?

I believe I have set my bike up as per the manual but I still have problems with
1 A backfire on closing the throttle eg coming to a junction
2 Good power when accelerating or on higher revs but jerky/uneven when at lower throttle opening (eg when at a nice 50mph and I go to 4th )

Bike is Running without air filter
Main jet 210 (I read that from 1958-but not before- this is correct when running no air filter). Carb was refurbished professionally-no great wear since.

Plug tends to foul up or lose efficiency quite soon-new plugs help whereas cleaning & regapping old one rarely does.

Has anyone found that with todays fuels /or machine wwear, that a different plug grade (I run NGK B7ES) or a change to any needle or jet is needed .

Thanks -Ian

Wavy · Post by **Wavy** » Mon Jan 03, 2011 9:25 pm

Have you checked the float needle and seating?

hamiltia · Post by **hamiltia** » Mon Jan 03, 2011 9:59 pm

Thanks -yes they seemed ok..

paul knapp · Post by **paul knapp** » Mon Jan 03, 2011 11:01 pm

The fuel level could be too high in the bowl! Giving lumpy running at part throttle openings, fouling plug and popping in exhaust on over run.
Check that you have NOT fitted a washer between the bowl and float needle seat housing.
The fuel level height indicator is the protruding dot under the letters AMAL on bowl cover.

1608 · Post by **1608** » Tue Jan 04, 2011 1:19 pm

Whilst on the subject of floats/needles etc, Would swapping the brass needle for a lighter nylon one make a difference to the fuel level. Logically one would assume that as both needles are the same length there'd be no difference. But the additional weight of the brass needle, should theoretically, hold the float down longer.
Any views ?

Duncan · Post by **Duncan** » Tue Jan 04, 2011 6:58 pm

Ian

Assuming that the backfire is in the exhaust and not spitting back through the carburettor then you probably have an air leak on the exhaust system, try applying silicone sealant where the down pipe enters the head and on the silencer/down pipe joint.

You say that the carburettor has been refurbished professionally do you know exactly what that entailed (i.e. a clean up and all the old bits put back on or resleeved and all new slides, jets etc)?

I am currently running my 350 on a B6ES as it used to run rich even with the needle dropped by a notch.

hamiltia · Post by **hamiltia** » Tue Jan 04, 2011 8:06 pm

Thanks all
No, Theres no washer in the float needle assembly
Q..How to check fuel level since carb cover is opaque....a clear tube connected to some opening eg pilot jet cover?

The carb refurb cetainly involved a brass sleeve and new looking jets

I have silicone in those exhaust joints but as the head joint gap is fairly big I will re-do it

armstrongdreadnought · Tue Jan 04, 2011 9:07 pm

The factory way to get a good exhaust pipe/head fit was to enlarge the pipe by tapping a cylindrical tapered steel wedge into the pipe mouth-a bit at a time so as not to overdo it.

paul knapp · Post by **paul knapp** » Tue Jan 04, 2011 11:56 pm

quote: Q..How to check fuel level since carb cover is opaque....a clear tube connected to some opening eg pilot jet cover?t

A length of clear plastic tube pushed over the pilot jet (cover cap removed) will show you the bowl fuel level.
With the taps on, the clear tube method will also show if the bowl float needle is not sealing 100% by the continually rising of fuel level above the dot on cover.

With the header pipes correctly sealed in the head, and also at the silencer end, excess unburned fuel will still detonate within the hot exhaust giving a 'popping' sound on over run.
Air leaks make them louder!