Terrot MT 1, 100cc 2 stroke: non-starter!

[Terrotmt1]

Thank you all for watching and commentating, it certainly helps in these 'dark' hours!

IT FIRED!

Yep, I kid you not, it actually went bang several times, though did not run.

MY PLUG IS WET!

Yep, miracles do happen on a wet Tuesday.

so, what have I done to get to this high level of restoration?

Not sure TBH. Stripped the engine down fully and built it back up. The kick start gear is drawn incorrectly on the factory diagram, so having fathomed out how the mechanism works I did a dry build, confirmed the assembly and simply screwed it all back together.
Decided to try and effect a better case seal and close off the scroll bearing on the magneto side using a stack=up of O rings. There is a 0.25/0.5 compression on these when the flywheel is on, so I hope (with some oil in them) to effect a better seal that might last. I oiled well the clutch side felt seal while the cases were apart.

Set the timing at 4mm BTDC (a Frenchman says it should be 5mm).
Popped the carb back on. Fuel in the bowl.
Gave the kick start some hard shoves and it felt/sounded different.
After some more enthusiastic shoves it started to fire and stopped. Rested my arm and repeated, and bang it went several times and even a trickle of about 6 ignitions then no more.

I have left the exhaust pipe off so I can hear any changes more accurately.

going to ry 5mm BTDC and see if that helps.

Anyway, a few steps forward. Maybe the bloody thing will stop fighting me now.

[chaterlea25]

Hi,
What oil petrol mix are you using?

John

[Rex]

Can you shift it out of the way so I can have a look at the old Porsche?
I expect Barnier's put a curse on the little bike anyway..

[Terrotmt1]

For this lot I'm using straight petrol. If it fires and runs, then I can stop it quickly.
Can't imagine that dosing the petrol with 2 stroke oil will change much. (?)

today, as an experiment, I made an adaptor and fitted a new cheap 2 stroke carb for an 80cc engine. I hoped this would give the engine a rough but consistent fueling, but it failed to run.



The old Porsche is a 1973 911T with a 3.2 engine and a lot of mods.
Used to be my hill climb/road car and I've had it since 1988.
My main interest is hill climbing, the bikes are small side projects, though this one is consuming too much time!

[Rex]

Very nice too, and an unusual colour (to me, at least).
Sling the little Frog aside and go for a drive before the crap weather sets in.

[33d6]

I wouldn't use straight petrol. If it is supposed to be running on a 5% mix then the carb is 5% out before you start plus the oil forms a working part of the crankcase seals.

You amused me with the "why is something so simple so bloody minded?". We 2strokers all find out the hard way that simple doesn't necessarily mean easy.

Cheers,

[Terrotmt1]

Had a surprise this afternoon.
In a weak moment I choked the carb with my finger (like a model aeroplane engine), gently eased it over a few cycles, returned the kick start to the top and gave it a healthy stab down by hand.

It RAN for 5 seconds before running out of the last puddle of petrol I left in the carb bowl.
It sounded great too. Good to smell carbon Monoxide instead of hydrocarbons for a change in the garage!

Yes, time to add oil to the petrol. I would not like to have it run free of lube again.

I just did not expect it to run!

The 911 is coming off the road very soon for a re-paint, same colour, Champagne Yellow, a Porsche colour from 1968. Very easy to see the car any weather. I painted it in cellulose in 1988 in a one car garage so it has done well. It will be pro painted next time.

[chaterlea25]

Hi,
I mentioned earlier that those old plain bush 2 stroke engines need a strong oil/ petrol mix
SAE 40 at maybe 12 to 1,
As said its the oil that makes the "sealing" work

John

[Terrotmt1]

Yes you did. Oil I have is too thin, so will get some for a classic.

[cardan]

I mentioned earlier that those old plain bush 2 stroke engines need a strong oil/ petrol mix
SAE 40 at maybe 12 to 1,
As said its the oil that makes the "sealing" work

I've read this lots of times, but I think it should say "worn out plain bush engines might actually run if you put heaps of thick oil in the fuel".

In my experience if the mainshafts are round and true, and the bushes are line reamed to give a close running fit, the motor will run fine on the usual (for modern oils) 25 or 30:1.

The key place to look for wear in an old two stroke is in the mainshafts/main bushes, and in the cylinder just above the ports (not just near the top as in a four stroke). A 2-stroke with too much wear at these places will not run properly. Sort it out, and you'll be amazed.

Cheers

Leon

[Terrotmt1]

Thank you for the comments.
The crank runs in 2 45mm dia roller bearings, both in great condition, the mag side has a close fitting bronze bush with the oil grove in its bore.
Clutch side has a normal felt seal saturated in car engine oil.
The areas around the barrel ports are clean and true, no scores etc, piston the same.
The engine was oddly clean inside when I stripped it, gearbox free of oil, almost washed out clean.
There was carbon deposits in the head and down pipe, case bottom was quite clean.
I think this engine is a low miles unit, but the gears could be in better condition, esp 2nd.
Looks like a lot of clutch less changes.
There are no spares, no orphan engines etc anywhere, this is a survivor of a bike, most must have been scrapped.

[Terrotmt1]

The larger Chinese carb arrived yesterday, and a little modern beauty it is too!
Made a simple adaptor to fit the flange on the carb to the inlet on the engine, added some fuel and put the choke on FULL.

Pushed the kick start down hard as ever and it instantly RAN!! And for 10 seconds until I closed the choke too far.
Repeated it the start and it ran and ran and ran....had to stop it by putting my hand over the inlet and flooding the engine.

AMAZING!
So, with this serious progress for 15 $ I need to tidy the adaptor flange, and get the throttle to open and close correctly etc and fit the silencer and see if I can tune it.

Also, with the assistance of Chambrier I have a new output sprocket, excellent customer service from Chambrier, very impressed.
Onwards and upwards!

[murdo]

It runs, good work.

[Terrotmt1]

Thanks. Really surprised how it just started.

On these early bike how are you supposed to stop them running?
There is a terminal post for the lights off the magneto and this should go via a switch but I can't see how to break the ignition circuit with the flywheel spinning.

[Rex]

Run a wire to earth the points?