My thundercat

[Landlockedpirate]

I feel for you, but welcome to the world of performance upgrades.

I have never messed about with an outboard, but I did build a Series 3 Landy. It started out with just a little tweek to the engine (Camshaft, Ported head, Free flow air filter etc) but with the extra power I needed bigger brakes. The power then munched the gear box, followed by snapped drive shafts, broken suspension etc.

I loved doing it, but relised I would never 'finish' the car, something would always need upgrading.

[Roflhat]

I know, fun and games eh!
I'm just putting a 2 liter engine into my car (67 vw beetle). Was meant to take 2 days, has taken over a week of breaking things to get it in...

Standard engine are so boring (=reliable) though... Half the fun is fiddling with them all the time, squeezing performance out of it. The other half of it is spending a fortune trying to get it running!

[dave3235]

Originally Posted by Roflhat

I know, fun and games eh!
I'm just putting a 2 liter engine into my car (67 vw beetle). Was meant to take 2 days, has taken over a week of breaking things to get it in...

Standard engine are so boring (=reliable) though... Half the fun is fiddling with them all the time, squeezing performance out of it. The other half of it is spending a fortune trying to get it running!

Hi


Shorly you can upgrade the gear box or is that it, or just where theres will theres a way

[Roflhat]

I was actually looking into this but I don't think it's do-able. As far as I know there are no gearboxes which will bolt on. The ratio on the 50 is 1.85, which is not too bad. The merc 55 has 1.64 and the yamaha 70 ces has 1.71, which both give better speed but don't bolt on.

Getting new gears cut to fit the 50 case is not financially viable unfortunately...

I was thinking (if the gearbox repair works) to extend the skeg - it's missing the bottom half already - to make it bigger than standard one for better turning but also to keep it in a straight line. I think one of the limiting factors to how fast I can go is actually being able to hold on to the engine at WOT. And hopefully a nose cone with LWP as well. Might need bigger props then though!

[dave3235]

Originally Posted by Roflhat

I was actually looking into this but I don't think it's do-able. As far as I know there are no gearboxes which will bolt on. The ratio on the 50 is 1.85, which is not too bad. The merc 55 has 1.64 and the yamaha 70 ces has 1.71, which both give better speed but don't bolt on.

Getting new gears cut to fit the 50 case is not financially viable unfortunately...

I was thinking (if the gearbox repair works) to extend the skeg - it's missing the bottom half already - to make it bigger than standard one for better turning but also to keep it in a straight line. I think one of the limiting factors to how fast I can go is actually being able to hold on to the engine at WOT. And hopefully a nose cone with LWP as well. Might need bigger props then though!

Hi

Do you think you may have hit an under water object, if thats the case just a bit of bad luck.

What about beefing up the gear box housing, or some form of tie rod from engine to gearbox.Also any avid tunners from Australia or America have they had similar probs worth looking into.

[spartacus]

Not so good. Just when you were finally squeezing a few more hp of it. Speak to Ian at Stornoway Spares on 01851 702504 or zenastewart@hotmail.co.uk

I picked up a new starter motor from him 3 years ago and the place was littered with Tohatsus in various stages of being dismantled, it was like a whale graveyard!

[dave3235]

Originally Posted by Roflhat

Started taking apart my engine today, got it completely stripped down today and got a few things done.

Started with basically a stock engine - boyesen reeds, exhaust mod, lighting coils removed and nukaru coils.

Plan is
Get the crank welded
Get the crank/flywheel balanced
remove flywheel ring gear
get the head shaved 1mm
polish pistons, head, ports etc.
yamaha 70 carbs
D1 exhaust tuner
BR8 HIX plugs - Think these are correct for a shaved head?
Mikuni triple fuel pump (reliability not performance)

Here's the coils:


Here's the yam 70 carbs next to the standard D2 carbs:

They're the square bowl type. Very tight fit on the tohatsu! Had to shave a bolt to get them to squish together enough. Think these are automatic choke? Not sure how I'm going to the get that to work...


Another small problem - the 50hp carb bolts are too short, so I've had to order 90mm long ones.


I was speaking to fast fred before I started so I knew this one -

You have to use the link from the tohatsu 50 on the 70 carbs. The 70 ones aren't adjustable whereas the 50 ones are.

Another small job -

You can see the step at the back of the carbs, to take advantage of the extra diameter of the 70 carbs you have to open up the reed block.

Hi roflhat.

Just wondering where you got your NAKARU COILS from,made phone call to one company is it correct that there is only two tips 1and 2 prong connectors.Also do they make for easier starting and fuel usage

[Roflhat]

Originally Posted by dave3235

Hi

Do you think you may have hit an under water object, if thats the case just a bit of bad luck.

What about beefing up the gear box housing, or some form of tie rod from engine to gearbox.Also any avid tunners from Australia or America have they had similar probs worth looking into.

dont think so, I was out in open (deep) water pretty much the whole time. I'll have to look into strengthening it, although it shouldn't really be a problem. As far as I'm aware nobody else has had this issue.

