250sx av gas or mixxed fuel jetting

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6/29/2016 6:29 AM

Ive got a 2014 250sx that im about to do a top end on. Ive also bought the new fmf 2.1 silencer and a works head pipe and a jd jet kit. that will go on when i do the top end. At rhe same time i would like to switchb to a more consistant fuel source like av gas or cutting pump gas with c12.

Does anybody have a insight on running straight av gas or cutting fuel?

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6/29/2016 6:38 AM
Edited Date/Time: 6/29/2016 6:39 AM

I'm not sure about the validity but, someone once told me that av gas was designed to run at specific RPMs and altitude to mimic real life conditions. They said that while it won't necessarily hurt the motor, it's not ideal. Your best bet is to find some ethanol free pump gas and if that's not good enough on its own, cut it with a mild race fuel.

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6/29/2016 6:48 AM

MXD wrote:

I'm not sure about the validity but, someone once told me that av gas was designed to run at specific RPMs and altitude to ...more

I have heard that as well, i was skeptical myself until i was recommended by someone at jd jetting to look into run the av gas. I have always run the bike on non ethonol 91 but it doesnt seem to be consistant enough on its own. What would you recomend if i where to cut the non ethonol with a race fuel?

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6/29/2016 7:03 AM
Edited Date/Time: 6/29/2016 7:09 AM

When I had Suzuki 2 strokes, I would run straight leaded Cam 2 110 octane. I could buy it out of the pump near my house for like $8.79/gal. On the dyno, it would probably make less power than straight pump gas since the octane was so high and the bike was 100% stock but it cured all the detonation, ran very clean and my butt dyno couldn't detect a loss in power. If it's consistency you are after and performance is not your main goal, I would say the least expensive fuel you can find that will get you above 95 octane when mixed. Check out VP T4 or VPR. I think it's the least expensive fuels they offer that would fit what you're looking for.

However, I'm no chemist. I'm sure someone more knowledgeable than I will be along shortly to either confirm or refute what I'm saying. I just know what worked for me.

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6/29/2016 7:05 AM

93 with up to 10% ethanol for my 15 250sx. No ethanol free in my area and I'm not spending $12 a gallon for vp. I do put some of the klotz octane booster/ stabilizer in and I can't tell a difference in power but it seems to start easier(first kick everytime) and has a fantastic smell. Obviously the race fuel would be best to use but it is not absolutely vital. Just my opinion though.

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6/29/2016 7:10 AM

The av gas i have access to is 100LL (low led) aside from the possible rpm and altitude issues wouldnt the av gas be very simular to the leaded cam 2 110? Il look into vp t4 as well!

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6/29/2016 7:11 AM

But most importantly, what is easy for you to get. That should drive everything. The Cam 2 was not ideal from a performance standpoint but it was perfectly safe and consistent so I ran it because it was at a 24hr gas station 20 minutes down the road. I would usually put the wife and kids to bed and make a little road trip late at night when I couldn't sleep. Convenience is King.

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6/29/2016 7:15 AM

Ben_Crowne223 wrote:

The av gas i have access to is 100LL (low led) aside from the possible rpm and altitude issues wouldnt the av gas be very ...more

Not sure if you caught my edit but I added VPR to the list as well. That's another good low cost option. Don't get thrown off by the "T4 is for 4 strokes and T2 is for 2 strokes" theory. I know plenty of people running T4 in 2 strokes. T2 comes premixed which is a turn off for me.

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6/29/2016 7:40 AM

AV gas will be the easiest for me to get. I live in rural vt and will have to drive out of state to get vp products consistantly. Thst being said i ride alot and could buy several pales at a time and use it in a reasonable period of time.

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6/29/2016 8:08 AM

Never had a detonation problem on 93 with up to 10% ethanol either. Where do you guys running VP buy it from?

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6/29/2016 8:25 AM

EEE299 wrote:

Never had a detonation problem on 93 with up to 10% ethanol either. Where do you guys running VP buy it from?

