Thai-fly

I am running a standard OS 3.5 OB and a Top Speed 2 hull. I have seen this combination absolutely flying at varios events. What modifications can be made to the engine to really get it to move? I am using an Octura x440 prop and 40% Nitro mix.
Thanks

10x8

I am no expert in regards to the OS .21 outboard. You could simply pipe it and go to 60% nitro. That may see a few more km/h. The fastest .21 tunnel I have ever seen was an OS that did 70mph, on You tube, germans I think. People send them back to the OEM factory to exchange piston, sleeve or do it themselves. Try rumrunner or intlwaters for more detailed info if no one else chimes in.

Good luck
Peter

GRANT ED

Adding a pipe to a standard OS OB is not very benifical as the exhaust port timing is too low to make full use of the pipe. 60% nitro is very high. Some engines can become very finiky at that nitro %. I'd suggest you try 50% first and see how you go. Maybe try a few other props. I found my TS to be a few MPH faster with a cupped and BC 1440 prop over the 440.

terry kelly

i run a woodstuff tunnel now , but when i used my os on my ts2 i was using a x637 and the engine propshaft about 3/16 in above the bottom of the sponsons, and about flat, this combo on 70 percent and the water restricted to help it warm up quicker and a 3rd channel needle i was gettin about 51 mph outta that deal, and that is stock exhaust and head shim removed and timing bumped to 188 degrees, later

terry

ozbryan

I got mine from James Clegg with his full mod set up on it, I ran it on 65% and found it was very easy to tune.

I also found the best prop for it was a 40x53 and i was running it on a TS2.

Thai-fly

Thanks to all of you for your contribution. I have learnt a lot and I am sure every bit of advice will help to get the most out of my engine/hull combo.
As a matter of interest how do you alter the timing?