Terrot MT1 Motorcycle restoration project

[911hillclimber]

See below with picture.

[911hillclimber]

It is oil from Villiers Services who are close to me and have lots of early 2 stroke experience albeit Villiers.
It is a blend sold under their own name, and states 20:1 ratio.
Getting the ratio right is hit and miss, but I'm closer to 30:1 atm having tried a smokey 20:1 a few months back.
It is green in colour when mixed.

As an aside, they refused to work on this engine...

Tactics tomorrow during the GP time will be exhaust pipe/silencer on (all new) and a hot plug.
The lawn mower carb arrived today, in a jiffy bag that pasted through the letter plate! It is SMALL!

[KS]

I'd be inclined to try a modern clean-burning 2T oil - 50:1 is commonplace.

[911hillclimber]

I'll try anything!
Hope Halfords sell it tomorrow.
Motorcycle shops are rare!

[Kneeslider]

Just a thought, but how long are you leaving the premixed petroil in the bike?

I once owned a Rotax powered 2 stroke microlight, and the thing would never start if the premix was over about a month old. Funny stuff.

Also worth a try is to cheat the plug heat range by heating the plug up to as hot as you can get it, then, wearing welding gloves, pop the hot plug back in and try again. If it won't run like that, then it won't run at all.

[911hillclimber]

Fuel is 1 month old, mix is almost every day.
I mix 400mL at a time.
Engine not in the bike but on a floor level stand fed by a fuel bottle fixed at a height above the carb as the tank would be, gravity feed of course.

Will try a very hot plug!

This engine will fire but only run badly and with no throttle response for about 30 to 45 seconds before it dies slowly over about a 5 second period.

[911hillclimber]

Bloody cold in the garage today, but tried a few things, all to no avail.

Full exhaust on with 2 stroke silencer, all new.
Fresh petrol and modern 2 stroke oil mixed to about 30:1.
No plugs at Halfords, so using the Champion plug I've used for years....

Engine starts, runs for a few seconds and dies. Best run today was 20 seconds.
Plug wet but drier than usual, but not dry just black/damp
This was with #84 jet where the Dellorto data says it should be an #90. Tried a #90 and it floods the plug.
Needle at max weakness position (clip at the top of the needle grooves).

So, absolutely no further forward with this comical situation and this engine.

Last shot is :
to go through all the jets again with the needle on mid-way height.
To re-fit the original carb and try with the silenced engine.

Then, I think I am at the end of all the options at my disposal.

Sell as a Starter/non-runner.

[Cortina]

You can't be beat by a simple 2 stroke .... you just can't..............

My suggestion : Start a "new" series of thought processes

for example : You're nearly sure it's a fuelling problem .... but is it ??
we all know there are only 3 things (groups) that stop an engine running - right ?

well , it's not a mechanical problem (or if it is , you can't solve by any minor tweeking)

so that leaves the other 2 (fuel / electrical) - all recent efforts have been aimed at fuel , but what if it's losing it's spark for either centrifugal or vibration , or heat or other reasons. Would be good to rule that one out (is there any sort of attachable induction triggered device , which would indicate the spark is happening all the time during your starting / brief running efforts.

there IS a solution ... you just have to find it !

[Cortina]

timing strobe light - mains powered

they should flash every time there is a "spark in the ht lead " ??

would that suffice ?

[Cortina]

... and when it's in my head

don't forget about the plug "issue"

I had an experience recently with a small 2 stroke chain saw ... long story short

I would have made a considerable bet that my "issue " with it was fuel starvation - it would start , but as soon as I tried throttle opening on it - it died / would not take the throttle .... all the indications of not getting fed.
went out and got the kit for a carb rebuild .... but first I popped in a new plug

sorted

just saying like ...............

[911hillclimber]

Thank you as ever!
Hard to keep my mojo for this thing just now.
Will look at what you say!

[911hillclimber]

I have a replica thread on this thing on classic motorcycle forum who are just as baffled as me despite 43,000 hits!

To Winston's magneto thought:

The original ignition core was sent to a French company to be re would just in case the spark was getting snuffed-out inside the chamber.
Came back looking good.
Screwed it back on as accurately as I could (was rivetted).

I have noticed the static coil is 'just' kissing the outer flywheel magnets with some polished metal on both sides, spotted this yesterday while checking the timing (yet again).

If the air gap between the two closes will this kill the spark? The core is grounded and so is the flywheel so it would be 2 earths grounded momentarily together, but not sure if this would make things ignition erratic enough to kill the engine?

There is no radial crank play (new crank ball races).

Old in-restoration picture, but it is the coil at '2 O'clock'

[911hillclimber]

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.

[210bhp]

Just a thought but when the engine is on that stand do you have a hole in the top of your gravity fed fuel bottle? Looks like you have a screw cap on there which might create a suction vacuum after 30-40 seconds of running hence the slow running death.

Regards
Mike

[911hillclimber]

There is a vent hole in the cap Mike.
It is an item designed for this kind of thing, but a bit cheap in construction....