Originally Posted by spartacus

Not so good. Just when you were finally squeezing a few more hp of it. Speak to Ian at Stornoway Spares on 01851 702504 or zenastewart@hotmail.co.uk

I picked up a new starter motor from him 3 years ago and the place was littered with Tohatsus in various stages of being dismantled, it was like a whale graveyard!

I know, bit of a bummer eh! Looking into getting a 70...
Yeh I'm going to call Dave Hargreaves in Bernera, he's a Tohatsu dealer and a welding specialist. I've already been speaking to him about getting bigger pistons for it

[Roflhat]

Originally Posted by dave3235

Hi roflhat.

Just wondering where you got your NAKARU COILS from,made phone call to one company is it correct that there is only two tips 1and 2 prong connectors.Also do they make for easier starting and fuel usage

Think they were these ones - Scooter Parts | Racing Planet UK | ignition coil Naraku Racing V.2 high output - 2 pins | Electric Parts | Vespa Primavera 50 2T 13- ZAPC532 | Vespa
Just 2 pins on them. I'd recommend changing the spark plug boot to the waterproof type. Like this -


The only difference I noticed was rebiability, the coils on tohatsu 50's are notorious for breaking. I'd already gone through a couple by the time I went for motorbike coils.
Coils can't improve performance, but they can make the engine run smoother if it wasn't firing properly before. Mine have worked well, I'd recommend them. You'll have to make up wires for them

[dave3235]

Originally Posted by Roflhat

Think they were these ones - Scooter Parts | Racing Planet UK | ignition coil Naraku Racing V.2 high output - 2 pins | Electric Parts | Vespa Primavera 50 2T 13- ZAPC532 | Vespa
Just 2 pins on them. I'd recommend changing the spark plug boot to the waterproof type. Like this -


The only difference I noticed was rebiability, the coils on tohatsu 50's are notorious for breaking. I'd already gone through a couple by the time I went for motorbike coils.
Coils can't improve performance, but they can make the engine run smoother if it wasn't firing properly before. Mine have worked well, I'd recommend them. You'll have to make up wires for them

Hi

Yes I did notice the spade connectors.Do the coils mount in the same place as original ones as I haven't taken mine off yet.Thanks for your reply.

[Roflhat]

Originally Posted by dave3235

Hi

Yes I did notice the spade connectors.Do the coils mount in the same place as original ones as I haven't taken mine off yet.Thanks for your reply.

They do on my tohatsu, not sure about other engines, you have to mount them somewhere different. I think on yamahas the coils are on the other side of the engine? ht leads may not be long enough

[dave3235]

Originally Posted by Roflhat

They do on my tohatsu, not sure about other engines, you have to mount them somewhere different. I think on yamahas the coils are on the other side of the engine? ht leads may not be long enough

Thanks for your reply.Yeh mine is a merc mariner, well the bottom half is think it's yam top half will half to do a bit of researching thanks again

[Attack Ducks]

Man that's some bad luck with the lower unit practically coming off like that never seen that happen before, has me thinking to check those bolts for tightness from time to time.

Still that's a bad-ass little boat you got there. Not too common out here I've only seen ONE on a local lake here...would have chatted the guy up but I wasn't able to catch up with him lol

Hopefully you can get it back together soon.

[Roflhat]

yeh bad luck but good luck that it stayed on! I'll be checking those bolts every time I go out from now on.

I've bought some "recoils" on ebay to put into the leg as some of the holes are a bit shredded. New gearbox is here so should be back together soon. Hopefully faster than before

[dave3235]

Hi

May be get a few sets of bolts and change at intervals.Did the bolts break when it all went wrong, or did they just come loose.

[Roflhat]

Originally Posted by dave3235

Hi

May be get a few sets of bolts and change at intervals.Did the bolts break when it all went wrong, or did they just come loose.

Hi,

I'll be checking the bolts regurarly definitely! I think they all just vibrated loose, there was no sign of them.

[Roflhat]

Got the new gearbox on
Took her out for a run, all seems well. It's weird driving it with a complete skeg, never had one before! Much easier to turn, still need to sort out the torque steer though, unbelievably sore in the choppy stuff we've got just now. Was blowy out and as said quite choppy, still I managed 51.5 knots, I couldn't hold her flat for more than a couple of seconds without starting to lift so I reckon there's still more. We cut down the timing link a wee bit so I run more advance, closer to 24 degrees.

Also the new gearbox obviously doesn't have the exhaust mod yet, so acceleration was pretty poor with the overhub chopper. Going to drill it out, open to interesting ideas for the exhaust mod. Was thinking maybe 2x 1" holes on either side, so 4 holes instead of 2. Not sure if it's strong enough then though.

[1eyedjim]

Will you photograph the exhaust mod pls? Tempted to do it to mine

[Roflhat]

Originally Posted by 1eyedjim

Will you photograph the exhaust mod pls? Tempted to do it to mine

Here's a thread on another forum - Exhaust mod (vids) - Thundercat Inflatables Forum (I'm Roflhat there too)
That was on my old gearbox.
Thinking about doing twin exhaust relief holes like this this time round.

[Roflhat]

Exhaust mod done