Hi everyone, Im New to the XR world. I have a 96 xr400 i got in trade for a tranny swap on a suburban. She was pretty ratty, but its come a long way!

I was Wondering if anyone else has tried e85? I am currently Running it in my bike, though the mixture is more like E70.It is running better than i could have ever though.

Mod History:
I started by swaping a JE piston (88.5 bore, 12:1 compression) Bringing it to a 430, the old rings were shot!

It had a FMF super trap exhaust

port and polished a little and reground valves with viton valve seals

I traded a guy my stock carb for a edelbrock pumper (love it, easy to use). I put a 17-E needle in it. This would normally go on a xr600, but with Alcohol(e-85) you need 25-30% more fuel flow.Though I will Probably get the 19-E needle as it is about maxed out on fuel.

and a K&N filter

I put new sprockets on +1 front -3 rear (for the street) with a 19 inch front rim and street tires.

Wasnt to hard to set up. i had use of a mobile wideband O2 reader, this worked really well for the tuning.

I want to get a hot cam and a new exhaust set up, but for now this thing rips! just as fast as my buddys 04 suzuki DR650!

Has anyone else gone this route? Why E85 you say? higher octane for the high compression, and being a street bike, the availability at the pump.

All those mods and lots of stock bikes out there are still lighter, handle better, and are way faster than your XR.  The beauty of the XR is in its uncanny reliability, not its power.  A DR650 is hardly a benchmark for a fast bike.  To each their own I guess.

StreetXR430, on 08 May 2012 - 10:54 PM, said:

Interesting. What kind of prices are you seeing on E85 in your area? I would imagine your mileage compared to gasoline would be a good deal lower any indications?. You might want to post up on the engineering and technology forum lots of "experimenters" there.

wallrat, on 09 May 2012 - 11:11 AM, said:

I didn't say it was the fastest bike on the road. I couldn't find any info on using E85, so i thought i would share my experience. It seems to be the trend in performance cars, so I thought why not apply it here. A 430 that's as fast as a 650 is a benchmark.

Chaconne, on 09 May 2012 - 04:31 PM, said:

Its $3.00 a gallon in MN. I would imagine that i would not save any money over pump gas. But its a lot cheaper than race fuel. I didn't ride the bike on the street before I ran this setup, so im not sure on before and after milage. Once I get it on the street I'll post my milage.

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It depends on the 650.  The DR is tragically overweight and underpowered for its size.  You do realize that the 650 weighs almost 100 lbs more for a gain of 8 hp over a STOCK XR400?  Any of the stock 450's (CRF, YZF, EXC, etc) would blow the pants off of that bike on any terrain.  Even the old YZ426's made as much HP from the factory as the DR650 and were over 100 lbs lighter.

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To make your slow, reliable bike faster than other slow bikes and trash your bike's reliability?


I'm not saying its dumb to run E85 or even modify engines.  I just don't see the point in doing it to a trail bike whose value and reputation lies in its uncanny reliability.

Edited by wallrat, 11 May 2012 - 08:32 AM.

With the 12:1 piston e85 is probably not a bad idea. Please dont get discouraged I am interested in your results as others probably are too.

Edited by jamesgardner83, 11 May 2012 - 12:16 PM.

Wallrat seems to be missing the point.  The OP already has the bike, not shopping for a new one.

wallrat, on 11 May 2012 - 08:25 AM, said:

Experiments like this usually have a point other than typical use. The OP is going to use the bike on the road and is already experimenting outside the bounds of what I would do with my xr4 which I love for what it is like you say.  But that said, what the OP is doing is an experimental adventure and using a reliable rock solid engine with known behavior to do this on is a good idea IMHO and makes real sense to me. I can just imagine trying to get my touchy yzf or any more modern 4T engine started with experimental fuel(s). Shit they don't even start that easy with recommended fuel(s).   Overall I think it is pretty cool stuff, wouldn't do it to my xr4 though, maybe I'll chuck some into my old snowblower though just for fun --old Tecumseh motor sucks anyway.

At one time its was considered suicide to ride a machine with a gas tank on it. Thank God those people didn't get in the way of advancement.

As I stated before, i got a bike for 0 dollars. It needed rings badly. It needed a oversized piston. For $100 i could put something in with more power than i had, But it needed more than pump gas. So i got a carb For $50 and tuned it to run E85.

Could I do this same thing on a faster bike? Yes!

Thanks to the supporters, I hope to see more adventurers in the future. For the bashers, your opinions are noted.

StreetXR430, on 14 May 2012 - 05:09 PM, said:

Cool. love to hear what dos & don'ts you turn up. Lots or room for innovation/experimentation 4-sure!   And ethanol is only one among the alternatives on the horizon.

Do you have an oil temp gauge? Curious to see what oil temps you are running.

jamesgardner83, on 15 May 2012 - 04:34 AM, said:

Good Question. I would not think of doing anything like this without a temp gauge. After a few hours of excessive abuse, I got 220 f degrees. not bad, but it is still only in the 70-80 degrees here in MN.

Yeah 220 is not bad at all. Could you try the same test with some race gas? Compare the oil temp on E85 and race gas. This would probably require you to re-jet so probably not possible. It would be an interesting comparison.

I have been reading about some tests run on E85 derived aviation fuel for High-performance, high-compression, piston aircraft engines .Looks like the benefits are:

Excellent antidetonation properties – ethanol doesn’t "knock," even at high compression ratio.

Ethanol burns faster and at higher thermal efficiency than 100LL or gasoline, putting more energy into motion and less into heat.

Evidence for higher thermal efficiency – exhaust gas temperatures for E85 and 100 octane are about equal, but cylinder head temperatures are much lower with AGE85.

The standard motor octane test method (ASTM 2700) doesn’t work for high ethanol-content fuels, because cylinder head temperature cannot be maintained at specified level.

Ethanol burns cleaner than 100LL, resulting in longer TBO(Time before overhaul).

Ethanol is currently cheaper than 100LL

Ethanol gets a pretty bad rap in the motorcycle world, but I think as long as you kept it fresh there are probably some benefits to burning ethanol.

Edited by jamesgardner83, 15 May 2012 - 04:38 PM.

jamesgardner83, on 15 May 2012 - 04:32 PM, said:

I do want to do some playing with race fuel. I have other needles for the carb and its fairly easy to adjust. Some time in the future maybe.

Ethanol is a great fuel for performance. Said to have about 105 octane. Only problem is the inconsistency at the pump. In MN its E70 now(still on winter blend). So ill have to add a splash of regular gas to it when it switches to E85. There is a performance shop across the street from mine, and they have a lot of issue running pump E85 cause it varies about 10%. On the serious applications (900+ whp) they use E90 ordered in 55 gallon drums.