Topic: Learning carbs the hard way on a 76 750SS

[Joe]

  Alot of guys say to keep the stock airbox, and I did for as long as I could.  I changed over to pods, and a 4 into 2 straight pipe setup that sounds  .
Of course the usual, I've had the carbs off about 5 times in the last two days, and about to tear into em right now.  I've got stock jets now, (105 mains) and a set of 112 mains in the shed, but so far I've just been messing with the needle jet adjustment. 
Stock setting of the needle jet is the 3rd groove from the bottom.  I tried the second, and first, and they both made the bike run worse than before.
I'm going to try putting the needle jet back at stock position, and change the mains to 112 (wish I had smaller ones).  I'll update you all with the outcome.

Any advice on air mixture screw positions? (currenty 1 3/4 turns out)

 

[dansvs]

This link may help you. Most say you must size the main jet first as this also affects the needle jet. Then the pilot jet then the idle screws. Good luck. I'm still fighting mine.



http://www.salocal.com/sohc/tech/carb/asmpg_mgs/jetgraph.htm

[Yoshi823]

When I put some K&N type individual filters onto the standard 750F2 carbs on my bike I ended up using 750K7 main jets, the needle had the circlip in the 3rd slot with half step shims underneath the circlips and the air screws out 1.75 turns. The pipes were standard modified downpipes with a track outlet. I didn't touch the primary jets.

[Joe]

thanks for the advice.  The keihin diagram will prove to be very helpful in fine tuning i'm sure.  I found a set of new mains (110) on a set of donor carbs I recently picked up, and it ran alot better. 
It does flatten out at around 1/2 throttle though, so tommorow I'm gonna lift the needle clip up one click and see how it does.

[TwoTired]

And you are not reading your spark plug deposits because.......

[Joe]

good point.....I'll check 'em out again tommorow before I pull the carbs again.