what effect would enlarging pilot jets on carburettors have on an engine?? run leaner?

It depends. Some pilot jets let air into the fuel, some let fuel (and a bit of air) into the the main air flow.

Ive been told by hole shot that the needles in my carbs are dropped as low as they can go and I need to drill out the jets by.5 mm,they said its the jet next to the one the needle goes in, Have I got the right one?? apparently it needs leaning of slightly?? im running a 135 main jet now.

bttt

Seeing as you've paid them a not inconsiderable sum of money to do the conversion, surely they should have put the correct sized jets in or mod the ones youve got to make it correct at the time?

I have to agree with chris on this one. Since you paid them so much, surely when they set the engine up, they did a 'proper' job? If not I could understand if the engine requires a running in period, but surely it should just then go back to be fully set up?

drilling it out by 0.5mm is a VAST increase in size, for a main jet you would have a noticeable change if you drilled it up by 0.05mm. Not sure how pilots differ though.

I think holeshot would sort it, its just the distance, so I asked them what to do and ill have a go, It wont hurt.

Be careful drilling them if you do brave it, as a slight slip could mean a tralier back to holeshot rather than driving. Could they not just send you the correct jets if they're so confident on the sizings?

Just got an email from jack its not the jets i need to drill its the 2 small holes on the slider next to the needle.

I wouldnt drive it to holeshot anyway its 186 miles each way!!

I have a drill bit that fits the origional hole which has '37' on it, jack said i need to increase it by ten thou at a time, I only have metric bits and my next size is 3mm is this too much?


[Edited on 30/8/06 by dilley]