So I work for an auto performance shop and for one of our company parties we all decided to build and race some lawnmowers. So I bought a MTD rider that is equipped with a Briggs and Stratton 18hp opposed twin motor, the model number is 422707. It is completely stock at the moment. What is the typical upgrade path to make this thing fast on a budget?
Here are some things I am for sure planning on doing:
-Remove governor, install throttle pedal
-Deck cylinder heads
-Build free flowing exhaust
Any info would be much appreciated.
Also, I already emailed Don about getting one of those DVDs.
What is your budget?
Here are some initial thoughts:
1. DO NOT deck the heads. Flatheads need a large transfer port cross section.
2. The 3-screw carburetor will probably be fine for what you are doing, it has the bigger bore compared to the 4-screw.
3. Try to find a used aluminum flywheel, I'd hate to see you get hurt.
4. Lose the factory brake setup. Spend the money and get a decent rear brake disc setup.
5. See if you can find a junk 46-cube, and rob the heads and camshaft. The heads will say 'MOD 46', and the 46 cam will also have a code with '---46' stamped on it.
6. Make a header that will scavenge well, a 2 into 1 style.
There are more safety modifications you should do such as steering and front end modifications as well.