fuel mixture

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mackam
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fuel mixture

Postby mackam » Thu Dec 01, 2011 5:44 pm

hi i have just bought a beta rev 3.can anybody tell me does it run on 25-1 if not what is the correct ratio thanks macka



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Re: fuel mixture

Postby Will » Thu Dec 01, 2011 5:55 pm

I run my Beta Techno and wifes Rev3 at 100:1
Sounds extreme I know, I was worried at first but was assured it would be fine. So far so good.



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Re: fuel mixture

Postby Bully fanatic » Thu Dec 01, 2011 6:23 pm

Hello Mackam, Most people run modern water cooled bikes on synthetic oil at either 100 to 1 or 80 to one but they are made to run on that amount of oil. Just make sure it is fully synthetic oil not mineral oil. 100 to 1 seems to be what most people run so I would go with that. Graham.



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Re: fuel mixture

Postby FM350 » Fri Dec 02, 2011 4:23 am

Running a trials machine on fully synthetic race oil at 80-100:1 for watercooled bikes, and 70:1 for air cooled is just fine, and will provide cleaner pickup and no need to service exhaust systems so often.

However most "fully synthetic" oils are nothing of the sort, as they will have been thinned down with up to 20% kerosene to allow use in things like scooters with autolube systems.

In general any oil which is JASO or API rated will have been thinned with kerosene, while proper race oils are higher viscosity and dont seem to be JASO or API rated, as in most cases they are not low smoke.

Using the scooter type "fully synthetic" oils in a trials bike is not likely to cause any sort of problems, but probably not that good an idea to run at the type of ratios you would use for a proper race type oil.

There is an awful lot of confusion about oil, and most people are using too much oil for good running and to maintain a clean exhaust, but this is probably a good idea, as the adulterated scooter oils which nearly everyone uses should not be mixed as lean as proper race oils intended for pre-mix machines.



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Re: fuel mixture

Postby Neo » Fri Dec 02, 2011 4:15 pm

Thanks FM350,

That was dam good information that I had not seen anywhere previously and makes a lot of sens =D>

Best of balance.
Neo


"Nothing more and nothing less than the vision of success"..... Ryan Leech
"TRIALS....It's not life or death....It's much more serious than that!!".....

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Re: fuel mixture

Postby FM350 » Fri Dec 02, 2011 7:37 pm

Found out about the thinned down "fully synthetic" oils from the tech guy at Silkolene/Fuchs, who also sent me a lab analysis sheet related to one of the better known ones, which clearly showed it did indeed have 20% kerosene content! Here in the UK Castrol XR77 is a genuine fully synthetic oil designed for pre-mix use, which seems ideal for use on trials bikes.



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Re: fuel mixture

Postby Tee-Why » Sat Dec 03, 2011 12:36 am

FM350 wrote: Here in the UK

Your comments may apply to the colder climates, and those that ride in colder states of Oz.

I would not recommend these ratios suggested to those living in WARMER zones:
FM350 wrote:Running a trials machine on fully synthetic race oil at 80-100:1 for watercooled bikes, and 70:1 for air cooled is just fine, and will provide cleaner pickup and no need to service exhaust systems so often.


This would be running closer to disaster for potential nip up, the result is expensive and inconvenient. I always think it wiser to play it safe and pull back from those suggested ratios and go for 70-75:1 for watercooled bikes (note how often you boil your bike and how lean the jetting is, you dont want to ratio's like whats suggested above if you have other issues). For aircooled, I like 50:1 as the tolerances are not comparable to the watercooled, especially to FM350's other comments elsewhere in regards to raising the compression by closing the squish area etc. etc. Pushing old aircooled bikes to that extreme will end up with a holed piston in our climate.

I would rather clean my exhausts every 2-3 years, and burn them out or chem clean it, as the accumulated oil in them in that time is marginal. New oils dont clog up exhausts like in the old days, even the new oils still coat the first bend in the header with hard burnt carbon, no mater what the ratio. Are people really that stupid to use scooter oil for injected oil system two-strokes in a premix machine? - buy the best synthetic oil you can buy.

Just be careful of chrome lined bores, I would respect them and not push them to a partial seize, the damage and cost is not worth it. People that want to run 100:1, do you intend to hang onto you bikes for very long? Or do you intend to flick them on every season or two? Then I would not be buying a bike of you knowing that.


I would rather push my twinshock than ride a modern!

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Re: fuel mixture

Postby FM350 » Sat Dec 03, 2011 6:06 am

The main reason for extra oil is to help with dissipating heat on things like road race and MX bikes, which have very high piston crown temperatures. For anyone using a trials bike for any amount of trail or road riding, its also a good plan to add more than the required amount of oil, as piston crown temperatures will be far higher than on bikes used purely for trials.

Anyone running synthetic type oils and using more oil than is appropriate will find exhausts get clogged more quickly than using semi synthetic or mineral oils at the same mix ratios. The reason for this is that oils designed around synthetic base stocks, will not burn as readily as other oils and around 75% of the unburnt oil will end up in the exhaust.

For those who feel that their trials bike needs the same amount of oil as a road race or MX machine, servicing exhaust system is going to be required every 6 months by anyone really serious, with a drop in performance being noticeable after 12 months use. Exhausts which are not repackable must be cut open in order to service them properly, and stainless steel wool adjacent to the core, with Eglass long strand packing material filling the rest of the cavity, works very well.



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Re: fuel mixture

Postby Neo » Sat Dec 03, 2011 6:19 am

Tee-Why wrote:This would be running closer to disaster for potential nip up, the result is expensive and inconvenient. I always think it wiser to play it safe and pull back from those suggested ratios and go for 70-75:1 for watercooled bikes (note how often you boil your bike and how lean the jetting is, you dont want to ratio's like whats suggested above if you have other issues).

I would rather clean my exhausts every 2-3 years, and burn them out or chem clean it, as the accumulated oil in them in that time is marginal. New oils dont clog up exhausts like in the old days, even the new oils still coat the first bend in the header with hard burnt carbon, no mater what the ratio.

Not sure how much of a "hotter climate" you are talking about but I live north of Sydney and I've run been running Castrol TT Synth at 80:1 in my two Sherco's for years now. I know the state of my engine internals very well indeed and what you describe above has certainly not been my experience. It's also worth keeping in mind that a clogging exhaust system can cause issues of it's own too.

I'm looking to lean upto 100:1 in the future and will be measuring the temperature of the barrel and header pipe before and after I make the change, so I'll post up here if I see any ill effects.

Best of balance.
Neo


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"TRIALS....It's not life or death....It's much more serious than that!!".....

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Re: fuel mixture

Postby FM350 » Sat Dec 03, 2011 9:09 am

100:1 will be fine on any watercooled trials bike, but I would suggest using a proper race type fully synthetic oil designed for use in pre-mix bikes, rather than TTS which is very thin to allow use in autolube systems, and must not be used at the sort of ratios which are perfectly ok to use with a race type oil, which is not thinned with kero for use in scooters.

On the Sherco it looks like servicing the exhaust is likely to be pretty difficult, and this seems a good reason to avoid excessive amounts of oil if at all possible. A very good race type full synthetic is Castrol XR77, which replaces A747 and has been specifically designed for pre-mix bikes running on modern ethanol bearing fuels.

Heres the tech data sheet for XR77: http://www.aral.de/assets/bp_internet/c ... _TDS_E.pdf




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