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

[Rex]

As a Scott owner and forum member I've seen similar scenarios to yours several times now. 
"I've just bought/rebuilt this old Scott and it won't run for more than a couple of pops, please help" is the typical question.
The old hands always answer that on a primitive two-stroke oil is an essential part of the sealing (compression) process, and if the seals, rings etc are dry then sealing is poor to non-existent and it ain't gonna run.
The Scott has removable covers over the transfer ports and the standard reply is to take these off and give the workings a good dose of thick oil. I know yours won't have these removable covers but it's something to consider. After all, when Pierre used to ride that bike daily to the garlic factory the engine never dried out, and no-one would buy a bike for the daily grind which couldn't be started.

Have you tried starting rollers?

[TGR90B]

Nah, buy a pushbike. You'll certainly get there quicker.

[Terrotmt1]

Thanks for the oil suggestion, adds to a previous comment about a higher oil dose to the fuel on an engine almost the same as the MT1.
Will give the fuel a thick dose and see.
I don't actually want this bike as a road runner, not interested in riding one of these, the purpose is simply to go them and move on.

I have a Peugeot BMA moped waiting.
I will be certain to get the engine sorted first!

As to rollers, no, but looking to buy a 240 v pistol drill that will run anti clockwise.
Should save my right foot from further injury.

[mini-me]

jumble list

https://www.calage44.com/region_paysdelaloire/

[Terrotmt1]

Thank you for the list, we will be back in the UK late Wed this week, but the link is very useful.
I bet I will still have by little Terrot in 2019...

[john.k]

Did you know that back in early 1963,at the time of the big freeze,the British government were so concerned that if the channel froze over,southern England would be invaded by a massive horde of Frenchmen in stripey jackets riding terrots ,mobylettes ,peugeots and other tiny mopeds, that the army was placed on standby to form a mass cordon around the channel coast...Obviously they neednt have worried............now if they were riding bicycles festooned with onions,it could have been a different story.

[Terrotmt1]

Onions are useful!
There is a big motorcycle autojumble in Kempton Park this weekend, could there be a carb there for this thing?
The MT1 was also fitted with a Gurtner carb.

[Rex]

Being mean I suppose the obvious thing is to take it there and flog it to some passing Frog...

[mini-me]

Thank you for the list, we will be back in the UK late Wed this week, but the link is very useful.
I bet I will still have by little Terrot in 2019...

I'd go for 2119.

Kempton Park is in my experience a washout unless you want jap junk, modern repro british bits at silly prices, but there will be a couple of opportunist sellers of old french tat there as usual, go in disguise, they'll be looking out for you Once they got a fish on the hook, they like to reel them in again

I'm rather fond of onion soup, but I make my own and use English onions. I'm on an 'avoid anything French' crusade these days.

[Terrotmt1]

Well, a year and more has gone!
Still have my little Terrot and it's back in the garage for some more fun.

I have replaced the ignition side of the magneto with a re-wired one from a specialist in France (78 Euro) as nobody could do it in the UK...

I now have a good spark that hurts if it grounds though your fingers....Timing is the factory spec of 5mm BTDC.

Back on the carb side.
It has spluttered repeatedly on the original carb (never done that before) the big Dellorto and even the little modern 50cc engine carb.

Best I've had is 3 seconds running.
Hoping to find a carb at the Nash show this weekend.

If anyone has a AMAL/AMAC type 903 carb, PLEASE contact me.

[R]

Best I've had is 3 seconds running.

A spoonful of petrol (petroil) down the gullet gives at least 4 secs of running,
so that would suggest these carbs aren't too flash in the running dept. ?

However ...
Have you tried choking it in any fashion, cold engines don't generally like running at all without some.
Unless you flood it fearfully, and then give it a fistful of throttle.

[TGR90B]

Once started, hold the tickler down and see what happens.

