5 replies to this topic

[cbf1000]

Theres an opportunity to buy a techno 250, with leaking crankseal. How big a job for someone pretty competent mechanically but new to 2t mo'bike engines?

Walk away? or buy cheaply?

[Stork955]

Gday, if you are competent mechanically, go for it. Its a pretty easy job.

Cheers,

Stork

[betarick]

Leakey crank seals sounds like mains are shot bigend gone needs a rebore and a piston! I would stay away could get very expensive! trust me i have been there with a techno.And they cant be rebored as the barrel is plated being alloy!

[cbf1000]

Thanks for the advice.

Stork955, you may be right, but I don't want my intro bike to trialing being a nightmare and turning me off.

betarick, thank you, may well have saved me from a lot of pain and frustration.

I'll look for something else that will painlessly introduce me to trialing.

[Steve_E]

Hi, I would do some investigating first before ruling out the bike. In the extreme case the main bearings could be gone this COULD Take out the big end and COULD score the barrel but unless its really bad (as you can not rebore as an oversize piston is not avaliable) the barrel can be re plated for about 90 quid.

I have done main seals on many different trial bikes from yamahas, betas etc and had no problems with other damage, Usually it has happened because the bike has been standing for a long time or the wrong gearbox oil has been used.

Find out the symptoms, If the gearbox side main goes the bike will usually start on a clean plug then die as it warms up and the oil gets thiner and enters the crankcase, causeing the plug to oil and the bike dies. Just hearing the bike run will tell you if the mains have gone.

If the Flywheel side seal goes the bike is usually hard to start and will rev irraticly sometimes on its own.

It's up to you at the end of the day but I would buy a trials bike that needed main seals. I would think twice if it was a crosser or enduro as they normally are knacked at that point.

If the bike is cheap it is worth a gamble as at the end of the day trials bikes will break for parts for more than a whole bike is worth normally.

[axulsuv]

Steve_E, on 04 February 2012 - 07:04 PM, said:

Hi, I would do some investigating first before ruling out the bike. In the extreme case the main bearings could be gone this COULD Take out the big end and COULD score the barrel but unless its really bad (as you can not rebore as an oversize piston is not avaliable) the barrel can be re plated for about 90 quid.

I have done main seals on many different trial bikes from yamahas, betas etc and had no problems with other damage, Usually it has happened because the bike has been standing for a long time or the wrong gearbox oil has been used.

Find out the symptoms, If the gearbox side main goes the bike will usually start on a clean plug then die as it warms up and the oil gets thiner and enters the crankcase, causeing the plug to oil and the bike dies. Just hearing the bike run will tell you if the mains have gone.

If the Flywheel side seal goes the bike is usually hard to start and will rev irraticly sometimes on its own.

It's up to you at the end of the day but I would buy a trials bike that needed main seals. I would think twice if it was a crosser or enduro as they normally are knacked at that point.

If the bike is cheap it is worth a gamble as at the end of the day trials bikes will break for parts for more than a whole bike is worth normally.

Like said above , Don't rule the bike out , May be cheap access to the most fun on two wheels ....
Glenn