av gas ....anyone run it/tried it?????

Wheelie-Gene · Post by **Wheelie-Gene** » July 6th, 2009, 8:26 pm

I have a local contact that has a friend that crop dusts. He can get me a good deal on leaded aviation fuel. I dropped off a 20gal drum, so I should have the jungle juice in a few days.

One of the Honda shops had a display of C12 (and some other fuel)....a 5 gal pail was $50-ish. Another place has 100 octane low-lead for about $8.50 a gal.
I'm expecting my 20 gal to be about a hundred dollar bill.
I used to run it 50/50 w/super unlead in my blower car....it had such a sweet smell.

Any thoughts???

Post by **AlisoBob** » July 6th, 2009, 8:55 pm

AV gas works pretty good blended 50/50 with Super.

Its obviously blended for low rpm, high alitude use.... but it works well.

Even though its "low lead" .....this is by aircraft standards.

DO NOT wash parts with it barehanded.....

If you run it long enough, the insides of your motor look like its was painted with lead.....

Be careful.

Wheelie-Gene · Post by **Wheelie-Gene** » July 6th, 2009, 9:04 pm

I know its hazardous qualities. Some bad stuff, no doubt.

For now, I have no clue of the rich/lean octane #s.

4Z · Post by 4Z » July 6th, 2009, 9:59 pm

Av gas is a staple for many mod sled motors. High alt, high rpm.
the nice thing is that av gas is consistent on quality.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » July 7th, 2009, 5:21 am

it'll run, but in our dyno testing anything over av gas makes more power, it just doesnt have the burn rate. VPs mr11 cut with pump premium is some excellent juice,probably best we've ever run, and its cheaper than mr9,u2, or u4.2 right now too

Wheelie-Gene · Post by **Wheelie-Gene** » July 7th, 2009, 10:15 am

Roostius_Maximus wrote:it'll run, but in our dyno testing anything over av gas makes more power, it just doesnt have the burn rate. VPs mr11 cut with pump premium is some excellent juice,probably best we've ever run, and its cheaper than mr9,u2, or u4.2 right now too

That's good to know.
I'll have to see where that's available.

lewisclan · Post by **lewisclan** » July 7th, 2009, 10:26 am

I use to run the shit out of it

100hp honda · Post by **100hp honda** » July 7th, 2009, 4:46 pm

ill stick with VP. keep us posted on the AV gas

redrocket190 · Post by **redrocket190** » July 7th, 2009, 6:27 pm

I stand by a recommendation to mix C12 and 91 pump gas for the CR480R because it clears up the jetting and makes it easier to start, but for the stock or mildly ported CR500R engine, isn't this all a bit overkill unless you've bumped the compression?

Wheelie-Gene · Post by **Wheelie-Gene** » July 7th, 2009, 7:15 pm

As of yesterday the 480 is easier to start....I installed a decompression valve.
I had a routine down, I could get it lit w/3 to 4 kicks when cold. I just made damb sure I didn't kill the thing 'till I was ready to.
I made the mistake of stalling it one day across town (45-14 street gearing). It must have been loaded up 'cause I thought I was never going to get it restarted.
Now it doesn't matter if it's cold/hot. I can rabbit kick the bitch and it'll bust off in 3 to 4 every time. More like kicking a 250....I started a decompresser thread over at engine tech.

The 500? It recieved Glenn's cylinder and head treatments. So yes, compression is border-line pump gas compatible.

I just figured that even though it's leaded aviation fuel, at least is a higher octane than straight super.....and it does have lead.
No doubt the old H1 will benefit. I have to haul gas in for that one. It runs like shit on the local horse piss.

4Z · Post by 4Z » July 7th, 2009, 9:25 pm

Wheelie-Gene wrote:
The 500? It recieved Glenn's cylinder and head treatments. So yes, compression is border-line pump gas compatible.

