avgas over 98 fuel

[hagon_84]

does running avgas instead of ron98 need a jetting change over like u would with methanol at current im running 98 with castrol tts full syn at 32:1. i no there are alot of meth heads on here  but for the average rider is there really any point running methanol or even avgas

[270YAM]

I have very little experience with jetting for avgas or methanol, my understanding is that you will most likely need to increase jetting slightly if you change from 98 to AVgas, but not nearly as much as you would have to increase if you changed to methanol

[matcho mick]

think this questions been done to death ,but fwiw,no biggie with avgas/98,just concentrate on your riding eh? ,

[35elsinore]

Hi Hagon, I run both avgas and 98ron pulp with no jet changing. I do believe that the bike runs a tad cooler on avgas. You also mentioned TTS, I was a castrol user most of my life but after talking to a tuner it was suggested TTS can tend to fuel the bike up at low RPM. [pre 75 2 strokes] I have since changed to motul 800 and on the 125 it has inproved low RPM ridability.
This is only my opinion, the knowlegable ones might shoot me down in flames.
Cheers Troy

[Nathan S]

If the bike runs properly on 98 WhyTF would you put AvGas in it?! If you want to lose some HP, just put a rag on the airfilter or something.

AvGas has two good points:
Consistency and detonation resistance. Everything else about it is pooh for car/bike use.

[Lozza]

Avgas  and 98 require 2 different tunes, much more than a jet change.

[firko]

  think this questions been done to death ,but fwiw,no biggie with avgas/98,just concentrate on your riding eh?

Well spoken my fibreglass friend .
I've run Avgas and methanol in the past but now I'm getting my bikes going again after a lengthy layoff it seems to me that they run just fine on 98 with Motul on 30:1 and no other major changes. I'm not going to stuff around with it too much, lifes too short to become a jetting junky . 

[Tim754]

Run both in my four stroke Honda's subject to resetting tune ,All good but I do tend to run more Avgas. * Tim754


* ( Well Cos I can get it for 37 cents a litre )

[35elsinore]

Nathan, WhyTF i use avgas is the fact it last unlike modern pulp. If you dont get the time to ride very often then avgas is a good option. I also fine the bikes run fine on both avgas and pulp without any jetting changes. Im certainly no bike mechanic but after winning a state title four years in a row I must be doing something right. I only wish I could buy it for 37c a litre.
Happy riding Troy

[Mike52]

Avgas has yummy lead in it and that should be a plus for wear at least.

[IT400C]

I used to use avgas regularly back in the 90's...

from what I remember:

• very consitant octane rating
• stores well with dropping big octane numbers
• burns extremely cleanly - no carbon deposits at all come rebuild time
• Didn't require any jetting changes to my late 90's YZ's
• I was told it wasn't well suited to high revving motors, airplane motors are low revving lumps that run long periods at constant revs, and that's what the fuel is designed for.  But saying that, I had no trouble running it in 125's
• Avgas and Motul 800 made mowing MUCH more enjoyable too!

At the time I lived not too far away from Archerfield Aerodrome, so it was easy to get hold of..  I'd probably use it again if it was readily available and I got all keen again, but at the moment, just going past the local BP on the way to the ride suits me fine.

[David Lahey]

for air-cooled Trials competition use, where the low speed jetting has to be as lean as possible, AVGAS is a bit more forgiving in regards to hot motors, imperfect jetting and old fuel, compared with 98

[tony27]

Use it in my modern trials bike but not for the same reasons as Feetupfun lists, I'm running it to avoid having to buy yet another fuel tank due to swelling caused by the alcohol in 98 over here in NZ

[PEZBerq]

Tony, do you drain your fuel after every ride day/weekend? I do that on all my Acerbis plastic tank Husky's to try to stop them staining brown. Might help with the swelling problem you experience? I use a rubber squeeze bulb in line siphon device to empty the tank completely.

[Mike52]

ohhh look.

http://www.spiritpfc.com/faqs.asp [ btu one ]
http://en.wikipedia.org/wiki/British_thermal_unit [ what a btu is ]
http://www.mainepublicservice.com/media/3467/fuel%20and%20energy.pdf

Read the octane rating bit in this one it appears to say that 98 Ron is not as good as 100 avgas.

Quote " however, both Shell and BP produce fuel at 102 RON for cars with high-performance engines,"
http://en.wikipedia.org/wiki/Gasoline


Avgas has 125000btu,s which is exactly the same as fuel with no ethanol [ ethanol fuels have a lower btu rating ]  and  100 to 130 octane which is higher than fuels with ethanol added..

Logic and maths says that avgas should run great in a high combustion ratio engine that does NOT have an oxy sensor or a cat converter.

We always used avgas in our super street drag car with very good results , but then it had a 13/1 comp ratio.

Always drain my fuel Pez for the same reason as you.