4 mil build

[bansman76]

hey guys. need a ballpark idear to start jetting on:

hot rod 4 mil crank

.40 over cylinders-play/dune port for 4 mil by f.a.s.t

pro circuit pipes

stock airbox no lid with pro flow adapter and k&n filter

+4 timing.

pro design head with 23cc pump gas domes

140lbs of compression each side

1200 ft above sea level

   thanks for the advice

[bigweav81]

Why not call F.A.S.T?

 

Sent from your mammy house

[sleeper06]

340 main , 30 pilot needle 4 th clip

[bansman76]

Forgot to add chariot cages with boysen reeds. Will be upgrading to vf4's.

[Atomic Monkey]

340 main , 30 pilot needle 4 th clip

Sleeper is right on. The 30 pilot is what you'll need for Vf4s anyway. I have a very simular build at the same elevation, and this is where I started with my jetting too.

[camatv]

that exact jetting would be a great >starting point< for pretty much any stock cylinder build with open air filters and porting.. 

[bansman76]

Emailed f.a.s.t Jeff said 27.5 pilot. An start with 340 main. I currently have it running on 27.5 middle clip. And 340 main. Starts easy and runs good but when I check the plugs on the pilot jet check it looks lean to me( going by the jetting info in the tech section ). Haven't done the mains plug chop yet but that will be done this wknd. Thanks for any and all advice guys. I am no jetting guru lol

[okbeast]

I've never worried about what my plugs look like for the pilot circuit. Do a main jet check and if it runs good in the rest of the rpm you're poetically good to go.

[bansman76]

i rode it for a few this evening in the yard lol.  had just a slight stumble going from idle to 1/2 throttle.   i played with the air screws a little and got the stumble gone i believe and the idle sounds better.  i have the airscrews at 1 turn out from lightly seated.  should i still go ahead and put the 30 pilots in or should i wait and do the mains first ?   thanks guys

[98_sheester]

Mine as well put the pilots in when you d the mains since your in there already

[Strm Trpr]

i rode it for a few this evening in the yard lol.  had just a slight stumble going from idle to 1/2 throttle.   i played with the air screws a little and got the stumble gone i believe and the idle sounds better.  i have the airscrews at 1 turn out from lightly seated.  should i still go ahead and put the 30 pilots in or should i wait and do the mains first ?   thanks guys

 

If you're 1 turn out, yes, go to a 30 pilot.

With idle screws installed and TORS eliminated I set my idle to 1500rpms with a digital tach from ebay.

http://www.ebay.com/itm/LCD-Digital-Engine-Tach-Hour-Meter-Gauge-for-Racing-Motorcycle-Black-US-STOCK-/291261653224

I also sync my carbs with a FAST Carb Sync Tool http://www.farmandsandtoys.com/partdetail.asp?partid=59 at idle and ~5500rpms.

 

How to sync, in case you do not know.

Part 1 https://youtu.be/8FDcsojwVxc

Part 2 https://youtu.be/IZEBfFZUygM

 

Dialing in the airscrews should be done after the above tuning is complete.

You can feel and hear the throttle crack open sharply with no stumble off idle when your airscrews are dialed.

[bansman76]

Thanks for the advice guys. I actually have a sync tool but forgot all about doing that part. I did remember to eyeball the carbs. I'll be taking the air box back off to do that either tonight or tomo. I might say hell with airbox and put my 2into1 filter back on it for ease of jetting. Lol.

[camatv]

if synch is off  needs to be done before jetting most times...

[bansman76]

Finally got the time to sync carbs. Turns out my eyeballin was pretty damn close. A very small minor adjustment was all that was needed.

[bansman76]

Thanks for all the advice fellers. Removed airbox put toomey 2-1 air filter on for now (til I get pods). Installed 30 pilots for when I get V4's. 4th clip on needle. 350 main jet. Synced carbs and adjusted air screws. Done another plug chop today and sent pics to Jeff. He says I could safely drop to a 330-340 main and be fine. No stumbles , no flat spots. Shee runs great and very powerful. Big thanks to all