Tohatsu 120A2 upgrade to 140hp

[CohoCoho]

I read an old post about changing the timing and max throttle position to get an extra 20hp out of my motor. Are there any side-effects and is it really worth it? Went through the parts lists for both and it looks like the upper carburetor assembly was the only part different between the two.

Thanks!

 

[pvanv]

Works fine. The throttle is limited on the old 120s. That's how they detuned the 140 to a 120. You bypass that and adjust timing accordingly.

 

[CohoCoho]

Thanks, I went ahead and did it, hacked off the limiting tab. Having a little trouble getting it adjusted to go to full throttle and pull the whole way back on the timing at idle, maybe some wear in a bushing somewhere? It started with muffs, will put it in the water tonight.

 

[CohoCoho]

Thanks so much, Paul, I'm thinking I'm right about there. I'm still having a bit of trouble getting the carbs fully open, thinking the plastic roller on the top carb that rides on the advancer may be a bit larger in diameter on the 140. I had to completely remove the high speed stop to get it to nearly fully open. Still, a very noticeable increase in performance!