34mm pj jetting

[Jimmy Regan]

Elevation: 1500 ft

Temp: 60 to 80

 

Mods

Engine: vitos 397cc 4 mil long rod

Head: pro design cool head. 22cc domes

Exhaust: Toomey t5s

Intake: no airbox lid. K&n filter w/outerwear. Tdr intake w/internal crossover tube.

Carbs: 34mm Keihin PJs

Electrical: 3° advance timing plate

 

I'm currently rebuilding my motor. Going from stock bore to 66mm. Stock mikuni carbs to 34mm pjs. Also adding the cool head, tdr intake and advance timing plate. I haven't dealt with keihin carbs before and I would like some input on where I should start jetting wise.

[rubberneck]

CEL needles in the middle, somewhere around a 158 main and a 48 pilot should get you close enought to fine tune

[Jimmy Regan]

Alright thanks. Also have Boyesen reeds. If that will make much of a difference.

[rubberneck]

not really that combo will get you close may need to move needle around a bit.  just check your plugs.  my 4 mil with PJs and T5s ran 160s at sea level and was a bit fat

[Jimmy Regan]

Alright will do. Thanks for the help.

[trickedcarbine]

Idle..... Screw both choke knobs clockwise so that they are all they way in. Use paint pen, white out, tape, or something to put a mark on both knobs so you can keep track of where they are rotation wise. Not turn them both 7-7 1/2 turns out. Should idle nice.

[Jimmy Regan]

Have the carbs apart. Throwing in a 160 main to be safe. And I'm noticing the slow jet is bigger than 48. Looked it up and stock is 55. Don't really wanna go down sizes do ik?

[trickedcarbine]

See if you can get it to idle ok with the 55 with the idle set per above spec. Can always work down if it's just two slobbery feelin'.

[Jimmy Regan]

Well that's what I'm trying to figure out. I just would have figured you'd wanna go bigger. These carbs are new to me tho. Well my whole motor pretty much will be. I'm still learning.