fuel mixture

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Neo
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Re: fuel mixture

Postby Neo » Sat Dec 03, 2011 9:47 am

Thanks for the info FM350.
Now finding a supplier might prove to be a challenge here in Aus. Castrol AU Website only has only the A747 listed (as a SPECIALITY PRODUCT) and gives no details of who would stock it .... Does Anyone know who stocks this in Aus?

FM350, can you recommend any others too?

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 Tim Barwick » Sat Dec 03, 2011 10:16 am

Im sure gas gas recomend's 100-1 in there manual with gro oli which is quite thin so they would never do that if they thought it was going to harm the engine,
I had a 97 beta that i ran on 100-1 with motul 800 for 3 years (the bike was already 3 years old when i got it) and i did a top end rebuild on it after 6 years running and the amount of oli on everything was amazing you would think it was on 50-1 so 100-1 for a modern trials bike is plenty.
I also have a gas gas ec300 enduro bike that i run on 50-1 with gro and i flog that thing and there is still oli leaking out of the pipe after every ride, so i wouldnt be running any trials bike on anything richer than 70-1 all your doing is making a smoke machine that run's bad.
All our twinshock's have run on 80-1 for there whole life and the ty we have had since 1989 still the same engine !!



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Re: fuel mixture

Postby brownie » Sat Dec 03, 2011 2:06 pm

Supercheap sells Castrol A747 but you might want to read Castrols recommendations for its use first

http://www.castrolmoto.com/au/our_oils_new/a747.php

Not a oil I'd be using in a trials bike, it may be good if your doing 10,000rpm plus constantly



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Re: fuel mixture

Postby David Lahey » Sat Dec 03, 2011 3:07 pm

I see that Castrol A747 has Castor oil in it. I remember spending hours using files, scrapers and sandpaper to get the incredibly hard baked-on carbon out of the exhaust port, off the inside of the head and off the piston crown on my IT175 when I was a kid after using Castor oil as my premix oil. There is no way I want that stuff anywhere near my air-cooled trials bike motors. With the oil I use in my premix nowadays, the only deposits I ever see are a thin, soft coating in the middle of the piston crown and inside the head that wipes off in a flash with a scotch-brite pad and carby cleaner.
As for engine life, I have a TY250A that has never had the cylinder head off since it was new in 1974, and it still has great compression and is quiet mechanically. I estimate it has done about 4000km of off-road work.

Current oil mix for my air-cooled trials bikes is Penrite Hi-Per semi-synthetic at 40:1. Up until a few years ago it was Castrol TTS at 33:1.

The TTS is terrific oil and I only stopped using the TTS because I heard that fully synthetic oils (like TTS) are not as good as semi-synthetic oils for protecting the rolling element engine bearings from corrosion during extended non-use periods. If I only ever rode the one bike it would get much more frequent use than my bikes get and I would then use TTS or another good fully-synthetic oil.


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don.howison
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Re: fuel mixture

Postby don.howison » Sat Dec 03, 2011 7:25 pm

Don't forget it's not just about oil ratio. You also have to make sure your fuel mixture is correct. In the past I have been sitting waiting to go into a section and you hear someone ride by with the bike running incredibly lean. The motor is screaming out wanting more fuel. If it's running lean on fuel it's also running lean on oil.



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Re: fuel mixture

Postby FM350 » Sat Dec 03, 2011 8:07 pm

A747 contains castor oil and is certainly not suitable for use in low heat trials motors, as the castor content will lead to varnish build up over a period of time, and unless motors are stripped for service on a regular basis (as road race or MX) this can lead to problems.

Castrol TTS is not fully synthetic as it contains 20% kerosene, to thin the PIB low smoke additive in the oil enough to make it usable in things like scooters with autolube systems fitted. No problem using it in trials bikes though, but not a good idea to run at the type of ratios you would want to use with a race type fully synthetic intended for pre-mix machines.

Primarily the reason semi synthetic or even mineral oils are recommended for use in trials machines is due to synthetic oils not burning anywhere near as easily as alternatives, which will result in exhaust systems which get clogged pretty quickly when full synthetics are used at the type of mix ratios appropriate for high heat motors such as road race and MX.