Just curious, did you do a installed CC to get volume and if so, what did you come up with?
I did a flat plate and installed on my stock dome and came up with 11:1. I thought these were much lower, but did it 3 times to check myself.

Nodge · Post by **Nodge** » July 8th, 2009, 7:51 am

I used to run Avgas at 24:1 with PJ1 Goldfire Pro in my old 1986 CR125.
It was ported and shaved, and destroyed all my friends newer 125's much to their dissapointment.

Wheelie-Gene · Post by **Wheelie-Gene** » July 8th, 2009, 5:50 pm

4Z wrote:
Wheelie-Gene wrote:
The 500? It recieved Glenn's cylinder and head treatments. So yes, compression is border-line pump gas compatible.
Just curious, did you do a installed CC to get volume and if so, what did you come up with?
I did a flat plate and installed on my stock dome and came up with 11:1. I thought these were much lower, but did it 3 times to check myself.

What CC did you come up with? The head is still clamped in the Bridgeport to recieve its decomp valve. It won't be installed until verify that the TDC mark is actually at TDC.

Glenn didn't give a final comp ratio, he just said it would run on pump gas. Borderline of needing fuel in the mix, but safe on 93.

4Z · Post by 4Z » July 8th, 2009, 7:51 pm

Gene,
I am on the road at the moment, I will check my notes and post both FP and in stalled.

I did the solder squish and my .090 was hardly touched.

Other than the Millar valve, It is all stock.
So, with the spare head I have, my plan is to bring the squish down to 50-60 thou and see what that nets me on CR gain. My math skills are not of the caliber to figure it out on paper with a calculator. I prefer the "hands on" approach

Results will dictate what angle to use (or sneak up on) the target of a 12mm wide squish band. Assuming that by removing 30-40 thou from head will bring CR high enough to pull material out of the dome. Looking for a 11-12.5 CR at the end.....

Post by **AlisoBob** » July 8th, 2009, 7:54 pm

4Z wrote: I prefer the "hands on" approach

I prefer the compression gauge approach.

Where the exhaust port closes has a tremendous impact on cylinder pressure, shaved head or not.

4Z · Post by 4Z » July 8th, 2009, 7:59 pm

AlisoBob wrote:
4Z wrote: I prefer the "hands on" approach
I prefer the compression gauge approach.

Where the exhaust port closes has a tremendous impact on cylinder pressure, shaved head or not.

Are you talking about a "foot" driven RPM?

Gage or actual CR, what ever works for the guy behind the bars.

Wheelie-Gene · Post by **Wheelie-Gene** » July 8th, 2009, 8:59 pm

4Z wrote:
AlisoBob wrote:
4Z wrote: I prefer the "hands on" approach
I prefer the compression gauge approach.

Where the exhaust port closes has a tremendous impact on cylinder pressure, shaved head or not.
Are you talking about a "foot" driven RPM?

Gage or actual CR, what ever works for the guy behind the bars.

There's many factors for this application. A 4 stroke is easy, all variables are constant, unless you nit-pick and figure vallve overlap. AKA, the old "you can run 10:1 compression with pump gas for the 'ol small block Chevy....but wait...you can get away w/10.5:1 if you run a 300* duration cam".

Bob stated what I was thinking, port height plays a factor in static compression. I read a thread for the old Kawa triple on cylinder compression. Many tuners will mill the heads to a specific PSI to obtain a related comp #.

Cylinder pressure, compression ratio.....we all know that a 2 stroke really sings when it's brought up on the pipe. When does the natural supercharging effect come into play when getting down to the nitty-gritty of number crunching.
Glenn milled off just enough to fully remove the ridge and he cut the cylinder base to bring the piston up to the top edge of the cylinder.
I've never researched the 500 comp ratio, but I would guess 8.5:1...9:1??? Cutting the base, milling the deck, shaving the head...all to a maximum. Would a guestimate of 11.5:1 be out of the question?

