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

[The Artful Bodger]

Many happy ones for tomorrow! At least the new one has pedal power, you'll be able to get somewhere engine or not. I think you need an award for persevere if nothing else, if you look at it as a learning curve you'll get a diploma by the time you're done!!
  If you do change the seals try to find some proper lipped seals rather than O rings, there's some pretty slim ones around. The lipped seals will seal better the more pressure that's behind them, O rings won't seal so well and won't take up as they wear.
  Keep one thing in mind though, the oil seals allow a vacuum to form in the crankcase to draw in fuel and air, they then allow pressure to build in the cases to push the fuel air mix via the transfer ports to the combustion area. Air will always be present in the combustion area if the piston's down so adding fuel via the plug hole you have a "good to go" situation in the combustion chamber. So it should fire, if everything else is correct, even if you take the carb off altogether.
  Even with leaky seals it should run to some degree (with a carb.) once it has started with fuel down the plug hole, hard starting is one sign of leaky seals but the other is the engine revving right up as it sucks air in around the seals so acting as if the carb slide is open. If it slow runs and dies as the throttle is shut off it isn't sucking in air around the seals.
  Not being there to see and experience exactly what's happening makes it difficult to guess what's going on. You can try soaking the felt seals with oil as this will both swell them and give more of a barrier to air getting sucked in and out.

Colin

[Terrotmt1]

Thank you Colin.
A wet, cold and all other weather things on Sat with the race car, not good!

Just spent an hour on the bike.

I've fitted the Villiers carb now in a hope things could change for the better.
It started after a dozen kicks (a few were full of promise, but it never fired up) and ran 'heavy' or '4 stroking'.
Ran it blipping the throttle for about a minute, and then stopped it.
Refuses to re-start as ever.
The plug is wet, so flushed with brake cleaner and it nearly restarted, but has not run since.
If I leave it for 15 mins it almost starts on the first kick, 1/8 throttle open. There is no choke on this carb.


I know the petrol down the plug hole has never given any hope of a start in the past, so will try again for the last time.

I am getting nowhere now, just ploughing the same field time after time, so I think it is time to strip the engine out and fit lip seals both sides of the crank. I can fit them I think so they can be removed without splitting the crank cases or removing the engine.
Pity to take 1/2 the bike apart for this, but something has to change to get this sorted.

Bigger pity is a French man emailed to buy the bike! Typical.

[iansoady]

Sell it to him quick......

Tell him "needs slight adjustment to the timing".

[mini-me]

Bigger pity is a French man emailed to buy the bike! Typical.

The lord moves in mysterious ways, [so I am told] get shot of it quick!!

Then again yesterdays date might be a clue, its a poisson d'avril over there.

[Terrotmt1]

Tempting, but I can't do that.

Firstly, I HAVE to sort this out for my personal satisfaction. I have never been beaten by this kind of thing, can't break the mould!
Secondly, I'd feel guilty! 

Tried the petrol down the plug hole again, level tea spoon full, put the plug back in PDQ and gave it 10 good kicks with a hint of frustration with each stab in 1/8 open throttle.
Nothing.
Time this afternoon/tomorrow to take the engine out, bike down into the shed and strip it down for the lip seals.

Finally, never thought of the April fool's Day.....

[Terrotmt1]

I know Colin said no, but why not just fit these?

http://www.vxb.com/v/vspfiles/photos/KIT17764-2T.jpg

[mini-me]

If a two stroke four strokes it is generally because its got too much fuel.

It be a bugger if when you do get it running it will be doing that lovely two stroke trick of running backwards!!!!

[Terrotmt1]

 

I can get jets for the Villiers carb easy. Might get some smaller ones and try it before dragging this engine to pieces.

However, the thing will not even fart with the tiny original carb! (good nick, correct jet)

[The Artful Bodger]

You say that with the Villiers carb it started ran (after a fashion) for a bit then stopped with a wet plug. Cleaning the plug then putting petrol down the plug hole is a bad move, why put more petrol inside the engine when the plug came out wet, you're doubling the problem.
  Wet plug means too much fuel OR engine missing and not burning the fuel.  A wet plug really points against seal issues, how can fuel be getting up into the cylinder if the seals are leaking? A seal issue would mean no fuel is reaching the cylinder to fire, or it would be running very lean as air is getting sucked in. Either way not a wet plug.
  Try turning the petrol on from the tank and allowing the carb to fill, then turn the petrol off again. If (and when!) you get it started, as the level in the carb drops the engine should pick up and run smoother eventually revving right up as it runs out of fuel. If this doesn't happen then it's an ignition issue.

