My '74 Mar is really, really difficult to start from cold. Lots of kicking, plug heating and tickling it eventually fires and runs.

 

There's no 'almost starting' - the penultimate kick is no different from the previous 20 (or 30). 

 

When it's warm it runs and ticks over fine and will re-start first time but leave it a few hours, let alone days, I'm back thinking of selling !

 

Current plug is an NGK BP5ES 

 

Any ideas ?

 

 

Low compression or faulty Motoplat ignition. 

 

http://www.uk-motoplat.com/home.html

I tend to think the Motoplat ignition is failing so a repair or new system from Steve Sell Marlimar OSSA.

I run an NGK B7ES in my 250 gripper, I have tried a 5ES once but it ran very hot and nearly nipped up.

I would look at the flywheel/back plate position to top dead centre, i think from memory i have mine set at 2.5mm before tdc. Also whilst your in there change the crank seal.

I once had the opposite of your problem, bike started great warm the engine up ride to the first section walk it then return to start the bike - nothing? when it cooled it would fire up it turned out to be a faulty spark plug cap.     Steve.

 I doubt the stator is the issue if it runs good when warm. At 40 years plus the seals are more likely the problem. Speaking of the stator, has the wiring been moved to the top of the case? When new, they were under the motor.

Edited June 12, 201511 yr by lineaway

Tickling! that takes me back. I remember you really had to flood some of the old bikes (Bultaco specially) to get them to fire.

 

Just a guess, tip the bike over until you see the fuel run out the carb and see if that works.

On my own 1976 MAR it was always difficult to start until I replaced the Amal concentric carb with a VM 26 Mikuni.

{these have a proper choke circuit instead of the silly Amal tickler idea which seems only good for washing the engine clean}

starts with 1-2 kicks ever since .

As other people have mentioned , could also be Crank seals or ignition playing up.

hope this helps

Is the plug fairly dry even after all that kicking?

If so it sounds like worn bore and rings.

From cold it's not creating enough suction to lift enough the fuel air mix to fire up.

 

Once you've finally got it running and warmed up, the piston and rings have expanded enough to create enough of a seal to fire up again without issue, that is until it's cold and the piston has contracted.

Edited June 12, 201511 yr by goudrons

On my own 1976 MAR it was always difficult to start until I replaced the Amal concentric carb with a VM 26 Mikuni.

{these have a proper choke circuit instead of the silly Amal tickler idea which seems only good for washing the engine clean}

starts with 1-2 kicks ever since .

As other people have mentioned , could also be Crank seals or ignition playing up.

hope this helps

The tickler actually put fuel in the cylinder. Worked much better for starting purposes. And yes I had a Mar when new.

The tickler actually put fuel in the cylinder. Worked much better for starting purposes. And yes I had a Mar when new.

You may well have had a MAR when new { I don't see what difference that makes } , but I know from my own experience with my own MAR that starting was terrible with the Amal , but has been much improved with Mikuni fitted the last 5 years.

I never found that tickler thing to be good for anything, apart from soaking the spark plug {and engine cases}.

anyway some people love Amal carbs & have no problems with them, you must be one of those people and I am glad it worked ok for you.

One thing to remember if it your MAR still has the original AMAL concentric carby, is that for the fuel level to get high enough to run into the engine while tickling (which is what you want) you may need to lean the bike over a bit towards the side opposite the tickler. If you have the bike vertical or leaning the wrong way while tickling, the fuel runs out the tickler tell-tale hole, rather than into the engine.

I have the original AMAL carby on my M49 Bultaco (and it still works beautifully) and unless I lean the bike to the left while tickling, no fuel goes into the engine, it all comes out the tickler tell-tale hole.

You may well have had a MAR when new { I don't see what difference that makes } , but I know from my own experience with my own MAR that starting was terrible with the Amal , but has been much improved with Mikuni fitted the last 5 years.

I never found that tickler thing to be good for anything, apart from soaking the spark plug {and engine cases}.

anyway some people love Amal carbs and have no problems with them, you must be one of those people and I am glad it worked ok for you.

Yes, I always got along with the Amal. Had one a Cota 200. Anytime that bike did not start in two kicks meant that the pilot jet was plugged up.

Remembering back to my last encounter with an Amal carb, an old way was to hold your thumb

over the tell tale hole to prevent washing the engine and putting the fuel where it belongs.

I have 5 Amal 627's on hand in a box on the shelf.

At the present time have 1 Mk 1 MAR in the family presently (Mikuni carb of course).

The Sammy Miller Highboy I have still has the Amal. One kick wonder. Point being, no matter what carb you have it all comes down to everything being set right. Good luck.

You've probably got this sorted now but the only MAR I had difficulty starting had the same symptoms as yours, the previous owner had started it with ether for years to save messing about kicking and kicking and once it had been run it would start reliably all day even if it was stood several hours.

 

The problem was piston rings that were so worn they were less than a 1/2 of the thickness they should have been. A new set of rings (the bore was still ok(ish) and it started from cold no problem with just the tickler to flood it.

Incidentally it didn't really feel down on compression when turning it over on the kickstart.

 

If you have checked everything else then I would have a look at them, or even borrow one of the screw in compression testers with a flexible pipe to test the compression accurately