Or some of us who hang out in the high performance area reads the stuff here as we compete with Hondamatics.
Improving midrange torque is what you're seeking. Unless you really know the formulas, cam theories, and your exact motor specs including cylinder head airflow, you won't be able to make a noticeable improvement with a custom grind over an off the shelf cam. Web Cam doesn't have a Hondamatic knowledgeable salesperson to guide you to the "right" cam profile. I've talked with Web Cam in the past and had them make a "custom" Hondamatic cam based on the profile number that I requested. They gave me about 4 different part number profiles for me to chose from. Did my "custom" web cam grind make a lot more power than the commercial standard 295 grind? It made a little more top end, but the ET differences were minor. (It was worse) Could I have found a little more with cam timing changes? Possibly, but it wasn't worth my time. Use an adjustable cam sprocket, advance the cam to bring the powerband down. Only with a chassis dyno or passes on a dragstrip will you be able to tell the difference. Your butt won't know the difference.
Torque increases make the bike quicker in the midrange of rpms which is where it will spend most of it's time. The two speed transmission limits the rate of acceleration. If you gear it for say 40 mph at 10,000 rpm in low gear, the 295 cam advanced about 5 degrees will be quicker than any other cam I know of. The bike will be very, very buzzy running around on the street. No, it will not be keeping up with most clutch modern 4 cylinder bikes you find. (If they know how to drive them)
Two things that will make a noticeable improvement in acceleration: More compression and or more stroke. Neither comes cheap. Both have practical limits. The only other thing that can help you travel quicker is to reduce the overall weight. Stock wheels are very heavy by today's standards. Less wheel mass will give you quicker acceleration.
Getting the fuel/air ratio correct across the powerband is a challenge with the carbs that you'll use. Some dyno time can really help smooth it out. If you put in a bigger main jet for the cc increase and power improvement, you may have a good top end. The idle circuit will be very rich. Yes, it can be corrected, but do you know just what the idle circuit needs for correcting the issue? Needles need to be in the correct slot for the midrange to be right. To get it exactly right, you may need modified or different needles.
With a budget build like you're proposing, you won't know a 2 ft/lb torque improvement at 5 grand without a dyno or ET slip. I helped a member with an 836cc, 10.5 to 1 compression, well ported head with good valves and valve springs, and a 4 to 1 open exhaust. Dyna ignition. It started out with a -75 cam which is what the clutch bikes like. They used the adjustable cam sprocket to advance the cam when it was installed. Then they opened up the valve lash to make it act more like a smaller cam. We put the 295 cam in as the replacement, advanced it 5 degrees, and ran it down the track with stock valve lash for that grind. The 295 cam was over a half second quicker in the quarter mile vs the -75 one. That's on a 12 second Hondamatic. It was refined to 12.3's best in that combination. It runs high 7's in the 1/8th mile. Your bike may run middle 8's in the 1/8th mile if you get everything right. That's low 13's in the quarter mile.
There's several videos of that bike mentioned above on you tube. The oldest video was it's first time out where it ran 13.2's. You can see and hear how sluggish it was in the lower rpms. (-75 cam). We got it into the high 12's with refinements. It ran 12.3's with the 295 cam swapped in. (no other changes) The mph fell off from about 116 to 112, yet the bike got a lot quicker. That's midrange improvement at the expense of some top end power.
If you want stoplight to stoplight automatic acceleration, you don't want a 4 cylinder Hondamatic. Find a Suzukimatic twin, put in bigger pistons, tune it right, and you'll beat a 4 cylinder Hondamatic to 40 mph every time. You're starting with a much lighter bike with a longer stroke. It could run middle 8's all day long in the 1/8th mile at around 81-82 mph. The Hondamatic may catch it at the end of the 1/8th mile, but the Suzukimatic will be ahead for most of the track.
Having raced Hondamatics for over 25 years, I don't refer back to someone else's postings. The quote that kandrtech used was mine from last year. I've also raced Hondamatic twins and own a Suzukimatic twin.
Here's the Hondamatic 4 cylinder performance bible:
http://forums.sohc4.net/index.php?topic=61876.0 Most people on here know Sam Green and his bike.
The most viewed topic on the high performance forum.(over 149k views) Lots of junk in there, but some very good information found within. I recommend reading it in small chunks to prevent unintended sleep.
Good luck with your build. Come over to the high performance forum if you want other opinions.
