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

[Terrotmt1]

Thank you John, you have made me doubt my approach to timing this bike now.

From what the French have told me:

Determine tdc using a rod placed down the plug hole. The plug is vertical so the rod will rest on the crown of the piston.
Rotate the crank until the rod enters the cylinder, following the piston by 5mm, thus the piston is now 5mm before tdc.
Place the flywheel onto the keyless tapered shaft of the crank and align the mark on the mag(statick part) to the line on the flywheel.
Tighten the nut (which is rhd thread)
Turn the flywheel so the cam area is under the heal of the points assembly and set the gap to 0.4mm

I have consistently followed this procedure, about the only common denominator in this whole saga!


I have tried the drill electric starter and got me nowhere!!

[mini-me]

You do not mention turning the engine BACKWARDS to find TDC?
really you should bring the piston up to the 5mm mark.

Ignore me if thats what you have done

[Terrotmt1]

To explain myself better:

My rod has 1mm marks on it.
I turn the engine to reach tdc judged by feel and watching the 'mm' move until they stop = tdc. Note the mm mark that = tdc. Note 5mm from that 'tdc' mark.
Rotate the crank back until about 10 'mm' marks have moved, return the crank towards tdc and the '5mm' mark.
I think this will give "5mm btdc" as stated in the terrot 'manual-handbook' I've downloaded.

Most modern 2 strokes use 2mm btdc. Ive tried that and nothing happens.

The few times this engine has in fact ran has been with '5mm btdc'

In said handbook and other references, there is no mention of a timing routine different to the one I've given.
I assume the 5mm btdc has the magnets in the correct position to each other?

The hub of the flywheel has a steel strip welded to it that covers approx. 100Deg of the 360 of the hub. The points abruptly climb onto this ramp, the points are then open 0.4mm for this 100 degrees (approx.) before coming off the 'cam' and presumably the points close, the energy stored in the coil is discharged to the plug lead, plug, and it creates a nice explosion....if only.

writing this now makes me realise that I have not checked the points are actually closed off-cam! However, when testing the sparks on the plug, plug out of the engine to ground there is a stream of sparks in-line with the 8 or so cycles of the engine/kick start.
Every time I have checked for a spark this way there has been a stream of them.

While the points heel is on the flywheel hub, not the raised section I call the cam the points should be touching with some force given by the spring in the points mechanism.
The heel rises up the ramp to the plateau of the cam in about 3 to 5 degrees of  rotation. so the points then have opened and gapped to 0.4mm.

The heel then rides the cam for about 100 deg before coming down the cam ramp so closing the points and the spark is released from the coil.

In all this curfuffle I can't see why the spark does not arrive at the right place, right time or close enough to give a running engine more than once in a blue moon!

Talk about going round in circles.

[murdo]

I always understood the spark to fire when the points opened, collapasing the field of the coil so causing it to discharge. If your coil fires when the points close again then the timing will be out by the 100 degrees you describe.

[Terrotmt1]

Ok, but if the flywheel is in the right place to the crank ( the piston is 5mm btdc, the magneto marks aligned) then the points will open and close at the right time and the spark arrives at the plug on or just after tdc and explodes on the down stroke.

As long as I set the points gap with the heel on the cam plateau the points will open and close at the right point in the cycle.

In all this mess, the engine has on occasions run, and a few times run well and predictably.
It has never restarted straight after stopping.

If something was broken (electrically) then it would never run?

I have found a company in France with new points, a new heel, and even an exchange rebuild coil for the Magneto.
About £100 delivered.
I will order the points and heel first, and see if they will tell me how to test the resistance of the coil.

[Terrotmt1]

Daily up-date!

Breaking news is that I removed the mag from the engine and made some detailed adjustments to the points, ie swiss filed a few parts to get more 'throw' which allowed me to move to the next tweek.
I found a large alum bar that fitted exactly the central bore in the mag back plate. This then allows the points to be gapped 'off the engine' which I expect is how the mag was sent to Terrot on the production lines. The bar's radius is the same as the flywheel's hub and cam radius!
I managed to get a nice feeler gauge fit to 0.4mm +/- a knats whotsit and also determined this is a 'right hand' version of the mag.
Put it all back in but set the btdc @ 2mm not 5mm.

With the Villiers carb on and the piston in it set (stuck!) at 2mm from fully closed (no throttle cable yet fitted), turned the fuel on, and not waiting for the bowl to fill, I kicked the thing 4 times, nothing.
On the fifth there was a 'peep', on the 6th there was a 'PEEP' and the 7th it fired and ticked over like my Porsche! At that moment it sounded as good as the 3.2 litre flat 6!!

It sat there running I guess at 500rpm and sounded great and very different in a good way. (no smoke!)
After a minute of this excitement and the tick oh so consistent I couldn't stop it, so simply covered the mouth of the carb and it died after about 3 seconds.
I ventured to fit a throttle cable which did not work...

Awkwardly, it was time for lunch! So play stopped for the day. 

Will try to move further tomorrow.

I will now order I hope a set of points and a new heel from 'Pieceallumage' in France who's site shows they have these NOS.

Is this 3 steps forward or just a false dawn?

[murdo]

Good work.

[The Artful Bodger]

Sounding promising!
Colin

[iansoady]

Excellent.

[mini-me]

He gets the  perseverance prize though for sure.

And a rosette from me for not being thin skinned.

[Terrotmt1]

False dawn as I thought...

Got a 'throttle' connection to the carb so tick over to wide open.
Fuel on etc and after about 10 kicks it started and responded to the twist grip.

Enthused, closed the throttle shut and the engine died. There is no switch on this bike, and the original carb kills the engine when the twist is fully closed, maybe this Villiers works the same?

Anyhow, gave it a minute to cool a bit and it refuse's to start, not a peep.

One thing is very notice able is that with all this multiple kicking the engine can feel very 'de-compressed' seeming to have zero compression some kicks.
Leave it a bit and the next kick you can feel compression.

Checked the points, and they were at 0.6mm so closed them to 0.4mm.
Tried to re-start and still nothing.

What a joke this all is. Hard to keep the mojo at this point and the roaming scrap man appeared just when I hit the low point. Oh so tempting, just get rid of the bloody thing and move on.

Will feel better tomorrow, so might have another go but I can't see what else to do.

French Tat indeed!

It would make a nice shop display mind, maybe that is the right place for it or give it to the National Motorcycle Museum.(if they would want it)

[mini-me]

If I remember correctly these ancient two strokes were not meant to tick over, might be wrong.
For oiling reasons I think, has your plug oiled?

When I were a lad and just started I was told two strokes go best flat out and worn out, or buggered as the bloke said.

Your rosette is canceled

[Terrotmt1]

Do I get 2 if I crack it? 

[mini-me]

nope.

[Terrotmt1]

Mean! 
 

I have noticed when positioning the flywheel to the crank that the marks align when there is a strong magnetic 'positioning'.
The marks nearly align themselves.
Is this normal?
Also, when trying to start the bike with the filter off the Villiers carb neat fuel is spat out to the floor, not a lot, but you can see it in the sun.

This situation broke my sleep last night, but no light bulb came on so other than repeat all I've done before, again, I cannot see what else there is to do.