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

[iansoady]

I think I may have suggested Nametab in Redditch. Simon there will sort you out.

[TGR90B]

If the piston you've ordered is correct for that engine why suggest that it's rebored to suit a completely different (presumably) 4F piston?

[mini-me]

Looking at the new rings I fitted, they are very poor, really not very circular when slipped into the bore.

another tree wrongly barked at?

In my experience it'll be the bore that's out of round.

It occurs to me that for all this wasted cash, you could have nipped over to a couple of the large autojumbles in France, had a bit of a holiday, bought a couple more  decent engines of known quantity and still have spent less money?

Or you could even have paid me to do it?

[Terrotmt1]

It was a comment made by Villiers. Services a few weeks ago when discussing the piston and bore.
He asked me to find out what clearance to machine to.
The piston on its way is NOS Terrot, no idea who made it in 1950 ish, so no body to ask.
I had 3 thou in my mind, but using a period Villiers engine of comparable age and performance I thought would be a guide.
The new piston will be given to the machinist with the barrel.
I know Nametab from a 9E engine reborn they did for me.
They only do race machines I think, all spares have gone to Villiers Services.

I should think Nametab would be an excellent place.
I also have Beadspeed close, they do a lot of Lambretta stuff, and did my Honda reborn with new pistons (2 beautiful Honda Pistons for £20 each....).

A trip to rural France for some parts sounds good!

[iansoady]

Nametab were still doing rebores etc less than a year ago, but I think they have stopped selling spares. They do seem to know what they're about with 2 strokes.

[Terrotmt1]

Yes, their site says all machining can be done to old Villiers, but a 2 stroke is a 2 stroke when considering 1950 'technology' so a 'villiers' tolerance should be fine.
I've read 2.5 to 4 thou is about right, so 3 is even better.
I was a bit put-off when V Services asked me what clearance was needed, I expected then to advise me.
Anyway, doubt I can get the parts to anyone next week as things are particularly busy.

Villier 4E engines are as rare as Terrot MT1 engines....

[mini-me]

buy a running one

http://www.siboni.com/html/fiche.jsp?id=2901646&np=1&lng=fr&npp=100&ordre=&aff=2&r=

[john.k]

A rebore will leave the ports sharp edged,so dont forget to bevel the edges .

[Terrotmt1]

Thanks John, I would expect the machinist to dress the edges after the bore?
Will ask them to do this, thanks for the heads-up.

These bikes do come up complete and for sale sometimes, but not in real numbers.
I think the Terrot lads look down on them.

I don't think Terrot got back on it's feet after the war, sold to Peugeot in the late 50's.

http://www.classicbikesuk.com/stock/3155TerrotE.jpg

[mini-me]

Actually Terrot was the BSA of France after the war,  on a par with Motobecane, no other firm made large 4 strokes, police and Army used  Terrot and their 350 and 500 were not bad bikes.

What stuffed the french bike industry was French Govt anti bike legislation.

[Terrotmt1]

Piston and barrel now at Villiers Services, gone for a 3 thou piston clearance.
They will dress the port edges too. Should be done by Thursday this week.
Rings are nice and close in the piston grooves etc, so fingers crossed this could be good.

Also, the new points and cam follower (all NOS) arrived today.

Should have it all back together for the Big Start during the weekend or before.

[Terrotmt1]

After a few mis-communications, V Services finally bored the barrel, honed and dressed the ports, got it back this afternoon.
Fitted the NOS points and the new heal and now have total control over the points gap!

Planning to bolt it all together tomorrow with the Big Carb and see if it works.....

[Terrotmt1]

Well, this French affaire still will not surrender to me!

Gapped the rings to 9 thou, put the piston on the rod and the barrel onto the piston with a struggle as everything is so sharp.
The engine would not move.
Took it all apart and tried the piston in the bore without rings, lovely slip down the bore.
Put the bottom ring on and the same thing, full piston travel.
Removed that ring and fitted just the top ring.
The piston jams solid and eventually it is obvious that the ring ends of the top ring fall into the largest (inlet) port!

The new piston has it's brass ring locator pins in the wrong place, or at least the top ring is in the wrong place. Comparing the old piston (on the left in the pic) to the new one, the position error is obvious.
Just what else can get in my way?

I have complained to Chambrier just, so will wait for a reply. I can re-drill the piston and re-position the pin but the pin is 1/2 in the ring groove and 1/2 in the piston body, thus it is really a job for a good milling machine, so might have to go back to the man who did my case and another £40.

[mini-me]

I think this engine is bored to death.

[Terrotmt1]

 
Just how I feel....
Maybe just one day it will be done.
I wonder just what else can get in my way?

Maybe the MT1 engine was changed in that the ports were repositioned before or after mine and the ring stop positions changed to suit.
Anyway, there is a huge 40mm wide land in the bore 180 deg opposite the current location. why the designer did not put the pins there I'll never know.

There are bosses inside the piston skirt to take the pin depth, and both pins have missed them, you can see the pins sticking out inside the skirt.

Friday afternoon piston machining.