telecat Posted May 11, 2005 Report Share Posted May 11, 2005 In the UK the Main Petrol available is 95 RON also available are BP Ultimate And Esso at 97 RON, Shell Optimax and Q8 98 RON and Leaded fuel sold by Bayford. This is because there is a clause in the fuel act that states Leaded 100 RON must be sold up to a percentage of unleaded fuel. The web site is www.leadedpetrol.co.uk. The only reason NOT to use leaded petrol is if the vehicle you are using has a Catalytic converter. The lead coats the metal inside, (platinum) so stops it working. Trials bikes don't have cats as the oil mix stops them working. Quote Link to comment Share on other sites More sharing options...
ringo Posted May 11, 2005 Report Share Posted May 11, 2005 Well now, I have to say that this has turned out to be quite informative for everyone, myelf included. Thanks to all! HondaRS, I certainly hope I didn't offend you. If you happen to come to our nationals and El Trial I'd like to offer you a cold beer. That goes for any of you out there. I'll be at the gate along with the rest of my buddies so have your $10 bucks ready and plan on the best trials weekend you've ever had. Quote Link to comment Share on other sites More sharing options...
paulmac Posted May 11, 2005 Report Share Posted May 11, 2005 Now come on Ringo - don't go all 'Fantic' on us... Paul Mac Quote Link to comment Share on other sites More sharing options...
copemech Posted May 12, 2005 Report Share Posted May 12, 2005 I've never seen Ringo be so polite, so I'm going to risk putting in my 2 cents worth here just for giggles. Most "AVGAS" sold here in the US is what is known as 100LL, or 100 octane aviation fuel, low lead (blue in color). The "LL" part is relative, and is only in comparison to other aviation fuels which had a even higher content of lead (or T.E.L) tetraethylwhatever. Modern 100LL has approximately three times the T.E.L. content of what some of us remember as "leaded" auto fuel and is added primarily to help preserve the valves and seats in aircraft engines which were not designed to run on unleaded fuel. This LEAD serves no useful purpose in a two stroke engine! It can however in some cases cause premature fowling of spark plugs due to residules that may cling to them. It is the higher OCTANE(resistance to premature ignition) rating that is needed in high compression engines that prevents pinging and clatter due to preignition and detonation. I believe that most modern trials bikes are recommended to use between 93 and 100 octane fuel. Engine designs vary somewhat. EXPERIENCE: It has been suggested that EXCESS octane in your fuel does NOT increase available horsepower. I seem to recall that a recent dyno test performed by one of our resident members proves this to be the case and I believe it to be so, as higher octane fuel is basically more difficult to burn in a engine that does not need it. It has also been said that the higher octane fuels have a "smoothing" effect on a trials engine. I also believe this to be true because the dyno results show the engine to be producing less actual power. Go Figure! I have used 100LL in trials engines for the last five years with good results. Maybe I change "sparkies" every four months instead of every six, I really don't keep count, I just change them out if the bike starts getting a little hard to start. Speaking of hard to start, I have had some problems on hot restarts on hot days similar to what is known as "vaporlock"condition. I relate this to the fact that AVGAS is designed to atomize and combust well at lower relative temps(at altitude) than auto fuel. A hot day in Texas with a hot engine and a carburator on a Sherco sitting right next to the exhaust is quite the contrary! So I have been running a 50/50 mix of avgas/pumpgas for tha last year or so and it seems to be ok. I'm not sure what the octane really IS as I have read that it only takes 1/3 to 2/3 ratio to increase the octane, in other words, 1/3 gal 100 octane mixed with 2/3 gal 90 octane will yield 1 gal of 95 octane, NOT the 50/50 mix that you would presume! OTHER FACTS, As far as I know, RYP/SHERCO has been using straight pump gas for the last couple of years. I do not know if any other octane boosters are added but I'm sure Ryan would tell you. It seems that many manufacturers are either lowering compression or modifing combustion chamber design in an effort to allow the use of lower octane fuels. My old 98 Scorpa (rotax) would ping like hell if I did'nt run the 100 octane in it! Other engine designes may not be so forgiving, so you may need to vary your mixture accordingly, try it your self and see! So there ya go Ringo old boy, I hope that makes everything just as clear as mud! If you ask a fuel engineer about all this stuff you can't understand his reply any better than mine, the the end result is the same! I'm ready for that beer now ! Cheers, MC Quote Link to comment Share on other sites More sharing options...
