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

[Terrotmt1]

Halfords: yep, local and easy and a hope for a 'hotter' plug, had to get some 2 stroke oil anyway.

Been on ebay France so many times, nothing. Never seen one on there for sale, AMAC 903-165.
The Gurtner equivalent are also rare, Terrot used both.

The original carb has a simple dished disc to cover the inlet, not a filter, just a stone/grit guard screwed right over the intake, the choke plate is housed behind it.

Starting, let alone running, is worse with the exhaust on.

Mini: quite possible I am up the wrong tree, but when any running simply wets the plug and part fills the case then far too much fuel is getting drawn in.
That fuel can only get in via the carb system.

With every 'suck' action too much fuel is drawn in hence the effort to stop that.
The case fills, the rich vapours get to the chamber and a spark fires it for a while until the dry plug I start with get flooded and stops the spark jumping across the plug.

About 10 to 20 seconds and it all happened. I have to wash the plug every time after it stops.

Please, what other tree is there to climb. The spark is like an arc welder striking (outside the engine) and I have compression.

On the multiple kicks you can feel the engine forcing on the kick when you 'edge' the engine to the compression stroke before pushing down.

[john.k]

The motor is already mounted on a stand......I would hook up an electric motor with a V belt drive to the outside of the flywheel ,motor the little engine at about 500 rpm,and experiment with increasing the fuel supply from nil to full on via a tap in a mower tank.You could also rotate the terrot with a big electric drill ,but the drills generally have too much starting torque ..........never the less ,this is how I start my 8hp B&S on a rider mower ,since the recoil  busted many years ago.This engine was also impossible to start manually,due to advanced wear in the carb,but a few seconds with the drill ,and we re off mowing.

[murdo]

I do the same with a half inch drill and socket on the Villers 7F on my firewood saw bench. Could be pulling the rope for 20 minutes with only a few backfires for the trouble. Lot to be said for 'electric' start.

[Terrotmt1]

I've tried the power drill start some time ago, but the compression of the engine was too much for the 240 volt drill and the armature started to really smoke!
It did not start.
I know of a young woman on YouTube with a Terrot MT1 with an identical Dellorto and it only starts by a good bump start!

Hope to get a good few hours on it tomorrow.
On YouTube there are videos of these engines starting with 1 kick, running and ticking over when warm!
All in France.
Maybe the bike is home sick....

[chaterlea25]

Hi

so using the Champion plug I've used for years....

FFS go and buy some new plugs !!!
There must be a lawnmower shop nearby

John

[R]

On YouTube there are videos of these engines starting with 1 kick, running and ticking over when warm!
All in France.

Ask in your best French (translation) if you can borrow their carb !?
(or if they have a good spare).
That would really sort out where the problem is.
You could take your engine on holiday as handluggage ?!

I agree you need a crate of new plugs.
We had a villiers lawnmower when I was a kid, and it was nothing but trouble.
A new spark plug was a total revelation, I was a convert
No more oiled plugs, no matter what you did...

[R]

Been on ebay France so many times, nothing.

Pair of KLG CL1 plugs, new.
They are in Texas though.
And not entirely cheapish.

https://www.ebay.fr/itm/Antique-Original-KLG-CL-1-Spark-Plugs-Original-Box-With-Paper/182444697458

Edit. There are also some CL3, at a more respectable price and closer to home.
Whether they are hotter or colder though ??
https://www.ebay.fr/itm/1-Bougie-ancienne-KLG-CL3-allumage-essence/263806668729

[Terrotmt1]

Ok, in the interest of time, I will go back to Villiers Services as they are close to me and see if there is a 'better' plug and get a few nice new ones.
The original plug I still have and works (as in sparks) but that  oils up just like the Champion.

Might be a welcomed thought, on another forum, someone who works on vintage cars recons it is down to the magneto but I have a new coil.

NOW:
I notice that the new coil (original core) 'just' kisses the outer magnets on the flywheel.
Not sure if this is bad news?

[Rex]

Clearly it shouldn't touch, but didn't you say the spark was good until the plug wets?

[Vreagh]

A new coil is useless without a good condenser and clean points.

[Terrotmt1]

Just taking those 2 points...

Went to Villiers Services and had a long chat with the boss, quite shop, so had the time.
We went through the basics, and then did the same again!

Bought 2 hot plugs, one dimensionally the same as the original/Champion plugs, the other with a very extended tip.
Came away with a new condenser...

He winced when I said I had soft soldered a thin brass sheet base 'plate' to the new (from them) condenser in order to mount the condenser into the deep pocket of the magneto.
He thinks the heat might have 'ruined' the condenser, and he had seen this before, once.

He suggested I wire the new one outside the magneto with an extended lead which I can do, but have not yet tried (tomorrow's job). Might have to drill the case to get access.

So, I resumed battle.

Jetted the car (still the modern/new Dellorto) with an #85 and the needle at full depth (weak) and with the coolest of the hot plugs.

Started quite well, ran for some 1/2 a minute with a different note, still a heavy note and still little throttle response, but it did this with no choke (to start it).

Let the engine die as it was good and hot.
Removed the plug and it was DRY, bit dark and looked almost weak! Case was empty. NEVER had a dry plug with an empty case. Progress?

Containing my excitement, changed the plug to the hottest one with extended tip and checked the piston did not hit it!
One kick and it ran exactly the same and for the same time.
Removed the plug, and it was looking weak with a light shadow on it, dry case.

Richened the needle 4 groves and it made no difference to either plug performance.

Paused, and re-fitted the original carb, original jet etc. Changed nothing else.

The engine ran exactly as with the Dellorto which I was not expecting.

The running today of the engine has been visibly erratic and with the occasional flame back fire and the flywheel speed was changing at a constant throttle position (ie wide open).

Sometimes the carb would cough and shoot some fuel vapour out.

For one or two seconds the engine would find a 'sweet-spot' and sounded nice, then back to rough.

It must say something that a change of carb  had no effect?

Condenser change tomorrow after some making of Xmas presents for the wife while she is out shopping!

Am I moving forward or just found another blind alley?
It all sounds ignition all of a sudden to me.

[mini-me]

you soldered to the condenser?

[Terrotmt1]

Yes, but nearly 2 years ago, BUT I think I glued the base plate on, can't remember the, tomorrow will tell.
Still have the original, but will try the new one first....

Lol!

[DM]

If you have glued the base plate on it's likely are the glue is acting as an insulator and the condenser is not in circuit.

[Terrotmt1]

DM:
Exactly!

Getting it apart this morning. Will post a picture.
At the time, or since, I couldn't find a new condenser with such a mounting.
Villiers suggested mounting the cond outside of the engine with a long wire to the connection and so earth the Cond on the engine.

Here is the mag whist I was stripping the engine down for the first time.