Kick starting a Mc101

[ozflea]

I posed the question on another forum called hand starting a Mc 101 and heres the reply i got from Steve O'Hara ace McCulloch man on Kart engines.

Starting with my question.
Well Steve this 101 i own is a brute of a thing and since i'm not built like the back end of a bus how do i start this thing by hand starter, i know that i should keep the head close to the piston but even with a decompressor fitted it near tears my arm out of it's socket as it blows the decompressor closed after the first pass that wacko Bob's on his way to hospital armless again.

Can i find a way of lowing the compression and still have a competitive engine or do i do away with the hand starter and go electric start, ie 12v car engine starter.

I feel that if i persist in trying to hand start this beast i'll only end up with a heap of broken bits and pieces.

What thickness in head gaskets are there to assist in adjusting it to something more suitable.

Mc Bob.

P.S You were right about that Galvin manifold and the BDC's i may have to make something to suit the top of my V12 reed manifold as i have one already.
How would 2 BDC's go on top of the V12 providing i got the adaptor machined up ??
_________________
The one eyed Mac Man from downunder

Steves Responce.

Bob,

If it were me I would design and fabricate an on board starter powered by a compressed gas canister like they use to charge up paint ball guns.
Of course that would take a bit of engineering and fabrication skill that may be unavailable so here is another idea.... the problem is not that there is too much compression... it is that the motor wants to fire on that first pop and you don't have enough torque or inertia to carry through the top part of the stroke and get the combustion working for you. The solution is to rig up a simple kill switch with "doorbell" type switch. Mount it so you can hold it down with your thumb or one finger of the hand you use to hold the saw and wire it to the "off" position while it is depressed. Hold the button down while you yank the recoil handle and let it up after the motor is cranking over.... basically as you are nearing the end of the full pull of the rope. I'm betting you would find that you can get a full pull of the rope without kick back if you have no spark so the trick is to disable the spark until you have the motor spinning and you are ready to let go of the handle.
Hope this idea helps..... let me know how it works out.
Regards,
Steve O'Hara

Hope this info helps out my fellow Mc 101 lovers who wish to save on starter ropes and starter components.

Mc Bob.

 

[paz]

bob i reckon you should do the honourable thing and "loan" it to a young tacker thats stupid enough to keep trying to start it even after he has had his fingers stretched........did i mention my hand was up...hehe

 

[shtoink]

I have been wondering if it would be feasible to setup some sort of pneumatic wrench to start the saw with. Have an air compressor an air wrench handy, connect it, pull the trigger and go. It sounds like you could eliminate the pull start completely and shave some weight, too. I guess the main concern would be undoing your bolts with it. I'm a newb on this one for sure, so let me know it this just sounds like a half baked idea.

I guess the another idea would be one of those kick starters that you would up with a couple kicks to get the spring nice and tight and release with a button. Maybe something simple like that would work in combination with a pull starter. Give it a couple quick pulls to charge and the git the button to release.

I'm just trying to look at this with fresh eyes and throwing ideas out. It's usually the crazy ideas that turn out to be the good ones. I just hope these are crazy enough to work and not retarded.

 

[Al Smith]

Well,the impact wrench would be an option except for one thing,it would spin the nut off the flywheel.The engine rotation is clockwise looking at the clutch but counter clockwise looking at the flywheel and it has a right hand threaded nut.It was thinking out of the box though and a good hearted effort.

 

[whatsnext]

Well,the impact wrench would be an option except for one thing,it would spin the nut off the flywheel.The engine rotation is clockwise looking at the clutch but counter clockwise looking at the flywheel and it has a right hand threaded nut.It was thinking out of the box though and a good hearted effort.

You might be able to do as he says if you bypass trying to use the flywheel nut as the drive. Some sort of keys cut into the flywheel would make sense. I wonder if there isn't some way to kill the ignition for the first couple of revolutions to allow the operator to build up some revs before the ignition kicks in? Also,I'm not sure why these things would be that hard to start but who knows. If you could make an adjustable timing plate, it would allow you to retard the timing a bit for starting. My grampa's farm tractor had just such a device so it's nothing new.
John............

 

[Al Smith]

It is,in fact the advanced timing that causes the kick back.The timing plate thing has some merit.Another option could be a trigger device,in place of the points with a detector to increase the timing at a certain rpm.I've thought about it but too much thinking causes my head to hurt.

 

[cbfarmall]

You had to be careful hand-cranking those old tractors. One false move, and you could put your elbow into your teeth. Before the spring timing advance, those old magnetos had the manual detent levers. Just had to remember to retard the spark.

Chris B.

 

[ozflea]

Thanks fellas for all the tips and words of wisdom, i think i'll take the option of a younger and bigger fella to run the Mc 101, i'll just stick to the 91b/1 to make sure he's working hard as it's been my main comp saw and so far has been the one to beat, i'm not saying that the 101 aint quicker but at least i can start my other 2 as i have a quick Mc 92 as well that i'm putting back together now into a new chassis and i'm building new fuel tanks for the 3 of them.

I was talking with young Justin Beckitt Australian Champion Axeman and since he's big enough and strong enough to hand start a jumbo jet i might offer him the chance of running my Mc 101 as a partnership type thing, ie my saw but he does the sawing.
Besides that he doesn't live to far from me and i have known his old man for many years. And we could with a little luck be a good team.

