VintageVmax.com

After last years problems with mag side pistons I was wondering what people where using for gas.I thought about 94 octane fuel & adding some lead supplement what do you guys think ????

also i've been wondering but keep forgetting to ask.... what is everyone doing with the ethanol stuff? the pumps at our 1/2 way point gas station say "contains ethanol" of course the people that work there dont have a clue.... im just wondering what it will do with our older stuff..... in the meantime im filling cans from another gas station that doesnt mention ethanol.....i started running 93 octane this year but had always ran 87 before.... once i get my egt's ill be able to experiment more

I remember back in the 80's when the gas containing alky became mandated here in the Metro Milw. area, surrounding counties were not required to use it. It became a jetting problem for many, especially if you jetted close to the edge.
In kart racing, some engines use pure alky as a fuel, the 2 cy's use gas/oil. on the gas fed engines we use a tool called a Digitron, it electronically test the quality of fuel and will pick out power adding ingrediance. It is sensitive enough that we have to specify a spec gas station, there is to much variance from one station to another. Much of this has to do with the amount of alky added to the base gas from different suppliers.
Alcohol has several benefits over gas as a fuel, it also has draw backs. In racing, it adds more power then gas, it also is much cleaner burning which is why it is added to pump gas. It is corrosive to aluminum and some rubbers, which explains the grey/green crap you find in the bottom of your float bowl each fall. Alky has a much lower thermal output then gas, so requires more volume to produce the power increase thus, larger jetting.
Pump gas uses only a small amount of alky, factory jetting is USUALLY pretty rich and safe in MOST situations. Problems come when several issues stack up at once. Some gas stations have a water build up problem in their tanks, water takes up volume in each drop of fuel, which makes it lean. Cold weather requires more fuel, which again makes it leaner. Now add in a gas with a higher content of alky, which makes it leaner yet, and you could see problems. Being plenty rich hurts HP but it also is much safer when these conditions all come together at once.
I haven't begone to dial in my jets where I want them yet with only one ride. As I suspected, my problem was in midrange, part throttle cruise.. Temps were easily 1250.
It took a while to get what I wanted on my SRV, almost all of the tuning was with the needle jet and needle. What I do now is choose a main that I think will cover the temps, I'll be in. The main seldom changes unless its really warm or really cold. I chose a main where I can set the needle clip in the second leanest position. That means I can go one step leaner if I want without changing mains or 3 steps up, to fatten it up if I run into colder temps, bad gas ect.. The advantage is I only have to un screw the cap and move the clip. rather then pulling the carbs to change mains on the trail, takes less then 5 mins and no tools.

good reading... bob, exactly how far from the piston do you have your egt probes on your vmax? i would like to set mine up the same way as yours so i can at least kinda compare numbers with what your seeing...

Mine are 1 3/4 in from the very edge of the pipe, the part that presses tight against the flange on the engine. Remember there will be some difference from gauge to gauge altho digital are suppose to be pretty close.
My taper bored carbs should show up here today or tomorrow, I have the 39.5's on the SRV and ran well the other night

yeah all guages are going to read the same but i might as well try to make it the same as the "standard" i heard/ read that the probes are supposed to me 5-7" from the piston, is that what you did bob? seem like that might be about 5 inches from the piston...

I matched mine to what I have on the SRV. also on the VM it was where thy fit well, well until the clamp hit the loops for the springs, guess I didn't look close enough at that first, but it worked.

In Canada we don't have a choice with fuel it has 10% ethanol no matter what.Yesterday I was able to take mine for a ride & found the the mid throttle temp on my EGT's was higher than full throttle.Midrange temp was around a 1000 or a little more. I went & got 94oct fuel & added some lead supplement I guess we will have see what happens thanks

Hi Guys,

Startron is a fuel additive and I add it to every tank, jug, whatever... last year Maine went to Ethanol and many sleds were burning down. Just add the startron, or the blue marine stabil and you should be good to go. I use 93 octane in my max's. My carbs stay clean, in fact, this was the first year I needed to clean my pilot jets in my 86 after 10 years....the bowls were nice and shiny as well.....

Happy New Year everyone!!!

well guys thanks for all your advice so far my 89 has been holding together I am still going to jet it a bit richer for safey reasons but I am happy TTYL