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Discussion Starter #1
Hey i got the Hmf full system on my 450. I am having some trouble with it. i cant seem to get it jetted right. First i put the 180 in and seemed to lean. I was racing flat track and i would go out and about 5 laps it would cut out, back fire real bad and then shut off. Was real hot. So then i took it in and had a motorcycle shop jet it for me. They put a 200 main jet in. So i took it back to the track and was doing the same damn thing, The motorcycle shop said they didnt have a propblem with it. But the plug is way black. So i put a 195 main jet in and the plug is still black. So i put a 179 main jet in and ran ok didnt have much time to run it, but seemed to lean again, cuz it heated up fast and i ran it for no more than 3 minutes then came back shut it off and the exhaust was lettin out hot exhaust for like 2 minutes shut off. i have the cam mod done thats about it. got any ideas? thanks
 

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I haven't heard of anyone running any jet over 180 unless they have alot of mods.

Your cam-mod / full pipe combo should put you in the 175-180 range. With a K+N and maybe an intake you could be at 180+ depending on altitude. What needle are you running+What clip? What pilot.
The best info is in the jetting faq pinned to the top of the performance section.

Most of the "Jet it yourself-ers" are having to wade through all the posts and make sense of it since without alot of hit and miss, no one can tell you what to jet your 450 at. Your plug reading should get your jetting right on.
 

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I Found the key with mine was the needle, and the pilot jet, i use a #180 main, but the main jet is(from what i hear) 3/4 throttle to full throttle, and the pilot jet is for under 3/4 throttle( may be mistaken).Get rid of the #45 stock pilot and goto #48,and set your needle at #6 (if you did the cam mod) #5 without the cam mod.ALSO play with your air fuel mixture,I use 2 3/4 turns out, some use 3 turns out.
JOE from HMF will know a hell of a lot more then me, but thats what i had to do to stop it from running to lean.
GOOD LUCK!
and talk to Joe!!!
he usually is here everyday.
IF not call HMF @ 216-631-6980
Business Hours: Mon-Friday 8:00am to 6:00pm (EST)


http://www.hmfengineering.com/
 

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Discussion Starter #4
Hey thanks for the quick reply should help me tomorrow alot. Ill tell ya how it goes. But still insure where all the jets and w00ter is. Ill have to ask someone at a motorcycle shop
 

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your problem lies with your needle and clip position.. your over compensating with the main jet in an attempt to fix what was not done correctly. Get a GYT-R (YZ) needle and put it on the 4th clip to start.. Get a realistic main jet of around 170 to start with depending on your intake mods.

200 main jet.. what is your dealer on? Did they actual charge you for this??
 

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Discussion Starter #6
ya they charged me 80 dollars and wont fix the problem. is it hard to get to the neddle. we tried once and couldnt get it. and what you mean get a yz needle?
 

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If you were jetted rich at first, then you may have fouled your plug. If you pull it out and it is real black put a new one in before running your next jetting settings. I just recently went through this with mine these yfz motors will foul plugs if you are not careful.
 

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Originally posted by metalmellinium@Jan 20 2004, 11:07 AM
ya they charged me 80 dollars and wont fix the problem. is it hard to get to the neddle. we tried once and couldnt get it. and what you mean get a yz needle?
no it is not hard..

I wrote up a step by step instruction on it and DADDOG posted it on his site.. find his site and follow the steps..

You need the needle out of the GYT-R jet kit.. same as the YZ bike needle.

Call Bob at Magnolia Tractor for one.
 

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You should definetly check Daddogs site out, here it is:

Daddogs Site for jetting

After reading through all his jetting info, that is what gave me the confidence to jet my own quad. you should definelty switch dealers ,the head mechanic does not know w00ter. Your stock clip is on position 3 most likly, you need to get to the clip and put it to 6 since you have so many mods. There is NO WAY to ever go over 180m, also you need to put in a bigger pilot. Anyways check out daddogs site, it is a VERY big help.
 

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Your problem is the needle. Like others said, you need the yz or JD needle on the 4th or 5th clip. And never say never about jetting. I'm running a 182 main. And I have talked to alot of others running a 185. It's cold this time of year.
 
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