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rmcr250r

Jetting for temperatures below freezing.

11 posts in this topic

Whats a good jetting setup for a 09 yz450 in temperatures below freezing? And while im here what type of oil is best for these types of temperatures.

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If you have a baseline jetting for say, 70 degrees, compensate for the low temps by going 2% larger for each 15 degrees drop in temp with the main and pilot. So, if you're at 25 degrees, and your 70 degree jetting was 45/165, go to 48/175 or 48/172.

You manual tells you what to do about the oil. Any good 10w-40 is OK down to 10 degrees. A 10w-30 can be used, but I wouldn't unless you expect temps to stay below 60.

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another thing you may want to chang is the plug. the manual on my 600's tells me to change the plug in cold weather riding....it makes a BIG difference!!

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If you have a baseline jetting for say, 70 degrees, compensate for the low temps by going 2% larger for each 15 degrees drop in temp with the main and pilot. So, if you're at 25 degrees, and your 70 degree jetting was 45/165, go to 48/175 or 48/172.

You manual tells you what to do about the oil. Any good 10w-40 is OK down to 10 degrees. A 10w-30 can be used, but I wouldn't unless you expect temps to stay below 60.

right now its stock jetting with 160 main and 45 pilot so ill gives those two examples a try. With the stock jetting it ran pretty crappy in 50 degree weather so i guess ill have to experiment.

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Use a 10w30 that doesn't have the starburst 'energy conserving' symbol on the label. Many of the "high milage" oils fit this, some don't.

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What the heck are you doing riding when it is that temperature?

what else am i gonna do while waiting for the tip ups to pop up:smirk:

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I ice race my 450 in the winter. It's a blast to be able to run a bike in 5th gear though corners, dragging a peg. I never thought riding in circles would be so much fun.

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I never thought riding in circles would be so much fun.
You should give speedway a try sometime. 170 pound bikes with 60 HP, 0-60 in 3 seconds, no brakes. :moon:

speedway-johann-pongau_sm.jpg?t=1261640294

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Yeah that looks like it would be a blast. Those bikes are set up nice. I wouldn't mind having one of those for the lake.

This is my ride. #59 is the guy no one can touch and he rides a 20+ year old yz250!

IMG_5826.jpg

IMG_5850.jpg

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