Suzuki 10CI Power UP

**microbream** · 09-18-2011

Hi Guys,
Just had my first run in the worked Suzuki 10CI,here is what i did to her.
Compression was 110psi and squish band was 2.3mm. I shaved the head 1.0mm and block 0.2mm, now i have 180 psi and 1.1 squish band.
Ports were mismatched with cylinder sleeve and port time area peaked at 5500rpm. I mildly ported the exhaust port to correct mismatch and widened them by 1mm. Also removed all casting steps and parting lines along exhaust and intake flow path. Special attention was given to transfer port near main bearing to remove large sharp step. This resulted in port time area peak rpm increase to 6500rpm.
Reed valves were checked and i was impressed with the size and flow rate, they have 6 petals per cylinder and large area. May change petal from ss to fg or carbon later on.
Carburettor has been swapped from a butterfly Mikuni BV24 to a slide valve VM26. will start with a 100 main jet. And have made a velocity stack to suit.
Fuel pump has been rebuilt and timing advance is adjustable from 10 to 28 deg BTDC. I have also changed to plug heat range from 6 to 7.
I will run 95 octane fuel with 30:1 mix. Oh i have also enlarged the exhaust relief holes on the midsection. I don't no whether this gives any performance increase, but is sounds 'HOT'.
The prop is a repitched 8" x 10.5" bunny. With the stock engine she was running 25knots (30mph), i am aiming for 30knots (35mph)

And the result was awesome, started off with tame timing (15deg) and a light throttle, then i got stuck into her!
still running the stock carb WOT rpm increased from 5600 to 6100. And i hit the magic 30 knots. She now keeps on the plane at 3800 and top speed is just a throttle twist away. Whats better is i have pushed though the 'porpoise' zone and she rides flat and fast.

Next the bigger mikuni goes on and timing will be increased till around 20-25btdc.
I must admit when i did a comp test and it spat out 190 I was a bit scared of starting her, but she has come back from her first test with both pistons intact, and loverly dark tan dry plugs.

Cheers Microbream

ps. even scored a bass on a popper in early spring here in oz!

**microbream** · 10-27-2011

next mods will be vee pad hull mods, new carb and adjustable tilt.
ATM running the stock carb max rpm is 6100 @ 30mph.
Any ideas for an adjustable tilt system, atm i an stuck between two pins, higher pin = 6100rpm but bad poiposing untill i hit 6000. Lower pin she rides flat but only hits 5800?
somewhere between the two should be ok.
i don't have much weight to shift around or much more power left in the Suzu.
i dont want a power trim just something i can adjust

**Fastjeff57** · 10-28-2011

Nice work! Sure is gratifying to make all those changes and see a solid improvement.

On tilt adjustments, I'm working on my second electric cylinder tilt system, and the latest design could be the answer you seek. (The cylinder and ram will poke through the transom and push the tower back and up.)

Here's my suggestion: Make a "Y" shaped "hand" to push the tower away from the transom and make it adjustable. Weld the hand to an all threaded rod and run it through the transom with washers and nuts on both sides. You can then fine adjust it to any amount of tilt you need.

Jeff