i was just wondering what other ppl run in there trx310R's? they guy i bought my '88 R from and ct's website says to run a 50/50 mixture of 92 pump gas and 108 or higher octane race gas. Octane booster costs too much so i bought about 15 gallons of 110+ octane fuel. I'll probably mix it w/ 92 pump gas to save money. I dont know the comp. on my R yet because i need a compression tester but what is the highest comp. u can have to run pump gas?

 

The 250R manual says above 92 octane only and that is on a stock motor (155 psi cylinder pressure). I am rebuilding and will have about 175lbs and I will be doing the same as you, Turbo blue $3.10 p/gal (unleaded) 104 50/50 mix with 92 unleaded and that should run O.K. with out pinging.

If you hear anything different, I would like to know. Thanks

 

My motor cranks 220lbs.I need 100 octane so I can mix pump/race fuel but I run straight race gas.A couple extra bucks on gas every weekend isnt gonna break me. A coolant reservoir is just extra weight,ditch it.

 

I run 220lbs in my TRX350R and have used AVgas for about 4 years now. It doesn't run as cool as the race gas and may not generate as much power output on the burn but at 110 octane it works good and only about $1.60 a gallon. In general you can run up to about 170-175lbs before having to run greater than 92 octane.

 

Where do you get the AVgas and whats the pros and cons compared to Race gas?

 

You can get AVgas usually at any small airport. Ask for 100LL (LL for Low Lead) which is 110 octane. If the airport allows you to pump it yourself it runs about 1.60 to 1.75. If they have to pump it then it runs about 2.00 - 2.25 a gallon. AVgas doesn't have some of the additives of race gas that allow it to burn cooler. I have never had a problem with it and have been running it in my quad for about 4 years now and have also ran it in jet-skis too. It burns clean and since airplanes use it you know it will be consistent.

Jeff

 

I have read via MacDizzy that 180-185 is the MAX for pump gas. My current motor with its 23cc O-ringed Cool Head PEAKS AT 180 PSI on my compression guage. I am running 93 Shell and it's not pinging whatsoever. When you run the higher PSIs you need to make sure your jetting is SPOT ON. Start richer than you ever think you'd need and work your way down. It works WELL for me.

 

That depends on the degree of compression you're using.

Octane boosters do not technically raise octane numbers, despite popular opinion. They stabilize the fuel so that it can burn properly in high compression engines.

Running too low of octane in a high compression engine will result in the gasoline pre-detonating or knock, as some call it. This can burn or blow a hole in your piston relatively quick if prolonged.

Below you’ll find a snippet of some technical documentation I’ve drummed up and my references (just in case someone wants to debate me)
Compression Octane Number Brake Thermal Efficiency
Ratio Requirement ( Full Throttle )
5:1 72 -
6:1 81 25 %
7:1 87 28 %
8:1 92 30 %
9:1 96 32 %
10:1 100 33 %
11:1 104 34 %
12:1 108 35 %

Reference 1.
- Chapter 20. K.Owen.
Automotive Gasolines - Recommended Practice.
SAE J312 Jan93.
SAE Handbook, volume 1. ISBN 1-56091-461-0 (1994).

You can get away with running lower octane than listed above, but the values listed are basically the most efficient to use.

Also, keep in mind timing plays a huge role in regards to comp ratios and octane (in respect to 4-stoke engines otherwise squish). The higher your timing the more octane you’ll want.

I hope this helps.