Hello people,

I have only jus joined forum so go easy on me,

Basically i am new to trials, But not really new to bikes!

Me and a mate have jus bought a ouple of beta's, The only prob is after i have had it home and gone for a play in the woods i have noticed a knocking/Pinging noise when engine under labour, Lets say if i climb or give give it beans it will start pinging on me, no loss of power that i could notice. .

Does any one have any ideas??

Regards

James

Are you running it on Super unleaded?

Are you running it on Super unleaded?

Hi martin,

To be honest i only bought the bike today so i have no idea what fuel/oil is in there, Not even sure the guy has the correct mix!

I stripped down the top end this evening and de-coked everything possible and had a good root around, engine bearings seem to be in good cond, There is slight play between piston and barrel But thats about all i could do for now, i gave it a ride and bought the temp up and the pink/knock seems to only start when engine is warm....

Does this help..

Regards

James

98 octane may help.

Hey James

Beta's need fresh high quality high octane gas. Run fuel:oil at 70:1, and only use quality synthetic oil. Keep the air filter clean and properly oiled. Use an Iridium spark plug of the correct heat range. Keep it decoaked is a very good move. Flush the exhaust out with a bit of petrol to get goop out of the insides. Repack the muffler often. I retarded the timing on my 270 a but.

It was better, but never really fully stopped it knocking......

I 've only got a little un (thats a quote to regret|)..no a 200..It might just be that you could try adjusting the airscrew (have you?).little bit less air may be all it ineeds.

I 've only got a little un (thats a quote to regret|)..no a 200..It might just be that you could try adjusting the airscrew (have you?).little bit less air may be all it ineeds.

Agree, mines a middle size one (250) and I was quite worried by the knocking, but half a turn on the mixture screw sorted it right out!!

SOB. You mean i could have turned the air screw in a little and saved all that work...... what a knob i am.

At least i had the presence of mind to own the big one.....

I have nearly resolved the problem, I changed to super unleaded and bvm recommended oil, De-coked and new piston,

I adjusted the mix screw by one turn (cant remeber if i leaned or richend) but it was working fine for half of the day riding then it started playing up knocking and pinging,

I stripped down the carb and check obvios and rebuilt again, The only problem i found was to the rubber part between the carb and reeds, It was split a little but dont think this would afect performance, So my questions are:

What is the part number for the rubber thingy??

What is standard mix? Ie how many turns from tight should mix be??

Anyway, after fidling about the bike runs ok, but will pig every so offen, And pings more when hot??

Any ideas?

Cheers

Gday, keep in mind that the mixture screw only affects idle mixture... Check ignition timing, needle and main jet sizes/positions. Is the front pipe clean?

HTH

Cheers,

Stork

Gday, keep in mind that the mixture screw only affects idle mixture... Check ignition timing, needle and main jet sizes/positions. Is the front pipe clean?

HTH

Cheers,

Stork

Do you knoiw how to check ingnition timing? I have cleaned front pipe best i can, I cant find a way of getting in there to clean it properly

Gday, its best to use a timing light to see what is going on, my Techno has timing marks on the flywheel and I would assume the Rev 3 has also. There are photos on the net somewhere that you can look at to see the basic alignment of the stator to the engine case.

Cheers,

Stork