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07 cr250 jetting

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Another problem I have is jetting. I suppose it could be due to the reasons in my previous post of changing from a 125 to 250. My problem is I can never get the bike lean enough with jetting and haven't tried anything higher than 50:1. If I go too lean on jetting my bike will rev on it's own in the air. I can be in the air with no throttle and it shoots up to like half throttle by itself. Agaiin only reason I want bike lean is so i can use clutch like 125, not sure if this is possible.

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Getting the jetting leaner or richer should be done thru the use of jets, not your fuel/oil mixture.

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Another problem I have is jetting. I suppose it could be due to the reasons in my previous post of changing from a 125 to 250. My problem is I can never get the bike lean enough with jetting and haven't tried anything higher than 50:1. If I go too lean on jetting my bike will rev on it's own in the air. I can be in the air with no throttle and it shoots up to like half throttle by itself. Agaiin only reason I want bike lean is so i can use clutch like 125, not sure if this is possible.

Putting less oil in your gas actually richens the fuel/air mixture that your bike burns for combustion. so if you are leaning out your fuel/oil mixture in your gas to try to lean your bikes jetting, you are going exactly backwards. You need to pick a oil/fuel mixture level and then jet your carb to match it. I like 32:1 on my 125.

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i was running 32:1 all the time and changing my jetting. Since I wasn't getting the desired results that way I went to 40:1 and so on and kept messing with the jetting. I ended up getting pretty close at 40:1 with some jetting modifications but I still couldn't get the magic out of it. Maybe i'm too used to 125's and I have to use the 250 different.

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i was running 32:1 all the time and changing my jetting. Since I wasn't getting the desired results that way I went to 40:1 and so on and kept messing with the jetting. I ended up getting pretty close at 40:1 with some jetting modifications but I still couldn't get the magic out of it. Maybe i'm too used to 125's and I have to use the 250 different.

It is possible that you have other issues that are causing your lack of bottom end...other then jetting. You probably want to make sure your carb is really clean, check your float level, check for proper compression, make sure your power valve is adjusted and working properly. All of these things can affect your power curve.....along with jetting.

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What model pwk is it? What are the benefits? I also have a rad valve, that added some power but not the total change I was looking for, is the tassinari better? Have a pc pipe and shorty silencer as well. Nothing seems to get at the bottem end or help my clutch, at best everything I have has only smoothed out overall power. I am going to send my head and cylinder to pc, could that help the clutch action out?

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my bike only over heats after i changed my piston and used an iridium sparkplug what can i do to make it stop?

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What model pwk is it? What are the benefits? I also have a rad valve, that added some power but not the total change I was looking for, is the tassinari better? Have a pc pipe and shorty silencer as well. Nothing seems to get at the bottem end or help my clutch, at best everything I have has only smoothed out overall power. I am going to send my head and cylinder to pc, could that help the clutch action out?

the Rad valve is a good Reed Valve but also requires leaner jetting then stock.

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I just picked up a new just out of the crate 2006 CR250. I read alot about the PWK carb conversion ,and may eventually go this route ; but at least wanted to give the Mikuni a shot , before spending the money and time on a new carb set-up.

The first thing I did before ever riding the bike or doing any jetting was to send the cylinder head out to RB designs to correct the squish band.

Then I bought the JD jet kit , and installed the recomended jets and needle.

I have to say this thing runs great ! Excellent throttle response ,no pinging , and a nice cocoa brown spark plug color. The different needles are the key to the JD kits.

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I just picked up a new just out of the crate 2006 CR250.

Where did you find this? Are there more available?

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The first thing I did before ever riding the bike or doing any jetting was to send the cylinder head out to RB designs to correct the squish band.

Very smart move, some of the best money spent on the '05-'07 Honda. Let me guess- your stock squish was 0.084" before sending it to RB???

Edited by APBT

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