Hi All, I usually fill up my 77 jota with 98ron super unleaded petrol ,whilst taking advantage of the spring-like weather yesterday i pulled into my usual garage to find they had run out of it, i tried a couple of other local stations and they too had run out, so i reluctantly put a tenners worth of normal 95ron in it...what do you people generally use in your bikes?, my original owners manual clearly states that anything less than 98/99 octane fuel can cause engine damage!...gulp.
Petrol
- Thread starter philw
- Start date
The Sock
Hero member
- Location
- London, England
The potential damage would be caused by pre-ignition/detonation/pinking, Phil. Unless you have cloth ears, you'll hear it.
Mine, which has a high comp Motodd prepared motor, will pink on 95, hot days, large loadings.
If you hear it pinking, just ride with a light throttle until you can top it off with 99. If you don't hear it, you could save a fortune on petrol, on long runs. Best not to use E10 if the bikes going to sit unused for an extended period (eg. winter).
Rob
Hero member
- Location
- Midlands, UK
But the fuel rating being sold has already factored this in!
If your '77 bike still has its original UK pistons and cams then I too would want to use 98/99 RON. Currently it has the added benefit of no ethanol, in some parts of the UK at least. As Hamish says, keep an open ear and light throttle.
martymoose
Hero member
- Location
- Sydney, Australia
Hi Pauls, not sure where you are, RG6? By the bloke on your video I'm guessing your in the UK. What is he actually measuring? E10 fuel has 10% ethanol right? So he's saying it ranges from 7.5 down to 2.5% ethanol? So what is this bloke proving? What is going to "kill your engine"? There where claims originally that ethanol was abrasive and caused wear in injectors. I haven't seen that in Oz. We get our fuel from signapore, no refineries left here. 4 main types, 91, 94 E10, 95, 98. Brett tells me that legally they can sell non ethanol fuel with up to 5% of the stuff in it. (Government did a dodgy deal with producers).
I see a lot of carbon buildup on valves on bikes running 98. The worst was a 1200 Bonneville, could have sworn it was big end/ little end, turned out to be pistons hitting the carbon. Throttle bodies off, spray some three bond engine conditioner on the backs of the valves, turn motor over by hand to open the valves and squirt it in. Leave to soak, then an Italian tune up. Fixed.
750 with points, easy to set up for timing, it will run happily on 91 or 95. Triples running ignitech, (3c and 3cl), run well on 95, but needed the laptop to tweak the timing. The 6 plug 3cl needed a lot of trial and error, very custom curve, whereas the 3c , jota pistons, Ricky racer cams, used one of Reds curves, but needed to knock a couple of degrees out of it.
I see a lot of carbon buildup on valves on bikes running 98. The worst was a 1200 Bonneville, could have sworn it was big end/ little end, turned out to be pistons hitting the carbon. Throttle bodies off, spray some three bond engine conditioner on the backs of the valves, turn motor over by hand to open the valves and squirt it in. Leave to soak, then an Italian tune up. Fixed.
750 with points, easy to set up for timing, it will run happily on 91 or 95. Triples running ignitech, (3c and 3cl), run well on 95, but needed the laptop to tweak the timing. The 6 plug 3cl needed a lot of trial and error, very custom curve, whereas the 3c , jota pistons, Ricky racer cams, used one of Reds curves, but needed to knock a couple of degrees out of it.
martymoose
Hero member
- Location
- Sydney, Australia
So, bottom line Philw, what ignition are you running, and then you can adjust your advance curve to suit the fuel. Find a good long piston eating hill, and give it the berries son!
I use 95RON in all of my LAVs here in AUS on recommendation from the chaps in CLNSW some years ago.
CORSA has done 34,000kms in last 6 years, RGS, 10,000kms in same time, all on 95.
Both run Sasche ignitions from RED, timing and tune on CORSA by Brett.
I don't hear any pinking under load, but being a lot older and more cautious than in the 70's and 80's, I'm far more gentle on the bikes than I used to be.
As Marty said, give it the berries on a long steep hill. If it's going to pink it will.
Dellortoman
Hero member
- Location
- Tasmania, Australia
When I put Mikunis on my Jota I took it in to a mate's bike workshop to tune it on his dyno. Once we'd got the jetting pretty right, he asked what fuel was in the tank. I told him 98. He said he'd had a lot of bikes in his shop with knackered engines, or engines choked up with carbon/ash that were running on 98.
He said my bike should run fine on 91 and it's a cleaner burning fuel.
To prove the point, he hooked up a tank of 91 to the carbs and did another dyno pull. Exactly the same power trace and no hint of pinging. He didn't have an explanation as to why 98 made a mess of engines, but his recommendation was to steer clear of the stuff.
Since then I haven't been too fussy about the advertised octane rating. The bike will run 91 no problem. I think the CR of my Jota is a bit over 10:1, maybe as high as 10.5:1 (standard Jota pistons + 0.3mm shaved off the head). Perhaps more modern engines with CR up around 12 or 13 need 98, but it seems our old tractors don't, so long as the ignition timing isn't too radical.
He said my bike should run fine on 91 and it's a cleaner burning fuel.
To prove the point, he hooked up a tank of 91 to the carbs and did another dyno pull. Exactly the same power trace and no hint of pinging. He didn't have an explanation as to why 98 made a mess of engines, but his recommendation was to steer clear of the stuff.
Since then I haven't been too fussy about the advertised octane rating. The bike will run 91 no problem. I think the CR of my Jota is a bit over 10:1, maybe as high as 10.5:1 (standard Jota pistons + 0.3mm shaved off the head). Perhaps more modern engines with CR up around 12 or 13 need 98, but it seems our old tractors don't, so long as the ignition timing isn't too radical.
Tippie
Hero member
- Location
- Dr?bak, Norway
Most modern engines have all sorts of sensors detecting knock and lots of other parameters that determine every facet of tune. They can run just about any fuel. My SF2 and race-bike both have 10.5:1 compression, I run the racer on 98 and often run the street bike on 95 as 98 gets scarcer here, both are fine, and both have max advance under 30deg.
Andy
Hero member
- Location
- Auckland, roughly
I was told the same by a mechanic I met on a ride. Reckoned 95-98 was rubbish.
I think we’ve had this thread before… but maybe this time there’ll be a different result
Thanks for all the replies...my bike has an Ignitech system fitted by Keith Nairn and i've been running it on 98 without problems, i'll keep a close ear on things while the 95 is in the tank though.
Exmoor beast
Hero member
- Location
- Minehead,Somerset, ENGLAND OF COURSE
In UK E10 means the fuel could have up to 10% ethanol but may have less or none in at all. The fuel is altered to be more volatile in the winter to aid starting and less in the summer, so effectively winter and summer grade.
With the world as it is fuel will be bought from anyone that has it and the formula will be anyone’s guess.
My ‘69 750 GT runs fine on E10. Ethanol isn’t abrasive but has no lubricating qualities, Jaguar suffered fuel pump failures in Saudi years ago because their fuel is so pure they were wearing out due to lack of lubrication.
martymoose
Hero member
- Location
- Sydney, Australia
We dont get summer and winter formula fuels here, apart from diesel in the alpine areas.
The Sock
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- Location
- London, England
