Originally Posted by hrnts69
Iam gonna be running a Thunder Tiger .15 and a XTM .18. These are both pull starts. Iam wanting to build them up for this years racing.
If .18 is alowed the OSMAX 18TZ is the way to go,.
Your mentioned engines are running on a plug R3/R4?
You can raise the compression by taking out a headshim with using a colder plug (5 or 6)
Drill up the carburator by 0.5 to 1 mm can give more power.
A longer exhaust system can give more bottom power.
Higer Nitro content.