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Old 10 September 2015, 14:27   #151
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Country: UK - Scotland
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Was out again tonight, had the same 15p worked Solas on. Span it to 6600 1up at 48.9 knots, had a lot more in it but couldn't hold it flat out as it started to porpoise. 2up managed 7380rpm at 54.7 knots, the fastest I've gone so far and with an all round propeller. The bigger props should go a lot harder.
I think the plan over the winter when I come home is to rebuild the powerhead with all new gaskets and seals and get the crank welded.
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Old 11 September 2015, 06:10   #152
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Couple of photos:

A few props have been added to the collection:

got the steering damper setup today, it's just an old rusty Mercedes one
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Old 11 November 2015, 04:47   #153
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Couple of updates, even though I'm away been gathering some nice parts for the boat.
A pair of new props:
11.75x23p OMC Overhub cleaver


12x23p OMC Overhub cleaver


TSR billet cylinder head, the first one made for a Yamaha 70 so I'll be the guinea pig

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Old 11 November 2015, 20:32   #154
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Great thread, thanks.

Cheers
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Old 12 November 2015, 01:07   #155
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Hi

What benifits are you are you expecting from the head,any plans on a blited
Crank or is there no point.
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Old 12 November 2015, 03:27   #156
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Quote:
Originally Posted by Squid Boat View Post
Great thread, thanks.

Cheers
Glad you enjoyed it!

Quote:
Originally Posted by dave3235 View Post
Hi

What benifits are you are you expecting from the head,any plans on a blited
Crank or is there no point.
The new head has a positive squish band, the CES head had negative squish (not too sure why), so the combustion chamber shape is greatly improved. The same design has been used on tohatsu 50's with good results, over 1000rpm gain on some engines. I'm not much of an expert on cylinder heads but I've spoken to a few guys who are and they reckon this is the way to go.
A lot of guys machine the standard head to give it positive squish, but a re-designed head is even better. Another benefit is that it doesn't use gaskets, but O-rings instead.

Not sure about the crank, once it's welded it's strong enough for all the RPM this motor will see. I was thinking about designing a custom flywheel, but making it too light gives jittery idle. The top speed isn't usually affected, just acceleration.
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Old 12 November 2015, 05:52   #157
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That head looks too pretty to use on an engine. It looks like a very fine bit of workmanship. What sort of money does it cost to get such a head made up. Not needing one just nosey

TSM
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Old 12 November 2015, 05:59   #158
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That head looks too pretty to use on an engine. It looks like a very fine bit of workmanship. What sort of money does it cost to get such a head made up. Not needing one just nosey

TSM
I was thinking the same, shame to put the cowling on now! My mate got one for the tohatsu 50 (the one in this thread) too, so lots of testing needs to be done.
It was $535 Ausd before shipping, around 250. The tohatsu ones are a wee bit more expensive, $720 each because they come with a billet thermostat cover too. Shipping for both the heads was $205.
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Old 17 December 2015, 06:54   #159
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Got home a couple days ago, stripped the engine down. Looks like one of the centre main bearings on the crank has had it, which is apparently quite a common problem on the Yam 70. So I've now bought another 2 complete powerheads, hopefully one has a decent crank in it. Was also given a 60hp head, unfortunately turned out to be a merc or mariner, non-removable cylinder head. Was looking into having the bearing replaced, maybe have the crank dynamically balanced while it's being done, but its pricey.
Put the back half of the powerhead together, TSR head is on, all new gaskets and seals going on. Just doing welded crank and TSR head for now. You can get pre-ported liners for 145 each, maybe build up one of the other power heads with mod parts

You can see the difference in head shape here, this is the original CES head
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Old 17 December 2015, 07:03   #160
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This is a side project I'm working on for Uni, modifying a surface piercing propeller. I sent the propeller to a company who scanned it and created a point cloud. It's based on an 11x18p Mercury Cleaver. Got the IGES file back a few days ago, here's a couple screenshots from Rhino




I've bought a 13 spline RUBEX hub which I'm going to use as a reference to model around, I'll start modifying the design hopefully towards the end of January
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