I installed a UFO and the performance is even better. I still have a dead spot when you hit the throttle. It gets worse when it is hot. It will take 2-3 seconds for it to rev and take off. But when it takes off it is very strong. What is the reason for putting in a smaller pilot jet with the UFO? Everything is awsome except for the 3 second take off lag. Any suggestions? When it is cold the lag is not there but when it is hot it takes a few to get going.

 

2Many, it's been a long time since I messed with those. Seems to me there was a nifty booklet that comes with the install guide. Said something about the smoothing of the airflow/great effeciency, is why the pilot circuit could be leaned. Have you checked your idle-1/4 throttle jetting? Maybe try (check jetting first) but a 1/4 turn out to lean things just a bit more.

 

I've had a lag problem with mine ever since I started to putting mods on it.
It was pretty close to perfect after I installed the keihin air striker carb but
still had a small lag most noticable if you quickley hit full throttle from a dead
stop. Then I had the flywheel race lightened. BINGO!!!! So whatever lag was
there is gone now. Faster revs eliminated the lag. I'm still waiting for 2 of
my crank bearings to come in but before it went down it pulled like a MODIFIED
400 scrambler.

 

yo. the booklet says the major tuning change we have seen when installing the UFOs is in the pilot jet circuit. the jet pilot jets ned to be reduced by approximately 50% ( example: if stock pilot is a # 50, then reduce to a #25 - this usually put you close to correct size+/- one size). pilot jets are in increments of 5 .......... Your pilot jet feeds fuel from idle all the way to full throttle. when you you reduce the pilot jet, you also affect the main jet. 4 to 6 pilot jet sizes in the increments of 5 equal approximately one main jet in increments of 10. changing from a #60 to a #30 is a reduction of 6 sizes ........ if you started with a #300 jet, dropping 6 pilot jet sizes would make your #300 main jet equivalent to a #290 jet.. got this info from the ufo booklet 2manytoys...... hope this helps ..... im going to try a #15 or a #20 pilot jet.... running a 180 main jet. then after changing out pilot jet im going to try a 185, and do a plug check... hope this helps.. Hey if your booklet says somthing differ tell me ok.... my pilot jet wont get here until this wed.. or thur... Orderd from carb warehouse a #15 and a #20 ...........

 

I am already running a 200 main and dropped to a #20 pilot jet. When it is cold it does not have the lag and it is hard to keep the wheels on the ground but as soon as it warms up it takes 2-3 seconds for it to rev and the wheels wont come up. By that time everyone else has already taken off. Once I get going it really pulls and the throttle response is there. I like the increase but still cant figure out the 2-3 second lag when warm.

 

mines does a little when warmed up..... mines has a #20 pilot jet gonna put a #15 in it...... almost sounds like it is still running rich....... maybe.... thats all i can figure out ......... kinda sputters then goes......right... go to www.thunderproducts.com and read on the ufo

 

Maybe this is a problem for Rick Ritter. No one else seems to know what the problem is. It pretty much started when I puy the pipe on and just seems to get worse with every mod. Other than that it runs real strong and smooth.

 

Try turning the pilot screw out 1/4 turn at a time....still check jetting. Note: it's only supposed to be effective up to 3 turns out.