Nightrider Posted September 17, 2004 Report Share Posted September 17, 2004 Here's the problem,I have a .40 over vito power piston ,Rad valved,FMF piped engine with 185 psi cylinders,K&n air filter with a mildly vented lid.The engine originally had mikuni 28mm flats on it ,but I haven't got a throttle thats set up for them yet.So I had a set of stock carbs that I went through cleaning every orifice and rejetting them at 310 main,30 pilot and needle in the 4th clip from the blunt end.Seemed like a good place to start. I've never ran fatties and the jetting is totally different than my PC's. The problem is it starts and runs great with the choke on,but as soon as you kill the choke,the engine died.So I started playing with the idle& air screws and got it to maintain an idle after the choke was closed,BUT when I pull the choke,the engine runs better and revvs up.WTF What gives?could it possibly need a larger pilot?I thought 30's were perfect for fatties,considering I'm still running a lid with very little venting. Any suggestions?I've covered the obvious as far as choke tube,air leaks,carb sync etc. Quote Link to comment Share on other sites More sharing options...
Banchetta Posted September 17, 2004 Report Share Posted September 17, 2004 I'd pull the pilots and inspect them. You should be able to see through them. The choke circuit will bypass the pilots, so I'm guessing the pilot circuit is plugged.....carb slides in the correct side? What have you done for finding air leaks? Quote Link to comment Share on other sites More sharing options...
slowpokebanshee Posted September 17, 2004 Report Share Posted September 17, 2004 I agree, pull the pilots, and see if they are full of "grtape-jelly" or something. happens all the time to me, cheap gas, and sits too long in the float bowls, been told though if you run race gas it will not "gel" in the bowls, or go bad? any one else know of any truth to this? Quote Link to comment Share on other sites More sharing options...
2004LEBanshee Posted September 17, 2004 Report Share Posted September 17, 2004 I live by you and have stock piolts Quote Link to comment Share on other sites More sharing options...
United Pot Smoker Posted September 18, 2004 Report Share Posted September 18, 2004 (edited) when you pull the choke it should bog out and die. change the needle clip to the middle. make sure the floater bowls are on the right carb. ( the bowl with the gold or bronze ball at the botton if it should be on the left side, the side with the choke). are you running lean? it almost sounds like your pilots are lean. how does it run when you get it going? it actually sounds like your lean all over. you are mixing race gas right? Edited September 18, 2004 by United Pot Smoker Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted September 18, 2004 Report Share Posted September 18, 2004 Nightrider,did you get this figured out?When I ran stock carbs,I ran a 32.5 pilot.Let me know how you make out. Quote Link to comment Share on other sites More sharing options...
Nightrider Posted September 18, 2004 Author Report Share Posted September 18, 2004 (edited) Sickboy,I got it running with 30's,but it seems like it wants a tad richer,so I'll try 32's.I'm running a stock lid with 3-1 inch holes in it and 300 mains,needle in the 3rd clip and she really rips.That motor is a midrange monster! It runs great a idle and off idle,It doesn't have any stumble or bog,but when I pull the choke the engine revvs up a bit,not a whole lot,but just a enough to hear the change in rpm.The plug even comes out a tad wet,but the color has developed into a nice golden brown. I'll have to try the 32s and I'll let you know how its going.I'm running 110 race gas . Edited September 18, 2004 by Nightrider Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted September 20, 2004 Report Share Posted September 20, 2004 Let me know how you make out,I told you you would like that motor.I just welded the motor mounts in my shee yesterday ,and I'll send you some pics when I get a chance. Quote Link to comment Share on other sites More sharing options...
roosthrower Posted September 21, 2004 Report Share Posted September 21, 2004 Here's the problem,I have a .40 over vito power piston ,Rad valved,FMF piped engine with 185 psi cylinders,K&n air filter with a mildly vented lid.The engine originally had mikuni 28mm flats on it ,but I haven't got a throttle thats set up for them yet.So I had a set of stock carbs that I went through cleaning every orifice and rejetting them at 310 main,30 pilot and needle in the 4th clip from the blunt end.Seemed like a good place to start. I've never ran fatties and the jetting is totally different than my PC's. The problem is it starts and runs great with the choke on,but as soon as you kill the choke,the engine died.So I started playing with the idle& air screws and got it to maintain an idle after the choke was closed,BUT when I pull the choke,the engine runs better and revvs up.WTF What gives?could it possibly need a larger pilot?I thought 30's were perfect for fatties,considering I'm still running a lid with very little venting. Any suggestions?I've covered the obvious as far as choke tube,air leaks,carb sync etc. do you have some head milling done as well? with my compression tester, I get a reading of 150psi with my power pistons. That's also the number that vitos said I should get with a set of power pistons. Quote Link to comment Share on other sites More sharing options...
SICK BOY Posted September 21, 2004 Report Share Posted September 21, 2004 He's running a Noss head,and that motor does put out that kind of compression I know first hand. Quote Link to comment Share on other sites More sharing options...
roosthrower Posted September 21, 2004 Report Share Posted September 21, 2004 I guess that's the difference right there. I'm running a stock head and I'm at sea level. Quote Link to comment Share on other sites More sharing options...
Nightrider Posted September 21, 2004 Author Report Share Posted September 21, 2004 Sickboy,I went with a foam filter and shees dead on now.That motor can pull a 15/41 with 22 inch holeshots without breaking a sweat. That thing is a monster.It was definitely worth the swap! I'm gonna look for those reeds and send them out with the Clymers manuel tomorrow,I've been so busy tring to get this badboy running,I totally forgot.keep an eye out for an large envelope from USPS. Quote Link to comment Share on other sites More sharing options...
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