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XR400 '99 fuel range and gearing

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I just got this bike this past spring and have been having a ton of fun exploring and riding here in Utah.

Yesterday i went on a 65-70 mile ride and around mile 60 or so the bike started getting a little cranky. I turned off my fuel valve and tipped the bike over to try and get more gas on the petcock side. It helped a little but when i went to reserve it was back to being a happy camper. How far are folks able to ride on a stock tank?

I also noticed the previous owner switched the gearing from 15/45(i think is stock) to 16/44. Is that enough of a difference for me to notice? Just wondering for when its time to replace the chain and sprockets. I dont ride in the top of fifth very often(never) and if 1st had a little more bottom that could be good...

Notable info about bike and my ride yeaterday.

Mikuni pumper carb

Stage 1 cam

Ride elevation average 9000'

Thanks,

Matt

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Someone geared the bike for the street. If you're riding trail you should put it back to the stock gearing. Yes, its enough of a difference to notice. Riding trail with that gearing makes the engine work harder and would make me need to use the clutch more.

Its time to replace chain and sprockets when they aren't the gearing you want/need. When you notice the sprockets acquiring a hook shape. With the proper chain slack, when you can grab a link at the rear side of the back sprocket and pull it away over half the depth of a tooth.

If you replace sprockets because they're taking on a hook shape, change the chain too because its the stretch from a worn chain causing the sprocket wear.

With stock gearing I've routinely gotten 90 miles out of the stock tank.

Edited by Trailryder42

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Thanks for the info. A lot to learn with this thing. Do you think the gearing, which you said puts extra load on the engine (makes sense) would cause notable worse fuel economy?

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There's more to fuel economy than just gearing. What was that last 70 mile ride, street or trail? How aggressive is your throttle control? Proper jetting plays a part as well as proper float level setting. The XR has really good low end torque, but even so, too high of gearing for what you're using the bike for, like trail riding, causes you to need to ride a gear low to keep the rpms up so you're not over-lugging it and to have the throttle response you need.

Putting it back to stock gearing for trail riding will prevent you from needing to ride a gear low, bringing the rpms down and give you better throttle response without so much clutch work.

I rode a 2 stroke before buying my XR back in '99. I had to get used to not feathering the clutch so much, as the XR didn't need it, just open the throttle and its low end torque will pull.

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It depends on how you ride and how the bike is modified but XRs tend to get good mileage.  Some of the newer four strokes get lousy mileage. 

 

My friend gets 54mpg cruising at low RPM while trying to conserve fuel with 16/45 on dual-sport rides with his XR400.  That's over 200 miles with a four gallon desert tank.  He has the baffle in the exhaust.   

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If figure on 42 mpg street and 25 mpg dirt.

Dirt riding is more time in 2nd and 3rd gear.

I try not to go more than 60 miles between fuel stops. 75 tops.

Pushing sucks. Out of gas in the middle of now where could be dangerous.

On lots of narrow trails and steep climbs, I like 14/45.

Stock is 15/45 and gives more top speed, but 3rd is less usefull on narrow trails.

Get the 15/45 with a spare 14 and you can swap for specific rides.

The Austalian XR400, which is street legal, has 15/42. Closer to your gearing.

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I get about 40 mpg off road and about 50-55 on road. For off road, I don't like anything above stock gearing. On road like I mainly do now with the 400 I run 16/43 and there is a big difference in gearing between those 2.

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The previous owner had the bike set up to be barely street legal. I have no interest in riding on the street at this time. (I sold my street bike). Sounds like back to stock gearing is a good idea when the chain and sprockets are ready. I am riding trails in Utah. Everything from open desert(not as much) to mountain ATV trails(more). I haven't explored too much single track in the area. So with this stock 2.5ish gallon tank folks are getting a bit shy of a 100 miles? is that with the reserve? 

 

I am going to try to bring the bike in this spring to get the carb dialed in. Its been pretty difficult to find info on tuning the carb with the aftermarket parts the previous owner dropped in. And I have never done anything to a carburetor expect pull it off and clean it. 

-Stage 1 HotCam

-Mikunki pumper carb

-WhiteBros Exhaust

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For off road only, I would not try to push past 80 miles unless I had to. Reserve won't get you very far and depending on your average speed / hours of run time, you may hit reserve right around 80 miles.

 

2.5 gallons is total capacity of the tank. Figure 2 - 2.25 gallons is usable, the rest will be reserve and whatever is left in the tank that's below the petcock intake level.

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I routinely got 90 out of my stock tank, without reserve, but that depends on how aggressive you are with the throttle. Not a good idea to consider reserve as part of your normal range. Its a buffer for unforeseen circumstances, like having to back track unexpectedly, getting lost, etc..

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If figure on 42 mpg street and 25 mpg dirt.

Dirt riding is more time in 2nd and 3rd gear.

I try not to go more than 60 miles between fuel stops. 75 tops.

Pushing sucks. Out of gas in the middle of now where could be dangerous.

On lots of narrow trails and steep climbs, I like 14/45.

Stock is 15/45 and gives more top speed, but 3rd is less usefull on narrow trails.

Get the 15/45 with a spare 14 and you can swap for specific rides.

The Austalian XR400, which is street legal, has 15/42. Closer to your gearing.

The Australia XR 400 came with 15/40 standard. I usually run 15/42 and swap to a 14 for tighter bush work.

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Thanks for all of the advice. My mistake, the bike was set up 16/45 and in the box of goodies from the previous owner there was a 14 tooth front. Put that on and went out today. Noticeable difference. All of a sudden first gear feels like first, not almost second. Hills(loose gravel of utah) were a game changer. Previously I would spin my bald rear tire up hills. With the 14 on the front I could comfortably ride up toward the bottom of second. And creep, without spinning my tire, in first.

 

This came at its price. I found my self riding in 3rd and 4th much more. The high speed top end is gone. Thats ok, I sold my street bike. But with the gain in torque, I am not complaining. Way more get-up-and-go!

 

I expect to swap out the front sprockets as Kev_XR recommended. Maybe not every ride, but as I generally go in to, and out of the mountains by season.

 

Very cheap way to drastically change how your bike rides.

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