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09 300XCW Head Mods & Fuel Economy


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I recently picked up a new 09 300XCW and have noticed some folks reporting that in addition to a nice performance gain they are also seeing a significant improvement in fuel economy and range with head mods. If this is true it seems like money well spent (Improved mileage and performance) compared to a larger fuel tank. The performance gains are well documented, I am interested in people’s experiences with fuel economy with the head mods or SX head swap. I primarily trail ride fast open desert with a little mountain single track thrown in.

Thanks

Mike

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It's been my experience on my 08 300, that jetting had a much bigger impact on fuel economy then the head mod (Slavens). Of course, how hard you twist, has the biggest impact of all.

FWIW - I went ahead with the bigger tank, because I wanted to be able to go 100mi, without having to worry about ever running out (I have yet to hit reserve). Although I rarely ride that distance, being able to see how much gas is in the tank is more than worth the impact of the bigger tank.

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It's been my experience on my 08 300, that jetting had a much bigger impact on fuel economy then the head mod (Slavens). Of course, how hard you twist, has the biggest impact of all.

FWIW - I went ahead with the bigger tank, because I wanted to be able to go 100mi, without having to worry about ever running out (I have yet to hit reserve). Although I rarely ride that distance, being able to see how much gas is in the tank is more than worth the impact of the bigger tank.

What tank did you put on?

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Just got back from my first ride after getting the Slavens head mod done on my 09 300. I went roughly 70 miles on the stock tank and did end up getting into the reserve. I don't think my mileage went up at all, in fact if anything it seemed a little lower than I expected. in my experience these bikes can get around 75 miles on the 2.9g tank, beyond that and you're pushing it.

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The only time I acutally tried to figure out my mileage was shortly after getting the bike and running a dual sport ride of mostly 2 track. I was using the JD blue #2, 35 pilot and 162 main, running 50:1 Motorex. No engine mods, except hard parts pipe and Sparky. Since the bike was new to me, I was enjoying the twisting of the throttle and feeling that instant power that I never felt with my XR650L. So I wasn't casually riding those 50 miles, I was drunk with power and don't even get me started about the 120#'s less machine.👍

So, we stopped for fuel at 50 miles and I only put in just shy of 1.5 gallons

50miles/1.4gal=35.7mpg

I'm riding single track this weekend, the trail is 22 miles long, so I'll start with a full tank, ride one loop and see how much it will take to top her off just for shits and giggles.

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What tank did you put on?

IMS 3.8. I marked off half gallon intervals on the tank, now I ride with the gas I need. Ironically, even with the bigger tank, I think I actually ride with less gas.

My mileage is similar to Wrfrk - maybe a little better since I'm usually running at altitude and am jetted pretty lean.

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Must be the 3.7? Anyway that's what I just bought and put on. Hopefully I can go riding this weekend. Last fall I got about 75km til I hit reserve on the stock tank. I know that I really need to get my jetting in check because it was running really fat at 7c. Hope to get 120km+ with proper jetting and the ims tank.

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Correct me if I'm wrong, Cletus26, but I'm figuring your 75km is 45 miles and 125km is 75 miles? Numbers in miles are easier for me to understand. I'm still trying to figure out range on the stock 3 gallon tank for open desert riding. I'm told it'll go 60 miles (100km) safely?

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Your conversion is right. I hear you can get that mileage but I have been unable to. When I got the milage on my bike when it had only 20 hrs or so. Also like I stated my carburation is off. Not sure if it's the float or jets or needle but it was running rich even in the cold temps (40 f). So this probably is worst case senario.

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Must be the 3.7? Anyway that's what I just bought and put on. Hopefully I can go riding this weekend. Last fall I got about 75km til I hit reserve on the stock tank. I know that I really need to get my jetting in check because it was running really fat at 7c. Hope to get 120km+ with proper jetting and the ims tank.

It's actually more like 3.5, but the invoice says 3.8. You must really whaling on the throttle or your jetting is really rich. Even adjusting for altitude (you're not that much lower than I am in the winter), I still get much better gas mileage then you seem to be. Are you running Slavens' needle?

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It's actually more like 3.5, but the invoice says 3.8. You must really whaling on the throttle or your jetting is really rich. Even adjusting for altitude (you're not that much lower than I am in the winter), I still get much better gas mileage then you seem to be. Are you running Slavens' needle?

No not whaling on it. My altitude is between 1900 and 2400 feet. My bike is totally stock. 165 main 35 pilot 3rd clip stock needle. I think it may be my float and need to go a notch leaner on the needle. I'm going to try and get out to jet my bike in the next week or two now that the snow is gone. I mostly don't want to put in the work of jetting until I get a day close to summer temps.

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Jetting had a huge effect on my 125.

Initial fuel mileage when I started highway driving it was around 35mpg tops.

Leaning out the pilot and needle got that up into the 50s.

I stayed a bit rich on the main, about one size up from my coldest condition, since it isn't used for cruising.

Fuel mileage while trail riding is highly variable, hard to track. Driving on the highway is far more consistent for jetting as well as tracking fuel mileage.

As well as the jetting, my sprocketing was upped to 14/45 which slowed the highway revs down as well, although switching to 14/48 or even 12/48 has not caused me a hugely noticeable (not measured) drop in fuel mileage, when conditions warranted those gearings.

Get the main right, then lean the pilot as much as you can stand. Too much and it won't be drivable. You may need the choke more often or longer, let warm idle be your guide. Then find where the needle works best. Going as lean as you can on the pilot and needle makes for a crisp working engine, no spooge, no carbon and no risk of detonation. If you are in the right range the idle mixture will be near 1-2 turns and the needle won't be at an extreme either.

Guess which one was set up this way?

24607_412211985802_549110802_5543568_7634667_n.jpg

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