copemech Posted May 12, 2005 Report Share Posted May 12, 2005 ps- I deliberately excluded variables such as ignition timing and carburation to keep this discussion as simple as possible. plus- avgas is clean and stable for long periods of time neg- pump gas stinks and stains stuff and stuff(additives) will fall out of the fuel and "varnish" up components in the fuel system MC Quote Link to comment Share on other sites More sharing options...
ringo Posted May 12, 2005 Report Share Posted May 12, 2005 I've always laughed at people that say AV gas is unstable as it is intended for airplanes that operate at 3000 feet. That being said, all I can say about your post is that I've had the same spark plug in my bike for about two years. Maybe that's why I had to kick it more than once at the last trial. Quote Link to comment Share on other sites More sharing options...
brian r Posted May 12, 2005 Report Share Posted May 12, 2005 Pardon me Mr. Ringo sir, when you say "kick it" does that mean attempting to start or just getting p!$$## off and physically getting even with your Mototrials vehicle? BTW I read somepalce RYP's David Chaves uses Maxima octane booster. Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted May 13, 2005 Report Share Posted May 13, 2005 here in the UK my mate & I run super unleaded in our two-stroke trials bikes, they definitely run cleaner/better/more power less problems but there is only one independant garage locally where we can buy it, as for avgas we would love to try it but do not know where to get it from or how much it might cost does anyone else know Quote Link to comment Share on other sites More sharing options...
brian r Posted May 13, 2005 Report Share Posted May 13, 2005 Try your local small airport. I think someone suggested you use the gas for your ultra lite. If a trials bike isn't an ulta lite I don't know what kind of motorcycle would be. Quote Link to comment Share on other sites More sharing options...
telecat Posted May 13, 2005 Report Share Posted May 13, 2005 As an aside the reason I run 98 RON in my son's trials bike is because they is a sticker on the frame stating that the bike is designed to run on 98 RON fuel. (Sherco 125). Quote Link to comment Share on other sites More sharing options...
the artist formerly known as ish Posted May 13, 2005 Report Share Posted May 13, 2005 Come on guys, if you want to run cool, you got to run on heavy heavy fuel. Leaded fuel is heavier so has more gravitational swirl when entering the vortex of the venturi, when mixed with the air this causes expansion and molecular heating, the compression of the piston further heats the fuel until it is fully charged and ignited by the thingy mi bob with the little wire on top. The piston is allergic to heat and runs away from the flame front, to which the flame front says "sod this I'm off " and nips out the exhaust burning the crap out of Ringo's leg on the header pipe, prompting him to say things like "man that's hot" or "good job I had my shorts on dude, it would of burned right through my riding duds" skin heals duds don't. Wonder if they will let you run the gate at Duluth ringster, you could get in then Quote Link to comment Share on other sites More sharing options...
ringo Posted May 13, 2005 Report Share Posted May 13, 2005 THAT'S IT Ishy!! I'll be running the gate for our nationals and El Trial next weekend so I'll just take my "official gate person" bib to Duluth!! You don't think anyone will notice the difference do ya? Why do I have this funny feeling there will be more than one cop ridding around on wheelchairs this year? Quote Link to comment Share on other sites More sharing options...
jtt Posted May 15, 2005 Report Share Posted May 15, 2005 (edited) WARNING...long and technical in nature HERE is one of the best dissertations on AVgas that I've come across recently. Edited May 15, 2005 by JTT Quote Link to comment Share on other sites More sharing options...
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