Does anyone know what size jet is in the standard NTTC carb. I need to re-jet slightly smaller (it's 4 stroking) would like to know what the starting point is. Thanks for any help.
NTTC Carb Jet
- Thread starter calschantz
- Start date
Could you post a photo of your carburetor? Several of us would like to see the NTTC designation. Thanks.Does anyone know what size jet is in the standard NTTC carb. I need to re-jet slightly smaller (it's 4 stroking) would like to know what the starting point is. Thanks for any help.
Tom
I found a MOST AWESOME thread on this carb at motoredbikes.com
http://www.motoredbikes.com/showthread.php?24867-NT-Carb-Tuning-Basics
http://www.motoredbikes.com/showthread.php?24867-NT-Carb-Tuning-Basics
My issue, is I can only run and start my engine with the choke open... second I close it the engine shuts off.
That's the way it's supposed to work. With the choke closed you are shutting off the air. Air is one of the three things your engine needs to run. If you close the choke, lever up, and the engine doesn't die then you need to start worrying.
Tom
I found that the standard jet is .72mm, which is fine for a 16:1 ratio ( I guess), but on mine it 4 stroked unmercifully. I'm a firm believer that 16:1 is too lean a mixture and when breaking in the engine, it runs too anemic. After 1 tank of 24 to 1, I re-jetted to .66mm (SBP sells the jets for $3.95 each, not knowing what to get, I bought 5 sizes below .72mm) I'm running 37to1 (2.6 oz. to 3 qts. of 89) fuel. I tried moving the needle up and down , but it only effects performance from above idle to about 3/4 throttle.(works best for me at the second ring, factory setting). At WOT the engine runs just a skosh on the side towards rich. I determine this by the fact that pulling my 205 lbs. the bike pulls slightly harder when going up a moderate hill. It rolls about 31mph on the level with the throttle just short of WOT, when you come to a hill roll on WOT and it clears most hills (Connecticut hills) at 20 plus. I also bought http://www.widgetsupply.com/product/BLU01.html and looked up the converssion for mm to number bit sizes, and now I can "brew" my own. I can also solder the original .72mm jet and drill them to .66mm. The plug now runs a "dry light chocolate" color instead of the "wet black" with the .72mm. That's my story.
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The needle only controls fuel flow below about 3/4 throttle. Anything above that to WOT is a product of jet size. Above 3/4 throttle the needle is lifted out of the jet so the amount of fuel delivered to the engine is dependent on jet orifice size.
Moving the clip has no effect on performance above 3/4 throttle.
Tom
Moving the clip has no effect on performance above 3/4 throttle.
Tom