Thunderace pilot screw settings

wonkiwheel · Post by **wonkiwheel** » Sat Apr 12, 2014 5:22 pm

Phoned the man at my local Yam centrre asking for the baseline settings and he said 1.375!!! we both kinda gasped, anyways mine were set at 2.5 when i bought it a few weeks back and it was pinking and popping and the revs were taking and age to die off so it turned them out to 3.5 and was alot better but was the sound was a bob bob, not sure if it has been rejetted coz i aint pulled the carbs to bits yet but i have a remus naughty naughty race can on, it is now set at 4.5!!! the sound is smooth and the revs kill off instantly, is it a plausible senario to be set at such a high setting from the baseline setting???

YAMAEXUP · Post by **YAMAEXUP** » Mon Apr 14, 2014 11:34 am

Try phoning Yamaha UK technical department. They've been useful in the past when i've rung them about certain questions I needed a quick answer to.

But 4.5 turns out does sound a bit much

If you run the engine without the tank in place, try spraying something like WD40 or Damp Start around the inlet manifolds, one at a time. If the revs pick up momentarily then there's a leak on one of the rubbers letting in air, causing the engine to run weak on standard settings. Richening the idle screw to 4.5 turns may well be compensating for this.

banner001 · Post by **banner001** » Mon Apr 14, 2014 3:00 pm

after 3 turns out the screws are pretty much useless, you should be able to fit the next size up in pilot jet, that should richen it for you.

i suspect though that you might have a blocked or semi-blocked pilot jet, and thats why you are needing to turn the so far out...

wonkiwheel · Post by **wonkiwheel** » Mon Apr 14, 2014 6:41 pm

Thanks Yamaexup and banner001 yep i thought that 4.5 is a bit excessive i will try both the suggestions before resorting to buying some new pilots. Hey ho off to the garage i go!!

wonkiwheel · Post by **wonkiwheel** » Mon Apr 14, 2014 10:59 pm

Manifold rubbers good, carbs off and cleaned, all stock jets, all seemed in good order apart from a couple of pilot screw rubbers not seated correctly, test in the morning, fingers crossed.

wonkiwheel · Post by **wonkiwheel** » Tue Apr 15, 2014 9:27 am

Well 4.5 seems to be the one, everything back as it should, tried 1.5 turns, revs hung up when blipped the throttle, ran rough as a dog till 3.5 turns runs even better at 4.5, starts fine warm, cold, no popping spluttering surging or anything i can hear or feel...... next gona check the plugs see what state they are in.

banner001 · Post by **banner001** » Tue Apr 15, 2014 11:01 am

if it works...it works

but you might find that you can fit a larger pilot jet, and back the settings down so that you get closer to 2-3 screws out...it will give you a better range of adjustment then if you need to alter it for atmospheric conditions.

banner001 · Post by **banner001** » Tue Apr 15, 2014 11:52 am

not usually, i know the exup 1000 uses different pilot jets to my keihin zxr400.