tiny twin motors

I’d like to say in advance that I know it’s more efficient use a bigger motor rather than insist on twins. and believe me, I am looking as hard as I can, but I can’t find any suitable sized motor. The used motors I see are either too worn out, or too expensive. Buying new is out of the question for now. It just so happened that in my search for a suitable motor, I ended up with two 2hp’s. the deals were too good to pass up, so even if they were small, I bought them.
I have tried locking one motor and using the other one for steering, this configuration is not so easy, and could even be dangerous. So I want to copy this guy’s style:
[youtube]https://www.youtube.com/watch?v=US3LLyl9NYA&feature=related[/youtube]

on a single 2hp, my boat goes 5 miles per hour at half throttle and about 6mph at wot. i'm not after a bone jarring ride, i just want a tiny bit of improvement. i'd be a happy angler if my boat was as nimble as the inflatable in the video. Steering looks simple enough with linkages, I just need help with the throttles. The video shows a pair of the same motor (yammy 2ch), mine are different models/brands. One is Yamaha 2ch, the other one is Suzuki dt2. I’d like to run them in twin configuration and I need ideas on how to synchronize the throttles. Do I need tachometers for this?
I think the different propeller size and pitch will complicate things further. Any advice/comments will be highly appreciated. i'm not the sharpest knife in the drawer so illustrations/photos will help a lot.

Nice job on the boat you built!!
You won't need a tachometer, you can match RPMs by ear. I have done the same thing you are doing. Did it just for the heck of it as I had lots of Johnson and Evinrude two-cylinder 3hp engines around. I put one on a 14' aluminum Lowe and it ran 7.1mph. Placed a second engine on and it went to 7.6mph and then placed a third on the transom. All three engines only pushed the boat to 7.9mph. Wasn't worth the effort by any means but was a blast to try and keep them all straight, watch the GPS, and keep all the throttles at WOT. Enjoy what you have as a single engine or trade one or both off for around a 6hp on that boat. You wil never look back!

Pappy,
thanks for that. i'd gladly give up my tiny motors in exchange for a decent sized motor, but i'm having trouble finding one. i've been on the lookout for a deal on a used motor in good condition for 3 years now, so far these 2 small ones are the best i could find. the used motors i see are either too old and worn out(cheap but trouble) or too new (almost as expesnive as new). i'd hate to blow a big amount on a new motor fresh from the dealers, but it looks like it's the only way i can get what i want.

Keep your eyes out for around a 1978 or 1979 Johnson or Evinrude 6hp. Those were bulletproof engines. Anything in that horsepower up to around 1982 will do well.