Newbie engine problem

[Leonnvicky]

Hi guys I'm pretty new to the site. I used to have a beta techno when I was younger and now my boy had a bike I thought I'd get a gasgas to follow him around. The bike I bought needs a top end rebuild. Question is. Upon taking the head off I've measured the piston and its 59.85mm. It's supposed to be a txt 200 so the piston is supposed to be 63mm of I'm correct? Does this mean my engine is a 125cc bored to a 144cc? The only marking I can see on the engine are a few numbers and a 160 stamped on there. But I can't find any parts for a 160cc. All I need is a piston the correct size. And the piston that's in there now is a polini piston so it can't be standard surely?
Any help would be great! Thanks

 

[Leonnvicky]

Anyone have any ideas? My piston is 59.85
What size would my engine Be? Cheers

 

[(F5)]

I had a TXT200, a 2000 model. Was only a 163cc or something like that, not that you'd notice, it only troubled your ego, went better than my aircooled Beta 250.

It did rattle a bit and a new piston helped a little for 6 months. Still ran fine and new owner still running it.

This site is enduro based so only a few Trials guys here, there is a north American GG Trials site with more info.

On the bottom of the barrel will be a stamped letter, mine was a B. I replaced with the same size B piston as bore plating was pristine. 10+ years on you might look at yours carefully. Rings were pretty tight so check end gap.

I found the jetting responded going down at least one size on pilot and main. Delorto jets can be found, and even as a Honda part as they were used by Montesa which Honda owned. Again many year since I've bought stuff.

The inlet Iground out as the carb is offset to miss the shock but in turn you won't believe how bad it is. Grind the left edge of the reedblock and cut a nylon wedge to press into place on the right handside of the block. YYou'll see what I mean. 20 min with a file/saw and it picks it up a bit.

 

[cbutler]

Mike at http://www.tryalsshop.com/index.html can answer any question you may have on any trials bike.

Jim Snell was the trials guy for GG until the bankruptcy he can tell you ANYTHING about any gg trials bike http://www.trialspartsusa.com/repair-services.html

Supper people here to http://www.trialscentral.com/

 

[Zman]

TrialsCentral is devoted to trials bikes and I am sure they will know the answer to your question.