classic motorcycle forum

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.

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.

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.

Thanks John.
Terrot designed this engine this way as a cheap but reliable bike and there are YouTube clips that show them firing up in one kick!
The crank runs in 50mm dia ball bearings, the magneto side has this 15mm long bush, about 12mm ID and the scroll cut into the inside bearing face. Other (clutch) side is a simple felt seal.
So the mag side has a large ball bearing and then immediately the brass sleeve running very close on the crank shaft.

I'm going to leave this arrangement as original and try to sort out why there is a positive pressure from the inlet manifold when the engine is turned over quickly.

I think the piston is worn.

Did some probing this morning. Set the piston at TDC and put some air pressure into the case via the inlet manifold having removed the magneto and the clutch side cover.
This exposes the 2 crank seals so with some soapy water drowned the magneto side. Air simply gushes out of the seal!
On the clutch side there is no air passage at all, possibly because the other side leaks so much.

next stage is to try to seal the mag side seal to force the pressure against the clutch side seal.
The crank case gasket seal is leak free.

Hard to take a picture while pumping air into the engine by hand!

Thanks, it is a nice bike and I chose it to have a bit of a challenge after the easy-but-expensive Lambretta and the similarly ££££ Honda CB 175.
I was hope for this start-up to be easy!

Getting info on this bike is hard work, even the French Terrot site is lacking in response as these bikes I think were not popular in their day. Parts are even harder, no gasket sets etc let alone more intricate parts, like crank shaft seals!

Hello, I am at the near end of my restoration of my 1950 Terrot MT1, very much the French equivalent of a BSA Bantam.
single 2 stoke, all stripped, new rings, super clean carb and re-magnetised magneto. Fat blue sparks when you turn it over by hand on the kick start.

Should start?
Not a chance. Fresh fuel etc but absolutely nothing.
The plug has never got wet while I have tried and tried to get it going. I've tried Easy Start too, nothing. All the passages in the barrel are clear as is the lower crank case, head gasket it tight.
I've tried different timing positions, the French say 5mm piston Down from TDC, I've tried this and 2mm, nothing. Points gap is 0.4mm.

The fuel level is exactly to the top of the vertical main jet that the tapered needle goes into, the carb is an AMAL/AMAK and every hole (there are not many) is clear.

I am at a loss what to do try next, but the skip next door is tempting....
What am I missing here?

Hope somebody can help. The people on the Terrot.org site are not very forth-coming.
Thanks, Graham.