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Sweet, what midsection & gearcase is that?
Whats up wit the cilinder head and water routing?

Thanks, i hope it will.
Has some mild porting, shaved heads...
Thought about it, but i will loose ease of starting and i think i wont gain much...
It are tygon hoses, used with the merc engines...

Finally had some time, next summer we will be back on the water...

http://i166.photobucket.com/albums/u82/OS-tunnel/Mobile%20Uploads/image_zpsdecae981.jpg

Did planned to make fingerports but running out of time. That will be for next winter... This year testing with new mods.
I cut the squish band same as original, this is not so good? Can you explain...

Yes, from factory they already cut a little piece (cleft) out of #3 .
I am thinking to grind it completly level.
But not sure of effects on performance, did you try it or have an opinion about it?...

In the exhaust chest from the bottom cilinder, you have on top a longer quidance then the above cilinders.
Anyone that know\tested the effects if you grind it away? The omc 's did not have those i...

Did you already sold some over hub props, and did the owners tell you how it went?
Slip on hub, means hub you can easly change?

Hi Ron,

To bad we are several 1000miles apart :-) .
Visited you last year, and i will keep you to your promis to try the mexican food ;-) .
At least, did my boss contacted you about those...

I quess more slip on take off but what on high speed?
Will it give also a higher % of slip or no effect at all?

Hi all,

I run an f4 tunnel with yamaha 70ces,
Prop is a merc thru hub cleaver.
What would be the effect if i run an over hub propellor?

That would be nice Ron.
How are you? Visited you last year in september...

Never heard of a texas cut, can someone explain and what the advantages are and maybe the downside?
I run alsk the lerc cleaver on my tunnel.

Verado runs a supercharger, optimax runs aircompressor for the dfi system.

Do you have smartcraft that gives you the fault or the cds system?
Throttle flap doesnt do much, you can open it...

Polishing ports aint gonna do much...
Its the height, shape and angles that make the diffrence.
Calculate your compression ratio, adjust until you reached your desired values. 8.1/1 is good on...

slowly building further on the engine.
Made a portmap, squish, cc of each cilinder. Determind the height of the ports, compression ratio and now im starting to shave the cilinderhead.
It is a...

Got the flywheel back today, shaved 1.2kg of the total wheight.
If you want, it can be more... tomorrow i will balance it.
Also mounted the 90hp carbs on the intake and matched them together....

To me it Looks like the rivets holds the starter gear in place...
If you have experience with these motors feel free to post...

Im planning to drill the rivets out, machine the starter gear...

Or if someone can offer me a link to an exploded view of the flywheel...

I want to get the flywheel lightend, and have a few questions about it.
It has 3 rivets in it, when i drill these out will it seperate the ring/gear from the flywheel?
Also my engine has the 6j2...

but acceleration will be better, enhough i hope...
Boat is light, didn't wheight it but can lift the back alone.
Also have to watch my step while boarding or my foot makes a hole in the deck.
It...

Still bad weather over here but drove the cat 2 times last month.
First time was good, acceleration ok. Top speed fast!
After that run checked the plugs and the where on the lean side, to lean for...

With sort of oil.
Piston in tdc, fluid thru sparkplug hole and measure how much goes into it...

thats clear...
Now waiting for better/hotter weather. First test with the 70carbs and cleaver.
The i will try the 90hp carbs.

Thanks for the info, looks neat on the pics.

I have the round style, as i remember.
What do you do with the electric choke, does it fit the 90 carbs?
And the rods connecting the throttle levers of the carbs, do they fit?
The boat and engine...

Have already done all the things in the list, only not checked the tuner...
But i took a sneak peak in the cilinders before i bought it, togheter wit the compression test. An i could see the marks...

so i better check each time the core plugs, is there a way to secure them better?
Only drived the boat once with to small prop, i think i had then about 15psi water pressure...
Is the crank that...

it's ok, more to read...
I dont' want to start tuning the engine, just determine of the engine has mods or not...
And keep the engine safe, it's not for racing. just pleasure...
I'dont know the...

Hey Carl,

thanks for the info.
Have a picture of the boat when i just bought it, original stickers. looks old:)
2 piece head, by that you mean a removable cilinder head?
That is what i have......

Just bought an old f4 cat with looks like an almost new 70ces behind it...
Compression on all 3 cilinders are between 175 and 165 psi,
gearcase is mod with nosecone and low water pickup.
Has...