There is a local distributor that lives down the street from me who makes a bulk order a few times a year and sells it out of his garage. There is no mention of him or any distributors on VPs website. I hooked up with him through a friend who drag races with him. So I came across him by chance. I think there are more of those guys out there but they are not easy to find. My local dealership also stocks some VP stuff.

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6/29/2016 8:51 AM

MXD wrote:

There is a local distributor that lives down the street from me who makes a bulk order a few times a year and sells it out of ...more

I figured I could get it through a dealer if I tried. Man it's just hard justifying the money for me but maybe I'll look into exactly how much it would cost me a year and go from there.

I don't really see a point in running 50/50 with pump gas if you are looking for consistency. Only for detonation right?

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6/29/2016 8:57 AM
Edited Date/Time: 6/29/2016 8:58 AM

EEE299 wrote:

Never had a detonation problem on 93 with up to 10% ethanol either. Where do you guys running VP buy it from?

MXD wrote:

There is a local distributor that lives down the street from me who makes a bulk order a few times a year and sells it out of ...more

EEE299 wrote:

I figured I could get it through a dealer if I tried. Man it's just hard justifying the money for me but maybe I'll look into ...more

Yes, you would gain some consistency but you still have the ethanol issue to deal with. In my opinion, if you're cutting it with pump gas that has ethanol in it, you're not eliminating the issue, you are only reducing it. If you cut ethanol free pump fuel with race gas, you've eliminated the issue and gained consistency. But the only reason to cut it is to save money. For me, I could get ethanol free 94 octane for $4.50 a gallon at the time but it was 20 miles the other direction. So if I got 2 at $8.79 and 2 at $4.50, I was only saving like $8.58 per 4 gallons. I would have that going to 2 different stations along with the extra time so it was a wash for me to run 100% Cam 2.

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6/29/2016 8:58 AM

Been running Avgas in a YZ465 and 05 CR250 for over 3 years now. Not one mechanical issue at all. It beats running $12/gal C12 and godawful California pump gas all around.
BTW, how does a gasoline know how it is being run or in what?

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The older I get, the faster I was.

6/29/2016 9:00 AM

MXD wrote:

Yes, you would gain some consistency but you still have the ethanol issue to deal with. In my opinion, if you're cutting it ...more

Ok that makes sense. I don't think I can get ethanol free gas anywhere close. If I switch it will be to straight VP for the same reasons you said.

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6/29/2016 9:19 AM

captmoto wrote:

Been running Avgas in a YZ465 and 05 CR250 for over 3 years now. Not one mechanical issue at all. It beats running $12/gal C12 ...more

It doesn't but often times, it's formulated for specific conditions like compression, altitude, specific timing, specific RPMs and stuff like that. That doesn't mean you will have a mechanical problem necessarily, it just might not be ideal.

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6/29/2016 10:02 AM

MXD wrote:

There is a local distributor that lives down the street from me who makes a bulk order a few times a year and sells it out of ...more

EEE299 wrote:

I figured I could get it through a dealer if I tried. Man it's just hard justifying the money for me but maybe I'll look into ...more

MXD wrote:

Yes, you would gain some consistency but you still have the ethanol issue to deal with. In my opinion, if you're cutting it ...more

If i where to run a 50:50 mix i would be using non ethonol 91 pump gas. The gas station down the road sells it consistantly and is all i runnmy bikes on currently but i still seem to have some consistancy issues.

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6/29/2016 10:04 AM

Ben_Crowne223 wrote:

If i where to run a 50:50 mix i would be using non ethonol 91 pump gas. The gas station down the road sells it consistantly ...more

What kind of issues are you seeing?

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6/29/2016 3:23 PM

I have been going to local gas pumps getting 91 octane , ethanol free or with ethanol. Never had a problem with it in 2 strokes or 4 strokes. I always try to convince my buddy's I ride with to run race gas, then you get the smell without the 14$ a liter cost. That tip is free , the next will cost you

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6/29/2016 8:04 PM

Ive ran 100ll for years in 2 different yz250's, a 13 ktm350sxf and a 16 yz450. Never had any problems out of any of them.

