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Old 08 September 2014, 14:24   #101
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Looks like i didn't gain any RPM with the exhaust mod. Sounds better and acceleration is considerably better but the top speed remained the same.
I had a fiddle with the timing while I was out today but advancing or retarding it from standard both seemed to make it slower. What I can say is that putting the ignition closer to 24* made the acceleration even better, and that the other way made it worse. Makes me wonder why it didn't help the top end though..
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Old 16 September 2014, 06:43   #102
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Couple pics of my new engine:



Just bought it yesterday and not yet arrived at the house. Unfortunately I'm off to uni for 3 months so won't be able to try it out for a while!
It's a Yamaha 70 which has been shortened and with a CES 'box on it. Just been rebuilt by a marine engineer, should be good to go. Came with an 11x21g yamaha cleaver. Need to get a tiller for it, going to try and adapt one of our old hydraulic steering systems to go on as a damper. Will be staying electric start for now until I can source parts to convert to pull start.
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Old 16 September 2014, 06:45   #103
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Nice! What would you be doing with the tohatsu??
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Old 16 September 2014, 11:35   #104
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Originally Posted by lukewhiting View Post
Nice! What would you be doing with the tohatsu??
Think I might have to be selling it unfortunately! Yamaha still needs a lot of parts to make it work on a thundercat.
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Old 22 September 2014, 11:00   #105
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engine arrived today:






prop is absolutely mint as well


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Old 24 December 2014, 14:13   #106
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Got the wingplates off, had to remove the powerhead to get the bolts out...
Tiller is on, although the cables aren't connected.
The throttle cable on the engine is pull to open, whereas the tiller is push to open. Think I read somewhere about reversing a gear inside the tiller to fix this? Anyone know? I also appear to be missing a bracket of some sort to hold the cables in place, going to google it and see what I can find.
Looking at the engine more closely it looks like it is a genuine CES, or 90% CES parts, Here's a couple photos of what I mean about the cables.



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Old 05 May 2015, 05:30   #107
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Got myself a set of 90 carbs, bought the reed chest plate as well just in case the throttle linkage doesn't work. The roller for the throttle cam is on the bottom carb of the 70 and the middle on the 90. Photo of them on the 90:

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Old 07 May 2015, 07:48   #108
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Saw you are running NGK plugs. They are good but I don't think they have as far of a reach into the combustion chamber as some of the others. Also, not sure what yours requires but you might try the ones without the Interference Suppression Resistor to open your gaps.
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Old 07 May 2015, 07:56   #109
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I would want to check how's he space there is at tdc before sticking longer reach plugs in. Lad I know did it on a Jetski and blew his engine in minutes
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Old 07 May 2015, 08:02   #110
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I would want to check how's he space there is at tdc before sticking longer reach plugs in. Lad I know did it on a Jetski and blew his engine in minutes
Everytime I've compared NGK plugs to other plugs that are made OEM (stock) for the engine, they have been shorter. I'm not saying to look for longer plugs but that NGK tends to always run shorter than others even when built to specs.

If your friend ran longer plugs without measuring, then he is a fool.
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