I have quite a bit of respect for Jon Stoodley - but it does not mean he is always right nor do other tuners always agree with what he says.

I wouldn't trust that Stoodley guy if I were you....

I agree, I'm not always right (just ask my wife) and other tuners will disagree with me at times, just like I disagree with their findings now and then. But generally we will not be that far apart and can usually understand the other guy's opinion based on their background experience and level of expertise. I think part of the problem we deal with when choosing an oil ratio is that we are dealing with multiple variables, such as rider level, quality of premix oil, machine condition, state of tune, duration of running time, operating conditions such as a lot of high-speed road work etc. If you want to feel safe, you should go by the manufacturer's reccomendation which is usually on the "rich" side in order to try to cover worst-case riding conditions.

Even manufactuers are unsure what the "right" ratio should be: the 04' GasGas owner's manual states to run a 1.5% ratio and the 08' manual calls for a 2% ratio for essentially the exact same engine. Personally, I probably run a 65/70:1 mix as I always fudge a little more in the measuring container because it makes me feel better (there is also a psychological component to ratio choice as it is not all a mechanical absolute). So, I guess my advice would be to stay within "normal" rider usage range, but also take into consideration any unusual conditions you will encounter that may call for an adjustment.

Jon

Oh, and sometimes you just have to guess what ratio to run: one of the competition chainsaws I built for my Brother. Twin pumper carbs, welded cylinder for large ports, tuned expansion chamber and a very healthy dose of Nitromethane......(20:1 worked well).

Jon

ps. I thought we were getting a little too serious.....

Hi Jon

You need 100:1 in that chainsaw to stop all that smoking. You should also pack the canister with concrete to stop it getting gummed up, and add weight to help the blade through

Kidding

OILS/FUEL MIXTURE/LUBRICATION Fuel Mixture

Fully synthetic 2 stroke; 100 to 1 = 50ml of oil to 5ltrs of fuel

This is straight from the Ossa website. Those guys have faith in their machines and modern 2 stroke oil ( or are they bonkers?)

Edited December 19, 201312 yr by guys

Hey Jon ; Isn't your brother supposed to be wearing safety Glasses ???

How fast did it make that pass/cut ?

Glenn

Hey Jon ; Isn't your brother supposed to be wearing safety Glasses ???

How fast did it make that pass/cut ?

Glenn

Safety glasses are for two eyed sissies!

Faster than a guy cutting a block of cheese after having his finger pulled.

Edited December 19, 201312 yr by zippy

OILS/FUEL MIXTURE/LUBRICATION Fuel Mixture

Fully synthetic 2 stroke; 100 to 1 = 50ml of oil to 5ltrs of fuel

This is straight from the Ossa website. Those guys have faith in their machines and modern 2 stroke oil ( or are they bonkers?)

Did I mention that Montesa/Honda advised to use 80/1 in their 315R? No?

Oh, and sometimes you just have to guess what ratio to run: one of the competition chainsaws I built for my Brother. Twin pumper carbs, welded cylinder for large ports, tuned expansion chamber and a very healthy dose of Nitromethane......(20:1 worked well).

Jon

ps. I thought we were getting a little too serious.....

Nice picture for as old as it is. Looks like that answer S/A is holding that thing back from really singing!

Hi trials brothers .Wonder how often this question gets asked?

Here's my 2 bob's worth!

1 Use you head.Keep a diary of how your bike runs(2 stroke)on what day and weather conditions,what oil ,where your fuel came from and what grade.2 Don't expect to much of a bike if you don't maintain thing's as you should.3.Listen to sound advice and get the basics correct.

O.K here's a picture of one of the main bearings from my 14 year old GasGas Edition 280 TXT. This motor has never been apart.I base that statement on experience. The reason i stripped it was routine maintenance &more than normal vibration.

The bike get's run on Castrol 2 stroke racing oil @ 65-80:1 depending on weather and conditions,the air fuel ratio altered accordingly.

Iv'e had 2 baffle fires running at 80:1 whilst hammering it up hill for extended throttle openings.Thing is though never had a seizure.

Look at the deposits on the bearing.There was no significant amount of play considering their age,but they started to get noisy and vibration was coming through the bars whilst riding.

Make your own mind up with the info.

Edited December 24, 201312 yr by shyted

What is it you think is built up on the bearing?, it's not common, I've seen it before but not sure what it would be

My best guess would be that fuel condenses on the bearing surfaces and then dries out (much like in a carb)

Leaving deposits behind, probably builds up in the races as well causing a rough bearing and noise

Was there any buildup on the crankcase surfaces?

When I opened my Bultaco engine it looked even worse than that. I suspect the previous owner used that "classic" two stroke oil from Castrol that is known for leaving a muck behind in the engine...

Could be something like that, or cheap two stroke oil maybe...

I think it could be a mixture of several things.When i bought this bike it had ,on the whole,had been stood for two years.

Secondly i only saw no make scooter 2 stroke oil in the guys garage ,although no scooter .

But,the bike has been 100% reliable and i paid £1100 for it so i wasn't going to dig so deep at the time i bought .

How's the 280 guys? Done any demolition work on it yet?

Check out the pic's i will put on "what did you do to your GAS GAS today", bit of the forum tomorrow evening.

Edited December 23, 201312 yr by shyted

The 280 is a very stable and at the same time nimble bike.

I put a low compr. insert in the head and a slow throttle on it and this makes the bike smooth but powerful when you need it. I haven't lost control of it yet, if that's what you mean:-)

The best power control is in your right wrist imo.

But I won't be parting with my 4RT, I love it to much

By the way, I used to use Castrol Scooter 2 stroke oil in my 315R which left very little deposit in the engine and exhaust...

What is it you think is built up on the bearing?, it's not common, I've seen it before but not sure what it would be

My best guess would be that fuel condenses on the bearing surfaces and then dries out (much like in a carb)

Leaving deposits behind, probably builds up in the races as well causing a rough bearing and noise

Was there any buildup on the crankcase surfaces?

Only a little build up on the cases at the bottom end.Although there is some on the inlet tract and the upper area of the cases near the oil way.

Just think about all those collectors who never run there bikes for ages.

Never had a Jap bike do this but never had a 14 year old Jap 2 stroke trials bike .

Edited December 24, 201312 yr by shyted

Hey Jon ; Isn't your brother supposed to be wearing safety Glasses ???

How fast did it make that pass/cut ?

Glenn

"Hey Jon ; Isn't your brother supposed to be wearing safety Glasses ???"........No problem, he's a Lumberjack and he's o.k.......

Not sure how long but it was good enough for a first place. As you can see, even with a temporary bog from the engine, it cuts

quite quick. I had run a load of Nitro in it and it was a tad too much. A "full load" of Nitromethane is usually between 87 and 92%,

more than that and you can't always light it off with any degree of certainty (learned that from the fuel dragsters). Percentage of

Nitromethane is determined by using a hydrometer and reading the specific gravity of the mixture.

Jon