Colin

[Rex]

Is the carb definitely the right one for this bike? Wouldn't be the first project that's had any old carb stuck just to sell it.
That, and you can't trust the Frogs....

[mini-me]

 ze frog zey have ze chatback answer.

https://youtu.be/-Ro4DrewXHE

[Terrotmt1]

Colin always puts a smile on my weary face!

OK, when the engine/Villiers ran the other day it sounded'4 stroke' just as the engine has in the recent past with the Big Chinese carb on.
With both carbs, the engine will die when you fully close the throttle, and this I did the other day with the Villiers carb.
I guess it took 4 or 5 secs to stop. This would be normal operation.

The engine would not restart 10 seconds later.

After a rest of 15 mins I tried on 1/8 twist and it sort of hinted at a start but did not.
Took the plug out and it was wet (not oily and not black)

Cleaned it with brake cleaner and dried it. Re-fitted, and 20 kick, nothing but sometimes a hint of combustion.

It has not run since.

A few hours later, dried the plug and a dose of petrol down the hole, absolutely nothing during 20 kicks.
Put the bike away and wrote my 'Garage Report' above.
Did something far more positive after.

The sporadic nature of starting is silly, I have the spark at the right time, I have the carb selection (only the larger than original work) and the right fuel/mix.
I'm told elsewhere that the ethanol content in the fuel will stop it running, but I don't buy that.

The original carb is in great condition yet nothing happens.
When it does start on the big carbs although it is heavy and a bit smokey it does feel it would run for ages, no delay in responding to the twist grip, dies only when you fully close the throttle.

Does the bike run rich? Yes, I would say so, will it run with the smaller carbs? No.
Last week I gave it a go with the original carb, lots of kicks, choke plate over the inlet, and off etc and absolutely nothing. The fuel is right on the top of the vertical tube where it breaks into the main diameter of the carb. The mounting is tight to the port on the head, no filter fitted (it has a steel cup disc that mounts over the choke plate.

There we have it.
This is the original carb all cleaned inside and out. Piston is a nice slide fit, all holes and drillings are clear, float shuts off etc.

[iansoady]

Possibly when you close the throttle the mixture is going very rich (high inlet depression sucking excess fuel through). This may be flooding the crankcases hence its refusal to start. Your wet plug reinforces this view.

Why not set the carb so it does have a tickover position (via the cable adjuster if you have nothing else). With a 2 stroke even if you have the right mixture going into the crankcases, what actually arrives at the combustion chamber may be quite different.

And what the bodger suggests makes sense.

Mind you I am by no means a 2 stroke expert......

[Terrotmt1]

Interesting comment! (not that Colin is right... )

The bike is stopped by this method of fully closing the twist grip.
There is a 'Z' groove in the twist grip that is so formed that the start of the movement is where the carb is total closed off, then you get to the diagonal of the Z which is the throttle range and then it can stay at full throttle(!) The twist grip has to be turned to close the carb, it will not self close by design.
Maybe this is a early form of French Cruise Control...

It is easy to make and fit a brass finger that can ground the plug to stop the engine so stopping the fuel draw, good thought, but, again, the bike did not have this originally, so whatever they deisgned worked.

Maybe this engine is just too tired.
If I can make a better sealed primary case it will benefit the whole cycle. Getting a higher upper cylinder compression number will be hard to do.

[Terrotmt1]

Spoke to a recommended specialist today on 2 strokes, vintage to racing bikes.
'We' have done a lot of good work, and he agreed that it is something basic that is amiss.
He feels the primary design is good, so do not strip it yet.
After all the fuel tests/carbs etc he was suspicious it does not react to the kick with far more sucsess, esp the fuel down the hole.

This sent me thinking (yep, dangerous) about the sparks.

Magneto

I do not have the resistance values for a good coil on the magneto. Anyone hazard a guess for me please?
I have still the original HT lead on the bike. Connections are sound, contact to the coil is good (spring loaded brass button onto a brass tab on the coil). Any point in changing this lead considering there is a flow of sparks with the plug out?