When I modded my 250 many years ago I didn't put any factors into the equasion. I removed the head gasket, put a snake of Play-Doh on top of the piston and set the head on w/2 nuts....rotated the crank past TDC and measured the squish. I remember coming up w/something like 3/16"....so that's what I had removed. The head gasket was .050 +/-, that was the squish band. I don't recall running anything other than 93 unlead, and it lasted for many (many, many) years. I'm also ware of a small cylinder = less chance of improper flame travel.

I'm still waiting for my fuel to be delivered. I really thought I'd have it by now.
Looks like I need to make a phone call in the AM.

CR500R7 · Post by **CR500R7** » July 9th, 2009, 12:23 am

CR250 and CR500 compression ratio year to year.
CR250
81 7.5 to 1
82 7.6 to 1
83 8.4 to 1
84 8.6 to 1
85 8.6 to 1
86 9.0 to 1
87 9.1 to 1
88 9.1 to 1
89 8.8 to 1
90 8.5 to 1
91 8.5 to 1
CR500
84 7.4 to 1
85 7.4 to 1
86 7.0 to 1
87 6.8 to 1
88 6.8 to 1
89 6.8 to 1
90 6.8 to 1
91 6.8 to 1
92 6.8 to 1
93 6.8 to 1
94 6.8 to 1
95 6.8 to 1
96 6.8 to 1
97 6.8 to 1
98 6.8 to 1
99 6.8 to 1
00 6.8 to 1
01 6.8 to 1
Sorry I don't know more of the CR250 comp ratios, could not find the ratios for the 81 CR450 or 82/83 CR480.
I hope this is usefull, I believe these figures to be accurate.
If not, speak now or forever hold your peace.
I say thats a joke son, don't ya get it boy.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » July 9th, 2009, 6:21 am

i believe those #s that honda advertised aswell, BUT as soon as the scallops were introduced compression was lowered, then a different chamber in the head aswell, it did work on a calculator, but not in the real world.
I've had multiple guys tell me about cutting the base of the jug, sure its the right way to accomplish that port timing, but every cylinder i've installed with the thinner Cometic base gasket has not been cut on the base, but has the piston proud of the top of the cylinder, theres no room to cut it. So why not run the better quality gasket and not do the machine work?

LOVEMYCR500 · Post by **LOVEMYCR500** » July 31st, 2009, 11:53 am

has anyone tried VP's Q-16 oxygenated fuel yet? I was reading about it on a car drag racing site and it's sounds pretty impressive. Wouldn't be real practical in a general rider but for a dragger or hill climber that had to run gas, it appears to be pretty potent stuff.

Wheelie-Gene · Post by **Wheelie-Gene** » July 31st, 2009, 4:56 pm

I actually ran the 480 today for the first time w/the av gas.
I mixed a small batch 1/3 av to 2/3 super. I didn't notice any performance loss/gain, and I didn't run it fast enough to check head temps. The smell was a tad different, I'm sure 100% would smell sweeter.

I unloaded the bike in San Antonio and cruised a coulpe of miles over to the Honda shop. I needed some Hondabond and a jet came in that I had ordered. I rode up and parked by the service bay....everyone from the back of the store came out to see what just rode up.

When I went to leave, some of the sales guys were out front. I just had to float the front wheel through 4th when I left.

They had 5 gallon pails of different fuels in the parts dept. I was asking about the same stuff. The Q16 was priced at $50+.
I'll stick w/my $3.30 a gal av for now.

100hp honda · Post by **100hp honda** » July 31st, 2009, 5:14 pm

VP used to have a fuel called CMP but its discontinued now, ( i think Q16 is the sucessor to CMP but im not for sure). anyways, CMP was high octane oxygenated. i bought 5 gallons and tried it, i wasnt really inpressed because c12 seemed to work just as good and was alot cheaper. it stank like horseshit on a hot july day, and it melted through a milk jug. definatly not good idea to let it sit in the bike.

BannedCR500Riders.com

av gas ....anyone run it/tried it?????

av gas ....anyone run it/tried it?????