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Bad MPG help please(Kind of long post) Appreciate input and answers though!

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I picked up a used xr650l the other day, I have ridden it about 400 miles since. I've checked my gas mileage and every tank has been terrible compared to the last one I had. I used to get between 48-55 miles/gallon on the road. The best I have gotten so far was 40 mpg on one tank. The 40mpg tank was before I decided to make it louder by taking the after market baffle the previous owner had put in the stock exhaust. Here is what I know has been done to the bike; snorkel removed, K&N filter, stock exhaust(now without any baffle), also still has the smog pump on it. All my bad gas mileage was on midgrade ethanol free gasoline. I thought some of the bad mileage on the road was due to the 14T front sprocket and 45T rear sprocket. They needed changing along with a new chain(old one seemed rusted or frozen on some links) so I put it back to my favorite gearing for where I ride and put it back to stock 15T and 45T. I ordered four jets as well so I can do the daves mods. I ordered a 55 pilot, 58 pilot, 158 main, and 160 main. I think on my last bike I ran a 55 or 58 and 158 or 160 and I was pretty happy with it. I also am ordering a Unifilter tomorrow and I guess I'll spend the $20 for an IMS block off kit unless someone can tell me it's pretty easy to do yourself.

Ok with all of that said, (1) will rejetting help my gas mileage? I get a mean back fire every now and then, (2)could this be from just gas being wasted and igniting in the pipe? Also, the bike runs terrible a little before 3/4 throttle up to full throttle. (3) I'm thinking it has the wrong main jet in it? (4) Lastly, does removing the smog pump really do anything? I'm not really worried about weight. (5) Last question, do I need to wait until I get my UNI and IMS block off kit to rejet? I will get my jets probably tomorrow and then I don't know how long on the rest of the stuff. I may go ahead and order a slip on Big Gun pipe because a friend of mine has a big gun header for the XRL... I don't know what to do. I don't know if a big gun header really does it enough for me to want to spend the $130 on it. I would just like to get back up to 47+ miles/gallon. If the jets I ordered + UNI + smog kit(not sure if that affects any of this) + completely gutted exhaust and ground welds on the header pipe will work together I'd be happy to leave it at that. Thanks for any input or help! Seriously!

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Is the needle shimmed with a bunch of washers? Fuel mileage is largely determined by mid range jetting.

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I haven't taken the carb off yet. I guess it wouldn't be a bad idea to go ahead and order a new needle before I tear into it? I'd like to take the carb off as few times as possible. I've rejetted my other L a couple of time and am decent at it, but the fewer times taking it off is less chance for me to mess it up!

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Removing the smog chit is really only for looks,,it`ll help a little in decel poping and that`s it...

Changing the jetting from stock will affect gas mileage,,for the worse,,let`s face it,if you put in larger jets it`s gonna use more fuel..

It`ll run better,but use more fuel.....

That said,,i know a guy that got about 50 mpg or close to it and rode vthe 48 states and up here a few provinces ..he drove really easy,55mph was his usual speed..he had 55/158 with Daves Mods.......he easily beat that with stock jets...it`s all about throttle control.......

B

Edited by brianhare

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Yeah I believe the throttle control, I used to get 45-52 on my last XRL. Since mine won't run right at all past about 1/2+ throttle I figured gas is getting wasted or something. I was hoping the right jets would make the fuel economy better. I used to only get below 40 riding in the woods. Where I would get about 32-35mpg.

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Man, i want to know what all you guys are riding getting 30 mpg in the woods. I get about 20 tops poking around and exploring and 15 when i am on it and having fun. And thats on a 250 four stroke.

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You should get way better road mileage by changing the sprockets to 16/39 or 15/39,,that is good road gearing for 600s/650s .Half my 600s are 16/39 other half are 15/39.,,In fact that's good road gearing for the 400s as well..High road speed less revs==More mpg. Mind you that said should you wind it out in every gear naturally the mpg will suffer..Fifth should get you up to around a 100mph,, possibly more,,Not sure really as they get kinda wobbly above 80 so I've never done the max rev out on one..I always get worried about a chain chuck or an engine explosion as well at those speeds so I'm not Captain Gungho on extreme high speed running..

Edited by Horri

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To make carb removal/ installation easier, unbolt the air box and slide it rearward slightly. It won't give very much extra wiggle room, but enough to be worthwhile.

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From what I ( think I ) understand, removing the snorkel is a bad idea, unless accompanied by the entire "Dave's mods/re--jetting " thing.

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