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4 mil dune port plug chop results


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i have been having a very hard time getting my hjr 4 mil dune port dialed in correctly. kev recommened 330 mains ( stock cabrs) and it ran well but at the top end of the power band it would seizure. so i jumped to 370. ran like shit. down to 340. worse then the 330. went to 320. ran about the same. put the lid back on the air box for shits and giggles. and alot better improvement reved out good and didnt really seizure much but that was like 40 degrees out. since its in the 70's today im down at a 310 with lid on and its still damn seizuring at the top end of the power band. i did a plug chop and heres the results. please correct me if im wrong.... it should be a light brown color not bigger then 2mm. it looks really rich still so im thinking about dropping down 2 or 3 sizes on the main jet. maybe a 290? thoughts everyone please! someone with a 4 mil storker not ported was running 270 in the summer with the same elevation if im not mistaken so im guessing the dune port cant add that much air so maybe even a 280 main jet?

IMAG0382.jpg

Edited by bluebanshee98
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Were those new plugs? Also I run 310 in my stock stroke dune port 350. Seems like it would be to small for a 4mill. just my two cents.

geezez sorry about that guys i freaking chopped the wrong plug. heres the new one . this is how i did the plug chop. engine was already warmed and been riding for a hr. put the new plug in started it. punched it from 1st-4th and keep it pinned at 4th for about 3 seconds and killed it while throttle was pinned. i did this twice and pulled the plugs out, put old ones back in. seems almost on right now prob a lil lean but what the hell would be causing it to seizure at the top of the power band? i gotta check the gap on the plug

IMAG0385.jpg

Edited by bluebanshee98
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It was basically acting like a streetbike when you hit the rev limiter. I changed the gap on the plugs and adjusted the gap on the flywheel/stator pick up and I think it cleared up the problem. I took it down the street and it seemed ok. I'll report back when i get to go for a real ride. Sorry for the typo . I'm on my cellphone and it auto corrects and changes words sometimes

Edited by bluebanshee98
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