There's more than one to skin a cat ya know.

Mc Bob.

 

[shtoink]

You could put a hole thought the crank shaft to allow you to put a locking nut on it. What I am thinking of would be similar to those you find on the end of your drive axels. I just wonder if the sheering forces would be too much for the shaft after a hole was drilled sideways though it. I imagine that it would be a non-issue, since the crank shafts are usually drop forged and pretty stout.

Also, the doorbell type switch could could be downsized to a much smaller component that would easily embed into the handle. You could use one of those very small micro-switches and place it were you can depress it with your thumb while trying to the saw started up.

I suppose you could use an electronic device that monitors the rpms on the flywheel and kicks the spark on automatically. Something like one of those speedometers you use for bicycles might be a good start. You could possibly even do the monitoring and simple programming with those robotic legos.

 

[GOBRDGO]

If anyone has to figure out how to overcome this problem it would me. So far I put all my eggs in one basket and don't have time to reinvent the wheel if I want her ready by the 28th of August. Not all competitions are cold start right? The time starts the while saw is already running? That's my only hope for now. Also has anyone enlarged the pull rope hole in the aluminum pulley in the pull start to allow for a larger rope? I have a slightly larger rope but I can't get it thru so far.

 

[shtoink]

I believe that the hole in the crank shaft to prevent the nut from spinning of and air wrench would be the simplest. Even a high torque/rpm electric motor with a socket on the end might be better than an impact wrench.

This just popped into my head...

You could utilize the pully for the pull starter and get it started with an electric motor and a v-belt. The motor is sinning like crazy, they so go, you apply tension to the belt, and it fires off.

Should I stop with the ideas? I guess this is the reason I am going to school to be a mechanical engineer, huh?

 

[Al Smith]

I
This just popped into my head...

You could utilize the pulley for the pull starter and get it started with an electric motor and a v-belt. The motor is sinning like crazy, they so go, you apply tension to the belt, and it fires off. [end quote] This is exactly how they were started as kart engines.Back in the 60's[before the 101 Mac] they used a long shafted Ford starter with a vee belt pulley,to a special starter cup on the engine.Some of those engines had so much compression they had to reinforce the heads with long bolts ,through a piece of plate aluminum ,over the head and extending past the stuffing box to another plate. Running on alcohol fuel mixture,you absolutely could not pull them over by hand or at 15 years old,I couldn't. Those engines could,at best,make 10 or 12 races,before a rebuild.

 

[ozflea]

Actually i'm building a 12v starter unit as i type, got most of it built i used a early Ford 4 cylinder starter motor without reduction drive and fitted a Kart pulley to the flywheel side of the crank should have it finished shortly so i'll post a pic or two.

This is all built on a 1/4" base plate as i don't want this thing jumping around all over the place when i attempt to start the saw, it will have long leads to the battery and the saw will sit in a special forked cradle, only needing upward pressure on a belt once the starter motor is turning, once hopefully the saw starts all i have to do is lower the rear handle and move the saw sidewards to free it of the starter unit.
Note i may use a foot operated solenoid to activate the starter motor.

Mc Bob.

 

[GOBRDGO]

Shtoink, That's worst case scenario starting methods but cool. I'm closest right now to hand wrapping a rope on a pulley (like ancient snowmobiles or outboards used) to start her. This will eliminate the tiny rope diameter choices and recoil mechanical failure. I also want to incorporate the ignition control stated earlier by O' Hara. By the way I met a crane operator that used to know that guy way back in the day. We had a great conversation about alky tilleys and the golden age of MACS

 

[paz]

bob was going to sugest something like that,,,,my dad has a power saw(similar to hargan) with a briggs on it that he cant start now he is a little older,,,he made up a system that u slipped the starter onto 2 pins ,,the starter has a pipe handle attached to it and u just use a v-belt and push to tighten it....easy as...your idea for a cradle was exactly what i was thinking,,,,mac men think alike....

 

[shtoink]

I'm just glad nobody said my ideas were half baked!

 

[ozflea]

Well fellas here's the starter assy 12 volt.

I have sat the Mc 92 i'm working on to show the setup of cause the lump of wood propping up the back of the saw is not part of it as you sit the lower section of the handles in the cradle feeding the belt into place over the pulley and pull up as the starter motor cranks the saw over.

Hey presto 1 electric starter for a Mc 101.

Mc Bob.

Just needs sandblasting and a little Yellow paint and she's done.

 

[paz]

all you need now is an old foot solinoid starter set-up off an old austin truck or somethin and she'd be a ripper...pull up,,,foot on solinoid.....brroooooommmmm....im guessing your going to have a side cover on so the belt or fingers dont get wrapped up in the fins when she starts.....

 

[GOBRDGO]

Looks like it will work Bob.

 

[ozflea]

We'll soon get to see how much grunt the starter motor has when i hook up the 101 to see if it works or not.
Yes the motor in the pic's is my Mc 92 currently being set up in it's new chassis i have only to fabricate the upper brace between the front handle and the rear handle grip then i'll give it a test run followed by a strip down and a repaint.

Mc Bob.