Mammoth
Member
Im learning just like everyone else. I have smart friends and a pile of books that help me build things.
The best thing to do is get the engine breathing. The stock carb that comes with these engines is a restriction. Get a motorcycle carb. I like Dellorto they flow better than most and are straight forward on tuning. Good priced ones can be found on eBay if you search.
If you have a welder you can make an intake tube to the proper length. I built one out of steel for a 420cc some years back. It was made from scrap and works great.
Build a proper size and length exhaust pipe. 18 gauge 180* degree steel U bends can be found on eBay. If you don't know how to build pipes and your motivated a good book that will walk you through the steps is A Grahm Bell Four Stroke Performance Tuning. It might take a couple hours of reading and understanding, but it is possible and worth the effort.
Find a big air filter. The bigger it is the less the restriction. Here is a pic of the 420 I built.
Round off the 90* edge on the exhaust valve. It can be spun in a drill press and sanded off, or spun in a hand drill.
This lets the spent gasses pass by and out the exhaust better.
You could put a smog check valve on like I did to the 390. This always makes a noticeable difference.
When you start making hp you will put more strain on the internals like the connecting rod. These connecting rods look pretty fragile to me.
There might be enough left in the budget to get a billet rod.
The next level would go outside the budget. Take off the governor and get a billet flywheel.
When I build an engine I never set a budget aside. I more or less buy one part at a time as the money comes in. Kind of a step process.
The best thing to do is get the engine breathing. The stock carb that comes with these engines is a restriction. Get a motorcycle carb. I like Dellorto they flow better than most and are straight forward on tuning. Good priced ones can be found on eBay if you search.
If you have a welder you can make an intake tube to the proper length. I built one out of steel for a 420cc some years back. It was made from scrap and works great.
Build a proper size and length exhaust pipe. 18 gauge 180* degree steel U bends can be found on eBay. If you don't know how to build pipes and your motivated a good book that will walk you through the steps is A Grahm Bell Four Stroke Performance Tuning. It might take a couple hours of reading and understanding, but it is possible and worth the effort.
Find a big air filter. The bigger it is the less the restriction. Here is a pic of the 420 I built.
Round off the 90* edge on the exhaust valve. It can be spun in a drill press and sanded off, or spun in a hand drill.
This lets the spent gasses pass by and out the exhaust better.
You could put a smog check valve on like I did to the 390. This always makes a noticeable difference.
When you start making hp you will put more strain on the internals like the connecting rod. These connecting rods look pretty fragile to me.
There might be enough left in the budget to get a billet rod.
The next level would go outside the budget. Take off the governor and get a billet flywheel.
When I build an engine I never set a budget aside. I more or less buy one part at a time as the money comes in. Kind of a step process.
please don't take this wrong, why did you miss the angle using a sine plate? Couldn't you draw the chamber and pick up center of the sparkplug hole and use that as x/y zero? Just curiosity, I love this build.