My Thundercat - Page 7

roflhat · 21-12-2018, 05:12 PM

Put the new steering damper on today, old unit weighed 3.44kg all in, new one is exactly 0.5kg. Pretty decent saving and on the maximum stiffness it feels on par with the old one.

roflhat · 10-01-2019, 01:12 PM

A couple more wee things done, got the lower cowl and gearbox painted.
I sanded the skeg down some more along with a couple other tweaks.

Also designed a new cap for the end of the tiller, the trim switch always annoyed me. Probably saved around 20 grams too!

roflhat · 14-02-2019, 09:37 PM

Been doing bits and pieces to the boat, tried some flexi paint on the fuel tank which seems to be working alright. Not sure how long it will last though

Got an update today on the new boat, looking good, very pleased with the black valves instead of grey

Engine is nearly ready too, I'm away march until june so doubt I'll get a chance to test it, will be exciting times when I get back

roflhat · 25-03-2019, 09:21 PM

Boat is now finished, should be arriving in the UK this week

roflhat · 15-04-2019, 06:16 PM

New boat has arrived, fortunately the engine isn't done yet or else I'd be itching to get testing. Bought an old motorbike windscreen on ebay today, £13, the idea is to mount it on the tiller in front of the cowling to improve aerodynamics.

berat · 18-05-2019, 12:08 PM

Great work, inspiring

roflhat · 27-06-2019, 08:11 PM

Will be working away until the end of next month in France, still waiting on the powerhead so testing will have to wait

roflhat · 31-07-2019, 09:23 AM

Back to it at last, got the engine put back together on Friday and started testing. Had a few teething issues but the power is absolutely unreal. A lot better than it ever has been before, and still lots of testing and setup to do. Was having fuel issues, now onto ignition problems. Was all set for the race in Harris on Saturday when it started running on 2 cylinders, no fire on number 1. Tracked it back to what I believe is a faulty pick up beneath the flywheel.

If anyone has some spare pick ups (those black things beneath the flywheel) for a 60/70 Yam please let me know

Got some fancy new parts to try, and typical now that the weather is good enough to test high speed props I get engine problems.

Some helping hands working on the boat

roflhat · 15-08-2019, 08:15 AM

Got some testing done, 61.58 knots with the prop I set the record with. Engine wasn't revving enough so tried leaning it out with smaller jets but lost 4 knots. So now put bigger jets in all 3 carbs and will see what happens.

Still got problems with the ignition, tried new plugs and switching coils but no luck. Tested the resistance of the stator plate wires and they're all within spec so I've borrowed a CDI to see if that is the problem.

jw. · 24-08-2019, 12:25 PM

Quote:

Originally Posted by roflhat

Got some testing done, 61.58 knots with the prop I set the record with.

Man alive! You take care, wouldn't want you doing a Donald Campbell.

M.arco · 28-08-2019, 07:18 AM

Quote:

Originally Posted by roflhat

Been doing bits and pieces to the boat, tried some flexi paint on the fuel tank which seems to be working alright. Not sure how long it will last though

Got an update today on the new boat, looking good, very pleased with the black valves instead of grey

Engine is nearly ready too, I'm away march until june so doubt I'll get a chance to test it, will be exciting times when I get back

How is your experience with the flexi paint? Does it hold? No issues with fuel that will make the paint weak?

roflhat · 28-08-2019, 05:59 PM

Quote:

Originally Posted by jw.

Man alive! You take care, wouldn't want you doing a Donald Campbell.

I'm trying, always wear a helmet now. Have to be careful when opening her out, especially into the wind!

Quote:

Originally Posted by M.arco

How is your experience with the flexi paint? Does it hold? No issues with fuel that will make the paint weak?

It's not holding up too well, looking a bit scruffy already. Not too fussed, looking for a bigger flexi tank at the moment anyway, the 20L odd doesn't last very long any more!

roflhat · 12-09-2019, 12:45 PM

Didn't get anywhere near as much testing as I wanted to this summer, mostly engine problems. Got the whole engine apart now, I had a blown head gasket which was letting water into the cylinders. Cylinders are off for honing, the ports on number 1 and 2 are quite rough in the channels so will be cleaned up again. Ordered new pistons and rings, getting quite expensive this!

Managed to find the fuel additive I was after so I can test that, also going to try ATF in the gearbox.

Got some trials done with the new boat, feels really good, can't wait to try it with the engine going properly again. Old boat weighed in at 84.5kg, new one bang on 80.0kg. Engine was 84.0kg, I've since removed the jack plate and bolts so it's down to 82kg.
New boat is a foot shorter than the F10, no handles in front of the nose cone so it's a bit more aerodynamic too.

roflhat · 12-09-2019, 08:05 PM

Going to run a fair bit more oil from now on. Got the bores honed out today and I cleaned up the ports just now. Ordered 2 full sets of pistons and rings, will weight match them when they arrive.

It's not rust on the conrods, that's just the colour they are. Crank assembly is in pristine condition fortunately, bearings etc. and conrods all good

Also retested the trigger coils, the one feeding number 1 cylinder is absolutely dead, infinite resistance. Got a new (used) ignition plate and all 3 trigger coils are good so hopefully that's the 2 cylinder issue sorted.

roflhat · 16-10-2019, 09:06 AM

Photos don't seem to be displaying at the moment, hopefully they come back up

Got the engine back together, all new gaskets and running really well. Compression is up to 175psi across all 3 cylinders. Got some testing done on Saturday, hopefully more this weekend. My mate Andy White is very kindly making me a carbon fiber cowling. A lot of work involved but if it works should save around 3kg.

Also had the flywheel painted while the engine was apart, looks really smart. Did the pull start cover and a few other bits too

roflhat · 30-12-2019, 04:49 PM

Had the engine down on a dyno last month, Pete at Swordfish marine kindly sorted it out.
Didn't go to plan but still some useful progress, the oil pump block off was leaking, also had a pin hole in the cylinder head and a gas leak between the block halves, all now sorted. Performance started going down hill so took it apart, bottom piston had melted, most likely due to the oil pump plate leaking so not enough oil getting to it.

All back together now ready to test, changed to Castrol oil and different gear oil

roflhat · 13-02-2020, 05:47 PM

And here we are again,

Was hoping to get some decent testing done today, first calm day this year but had another breakdown. Only managed 2 hours running since the last rebuild.
Still a few things to test, best speed today was 62.51 knots which is the fastest I've had since Coniston. So things going in the right direction but some problems, thinking is the fuel is not upto the job. So going to try and get hold of Avgas 100LL.
Getting pretty tired of this now, can't afford to keep rebuilding it all the time. Don't usually lack motivation but struggling a bit at the moment.

roflhat · 13-02-2020, 06:23 PM

Had a thrust washer machined down, for the top speed runs I'll run this

roflhat · 29-03-2020, 11:13 AM

Right here we go, the last rebuild

Doesn't look like I'll be able to test for a while because the airport is shut and I need Avgas 100LL.

roflhat · 10-05-2020, 10:42 AM

Rebuild didn't last long, got the engine break in done then about 10 minutes of use before it went bang. On my last set of pistons now

My trophy shelf, most of them I'd rather weren't there...

Got some footage during engine break in
https://www.facebook.com/seumas.macl...91852507522692

Engine is now rebuilt again with the timing backed right off, pretty hopeful that was the problem. Also running the tell tale over my tiller hand so I can be a temperature gauge