Hi guys, new on the forum. After a few years of tinkering with twinshocks i have managed to get myself a fantic tx250 project. I am aware these are a 125, and the bike was purchased from a friend in pieces. 

I have taken some measurments from the engine today and noticed that it seems to have had some real nice work done. The Barrel has had a liner fitted with a copper spacer on the bottom , it is running a 69mm piston with two rings. It also appears to have been fully ported and is running a 25mm Amal carburettor. Using the piston measurments and stroke this should bring the bike out at 196cc. It also doesnt run a headgasket as the liner and head have been machined so it doesnt have to. Pictures attached. Any one know who done these mods as i cant find anything about a tx250 running this size piston online.

Thanks in advance

Doesn't look that special from the photos. What are you comparing the porting to? Looks like the cylinder head has not been seated properly as there are signs of combustion leakage. Can you show the rear of the bike and a better look at the ports is possible?

9 hours ago, section swept said:

Doesn't look that special from the photos. What are you comparing the porting to? Looks like the cylinder head has not been seated properly as there are signs of combustion leakage. Can you show the rear of the bike and a better look at the ports is possible?

Haven't got a photo of ports to hand, but assuming they have been tickled just to match port timing as it has a different piston in it. Plus I don't have anything to compare it to ?

Have you seen one running a 69mm piston before then with a liner that big? 

Im under the understanding a standard 125 runs a 54mm and a 200 (156) runs a 64mm. And they run with a head gasket. 

Where does it look like its been leaking? Its all very dirty at the minute and just how i Picked it up.

 

Edited January 3, 20197 yr by WJSmith

Picture 1 and 2 at the between the 1 and 2 o'clock position. Could be wrong as its only photo but certainly worth checking for distortion.

 You might have a 212cc engine Fantic made the TX250 (125cc) and the TX 350 (212cc) and thats confusing enough, I could never understand Fantics reasoning for calling a 125 a 250 etc?A more well informed Fantic officianardo will possibly be along to correct the details?

Common mod was to fit steel liner and use alternative piston. Very often Suzuki 185. 

Yeh i read up on that on here Nick, and TBH i thought that was what had been done. But piston is a lot bigger than the suzuki one they used. 

Ah well, ill out it back together and see how she goes ?

Last resort, track back on the previous owners if thats possible, start with the friend.Happy hunting?

I HAD A NEW FANTIC IN APPROX 1979 , IT WAS SOLD AS A 175 FROM FANTIC UK . IT HAD A SUZUKI PISTON AND IT WAS DONE BY VIC MADELY IN WALES FOR ROY CAREY AT FANTIC HORNCHURCH ( IMPORTER ) . IT WAS JUST  A FEW MORE CC,s TILL THE 200 (156) CAME OUT . HOPE THIS  HELPS .