Jet size help. Detonating. glowing head pipe and back fire.

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Well ill spray it while is running to see if it effects running befor i spend 50 bucks on one
 
Ok pilot jet is a 42.5 which is stock. The main says 165?
20131125_185419.jpg
 
Does anyone know that sign on the top? Is tgis a mikuni jet thats a 165 flow or a 1.65 diameter?
 
i really wish there was more follow up on this because i am having the same issue after my 366 rebuild. Pilot was running lean initially so i jumped to the largest size in my jet kit (47.5) and runs great now at idle and low RPM, but my header glows bright red after riding around for just 5 min. has a new cam chain and adjusted perfectly in sync on the camshaft gear mark and the flywheel T mark. Have a new big bore cylinder & cylinder head, everything is adjusted/set properly. I did notice that the *original* timing was like 2 chain links off from perfect sync between cam mark and flywheel mark. Strange part is that it wasnt glowing red with a smaller 45 pilot jet but now starts glowing red with a larger 47.5 pilot jet which idles much better. With the 45 pilot it would run better with the choke on, so i knew it was more on the lean side before. idles much better with the same idle screw adjustment.

I am now trying to figure out if the pilot air/fuel mixture screw is limiting fuel or limiting air. I would assume it is limiting fuel and would run richer with turns out from the stock 2 turns out.

Anyone else have any ideas?
 
Is that Wiseco piston one of the newer, high compression, pistons? If it's domed on top then it is. And Wiseco told me that if I ran their 12:1 piston, I should only use 100 octane regardless whether or not I could jet and tune for the compression on pump gas.
 
i really wish there was more follow up on this because i am having the same issue after my 366 rebuild. Pilot was running lean initially so i jumped to the largest size in my jet kit (47.5) and runs great now at idle and low RPM, but my header glows bright red after riding around for just 5 min. has a new cam chain and adjusted perfectly in sync on the camshaft gear mark and the flywheel T mark. Have a new big bore cylinder & cylinder head, everything is adjusted/set properly. I did notice that the *original* timing was like 2 chain links off from perfect sync between cam mark and flywheel mark. Strange part is that it wasnt glowing red with a smaller 45 pilot jet but now starts glowing red with a larger 47.5 pilot jet which idles much better. With the 45 pilot it would run better with the choke on, so i knew it was more on the lean side before. idles much better with the same idle screw adjustment.

I am now trying to figure out if the pilot air/fuel mixture screw is limiting fuel or limiting air. I would assume it is limiting fuel and would run richer with turns out from the stock 2 turns out.

Anyone else have any ideas?
You most likely need to run high octane fuel with that big bore.
 
You most likely need to run high octane fuel with that big bore.
So I bought the hot rods stroker crankshaft and the wiseco 12:1 piston 83mm, can I run that combo and not have any other problems besides the high octane fuel
 
So I bought the hot rods stroker crankshaft and the wiseco 12:1 piston 83mm, can I run that combo and not have any other problems besides the high octane fuel
You'll need a piston made for the stroker crank. 12:1 is borderline on a stock head but will definitely need 110 with a good ported head.
 
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