TRX250r.org

Author Topic: Av gas  (Read 239 times)

Offline evaneyeball

Av gas
« on: November 10, 2020, 07:39:42 PM »
I am currently running 110 race gas and it is pretty expensive for me. And I am buying a 350 with a race gas dome it's a esr cylinder and head from arlen. Could I run av gas or av gas mix in it with a esr pump gas dome.
LED built 269

Offline The norm

Re: Av gas
« Reply #1 on: November 10, 2020, 11:45:01 PM »
One of the best things about race fuel is that it contains lead. Lead is a fantastic lubricant. You are definitely too young to remember that all gas was leaded.
As far as Aviation fuel goes, I would stay away from it. It is designed to burn at high altitudes.
If you are trying to save money have Arlan set the cylinder up for 92 octane non ethanol.
Loren
1986 Trx250r-- Hybrid Engineering 391(Good bye super 310)
1986 Trx250r-- Hybrid Engineering  ported stock 86 cylinder
1986 Trx250r-- craigslist engine with unknown ported 89 cylinder.
1985 Atc250r-- Needs a lot of work (Super 310's new home)

Offline havinnoj

Re: Av gas
« Reply #2 on: November 11, 2020, 10:46:39 AM »
Yes race gas is getting expensive these days but like loren says lead is good for lubrication but it also really raises the octane as well. Also be aware that you the race gas compression ratios are aimed at cars - for example you can usually get away with pump gas at 13:1 in a 2 stroke.  Over that definitely want more octane.  Have Arlan get you an exact compression # and go from there.  A good cost effective performance option is always 50/50 mix.

Offline evaneyeball

Re: Av gas
« Reply #3 on: November 11, 2020, 12:09:36 PM »
Ok I will have arlen give me a real compression ratio. And I'll go from there. Thanks bolth of you.
LED built 269

Online 2Nubs

Re: Av gas
« Reply #4 on: November 12, 2020, 10:54:59 AM »
Ran AV gas with great results personally and saved a wad of cash. AV gas is leaded and manufactured to stringent standards for obvious reasons. If anything it is made to a higher standard. Iíve ran it in a 600+hp turbo engine as well. No issues.

You can purchase 100 and 110 at most small airfields for $3-6/ gallon. Iím sure you can get some added benefits with the $16/ gallon gas, but I like to burn a lot and Iím not made of money lol. Your results may vary.
Ď86 330

Offline Michael88R

Re: Av gas
« Reply #5 on: November 12, 2020, 10:02:46 PM »
I would run 50/50 race/pump at a minimum.   Pump gas now days is crap.  Have Arlen set up your dome for 50/50.
88í R Esr 330PV, Esr trx7 porting, Esr trx6 pipe
88í R Esr ported stock cylinder, waiting for rebuild when my son gets a little older

Offline desertR

Re: Av gas
« Reply #6 on: November 14, 2020, 10:45:04 PM »
No one has asked me, but I think you should put it together and sell it. Buy a bone stock TRX, and ride the crap out of it. Put normal gas in it and have some fun. you have blown up 2 motors in no time at all. Buying a 350 fire breather might give you bragging rights, but where does it end. You will need a bigger/better clutch and then the transmission will go, possibly taking out a case at the same time. Then a new crank. Add in a new pipe and carb, Chain and sprockets (the very best chain for a 350) for gearing, and you will be in so deep you can't see your way out. You are looking for a way to save money on race gas, the price of race gas is nothing when compared to a 350 motor. Swap parts off yours if you want, but a stock bike will last and be fun. There's a bunch out there for sale. Someone has to use some common sense here.
desertR

Offline Jerry Hall

Re: Av gas
« Reply #7 on: November 16, 2020, 02:42:03 AM »
No one has asked me, but I think you should put it together and sell it. Buy a bone stock TRX, and ride the crap out of it. Put normal gas in it and have some fun. you have blown up 2 motors in no time at all. Buying a 350 fire breather might give you bragging rights, but where does it end. You will need a bigger/better clutch and then the transmission will go, possibly taking out a case at the same time. Then a new crank. Add in a new pipe and carb, Chain and sprockets (the very best chain for a 350) for gearing, and you will be in so deep you can't see your way out. You are looking for a way to save money on race gas, the price of race gas is nothing when compared to a 350 motor. Swap parts off yours if you want, but a stock bike will last and be fun. There's a bunch out there for sale. Someone has to use some common sense here.
desertR

I think that the above is very good advice for a young guy that does not yet have the money or the experience necessary to own, maintain, tune and to ride these these hybrid engines to their full potential. 

The cost of experience is measured in how many pounds of $100.00 bills one has to burn through.  Good builders will give you more power, but more power adds a lot of stress to the these TRX 250R engines that their design was  bullet proof at 35 HP.  The stock CR250 design made  around 45 HP but was not bullet proof and required more experience and money to maintain.  The cost to own and maintain high HP engines is an exponential function.

The best gear materials 9310, 8620 with the best heat treat processes will never make a 250 transmission strong enough to be bullet proof.  The spacing between transmission shafts is too close and the gear diameters are too small.  There is just not enough room in the cases to put the necessary amount of metal to handle the torque these new cylinders can generate. 

The best 250 Crankshafts, clutches and transmissions are not anywhere as strong as the stock components that come in the CR 500, KX 500 or LT500 engines.  These stock 500 singles  Make around 45 to 55hp on my dyno.

I can get over 110HP out of the LT 500s.  These 500cc engines are very fragile at this level like the 250s are when they have more than about 60hp coming out of them.  The guys that are playing at this level have paid for the experience to learn to tune and operate stuff at this level and will continue to spend a lot to keep these fragile toys running. 

I have had the above conversation thousands of times with guys before I build them an engine package.  Once they realize they do not have the tuning skills, the money to maintain, and buy fuel, they end up having me build something that has a lot less power than what they originally ask for.  Are your builders having these types of conversations with you?

Offline evaneyeball

Re: Av gas
« Reply #8 on: November 16, 2020, 01:35:21 PM »
The main thing for me with the not liking race gas is it's hard for me to get because most of the times I go riding on week days and so I cant get the gas on my way there and theres a airfield 2 miles from my house and I was just wondering if it was anything comparable to race gas and I do know it would be very fragile and so would a lower compression head make less power with an easier gas for me to get and then in turn make it less fragile? It would be fragile either way but would it be more reliable with a lower compression head
LED built 269

 

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