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Jetting confusion

1611 Views 6 Replies 3 Participants Last post by  eric
I have recently added a HMF Utility pipe to my 500 foreman. Installed 165 jet and around 2.5 turns out on the a/f, also a new plug which wasn't gapped correctly(my fault). Seemed to run flat on the top end couldn't tell much power difference than stock. This was my first time tinkering with a carb i didn't want my bike running lean. I took it to a local motorcycle shop to let them professionally jet my bike. Now i live at 2000 ft and temp has been around 30-40degrees. So i got my 4wheeler back today. they took the 165 jet and put the stock (162) jet back in. and also installed a new properly gapped plug. didn't touch the air fuel. The bike seems to pull much better than before threw the gears. But shouldn't my main jet be larger? like a 165 or 170? i don't have a snorkel just a uni filter and hmf. I pulled the plug today after riding the bike for 5-10 miles. Ran it wide open till the top of 4th and killed it. The porcelain on the plug was white. L shaped electrode had a gray tint to it. The bottom of the plug where the threads are was black. Now this shop i took my bike to they build racing dirt bikes and work on anything with a motor in it. I have trust in them. but running my stock jet doesn't seem correct. Does anybody have any advice or tips for me? anything would be greatly appreciated!
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thats interesting. Every bike is different, my buddies Rubicon with the same mods ran best with a stock jet too, as long as the plug looks good, and its not getting to hot and running smooth, then you should be good.
according to your plug description your jetting is correct; if anything a hair rich...................leave it alone and start thrashing on it
well it sounds like time to give her ****! i think my a/f might need a little adjustment. can i just let it idle, check my plug, and adjust my a/f it its rich or lean? also dumb question.....when installing spark plug how tight should it be?
You'll feel the compression washer collapse and then give it a little more. I always put a little never-seize on threads before installation. Why do you think a/f screw is not right.
well i had messed with the a/f when u gave me that technique to go by and i adjusted it so many times im not sure if its dialed in. also on the tailpipe of the hmf its black like its running rich possibly?
well if it starts good and idles good and seems responsive than I would leave it
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