Boatmad.com


Reply
 
Thread Tools Display Modes
 
Old 18-04-2017, 10:20 PM   #81
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
Got out for a blast last night, weather was really nice, not warm though!
Engine is up at 70mm and revving a bit higher but roughly the same speed, 57.5 knots with myself and my girlfriend in it.
Went into a cave with it -


At the beach
__________________

roflhat is offline   Reply With Quote
Old 04-05-2017, 07:06 PM   #82
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
Was down at Easdale over the weekend at the Rib Rendezvous, had a really great time. Had an issue with the pull start before the event started, managed to get it fixed just in time on Saturday morning and caught up with the rest of the RIBs, over 30 the first day!
Covered over 90 nautical miles on the first day, plenty of chop so gave the boat a good run. Also some nice calm sections to go flat out, used around 80 lt of fuel - thirsty!






The thundercat was a very wet ride but a lot of fun!
__________________

roflhat is offline   Reply With Quote
Old 14-05-2017, 08:18 PM   #83
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
Boat and engine have been going really well lately, spent a lot of time cruising around here. Spent today fitting the primer kit in place of the chokes, haven't tried it yet but hopefully it should work well.


Should allow improved airflow as well, gives the air a clean channel down the carb throats


I also designed a new roller for the pull start, the old one was a bit worn!
roflhat is offline   Reply With Quote
Old 11-07-2017, 06:24 PM   #84
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
So unfortunately looks like my photos can't be seen any more, photobucket wants $399 a year to host them... If I have time at some point I'll try upload them to a new site and edit all the posts

Recently changed the head on the Yamaha, removed the TSR one and found it was letting in water


so I've stuck the original head back on, performance seems about the same but waiting on some flat weather to get top speed figures. The old head isn't in great condition, if anyone has a spare 70ces head kicking about please give me a shout!


Also found that there was some flex in the transom, more than I'd like so I had another jack plate waterjet cut, 12.7mm thick so I could countersink bolts and have the plate flat against the transom which should reduce the flex. Also had some pull handles cut using the spare ali, these ones are a wee bit too big to fit through the cowling unfortunately so I'm having another made.


Tried the original 70hp carbs on, the engine just won't run properly with them, feels like it's running on 2 cylinders. I've rebuilt the carbs with new gaskets, cleaned the jets with carb cleaner and the airline and the jets are immaculate, so not sure what it could be. Also very hard to start with them, put the 90hp carbs back on and it starts easier and runs fine
roflhat is offline   Reply With Quote
Old 19-07-2017, 06:15 PM   #85
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
Had some excellent weather last week, got out for a spin and got some footage with the drone

https://www.facebook.com/seumas.macl...72511886123442
roflhat is offline   Reply With Quote
Old 19-10-2017, 06:09 PM   #86
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
Not got out in the boat so much lately, getting into winter now.
Had the original cylinder head reconditioned, looks really good. Interestingly the genuine Yamaha head gasket is around 1.4mm, the aftermarket one is 1.2mm so might increase the compression slightly.

Trying to get the engine to work with the standard carbs too, it just isn't happy with them, won't idle and it feels like it's dropping onto 2 cylinders. I've now had them put in an ultrasonic bath so I'll try them again. Designed another version of the throttle roller as it still wasn't getting WOT with the standard carbs. Unfortunately the roller broke when I twisted the throttle, so having another made in a harder material.

Looking at having the flywheel lightened too, not by much. The homologation sheet for the 70ces says 3800 grams so I'll take it to that, it will obviously be heavier due to the pull start attachment on the top. I'll have it balanced too, I suspect it's fairly well balanced from factory but won't hurt to have a finer tolerance



roflhat is offline   Reply With Quote
Old 20-10-2017, 07:37 AM   #87
Registered User
 
bigboy's Avatar
 
Location: Belgium
Interests: Boating
Boat make: Hydrostream HST
Engines: Merc 2.5 200
Cruising area: The Schelde

Join Date: Dec 2005
Location: Belgium
Posts: 434
Cool project!
__________________
www.geocities.com/fletcher_arrowbeau
bigboy is offline   Reply With Quote
Old 22-10-2017, 05:19 PM   #88
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
Got the engine running yesterday and out for a run. Starts a lot easier now and runs smooth with the standard carbs and head which it hasn't done before. Throttle isn't opening fully yet - waiting for the new throttle roller to arrive.
New trailer arrived last night


Photo of some of my props


Did around 26nm yesterday, was nice weather but the throttle grip is still far too slippery so I removed the rubber section and designed a new one

hoping to have it 3D printed in ninjaflex which is pretty rubbery and flexible
roflhat is offline   Reply With Quote
Old 04-11-2017, 10:39 PM   #89
Thundercat guy
 
roflhat's Avatar
 
Country: Scotland
Location: Isle of Lewis
Occupation: student
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 348
3D print turned out really well, the grip feels really good. Very flexible too, just like the original rubber part but far grippier.



Got another throttle roller, made of resin so should be a lot stronger. The surface finish is completely smooth too, very nice piece


Bought this prop, was last used on an offshore racer with a Yamaha 60DES in the 80's. Looks sort of like a Hoss cut chopper, says 11x20 on it but measures closer to 10.5" diameter. Should go well on the Yamaha, possibly even better on the Tohatsu which seems to prefer overhub props
__________________

roflhat is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT +1. The time now is 01:11 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.