My prairie has always been very sluggish at low and mid range. I spent some time experimenting with my carborator and here is what I did. I eventually made a brass washer measured at .060 and shimmed my needle valve with it. I tried other thicknesses but .060 seemed to work the best for me personally. It really picked up my low and mid range. I have never been able to spin my 26" gators on concrete before but I can now. "Wow" what a great modification that was free.

I have a stock exhaust I bought off ebay for .99 cents due in any day. I can't wait to experiment with that also.

More to follow,
Mud

 

Great job. Keep the ideas coming

 

How exactly do you put the washer on and where? I've had the same problem but on a different bike. The needle valve is that small metal cilinder like thing with the tapered dark colored end right? Thanks.

 

?

 

Sorry, went riding all weekend and just now checked back in. What kind of bike are you having problems with? Honda's and Yamaha's, so I have been told have an adjustable needle valve. Kawasaki does not. I do not know about the other brand bikes If they are adjustable or not. I actually took a picture of what I did to help others and I want to post it in my photos but I am having problems getting the picture from one computer to another (Long story.)

The needle valve in question actually looks like a long sewing needle that goes directly thru the center of the carburator. You access it by removing the top section of your carborator only. The pointed end of it will go into your main jet while assembled. It also slides thru the diaphram. By raising the needle valve like I did I increased the flow of fuel thru the main jet almost as if I had re-jetted the bike to a larger size main jet.

If yours is adjustable than you will have a removable clip that you can position the needle valve up or down. (You want to raise it off your main jet.) While playing around I found that a .060 washer worked the best for my bike. That is about the thickness of a quarter. I had a brass washer that I drilled, cut, and filed to fit my needle valve.

I will continue to try and get my picture posted I hope this helps some. P.M. me if you have problems I believe I can walk you thru it, very simple mod.

When I went riding this last weekend I tackled more than a few hills and mud holes. That one Modification made my bike run so much smoother and stronger I thought I was riding someone elses larger CC bike. My partner rode behind me and said he was amazed at the rooster tails I can throw now.

Mud[img]i/expressions/face-icon-small-smile.gif[/img]

 

My bad, I wrote that the needle valve goes thru the diaphram and it does not. The diaphram is directly above the needle valve and spring.

Sorry brain fart,
Mud

 

Nice find, Nothing like tinkering a bit and finding a gem.[img]i/expressions/face-icon-small-smile.gif[/img]

 

Wow, I was just thinking of shimming that needle a while back to try to increase performance. Well, too late now lol. I just ordered a jet kit which has an adjustable needle. It will be about 2 weeks though so I will tinker around with that! Thanks, pics would be cool.

 

Finally got the picture posted. The very tiny washer I used was made from the larger washer that is cut up next to it. I highly recommend this modification. Just think if it does not work for you, just simply remove the washer. Nothing lost...

Mud

 

I'm defeneatly trying that. Wonder what size I should use for a 300...