As to selection of a true fully synthetic race oil, you need to look for products which are intended for pre-mix machines, that are generally higher viscosity than the scooter type autolube oils, and in most cases will not be JASO or API rated as they do not include PIB low smoke additives. Bel Ray MC1 is an oil I first used many years ago, and is a product which is designed for pre-mix machines, and may be much more easily available outside the UK than something like XR77.

Finally very thin scooter type synthetic oils are not great at protecting motor internals from corrosion, especially when bikes are used infrequently. However this is not the case with race type synthetics which are of higher viscosity, and offer very good corrosion protection.



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Re: fuel mixture

Postby Samy » Sun Dec 04, 2011 12:03 am

I'm confused. So which oil should I use in my modern bike? ;)

I have been using Motorex at about 80-1

Cheers



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Re: fuel mixture

Postby FM350 » Sun Dec 04, 2011 12:27 am

You need to use fully synthetic race type oil designed for pre-mix use. Anything diluted with kerosene to allow use in autolube systems means using more oil, and the thinned down stuff is not that great when it comes to corrosion protection on bikes which are sometimes used infrequently.

The difference between scooter autolube oils and proper fully synthetic pre-mix products is clarified in the mix ratios recommended by Amsoil here: http://www.amsoil.com/a/synthetic-2-cycle-oil

50:1 mix ratio is recommended for anyone using one of Amsoils very thin scooter autolube oils for pre-mix applications, while 100:1 is suggested when their fully synthetic race pre-mix oils are being used.

As trials motors are very low heat, I would think using a scooter oil at 70:1 for watercooled motors would be fine, but obviously better to use a product designed specifically for pre-mix use, which can be safely run at 100:1 in a watercooled motor.

Finally the fact that trials motors dont run very hot, means that use of any oil which is inclusive of synthetic base stocks, will mean exhaust clogging will occur pretty quickly, if they are used at the type of ratios suggested for road/race/mx use, where running temperatures are far higher.



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Re: fuel mixture

Postby Tee-Why » Sun Dec 04, 2011 1:30 am

Samy wrote:I'm confused. So which oil should I use in my modern bike? ;)

I have been using Motorex at about 80-1

Cheers


Samy, I use Motorex semi-synthetic in my watercooled, I have run it at 80:1 no problem. You would have no problems at that ratio.
I had a time, not sure why, the bike would run lean and ping or pink whatever the term, and run hot enough to loose coolant on a hot day.
At home, I dropped the fuel, cleaned the carby, new fuel mix, all ok, never found a problem. But I run it a little richer now, as I want a little bit of insurance.
I dropped the pipe off and the carbon build up was negligible after a year.

Was running Belray MC1, but the Motorex semi-synthetic is run for the same reasons David mentioned above.

But 100:1 is actually 1%, .........ONE PERCENT........., have a think about that peoples when its a hot day in the 30-35degC when trials season starts, not uncommon in the months of February March to still get hot days around Perth districts, especially in the areas of farmlands inland. I see these riders rev the crap out of their bikes before entering a section to "clear them", and running that lean, why do they need to be cleared, and at what a risk for a hot spot on the piston doing that?????????? Whats with that????????


I would rather push my twinshock than ride a modern!

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Re: fuel mixture

Postby FM350 » Sun Dec 04, 2011 3:14 am

A full synthetic pre-mix race oil run at the proper ratio provides far better lubrication than semi synthetic or mineral oil. Problems do arise though when synthetic type oils are used in trials applications at the type of ratios common on road race and MX bikes.

Motorex semi-synthetic is a low smoke scooter oil, and is not ideal for trials bikes as its intended primarily for autolube systems, and as nearly all low smoke oils are diluted with kerosene its really too thin (SAE20) to provide good corrosion protection on bikes which may be used infrequently.

I would imagine a fair number of main bearing problems on trials bikes are directly related to corrosion which occurs due to use of inappropriate oils, and which will lead directly to greatly accelerated bearing wear when the bike is next started and run.

Seems strange that people seem willing to compromise the life of their motors by using scooter oils, which are really not intended for use on competition pre-mix trials machines!




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