You can upgrade your HT engine to a +1 mm Stroker crank to be 27 cc HT engine
You will need a replacement slip in sleeve to go with the +1 mm crank, that is $120
This upgrade is considerably faster and it runs a lot better than what your HT does now. A modified WYK33 carburetor gives you the best performance, but a WT style butterfly carburetor works OK also. If at a later date you want to add the Pioneer head pipe to your Hot Pipe, that is worth a 1/4 HP but the stock Hot Pipe header works fine if you just want to stay with that one. The only difference in the head pipes is the spigot that goes against the cylinder. You can buy the spigot for $15 and saw your old one off and reweld the new one on your header (if you can do that) and now you will have the Pioneer header.
If You prefer buying a whole new cylinder assembly instead of switching your sleeve, you can buy a new HT cylinder casting from us with a sleeve installed for $200, we can do this with a standard sleeve or the +1 mm stroker sleeve for the upgrade.
Call or email us if you would like to do the upgrade.