Which engines drink...the least?

[SilverLake250R]

Hey guys, I am planning my next build, an XC 250R to replace my 450R, and I was wondering how to get more miles out of a tank of gas. I want to run pump gas, so that I can stop at any gas station along the trail. I was thinking of building/buying an engine in the 250-275cc range, possibly a PV, and with a low-end pipe such as a PT type 6. If you have experience with these types of motor setups, I would be interested in some info.

From my experience, high rev setups like to drink...a lot... my duner does- even though it is a stock cylinder, the larger carb and top-end pipe combo sucks gas.

I am planning on running a big tank, but even with that I bet I could only make it half as far as my 450 with a standard tank...

[86 Quad R]

i personally would build a really strong XC ported 250-265cc ATC short rod engine with either a RAD valve or CR intake and a 35a/s or 36 pwk and a good pipe to match.

[speedfreek]

I used to be able to get 4hrs out of my ported stock cylinder. And this was with some pretty aggressive riding. And you just cant put gas in it straight from the pump. It has to be pre-mixed.

[SilverLake250R]

I realize you have to mix gas lol...I have a 250R....

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs814.snc4/69401_583976748904_15305732_33693341_5876173_n.jpg

...but I can carry a bottle of oil easier than a whole jug of gas.

[SilverLake250R]

I guess it help more if you told me what engine mods you have, and then how many miles you can typically go on a tank.

I think talking about how many hours of riding you can do on a tank of gas is a much less accurate way to measure mileage...slow, fast, breaks.....it is hard to tell the actual "hours" of ride time.

I would guess my 250R can go maybe 25 miles on 2 gallons and my 450R can go about 75 miles on 3 gallons.

Here are some knowns:

• Smaller carburetor bore, better mileage
• Smaller displacement, better the mileage
• Less compression, better mileage
• Lower Octane rating, better mileage
• Colder plug, better mileage (to some extent)
• Obvious; the leaner the jetting, better the mileage
• The cooler you can keep your fuel; the better the mileage
• Higher tire air pressures, higher the mileage
• Kerosene based fuel additives or plain Kerosene (10%-30%) added to fuel will increase mileage significantly

Carlos.

[sixer3]

Originally posted by SilverLake250R
I guess it help more if you told me what engine mods you have, and then how many miles you can typically go on a tank.

I think talking about how many hours of riding you can do on a tank of gas is a much less accurate way to measure mileage...slow, fast, breaks.....it is hard to tell the actual "hours" of ride time.

I would guess my 250R can go maybe 25 miles on 2 gallons and my 450R can go about 75 miles on 3 gallons.

hit it on the head plus the obvious one which is gearing

[Burns310r]

Higher compression will yeild better performance and mileage.
Your extracting more energy from the fuel thats already in the cylinder.

So run pump gas with the highest allowable compression you can.

Just so you know.

[SilverLake250R]

Yes, right now I am planning on running pump gas with 180lb compression, a 35 A/S carb, and for a cylinder either a PC2000 265 PV, an ESR 265 PV, or a LRD 265 PV. I think then either an ESR TRX6 or a PT type 6 woods pipe and a Boyesen Rad valve.

How does that combo sound?

[86 Quad R]

Originally posted by SilverLake250R
Yes, right now I am planning on running pump gas with 180lb compression, a 35 A/S carb, and for a cylinder either a PC2000 265 PV, an ESR 265 PV, or a LRD 265 PV. I think then either an ESR TRX6 or a PT type 6 woods pipe and a Boyesen Rad valve.

How does that combo sound?

goed!

I should have been clearer as these two go hand in hand; lower octane & less compression, gives better mileage, yes run the lowest Octane “pump gas with the highest allowable compression”

Another consideration is the type of Oil you run as well as the mixture, 20/1 to 50/1…

Carlos.