I have no where close that sells non ethanol higher than 87. Plus by buddy works at the airport and they sump the fuel everyday to check for water. So I would get it free. I now run ms109 in my 16 yz450 and still run 100ll in my YZ295.

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6/30/2016 3:06 AM

I seem to cook alot of spark plugs, and get spark nock at an idle.

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6/30/2016 4:32 AM

Ben_Crowne223 wrote:

I seem to cook alot of spark plugs, and get spark nock at an idle.

Really? With stock jetting? And what premix ratio? Personally I just followed the other recommends jetting by digger and I'm still on the original plug and with very little oil at the exhaust.

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6/30/2016 6:51 AM

Ben_Crowne223 wrote:

I seem to cook alot of spark plugs, and get spark nock at an idle.

WVUpetro2013 wrote:

Really? With stock jetting? And what premix ratio? Personally I just followed the other recommends jetting by digger and I'm ...more

Its been jetted by the shop i got it from for the fmf system thats on it now. Ive always run it off ethonol free 91 pump gas and ive always used ams oil dominator at 50:1. The manual calls for 60:1 witch i think is rediculous.

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6/30/2016 7:35 AM

MXD wrote:

I'm not sure about the validity but, someone once told me that av gas was designed to run at specific RPMs and altitude to ...more

This is true! I use MS-109 1 gal to 2 gals of pump 91 octane gas. Run it in 3 different 2-strokes with great results.

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6/30/2016 8:13 AM

Ben_Crowne223 wrote:

I seem to cook alot of spark plugs, and get spark nock at an idle.

What do you mean by "cook"? Your problem might not be fuel. Also, what are your jetting specs? If your shop just grabbed the specs from FMF's recommendation, it might not be right. They test in dry weather which is the opposite of what we have here. I moved back from SoCal about 10 years ago with a 2001 CR250. It ran like a scolded dog out there. First ride out here in this humidity it ran awful. It was breaking up so bad that I thought I had an electrical issue. I ended up going 2 leaner on the main and dropping the needle a spot to get it back to what I had out west.

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6/30/2016 9:18 AM

All the talk about Av gas being formulated to run at a specific RPM and altitude are old wives tales that just keep being spread. Yet, I've never heard anyone who's used it have a complaint against it. I've used it exclusively for almost twenty years. It's always worked great for me, even in extreme conditions like -10f or high heat and humidity.

At 100 octane it's not much of a performance enhancer. But if your bike is on the edge, like my last 200SX or my current YZ250, it will keep it from detonating and allow it to run cleanly and consistently.

Pump gas these days is very inconsistent. From season to season there are different additives, and varying types and quantities of alcohol. All bad stuff.

If you have a small airport nearby you should give av gas a try. I don't think you'll be disappointed.

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6/30/2016 10:17 AM

Ben_Crowne223 wrote:

I seem to cook alot of spark plugs, and get spark nock at an idle.

WVUpetro2013 wrote:

Really? With stock jetting? And what premix ratio? Personally I just followed the other recommends jetting by digger and I'm ...more

Ben_Crowne223 wrote:

Its been jetted by the shop i got it from for the fmf system thats on it now. Ive always run it off ethonol free 91 pump gas ...more

I'm running my bike at 50:1 with motorex and its running great. Your oil should be fine as there are plenty of guys on ktmtalk running that with great results. As far as jetting, since I don't know what is in there I can not give much insight. I can say the hot set up that many 250sx owners are running is a 40pilot, NECJ needle on 3rd or 4th clip (rm250 needle), and a 172 main jet. Those 15 dollars worth of jets did more for the performance of my bike than anything else I have added.

Couple threads that may be of interest
http://m.vitalmx.com/forums/Race-Shop,42/Necj-needle-250sx,1288948

http://m.vitalmx.com/forums/Race-Shop,42/2015-SX250-TC250-Suggested-Mods,1282888

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