[Terrotmt1]

Thank you both.
The carb I'm currently trying is a new 50cc 2 stroke Chinese carb. The original I have I think is just too worn on the emusion tube though the needle looks great. The piston in the body is a very good fit.
It has given more near-starts with the Chinese carb than any other I've tried.
This car has a sliding choke plate just like the original one does.
The float level is set so to just get fuel at the very top of the jet tube but not flooding over at all. Starting/kicking over on choke with a stone cold engine seems to do little, but here is a summary of today's efforts:

Tried various timing setting using the small new carb off a Chinese something or other, around 50cc engine.
It has never run or even popped or farted with this carb, but it now regularly fires on kicking the engine over and several times has run for over 8 seconds!

I tried 3mm BTDC and to 5MM BTDC, 5mm being the spec from Magneto France in the day.
Changing the timing makes no difference at all, so it is now at 5mm btdc.

I have changed the jet hole (there is only one jet) by soldering up the jet the carb came with and using my range of BOC gas nozzle cleaning wires to set the fine hole.
The finest is 0.36mm dia.

The engine is so very close to running correctly, just not close enough, but progress!

After these 'prolonged (8 seconds) runnings the plug is quite wet and oily. I am using a 25:1 mix, fuel is Shell 99 octane.

Fingers crossed for Sat at the bike show autojumble.

[R]

After these 'prolonged (8 seconds) runnings the plug is quite wet and oily. I am using a 25:1 mix, fuel is Shell 99 octane.

Is there a drain plug in the crankcase, such that you could drain off any surplus fuel/oil mix lurking down there.
If it has a sumpful, it may be drowning ?
Have you tried giving it a fistful of throttle during these 8 second runs, ditto it may be drowning in fuel/oil,
and need a goodly dose of air to catch its breath.

Have you tried contacting Villiers Services, Villiers made quite a range of engines and just selecting a carb at random could be off anything.

I don't quite recall the entire jist of all this, have you inspected the condition of the crankcase seals.
If they admit bulk air, this could be a painful/ fruitless/endless quest ??

[Terrotmt1]

Hello R, thank you for your post.

To give all the details:
1950 engine original to the bike.
Re-bored, new piston and rings. New crank seals but using modern lip seals instead of the felt ring. Both sides of the crank sealed.
Sump drain added (M6 bolt) and this has drained a lot of mixture recently...
Fresh plug.
New ignition side magneto bobbin just fitted, re-wound in France. New points set at 0.4mm (as spec). New engine gaskets.
Engine was fully stripped to bare parts, everything cleaned esp the cylinder ports, all are clear.
All the attempts recently are without the exhaust system. Engine previously has run briefly with silencer on.
Silencer new from Villiers Services who are 5 miles away from me.

I have now compression and sparks and recent bursts of running (for a few seconds) prove fuel to be getting in.

After all runs the plug is soaking wet.

I have 3 carbs.
The original that is clean and all passages are clear, piston is a good sliding fit. Jets are original and to factory spec of the period. Jet tube looks a bit worn, needle looks good.
The second is a cheap new Chinese 2 stroke carb sold for cheap dirt bikes of 50 to 80cc modern engines, so thought to be 'suitable' substitute.
Third carb is a Dellorto rip-off from China. It's throttle dimensions are very close to the original carb diameters.

The engine this week has briefly run on all 3 carbs!
Non have sustained running and when it does catch pulling and closing the piston quickly does very little and seems to kill the running.

Last year I managed some minutes of running on the Dellorto but starting was very random and the engine (hot) would not re-start. The engine would not restart that day or several days after!

I am no stranger to these mechanisc, I have restored cars and bikes for 45 years, but this one refuses to get going.

Close to throwing it away (again) and putting it down to experience, but hate being beaten.
There is something fundamentally wrong here, just can't find it.

On the ignition side, the timing is 5mm BTDC (to spec) and I've tried 3mm btdc and makes no difference.

Villiers Services refuse to help me.

A long time ago: Original car fitted.



Dellorto carb fitted: