zarkoff Posted March 8, 2011 Report Share Posted March 8, 2011 hello there i was just wondering if anybody had any thoughts on wether petrol has changed over the years ( apart from the cost!! ) , a lot of people seem to have problems with carburation on older machines a mechanic told me that petrol has changed , so that settings on carbs ect maybe different. it could be worth bearing in mind when setting up carbs as i am right now. thanks . Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted March 8, 2011 Report Share Posted March 8, 2011 hello there i was just wondering if anybody had any thoughts on wether petrol has changed over the years ( apart from the cost!! ) , a lot of people seem to have problems with carburation on older machines a mechanic told me that petrol has changed , so that settings on carbs ect maybe different. it could be worth bearing in mind when setting up carbs as i am right now. thanks . If you look under the USA section higher up the index there is a thread which is very interesting about ethanol in petrol which should explain fully your question. Have a look 1 Quote Link to comment Share on other sites More sharing options...
zarkoff Posted March 8, 2011 Author Report Share Posted March 8, 2011 yeh cheers i had a bit of a read they are talking abou t avgas ect we have only 2 choices unleaded and super un leaded i haven't tried super but i might have a go in my old honda to see how it runs . my bike was built in the 70's probably designed earlier so fuel must have a role to play, lets face it it,s what powers our bikes , Quote Link to comment Share on other sites More sharing options...
b40rt Posted March 8, 2011 Report Share Posted March 8, 2011 Try octane booster as well, might make a difference. Quote Link to comment Share on other sites More sharing options...
helloyes Posted March 8, 2011 Report Share Posted March 8, 2011 It is because the petrol companys have been told by the government that they must mix a percentage of bio fuel in with our petrol ! so we are paying more for less ??!!! so what i have found is that you will need to lean the fueling out and maybe retard the ingnition if you get detination there seems to be no exact rule each bike is not the same hope this helps 1 Quote Link to comment Share on other sites More sharing options...
richty250e Posted March 8, 2011 Report Share Posted March 8, 2011 (edited) I would be wary of using 'super' unleaded as I found it caused my brand new fuel lines to swell. Gone back to normal unleaded and no further problems. I heard that up to 10% ethanol was added to normal unleaded to boost the octane, so maybe this affected the fuel line. Have also started adding Yamalube fuel stabiliser as a precaution to stop any gumming up. No further problems so far. Edited March 8, 2011 by richTY250E 1 Quote Link to comment Share on other sites More sharing options...
bpilgrim Posted March 8, 2011 Report Share Posted March 8, 2011 yeh cheers i had a bit of a read they are talking abou t avgas ect we have only 2 choices unleaded and super un leaded i haven't tried super but i might have a go in my old honda to see how it runs . my bike was built in the 70's probably designed earlier so fuel must have a role to play, lets face it it,s what powers our bikes , Hi, You can also get AVGAS from most airports over here. I fly from Liverpool and guys often come in and buy AVGAS for 'special' uses, often racing. The most common stuff is AVGAS 100LL, i.e. 100 octane, low lead. Apart from lead boosting the octane level, it gives added protection to I believe the valve seats, which is why it's used in light aircraft. You can get higher octane ratings, but I believe they were for military use (and are not available at Liverpool at least). The current price of AVGAS 100LL is about 1 Quote Link to comment Share on other sites More sharing options...
cabby Posted March 8, 2011 Report Share Posted March 8, 2011 (edited) I would be wary of using 'super' unleaded as I found it caused my brand new fuel lines to swell. Gone back to normal unleaded and no further problems. I heard that up to 10% ethanol was added to normal unleaded to boost the octane, so maybe this affected the fuel line. Don't you just love the internet Edited March 8, 2011 by Thedbf Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted March 8, 2011 Report Share Posted March 8, 2011 Hi, You can also get AVGAS from most airports over here. I fly from Liverpool and guys often come in and buy AVGAS for 'special' uses, often racing. The most common stuff is AVGAS 100LL, i.e. 100 octane, low lead. Apart from lead boosting the octane level, it gives added protection to I believe the valve seats, which is why it's used in light aircraft. You can get higher octane ratings, but I believe they were for military use (and are not available at Liverpool at least). The current price of AVGAS 100LL is about 2 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted March 9, 2011 Report Share Posted March 9, 2011 Our AVGAS has an SG that is quite different to car petrol from the bowser (AVGAS is less dense) and this can cause problems with carburetion when switching from one fuel type to another, particularly with bikes that have the carby leaned forwards a long way, like on Betas. AVGAS is fantastically stable fuel but is not permitted in sanctioned competitions. Luckily most service stations where I live still sell ethanol-free 98RON unleaded which works quite well in trials bikes. Quote Link to comment Share on other sites More sharing options...
minislim Posted March 9, 2011 Report Share Posted March 9, 2011 this current new fuel is playing hell with my bikes. firstly two of my bikes that have fibreglass fuel tanks have been gumming up and have left a polished residue surface in the carbs. which i am being told may now be knackered. so thats two petrol tanks and carbs destroyed. and now the latest in this saga is that it destroyed the plastic float in my carb too. which ruined my days riding in an event. i estimate the current cost of damage at around Quote Link to comment Share on other sites More sharing options...
woody Posted March 9, 2011 Report Share Posted March 9, 2011 I've always used Shell Optimax, previously V-max, for a long time now in my trials bikes and can't recall any problems with it. The bikes run fine. I use any petrol in my TL1000S road bike and it never seems to run any different. Quote Link to comment Share on other sites More sharing options...
1oldbanjo Posted March 9, 2011 Report Share Posted March 9, 2011 (edited) A local family use avgas and i hate queueing behind them as it makes my eyes sting Avgas 100LL runs richer than pump gas and you need to rejet if you want it to run well. Your eyes are burning because they have not re-jetted their bikes and they are running too rich. I used Avgas in my bikes and chainsaws for about a year - it ran OK but wasn't worth the 1.5 round trip that it takes me to go buy it. Avgas is not refined petroleum but is made from 70% Alkylate, 15% Isopentane, 15% Toluene and it keeps a long time and will not varnish anything up or cause corrosion. When it evaporates it leaves nothing behind but a little bit of blue dye. I have had problems with ethanol blended pump gas. It will dissolve fiberglass and some rubber parts, it rusted the inside of my Suzuki RL250 tank, and caused the fuel tank on my Sherco to swell and get very soft. It grew so much it started slide on the rear mount and there was a gap between the bottom of the tank and the frame and it was pushing the rear fender back. You can test any fuel for ethanol by taking a small clear bottle (soda bottles work fine), and fill it about 1/3rd with water. Carefully mark the level of the water and then fill the upper 2/3rds with the fuel you want to test. Put on the lid and shake for a about 10 seconds, then set the bottle down and see where the level of the water at the bottom of the bottle is. If the level of the water is right where you marked it - then the fuel does not have any ethanol in it. If the water level has risen it is because it has absorbed ethanol out of the fuel. I have found a source for gasoline that is delivered to farms for use in the bulk tanks that does not have any ethanol blended in. The ethanol blended fuel does not store well in the outside tanks farmers use, and it does not run well in their old equipment, and the distributor is not required to blend ethanol into fuel used for off-road farming. I have been using it for almost 2 years and my Sherco tank has not swelled and it runs fine. Edited March 9, 2011 by 1oldbanjo Quote Link to comment Share on other sites More sharing options...
bpilgrim Posted March 9, 2011 Report Share Posted March 9, 2011 Whilst we're on the topic of fuels affecting rubber and plastic components, I have a query: My Cota 348 has an original Amal carb, which I believe has a plastic float. When I first put the carb on, it ran perfectly, but now when the bike has been standing for maybe a week, the float seems to stick (I think), when I rev the bike and then the RPM drops, the carb dumps fuel out of one of the overflow pipes. It happened at my last trial and a guy said the float was sticking and he tapped the carb with a spanner, which cured it for the trial (but it still does it now and again). So is it the float that is sticking? If so, would this be caused by detergents in the fuel? I've been running it on Shell 95 which I believe doesn't have ethanol in it, but I've just read about shell 95 on their website: "Special detergents act on your engine as you drive to prevent the build up of deposits." Are these detergents damaging to rubber/plastic? Thanks, Ben Quote Link to comment Share on other sites More sharing options...
motovita Posted March 9, 2011 Report Share Posted March 9, 2011 so what i have found is that you will need to lean the fueling out and maybe retard the ingnition if you get detination there seems to be no exact rule each bike is not the same hope this helps Normally the adition of alcohol requires richer jetting, as you are essentially running watered down gas. There may be other factors at play though. Quote Link to comment Share on other sites More sharing options...
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