1993 Beta Trials bike oil mix and other ?'s

[MikeL]

I am new owner of a 1993 Beta Trials bike and trying to figure out some things on it.  Previous owner didn't know much about it and never even added gas - he was just flipping the bike.  I'm not even sure what model bike it is - it shows Tipo B6 and OL9401 on the tag, no headlight, white rear fender, orange front fender and around a 250cc according to the seller.  I found the 1991 manual online that one shows a 2% fuel mixture - which I assume to mean 50:1?   But, most of these forums say to run 70 or 80:1, with a higher octane fuel (around 100 octane if I can get it).  Most of those threads are referring to newer bikes.  If I'm using Lucas Semi-synthetic 2 stroke oil (since I have it) what are your recommendations on the mix?

I also need to change the engine oil.  Looks like I can run a 10w30 according to the 1991 manual.  Regular, semi-synthetic, synthetic?

Any other advice would be appreciated - things to look out for, what tire pressures your running, etc.

Thanks in advance for the help. Excited to go try this out - I've always wanted one.

-Mike

[dan williams]

‘93 Beta Gara. White rear with grey front. Orange fender is probably off a ‘96. 80:1 is fine with synthetic oil. Gearbox oil is not super critical as people run everything from gearbox oil to ATF to 10W30 motor oil without a problem. Clutch might be sticky when cold. Fix is noted above. Mikuni may piddle fuel. Fix is noted above. 
Don’t be too obsessed about oils. It’s an old bike. Take it out and have fun.😁

[lineaway]

The worst thing to watch for is a corrodid water pump and cases. Besides that its a fine bike.

[MikeL]

Sounds good, thanks.  I'll get the oil changed and take it out.  I already noticed the sticky clutch and the carb leakage.  What do you guys typically run for tire pressures?  I hate getting flats, but seems like you need to go low for grip.

[wheelieman14]

you can get away with 7psi F & 5 psi R for general Trials riding. For competition, I drop down to about 5.25 psi Front & 3.5 to 4.25 psi Rear. This past Sunday was the first time this year I needed to go below 4 psi to get traction in sloppy muddy conditions. This is for Michelin X-Lite or Dunlop D803GP Trials tires.

[trapezeartist]

I generally use 3psi in the rear and 5.5psi in the front. I suppose I would have to go up a touch if I was riding in rocks or was heavy.

[TMofCumbria]

The mix ratio topic can cause a lot of controversy. Beta recommends 25:1 if you are using standard 2T mineral oil and 65:1 on Bardahl fully synthetic. As other posters have said you can run at 80:1 on modern synthetics. The problem is if your bile is jetted for 25:1 and you switch to 80:1 it will run rich, not burn the oil off and look as if there is too much oil as the plug will be black and oily. I do not know if your bike has a cast iron liner or a plated bore or if the piston is forged or cast. A high silicon cast piston in a plated bore can do with much less oil than a forged piston in a cast iron bore. If your engine is worn use a thicker / more viscous oil and put more in, but whatever  you do get the jetting correct so plug is right colour.

Fuel. An engine with a bit of wear and low compression will possibly run fine on E10 but some older bikes Like Yamaha monoshocks do not like E10 and run much better on E5 or even higher octane if you can get it. If your bike pinks (pings and rings) and sounds a bit odd use higher grade petrol.

People refer to ATF as if its all the same, it is not and a Dexron 2 spec will probably damage your gearbox. Use at least Dexron 3 semi synthetic or preferably light gear oil or multigrade. 10w-40 works fine in most gearboxes.

[MikeL]

Thanks.  I took it out yesterday and had a great time.  Ran with 100 octane fuel mixed at 80:1, though I splashed in a little extra oil just before I left.  Still too used to my dirt bike mix.  Ran great.  A couple times it would smoke a lot for a minute or two, and then quit.  I'm wondering if it just pooled some oil in the exhaust and then finally burned it off?

Started at 7 psi rear and front and quickly lowered the rear to around 5 psi.  Definitely takes some getting used to the geometry, but only flipped it a time or two.  

I looked at some more Beta sites and now wondering if it might be a 1996 Techno 250?  Thoughts?  I am attaching a pic.  Websites showed the fork being inverted on the 93, and this one is right side up. 

Anyone from the Denver area that can recommend good trials areas not too far away?  I rode St. Mary's the other day.

I didn't get around to changing the gearbox oil because it looked clean.  I'll do that after my next ride.