Terrot MT1 Motorcycle restoration project

[911hillclimber]

Ian, firstly, thank you for taking the time to read and respond to this problem, you too Ashley.
Secondly, the Frenchman had filed the piston sides, not the lower ramp.
The ramp is as made by the factory, or rather its shape is.

I still feel it is simply too rich, but the float level is right and the needle is as deep into the jet as possible.
The inside dia at the top of the jet is looking far to big due to wear.
The main jet tube and bottom jet are the correct numbers for the carb on this engine.
Needle looks original and not worn, all parts are brass.

I can only weaken the mixture by fitting a fatter needle or a jet tube with the correct diameter.
Cannot find a new jet, or indeed any new or old parts, so it is down to what I can Machine on my lathe...

[911hillclimber]

I thout my 2 readers would like to ee the inside of this carb.
Also, measured the Dellorto carb which choke-wise is the closest I have to the AMAC for the diameters of the needle shank and the jet tube.

Del: Needle = 2.4mm, AMAC = 2.43
Del: jet tube = 2.68, AMAC = 2.88 or greater.

The Delolrto is new, so there is a dia difference of 0.28mm
The AMAC difference is about 0.45mm

Now, the AMAC is well worn, so I am thinking the difference should be the same as the Dellorto.

By fitting the Del needle to the AMAC jet tube I can get close to 0.35mm dia difference, maybe tighter.

So, that is the next move. I think I've been here before, been through so many combinations, but worth a try.

[Nine One One]

Graham,

In any of the pictures you show of that carb, it just looks ‘shagged’

Even the jets in the equivalent of the emulsifier tube look like they have been reemed out with a small uneven file?

Have you thought about a petrol lawn mower carburettor? Might be cheaper in the long run.

https://www.ebay.co.uk/itm/HONDA-CARBUR ... SwFutdR~ez

https://www.amazon.com/GOOFIT-Carbureto ... B07CC96JH1

https://www.ebay.co.uk/itm/15mm-Carbure ... 3038181515

https://www.motorcyclepartswarehouse.co ... gIzsvD_BwE




Even if just to prove it will actually work properly with something, it would just be the case of you making an adaptor to fit it to your inlet port (nothing for a man of your engineering expertise)

This seems a bit over complicated as to how a two stroke carburettor works........https://www.youtube.com/watch?v=tqfQ6B2_o_c

[911hillclimber]

Ok, I'll give another carb another go.
Have been through 3 modern Chinese carbs, all made beautifully and so cheap.
Might work!
Yes, the carb looks tired, 70 years old and has been touched by a French mechanic or 3 + me.
Christ, it's even older than me!

It will be interesting to see if this works.

[911hillclimber]

So, if some of you saw the thread on Easy Start you will know the story so far! ( )

The trials with the new Dellorto jets continues, and I seem to have a black damp plug so far, but with 'easy' starting (ish) so some more tuning required when time allows, but a thought occurred to me about the plug.

I know nothing/little about the heat ranges of plugs, but know the wrong heat can cause issues.

Thus anyone know which plug might burn better in this engine?

The new plug I have used came from Villiers Services, for this engine as their 'best guess'.
The code is Champion L82C.
I wonder if a different heat range might give a better burn?

The original plug still works:
Code is KLG Corunoite (KLG CL1)

Any thoughts please?

[Lightweight_911]

.

I'm sure you've already seen this page but it contains a lot of info on Terrot spark plugs:

http://terrot.club.pyreneen.free.fr/bas ... m-0001.htm


I'd be inclined to try a few different heat ranges of plug - NGK is always my preferred brand.

By way of an example, the engines in both my Giulietta Sprint & my Seven (Coventry Climax) are sensitive to the heat range of the spark plugs - too cold a plug & they won't start (or are very reluctant) ...

[911hillclimber]

Thank you Andy, Good job my wife is fluent in French.
Bed time reading!
I cannot find info on the plug that came out of the engine, but the engine will run on it.

[Cortina]

I would go for a more modern plug - an NGK , of the EV (memory ??) type - ie with a finer wire central electrode. It's obviously a short reach plug and I would not deviate from standard in terms of heat range number. I would be surprised if google did not turn up an equivalent to the champion one - but as you said that is only a best guess.
plugs make a big difference !!

[Cortina]

B7HV would be where I would start ?? (It's the V which is for wire central electrode)

AC

[911hillclimber]

Go idea!
The original plug is so old there seems to be little reference to it except the Matchless forum, and then it is vague.

There are lots of comparison charts I've stared at today, but I couldn't get a base to start with that is the same as the CL1 plug.

The CL plug I have has seen a lot of filing over the French Years...
Hope to find a plug tomorrow at Halfords or ebay.

Want a plug tomorrow so I can have a good go at the thing this weekend.

Thank you for your continued support, it gets me down at times it has gone on for so long, bloody thing.

Do I ever look forward to selling it.(running)

[Ashley James]

I’d use an NGK B5 or 6, 7 might wet easily

[Nine One One]

Graham,
These should help

https://www.opieoils.co.uk/t-spark-plug-heat-range.aspx

https://www.ngkntk.in/ngk-technology/im ... eat-range/

https://www.gsparkplug.com/shop/spark-plug-heat-range

[911hillclimber]

Thank you both!
I looked at the Green Plug site yesterday but missed the guide.
All 3 are useful, on the NGK site the bike's plug looks like #1 but damp or sometimes wet.

After each run where the engine self dies, I wash the plug with brake cleaner aerosol, and it washes off readily, wipe clen with a rag.

I'll get a range of these plugs to play with, a cheap experiment.

[Ashley James]

You need a brand new NGK plug as recommended for a BSA Bantam.

B is 14mm P is for a projected nose (not needed) 5 is the heat range (10 being an all out race plug) H is short reach and E longer thread and I’ve forgotten what the S stands for and can’t find my old plug book.

Two strokes are bastards with plugs, so always start with a new one.

Back to making Italian meatballs now.

[KS]

I'm sure you've mentioned it several times, but what two-stroke oil are you using and what mix ratio?