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has any 1 here installed a hot cams on their 04 yz250F, if so what is your oppinion on them, and do you have to re-jet

I have the same bike and installed Hot-Cams a few months ago. Here are my observations from another thread: https://thumpertalk.com/forum/showthread.php?t=280489

I installed a pair of hotcams and a Wiseco hi-comp piston and I was completely underwhelmed with the improvement. There was almost no difference from stock. So I started searching this forum trying to figure out what I was missing and I ran across one of the threads about opening up the airbox and handholes and removing the screen. I figured since the Factory4 exhaust and Hotcams allow more flow' date=' maybe I wasn't getting enough flow on the intake side.

(There was a) considerable improvement throughout the entire range and especially in the grunt factor. I'm able to run a gear higher in the tight stuff now and carry the front wheel over obstacles with a throttle blip and that's running 14/50 gearing.

I'm not sure how much improvement it would make with all other things being equal, but the combination of all of it made a big difference for me.[/quote']

As for jetting, after the hotcam/piston/airbox mods, my jetting was definitely off. I ended up going richer on the main to a #185 and using the JD red needle.

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just read a review in Dirt Rider on the Hotcams. they were not impressed with gains on 03+ bikes.

the auto decom. was a nice addition on older yzf's.

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I have the same bike and installed Hot-Cams a few months ago. Here are my observations from another thread: https://thumpertalk.com/forum/showthread.php?t=280489

As for jetting, after the hotcam/piston/airbox mods, my jetting was definitely off. I ended up going richer on the main to a #185 and using the JD red needle.

Where you running the blue needle before? In Texas you should have been running the red needle anyways I would think. What clip position are you running also?

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Where you running the blue needle before? In Texas you should have been running the red needle anyways I would think. What clip position are you running also?

4th down from the top on the clip position.

I bought my bike slightly used, but with the exception of changing the leak jet from a #70 to a #40 after I got it, it was jetted really well. It came with a OBEK-Q needle (which is a little richer) instead of a stock OBEK-R. After I did the hotcam/piston/airbox mods, I was flowing more air and the jetting wasn't rich enough to keep up. I tried changing the main jet first. It came with a #178 and I tried increasing it to a #182 then # 185 then #188. Something still wasn't quite right, so I ordered a JD Jetting kit.

Based on my crude measurements, the blue needle is a little leaner than my OBEK-Q (which is a little leaner than stock) and the red needle is a little leaner than the blue needle. I got the best results with the red needle and the #185 main. I'm planning to try the blue needle as soon as the weather cools off.

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