Extending reserve on desert tanks.

[Justin]

I decided to cave in and get a bigger tank after relentless ribbing from some of my old timer riding buddies (after all it is cheaper to bum gas on the trail then bring your own right?). With the stock 06 YZ450 tank I got an average of 55-60 miles a tank. With the WR petcock I had somewhere around 1/3 tank reserve. I have gone around 15ish miles on reserve with fuel to spare.

I only wanted a bit more capacity than stock so I could get closer to 100 mile range. I didn't want to go over 3 gallons as I HATE the handling penalty and looks of bigger tanks so I decided on a Clarke 2.6 gallon.

I figured the reserve would be a bit smaller due to the design of the tank but boy was I surprised to find that it was only a few ounces! Now I already had plans to increase the reserve to at or near 50%. I have always thought it was sort of stupid in most cases, to have anything less. After many searches I found very little mention of the fact that most desert tanks pretty much negate any usable reserve unless you run dual petcocks (ill get to why I like singles better in a bit) Here is what I did:

First I filled the tank 1/2 way and then measured down from the filler cap to the fuel level so that I could find how much length was needed to add to the reserve pipe (7.5 inches in my case).

Im using a WR steel frame petcock which faces opposite the aluminum frame WR petcock I have been using for years on my stock tank. The added benefit as you can see from the pic is that the tubing is brass instead of plastic, making lengthening much easier.

I then took a small pipe cutter and cut the pipe about half way between the screens (to avoid clearance issues with the cutter).

Once I had the 2 pieces separated I simply prepped them like anything you solder (like sweat on plumbing). I just used some 400 ish grit emery and cleaned the mating surfaces after with solvent.

I got a piece of brass pipe from my buddies hobby shop that was just large enough to slide over the petcock tubing (7mm ID). The stock pipe mic'd out at 6.97mm BTW.

It took a bit of elbow grease to get the pieces slid together (the tighter the better) but once soldered, it is super solid.

I wound up with 1.3ish gallons before reserve and a good solid 1.1+ gallon reserve, not including the "lean over" second reserve of fuel on the opposite side (where you would run the second petcock in a dual setup). This second reserve was just about 3/4 of a liter. So not an exact 50% but far more usable than a tiny amount that just gives you a warning that you are going to be walking a long way!

Heres whats left in the "other side" that you have to "tip over" to get. Not much but plenty to tell you to get to high ground. Sort of a second reserve that you would not get on a dual valve setup:

These measurements were taken on a stand so obviously in practice the amounts will vary. Since im running tank foam, the amounts will be more "repeatable".

Side by side comparison:

Fuel line routing:

So in closing, I now have a near 50% reserve, a large enough range to cover any loops I have ever ridden, and with tank foam and the low CG of the Clarke, I cant tell the difference in handling from a stock tank. Cake and eat it to?

[RiderX]

Nice write up, and very nice work.

[Justin]

Thanks!

[rjcook450]

Good idea, I also wanted increased range for trail riding, but didnt want a bigger tank for when i'm on the track, or the higher price of one, so I decided to go with the 1.3 gal acerbis number plate fuel tank, use when im on the trails take it off for the track and it was only $62.00, I have done a 50mile loop at a decent pace and still had 1/8th in the extra tank, and over 3/4 in main tank.

[RiderX]

Good idea, I also wanted increased range for trail riding, but didnt want a bigger tank for when i'm on the track, or the higher price of one, so I decided to go with the 1.3 gal acerbis number plate fuel tank, use when im on the trails take it off for the track and it was only $62.00, I have done a 50mile loop at a decent pace and still had 1/8th in the extra tank, and over 3/4 in main tank.

Do you notice the weight with the number plate tank? That's about 8 lbs of fuel about as far from central as you can get.

[rjcook450]

When I first tried it out to make sure it was siphoning like it should, I did it on the mx track, and i did notice the weight when charging into softer corners, the front end wanted to change directions very fast almost felt like it wanted to fall over, it took more effort on the handle bars, but when I got out on the trails i didnt notice it at all, it could be just getting use to it and also a little bit of the distraction from enjoying the scenery. In all I rate it very high, took a little modifying of the clamps, not much more than a few good hits with a hammer and buy bigger hose clamps, the one part i didnt like was there was no instructions at all on how to set up siphioning hose, but it didnt take much to figure out, I did cut some length off the hose and wrap the part thats in the aux. tank with stainless saftey wire and bend it so it would lay right at bottom of tank to get all fuel out. two of the guys i ride with are getting one also.

here area few pictures of it. http://imageshack.us/g/851/1001766f.jpg/

some video where you can see tank a bit.

[Justin]

Yeah I have thought about that aux tank in the past but I hate any extra weight on my steering. I dont even like the weight of a damper setup, but the penalty doesnt out weigh the benefit there! In fact I love Flexx Bars I just wish they wernt twice the weight of my Evos. Once I get ahold of a YZ250 I can make my FoFiddy strictly trail/single track and ill put the Flexx bars on it. Then setup the YZ250 like my CR250, strictly MX, nothing that adds weight that isnt absolutely necessary. (stock tank, plastic glide plate, no damper or hand guards, thin tubes, lightweight rim locks, etc.)

[zlathim]

Great write up. Very informative.

[Justin]

Thanks!

[Kevenater]

I'd have to get a different petcock. mine only has on and off...

[Jim813]

Nice write up, but what is the purpose of extending the reserve?

[grayracer513]

Nice write up, but what is the purpose of extending the reserve?

He said....:

I figured the reserve would be a bit smaller due to the design of the tank but boy was I surprised to find that (reserve) was only a few ounces! Now I already had plans to increase the reserve to at or near 50%. I have always thought it was sort of stupid in most cases, to have anything less.

[Jim813]

He said....:

I understand that, and I understand that extending the reserve would give you more fuel while on the reserve setting. But what I don't understand is why go through all the trouble? I mean, it's not extending total fuel range, and just seems like a false security or mental comfort.

[AZCrazian]

I understand that, and I understand that extending the reserve would give you more fuel while on the reserve setting. But what I don't understand is why go through all the trouble? I mean, it's not extending total fuel range, and just seems like a false security or mental comfort.

lol ?

[Justin]

lol

?

I guess its not for everyone eh? ?

[Jim813]

Am I missing something?

[grayracer513]

Am I missing something?

Some people prefer having a reserve rather than "keeping an eye" on their fuel level, particularly those who buy their tanks in black or something else besides the see-through "natural" color. If you don't, fine, but I don't see the value in denigrating those who do.

This mod addresses the fact that with an unmodified petcock, there isn't much fuel in "reserve" due to the smaller volume of fuel at the bottom 2" of certain desert tanks. It's both simple and effective.

[Wiz636]

Am I missing something?

To add to Grey's reply; the reserve also functions as a warning that you are getting low on fuel. With some oversize tank designs, by the time you hit reserve you already have so little fuel left that the 'warning' comes too late, i.e., you are just about empty.

By extending the reserve you are being 'warned' earlier that you are getting low on fuel....yet still have enough fuel to get back to the truck.

[Jim813]

I didn't mean to revile the OP, but IMO I just didn't see a big benefit and wasn't sure if I was missing something.

The way I see it, I'd be worried about running out of gas on the on setting and would most likely leave the petcock on reserve whenever riding, and especially racing.

[GodHunter]

Thanks for posting this Justin, can't wait to try it out.