The gearing is wrong for your application. You want the combination to be around 10,000 rpm in high gear at 100 mph. You can use a gearing calculator for your wheel diameters to help get the right sprocket combination. The 530 sprockets are plenty strong enough with a 530 racing chain for your application. 630 chain and sprockets just add unnecessary rotating weight.
How stock is this motor? If the carbs are stock, that's part of the problem. Removing the air cleaner puts more air into the carbs. They need to be jetted richer to run right. Unfortunately that introduces other problems with the idle circuit getting richer than you want. The easiest way to fix the carbs is to remove them and replace with CV carbs taken off of older 700/750 Seca's. An increase of a couple of main jet sizes on the replacement carbs will be a good starting point. They bolt up to a Hondamatic motor using stock K (clutch) intake manifolds.
The motor wants to be launched off of the rear brakes. You apply the rear brakes, add throttle, and release the rear brakes when the third yellow bulb on the Christmas tree comes on. That will give you the most consistent runs. You get on the gas only when the top yellow bulb (of the 3) comes on. Being on the gas for longer than that increases the risk to overheat your motor's oil. Overheated oil gets a thinner viscosity that never goes back to where you started. The only thing to do to fix the thin oil problem is to change the oil. You want a mineral based oil. Synthetics are too slippery which slows power transfer through the torque converter. An external oil cooler will also help the repeatability of the combination.
Your combination is about 150 pounds heavier than the Hondamatic bikes that we race. That will put an added stress to the clutch packs in the motor. They will start slipping over time with the abuse of racing. If you want to go fast/quick with a Hondamatic motor, you must spend some money. It can be done in steps over time, but it will not end up being a cheap race vehicle. Your goals need to be aligned with your budget.
The motor has small carbs, low factory compression ratio, and a very mild cam. Stock regeared Hondamatics run 13's in the quarter mile. Add about 150 lbs to the mix and you'll be around low 15's in your vehicle with a little investment. Sam's modified Hondamatic runs about a 12 flat in the quarter. His combination in your vehicle would be low/middle 13's. Is this quick enough for your goals? These are estimates that could be a little off.
You need torque to get the vehicle moving. Torque comes from compression, mild racing cams advanced for midrange improvements, good air flow through the cylinder head, and more stroke than stock if you can afford it. Tuning the intake and exhaust systems will also help improve the power in the lower rpm range.
There have been several topics that have covered some of the above suggestions. If you still want to try this, let us know your current status of the equipment and the budget to improve it. If it sounds like too much $$ and too much work, sell the motor and try some other clutch 4 cylinder motorcycle motor in it's place.
It can be a very consistent bracket race vehicle with proper modifications. Keep us posted
