Thanks: 
Likes: Hoping this motor will push my tunnel hull past the 100kph mark, 65mph is my goal.was already doing 60.5 mph with the standard powerhead, lightened flywheel and a milled head.
Hoping this motor will push my tunnel hull past the 100kph mark, 65mph is my goal.was already doing 60.5 mph with the standard powerhead, lightened flywheel and a milled head.
Last edited by ice_spy; 3 Weeks Ago at 09:03 PM. Reason: Wrong pic posted
The race never stopshydrospeed77 liked this post
Any feedback ? Does anyone see anything potentially wrong ? What sort of HP increase can anyone predict a ruff increase amount ? Im estimating approx a 6HP increase, possibly more when the +1 pistons go in with some mild & clean up porting. Are people feeling sceptical this will even work ?
Any comments or negative criticism welcome.
The race never stops
The reed blocks and reeds are much larger than the m40c reeds. This should improve the flow capability. Ive unfortunately lost one of the reeds shown in the pic, I had a friend make up these boyeson fiber material reeds , but unfortunately he no longer has the material. I may have to go a whole new set of carbon reeds now.
The race never stops
When I opened up the reed block on my Tohatsu 50 I saw no difference whatsoever. But when I put reed block stuffers in my Yamaha 70 the throttle response was noticeable better. I think it's more about how smooth the flow is rather than the quantity of air going through
Thanks Rolfhat, I too have noticed the increased throttle response with stuffers, at a small sacrifice of top end. Hopefully they will flutter ok, considering the bore and stroke is less. Airspeed is everything though, and the stuffers close the voids and reduce the volume to increase the airspeed. This is where top end they suffer due to not having the intake volume. Im going to play around with velocity stacks, or bell mouth intakes to smooth out the airflow. At the end of the day, its all about how much air you can pump through the engine and get it out the otherside. More flow = more power.
The race never stops
Used a spare head that had been milled for compression to see if its going to run or not.
To my surprise, she starts straight up. Needs timing connected yet, but at least now I know she is a goer !
ITS ALIVE !!!
https://youtube.com/shorts/xQz9F-7BS...SVH3-y4l96HnNu
The race never stops
Bolted on the powerhead , used the modified cut out bedpan to clear the bottom carby, fresh gasket and started it in some water. No need for chokes, she fires up straight away. Plugs are sooted wet, so I'd say she is running very rich at the moment. Just got to sort this timing / throttle lingage out now and she'll be just about ready to test on the water.
https://youtube.com/shorts/pddn1qGMd...RITBmoqcm_SZ3W
The race never stops
Set the timing , still got to make a throttle lingage but its sounding much better.
https://youtube.com/shorts/VadGxjIq2...KJt_SYf9CR_Icd
The race never stops
Fabricated the adjustable throttle lingage, and had to finely tune the cam postion. Seems to be alot smoother now, with no sticking points.
https://youtu.be/5rPb5MtWJ-o?si=oG1L8feIs0smaEqc
The race never stops
Boat has been in storage for the last 2 years, so now im re wiring the entire main loom up to the dash.
Thought I was going to water test it today until I couldn't get power to the starter from the push start button. Its looking a bit like a dog's breakfast at the moment, but will be all neat and simplified when done.
Hoping to get out on the water tommorow if all goes to plan. Can't wait, im feeling like its going to exceed 7k rpm.
The race never stops
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