Pro Circuit Jetting

[Snopczynski]

They have already given baseline specs twice in this thread. There is also a jetting thread in the forum that lists out what everyone has and uses for setups.

[MILO]

just put some pro circuits on bone stock bike.. elevation is 2000-2500.. weather now is 60-75... stock carbs, air box snorkle removed only.. have 200 mains in and not to sure on pilots. prob stock... ran before pipes were added.. now it starts and smokes like hell, and the "smoke" evaporates fast.. back fireing in left cylinder and smoking bad.. fresh gas 93. in it.. any help on a guess to what is going on and where to start on jetting.. i have 250 and 240 mains.. to play with.. stock needles.. thanks in advance..

 

how much did you run it with the 200 mains in it? with the PC's and snorkel removed you may have been running really lean and the quickly evaporating 'smoke' may mean other problems if it's backfiring & smoking from only one cylinder. You're best off to not even fire it up after the mods until you get a ballpark jetting set up.

Otherwise, double check everything. plugs, clean carbs, sync'd, set air screws around 1.5 out, no air leaks, etc. Make sure the crossover tube between the carbs is in place too. Might want to pull the reed cages & inspect reeds too. With the cages out you can see the piston to inspect for damage also. Pull the exhaust off to see the front side as much as possible also. If all is well, toss in the biggest jet these guys recommended & start dialing the mains.

[Snopczynski]

Did you put the slides in the correct side (directional). Do you have the choke balance tube on between the two carbs?

[stacman450]

200 mains ran forever stock. then put pipes on just to see how it did. idleing and all that stuff.. and like ive said the smoke and all that stuff.. everying is in place and no leaks.. just going to take time i guess. where is the best place to get pilots my cycle shop dont have any... thanks fellas o one thing it'l idle pretty good with choke pulled but when back in starts running bad.. also i jsut got some new plugs going to try them tonight.. thanks for all the info...

[F.T.W. Banshee]

i have pro circuits and my elevation is at 1500' i run 280 mains and 27.5 piliots.

[GrMeyer]

Contact a site sponsor for ur jetting needs. With the lid on and 25 pilots, turn the air screws 1 turn from seated. Make sure the gas is shaken to keep the oil from separating in the tank. But that takes a long time to happen. As long as the smoke is not white I would say ur good to go. Mine smokes like a forest fire till it gets warmed up.

[frog]

Contact a site sponsor for ur jetting needs. With the lid on and 25 pilots, turn the air screws 1 turn from seated. Make sure the gas is shaken to keep the oil from separating in the tank. But that takes a long time to happen. As long as the smoke is not white I would say ur good to go. Mine smokes like a forest fire till it gets warmed up.

 

 

If it was running O.K before you may have mixed up the plungers in the carbs.If you put the left in the right it will run like you have the choke on (smoke everywere)Check the toomey website it shows the correct possition.

[stacman450]

thanks guys.. this is the kind of advice and opinions i was looking for... thanks... ill keep posted on how it works out.. lol

[MILO]

the choke basically changes the air/fuel ratio to provide a ratio that's rich on the fuel side for starting. so if it gets better at idle by pulling out the choke, that means that you are on the lean side (more air than fuel) on the pilot circuit. you either need to turn in your air screws or go with a bigger pilot. you should be able to adjust the circuit with the air screws being between 1 & 2 turns out, going 1/4 turn at a time for adjustment. anything less than 1 and you'll need a bigger pilot, anything more than 2 and you'll need a smaller pilot. you can clean it up some by doing this but the pilot circuit really should be the last to play with. everything may change slightly after you dial in the mains & needle, which should be done first.

Edited October 4, 2010 by MILO

[MILO]

i have pro circuits and my elevation is at 1500' i run 280 mains and 27.5 piliots.

 

I have Pro Circuits & my elevation is about 1250'. I run 370 mains & stock pilots. It all depends on what other mods you have. You really do have to compare apples to apples when dealing with jetting. Plus every bike is a little different & needs custom tuned. That's why there is no magic #'s for jetting. Like Snop said, you need to establish a baseline & tweek it as needed.

[GrMeyer]

I have Pro Circuits & my elevation is about 1250'. I run 370 mains & stock pilots. It all depends on what other mods you have. You really do have to compare apples to apples when dealing with jetting. Plus every bike is a little different & needs custom tuned. That's why there is no magic #'s for jetting. Like Snop said, you need to establish a baseline & tweek it as needed.

370 mains? Wow that is rich! Is ur bike ported? Or are in like the artic somewhere?

[MILO]

370's - that's what Shee likes.

 

bored .020" over,Hot Rods 4 mil long rod stroker crank w/wiseco 795's, custom cut stroker domes in Noss head, HJR aggressive trail port, +5 timing advance, V3's, open air box w/ Pro Design foam filters, Pro Circuit pipes. Running Sunoco 110 race gas (std purple).

[Snopczynski]

370's - that's what Shee likes.

 

bored .020" over,Hot Rods 4 mil long rod stroker crank w/wiseco 795's, custom cut stroker domes in Noss head, HJR aggressive trail port, +5 timing advance, V3's, open air box w/ Pro Design foam filters, Pro Circuit pipes. Running Sunoco 110 race gas (std purple).

I run 370-380's in my 28mm mikuni tm's with pods at sea level.

 

Milo, you could benefit from a better reed setup.

[MILO]

I run 370-380's in my 28mm mikuni tm's with pods at sea level.

 

Milo, you could benefit from a better reed setup.

 

Ya got my attention bud. What kind of set up?

[Snopczynski]

Ya got my attention bud. What kind of set up?

if its truly low end and technical riding then low tension reeds on stock cages. You can also get special order mid-tension reeds as well. Most aggressive setup I would run is boyeseen carbon dual stage reeds. The vf3's on that motor are a high tension reed designed to move mass amounts of air. You'll never hit the optimum rpm range to see the full benefits of the vf3 setup.