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supastipa

2003 WR450 with 150 main Jet??

8 posts in this topic

Tore into the carb on my 2003 after about a month of owning and riding it :thumbsup: to replace the pilot jet with a new one to try and smooth out the idle. While I was in there I removed the main jet to see what it was - It said 150 on the side. Can this be correct?? Did 2003s come jetted this lean? Everything I have read in the jetting database on here points to most of you in my elevation/temp range as having a 165 or 168. Should I change it? Is there anything with the 2003 carb that would facilitate such a lean jetting. I'm here in Utah so we ride anywhere from 4500 ft up to about 8000 ft. Temp now is around 60 but should be in the 70s or 80s soon.

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Generally you go leaner when your up at higher elevations sounds about right for 8000 feet, 168 is what I have in my 08 but the stock was 162 for my year.

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Can't say for sure but didn't Dynojet kits come with jets that were marked differently? I seem to remember back in the day swapping out a jet in something I had that sounded way undersized with a stock jet (might have been a KLX650 I once had) which I later found out had a Dynojet kit in it and was the same exact jet.

Might be something like that. If it runs fine, leave it.

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Not sure who it was, but there definitely are jets with a different numbering system...

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Almost positive it is the main jet that came with the bike from the factory - the guy I bought it from never touched it. When I look up the carb schematic at RMATVMC it shows the 2003 carb with a 150 as (STD) but the 2004 shows a 165 as (STD). Is there any differences in each year's carbs or anything that would lead to such a lean jet from the factory on the 03?? Anyone else with an 03 take a 150 MJ out?

My bike isn't running that great (although I have no point of reference since this is my first bike), it's showing symptoms of a lean condition that I have read about here - back firing, glowing header, hard to start, etc. At this point, i'm sure I will end up with a JD jetting kit, just a little curious. By the way, my bike is stock with all the "free" mods done except the airbox snorkel removal (still can't figure out how to get that thing out)

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on my 08 the snorkel just pulled out... has rubber on both sides of the airbox plastic, I squeezed it and pulled it out... kinds hard to pull free

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Almost positive it is the main jet that came with the bike from the factory - the guy I bought it from never touched it. When I look up the carb schematic at RMATVMC it shows the 2003 carb with a 150 as (STD) but the 2004 shows a 165 as (STD). Is there any differences in each year's carbs or anything that would lead to such

Is there a stylized "K" (for Keihin) preceeding the 150? If so, at least you know it's the standard numbering system we are all used to, and not the Dynojet system.

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That may be the corked up jet. For an uncorked WR at 6,000 and up, a 155 is about right. A 162 at SL is correct.

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