Author Topic: Terrot MT 1, 100cc 2 stroke: non-starter!  (Read 5485 times)

Offline Terrotmt1

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Re: Terrot MT 1, 100cc 2 stroke: non-starter!
« Reply #210 on: April 09, 2018, 11:26:02 PM »
At the first strip down, I tried to remove the bush to replace it with a close fitting sleeve, but it will not shift and that is with the case really hot.
The crank journals are round and clean, the bearings are 'ok' but new ones will be better.
The lip seal is tolerant of some movement as it obviously conforms to small variations.

I've made up my mind to lip seal the crank just as my Lambretta was.

As to the cylinder bores; I will attack them tomorrow and see if any carbon I thought/think is steel comes free!
It is hard to photograph them but I will try again after my attack.

The transfer passage (single from the lower case) splits into a 'Y' within the barrel, my pic above is of the smaller of the Y passages, the main inlet is much larger, maybe 3 x the area.

If a good 2 stroke is a knacker'd one, mine should be hypersonic in performance (and start on command)!

As I said before, I fear there is nothing I can do to improve the barrel/piston fit, the rings are new and the ring gap is about 5 thou (2 rings).
A fresh standard dia piston would be better, but there are no score marks on this piston, no obvious wear marks etc.
The step at the top of the bore is extremely light now all the carbon is off.

I believe the barrel is original. The model (up to 1949) of this bike had a very different barrel, twin exhausts pipes, single carb, same spec as mine.

I will ask Chambrier if they have any oversize pistons, they have been good in the past to me, but none show on their site.

Hope to get several hours on the engine tomorrow. Thanks for your continued patience.

Offline Terrotmt1

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Re: Terrot MT 1, 100cc 2 stroke: non-starter!
« Reply #211 on: April 10, 2018, 09:02:34 AM »
Chambrier have oversize pistons with rings!
Std is 48.5, 49/49.5/50mm dia are available, 90 Euro.

Been busy.

The piston I have is 49mm so the engine has seen a rebore of +0.5mm in the past.
Went to V Services, and the Man was not impressed by the bore, "stepped and scored", "it's French so probably crap" (must be Colin's son)
He thinks a 50mm piston is best and that will get everything fresh assuming Chambrier have a NOS 50mm as they advertise. I await a reply from them.

The bearings and seals arrived from Simply Bearings, a 24 hour service for 18, not bad.

VS cannot machine the case for the lip seals on the (brass bush) magneto side, so the case will have to be machined somewhere here.
The new lip seal is 22mm OD and the brass bush about 21.3mm OD, so all can be done.
Wish I was back at work so I could DIY this in the proto shop.

So, my plan is to get the case machined and put the engine back together.
It is nothing to slip the piston/barrel/head back together and see if it will start/run.

If it does, then it gets sold.

If not, then I will get the piston and the barrel sorted and back together.
If this works, then it gets sold and someone gets a bargain and I get my life back.

If I do this what clearance is right for the piston/barrel?
Does 0.003" sound right??

Here are the pics of the ports.

You lot WERE right about the one port. There was an edge of hard grey crud on the edge or the port (exhaust) so I've clear the lot, not a lot came out to be honest, about 8 grains of sugar if that.
All are nice and open now:

Inlets: The port with the 'v' shape in one edge is from the carb. the other port is from the case under compression, transferred up the single port in the barrel base.





Exhaust (previously questioned)



Piston:

free photo hosting
« Last Edit: April 10, 2018, 12:24:08 PM by Terrotmt1 »

Offline john.k

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Re: Terrot MT 1, 100cc 2 stroke: non-starter!
« Reply #212 on: April 11, 2018, 04:41:25 AM »
Lawnmower technology all the way..not even loop scavenge.....certainly not going to be a rocket ship.....on the bright side....you wont be getting any speeding fines.

Offline Terrotmt1

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Re: Terrot MT 1, 100cc 2 stroke: non-starter!
« Reply #213 on: April 11, 2018, 01:56:04 PM »
Yes indeed, something of an obstruction on today's road, esp around here where bikes are invisible.
I won't ride it, restore and sell is my objective.
Wish the machine shop would hurry up!
Gasket cutting today.....   :o