classic motorcycle forum

Happy New Year to everyone 

I have just returned to working on my t140 (too little free time last year) and have started on the wiring.

I have managed to get everything to work with a little bit of playing with (lights, indicators, horn, brake lights including the tricky front brake switch) but I cannot get any joy at the sparkplugs. My bike is a 1978 t140v (pre electronic ignition etc., positive earth) but I have fitted a Sparx electronic ignition kit, 2 6v coils and new plus leads - I have also made sure that the cut off switch works correctly .

Tracing it through I have ~12v coming off the main loom at the 2 linked Yellow/White wires which I have connected to the white wire of the sparx ignition box but I only get ~3v out of the sparx ignition box via the black wire that I connect to the -ve terminal of the left hand coil. Where has the power gone and presumably because the coil is only getting 3v this is the reason why I am unable to generate any sparks.

Before I replace the ignition unit is there anything that I have missed or just got wrong?

Thanks

Mark

Dear L.A.B.

Thanks for your advice.

Going around the whole of the electrics I came up with two problems:

In the sparx left hand replacement switch internals some of the soldering was very poor leading to one wire being able to touch the metal case - I have now taken this apart and resoldered all the connections, and

In the rear light unit the small length of earth wire between the light fitment and the metal support had corroded. I have purchased a patent new unit but the wiring does not correspond to my old one. That had a brown and a brown/green whereas the new one has a black and red wire. Trying various combinations nothing works unless the red wire connects with the earth wire from the rest of the bike, fair enough but connecting the black wire I either get the rear light permanently on or only works with the brakes. How do I organise the connections so that the rear light comes on when the lights are put on and also shine (brighter) when the brakes are engaged?

Dear L.A.B.

Thanks again for your information and tips.

Best regards

Mark

Dear All,

Whilst working on restoring my t140 I am being to think that it may not be as original as I first thought and that some parts I have bought to help restore it may not be correct. My question is - is my t140 a proper t140e or just a t140v played around with? 

Its frame is DX07XXX and engine is t140e DX07XXX which I think that it was manufactured April 1978. It was first registered in Oct 1979.
It has amal Mk2 carbs with the breather tower into the air box.
It does not have an instrument centre console panel nor the more plastic looking black handelbar controls nor electronic ignition.

I have previously bought a t140e 1979 new wiring loom and have just noticed that for example, there are four lamp conectors for the front and I only have three warning lamps in the headlamp. This made me think that I should have bought a 1978 t140v wiring loom instead.

Before I waste any more drinking vouchers on the bike I need to make sure that I buy the correct parts!

Any thoughts would be appreciated.

Thanks
Mark

Dear All,

Thanks for all the comments.

£200 later and a lot of time it seems that the problem(s) might have been solved as the bike started properly yesterday. Some of the valves were sticking in the valve guides (hence I was loosing compression when the rocker boxes went on the cylinder head) and so to finally resolve that problem I have bought new valves and guides (from TMS) and had them professionally fitted and values seats done (at T&L here in Bedford). From LAB’s comments about timing I have rechecked this and it appears that the rotor mark seen through the timing hole was set against TDC rather than BTDC (checked this against Lunmad videos on Youtube – I think that these are very good). I now also have new rocker adjusting screws that use Allen keys (much easier than using the BA spanner type) and I have used loctite on the threads to assist keeping them in place. As far as setting the gaps I have now done by using the manual, seeing Lunmads video and also looking at Hughie Hancock’s videos so I am reasonably sure that they are correct. When the weather is good I will get in MOT’d and get it out on the road where it should be!

Next my 1978 t140e which is half complete.

Talking of which I obtained this as a box of bits and I am starting to work on the brake system. With the lockheed callipers I am looking to replace the pistons etc and give them a complete overhaul. The book says not to undo the bolts that hold the two sides together but since the callipers are not connected to anything and I cant get the rusted pistons to move, how else can the callipers be overhauled? I do not really want to get new ones and would prefer to overhaul as much as possible of the original bike

Thanks for the comments.

Taking the engine apart again, with just the cylinder head on (no rocker boxes) there is very good compression on both sides of the engine which I think means the head gasket and rings are okay. Fit the rocker boxes on and I lose compression on the timing side so I think that the valves are my problem?

So taking the cylinder head off etc I might get certain other work done, any thoughts on the following?

- any point having the cylinder head skimmed?
- my copper gasket is only 1000 miles old, anneal or replace?
- my t120 has push in exhausts, the t140 shop does a push in exhaust seal kit any one tried one of these?

Thanks

Taking the rocker covers off I discovered that the tappets have become undone (or have become loose) damaging the threads on the rocker arms and the tappets themselves and letting the pushrods come off. I am sure that my tappet gaps were correct and locked in place. Anyway new tappets and tapped rocker arms (5/16 CEI if anybody is interested, it also means that my t120 has unf,unc,cei,ba,metric and whitworth bolts etc!).

I have now put the rocker boxes back on with new gaskets and ensuring that the pushrods are on correctly (leaving off the carbs and rocker covers). The problem now is that there is compression on the left side but virtually no compression on the timing side even though everything seems in place. Any suggestions as to what might cause the loss of compression on the right side of the engine only?

I seem to spend far too much time in the garage than on the road!