Hard Starting T140V

[Walterph]

I have 1973 T140V. As far as I know it's internally stock, but have no way of knowing. It has 2 into 1 exhaust and Boyer Micro-Mark III electronic ignition.

It kicks back really hard when trying to start it. I have to jump and kick it hard (I weigh 200 lbs -14 stone for those across the pond) to make sure I get a complete stroke of the kick starter or it will kick back. The timing is right. Carb adjustment is close. I see others that basically just push the starter lever through its stroke with just a little effort. What could be causing this?



Walt

 

[solomon]

I have basically same bike. A '72 T120V upped to 750.

First off, I often find it very hard to kick through to start. I don't think it's just my technique, sometimes with full weight doesn't stroke through, stops at second compression. When cold (5⁰C), I had to warm it up overnight in house, couldn't turn engine over. I'm medium weight.

*
Second, there was a time it would badly kick back. Ended up being scared to kickstart it.

It might be your timing/the Boyer. I think my micro Boyer didn't work properly. When set correctly at high revs, think it was too advanced at low/idle. I swapped it for a Wassel electronic ignition and problem disappeared. Never kicked back since, or not with enough force that I remember.

 

[ManInTheJar]

I have 1973 T140V. As far as I know it's internally stock, but have no way of knowing. It has 2 into 1 exhaust and Boyer Micro-Mark III electronic ignition.

It kicks back really hard when trying to start it. I have to jump and kick it hard (I weigh 200 lbs -14 stone for those across the pond) to make sure I get a complete stroke of the kick starter or it will kick back. The timing is right. Carb adjustment is close. I see others that basically just push the starter lever through its stroke with just a little effort. What could be causing this?



Walt

I have a 73 TR7RV which I've just finished working on and had to work through some starting issues including being hard to start, kickback and overheating headers.

Kickback can be due to timing which is too advanced and/ or a weak mixture. First things to check are timing, air leaks on the inlet, valve clearances and plugs. Basically systematically working through all the settings, even those you think are OK.

In my case I set the static position of the ignition stator plate following the Boyer installation instructions (white dot through hole at full advanced position) then tried retarding it (clockwise) by small increments until I got to the point where it would start and run cleanly enough to set the timing with a strobe light when I found it was still slightly advanced.. I also found a slight air leak on the carb outlet.

I was working with a new battery and plugs (B8ES), newish Amal Premier Mk1 and new HT leads.

I found that a small change in timing had a huge effect on achieving a clean start, kickback is now gone and the bike starts and runs well. BTW I start it on the mainstand sitting on the bike, I find that is safer if you get a severe kickback.

 

[Walterph]

So, I finally had some time to check on my Boyer wiring. turns out the red wire from the boyer, and the red wire to the frame from the coil were on opposite terminals on the coil. The black jumper from the coil was attached to the same terminal as the red wire to the frame. My assumption is that this was causing a voltage drop to the Boyer (since the power lead had the coil resistance in series). Fixed that and kickback and hard starting has been solved. Seems to be running better overall. I'll blame the PO 'cause I don't remember doing anything with those wires, but since I can't even seem to remember where I put my coffee cup who knows?

thanks for everyone's input. I can now safely push the kick starter with no fear.

 

[Rocky]

Good news
Thanks for the update

 

[Rudie]

Boyer wiring
the red wire from the boyer

... should be connected directly to the battery +ve terminal. It is the supply to the "Transistor Box" electronics, they only draw about 250 mA so essentially there must not be any resistance between battery +ve and the Box; connecting this Red wire anywhere other than the battery +ve terminal increases the possibility of resistance in additional but unnecessary connections, or resistance developing over time.

the red wire to the frame from the coil

While this is what is shown in the Boyer fitting instructions, it is poor in practice.

Any electrical circuit starts at battery -ve and ends at battery +ve:-

. as standard on your bike, the ignition circuit is from battery -ve through the ignition switch and kill button;

. Boyer fitted, the kill button White/Yellow wire is connected to the Transistor Box White wire, the Box Black wire is connected to the coil (should be coil -ve);

. coil +ve to battery +ve, there is no useful purpose connecting the coil to the frame and then relying on a random connection somewhere else on the frame to battery +ve - as with connecting the Box Red wire anywhere other than the battery +ve terminal itself, this increases the possibility of resistance in the additional but unnecessary connections, or resistance developing over time;

. I always connect coil +ve either directly to the battery +ve terminal or at least to a nearby harness Red wire - as standard, all harness Red wires are connected to battery +ve.

The black jumper from the coil was attached to the same terminal as the red wire to the frame.

You are lucky that did not toast the Box.

the coil.

The original pair of coils has been replaced with single one with two HT leads? If so, it is possible the coil LT terminals or wires are not marked -ve and +ve, wiring convenience or best guess.

since I can't even seem to remember where I put my coffee cup who knows?

If you connect either both Box and coil Red wires to the battery +ve terminal, or the Box Red wire to the battery +ve terminal and the coil Red wire to a harness Red wire, reduces the possibility of later mistakes.