Electric motor to aid timing strobe

[solostax]

Situation:
Have several old Lambretta engines that need completely rebuilding.
Having a good size brick built workshop (shed) with stripped Lambretta frame used as a rebuilding jig, I would like to complete everything whilst in the relative comfort of the workshop.
On re-assembly the ignitions will be upgraded from points to 12 volt electronic .
Although previously successful with written instructions as per timing set up, I believe some performance could be gained by more accurate timing.

Problem:
Strobing a running engine inside the workshop is obviously dangerous (toxic exhaust fumes, possible petrol leaks,noise etc) but running up outside, even for short times, will annoy the neighbours!
The inconvenience of re-adjusting the timing after fitting the engine in the frame and road testing, I believe, can be avoided by strobing prior to engine re-installation.

Possible Solution:
As per Sticky’s tip of using a powerful electric drill to turn the engine (minus spark plug!), I want to explore the idea of a more versatile purpose built unit to do the job.
In thinking about such a device, Certain criteria are born in mind:
a/ Not too complicated or over engineered.
b/ Needs to be inexpensive ,possibly utilising junked electric motor /hardware from domestic appliances or car parts ,(washing machine , car starter motor?)
c/ Adequate safety features including fast stop brake.
d/ Speed controllability , i.e. the ability to spin the engine throughout the revs range. Possibly a foot pedal (like on sewing machine?) to control speed.
Speed controller electronics are cheap and far advanced in the radio control model world. A high power unit might be suitable for this purpose.
e/ Method of mechanically coupling motor to engine.
f/ Need for top end lubrication whilst spinning up.

The above are some initial thoughts and would welcome any input /suggestions etc.
All the best.

[coaster]

My thoughts fwiw:

An electric or air powered impact gun would do the job as would a decent sized variable speed electric drill and both are reversible so you can set the direction to clockwise rotation. the downside would be limited revs but going up to full revs is probably not a good idea due to the lubrication issue you mentioned, if you squirt oil down the bore it's going to get blown straight out of the plug hole, you could get a bit messy.

Re model aircraft speed controllers, aren't they for adjusting the throttle on RC controlled models? unless you mean electric motor powered planes in which case I wouldn't have thought they would be man enough

[dickie]

£100 gets you a suitable inverter to use with a motor around 1kW.

Then you need a used motor around the same size. You'd get a used one from eBay for £50.

Next thing you'll need is an electrical engineer who's used to working with inverters to wire it up and program it. If he's any good he'll steal the potentiometer etc from work.

This will give you infinite variability from around 0 rpm up to about 2500rpm. With an encoder (add about £100) you can be confident that the speed on the display is accurate +/- 2rpm (ish) without one it's accurate to about 100 rpm. I wouldn't bother with an encoder.

You'll need a good base and a flexible coupling to mechanically connect to the motor.

[Eden]

Sod the neighbours

[dave411]

Too complicated for me

[CHRIS in MARGATE]

Certainly not going to run any engines without lubrication.
In over 45 years I've never had a problem timing my scooters and I don't feel that I ever will. Neighbours; well if you get on with them there's no problem. If you don't get on with them, then they'll have 5 minutes of noise to complain about. Cheap tacho let's you see the engine's timing characteristics.
Good luck with your project but for me (and don't take this the wrong way), you're trying to "fix something that ain't broke".

[solostax]

Hi Coaster ( I agree that the lubrication issue stops this going any further),dickie (seems you could make this a reality),Eden(Love the advice but fear there might be retaliation),dave411(I was seeking a simple solution but failed) Chris in Margate(I agree with your philosophy but the quest to improve never stops.)
Thanks for the replies, and bearing in mind I was fishing to see if this topic has been aired before, I am pleased to see it being taken seriously
There probably is a good percentage of Lambrettas running around that are not working at optimum due to either carburettor jetting not spot on or perhaps ignition timing that works but is not perfect.
So, in the interests of making the timing issue more accurate and thereby extending the engines performance and reliability this topic must be worthwhile.
With reference to Stickys manual that warns of Inconsistent quality of the Indian produced clone Stators and flywheels there is a case that reinforces the requirement to double check with strobing.
It was the simplicity of Stickys tip of using an electric drill that seems so appealing but had obvious limitations that I wanted to improve on.
There seems to be a few problems that are apparent:
1/ Can operating /observing the strobe and holding the drill be accomplished single handed?
2/ Is, even a powerful drill capable of taking the revs higher than low/mid rev range?
3/ Because operation rotation is clockwise, would it be necessary to fully torque up the flywheel nut to prevent the drill from undoing the flywheel between every adjustment? This would require the extractor to be used .

[dickie]

On point #3. I had wondered about that, but i feel that for the comparatively short duration of the test it wouldn't be a problem. Also if you used an inverter you could limit the acceleration as this is the primary source for torque, not speed.

Alternatively could you connect to the front sprocket? Personally I think that partially defeats what you're trying to do, but just thinking out loud.

Or through the rear hub? That way you could spin the crank up to ~10,000rpm

[johnnyXS]

excellent idea I shall follow this thread with interest.

[johnnyXS]

There seems to be a few problems that are apparent:
1/ Can operating /observing the strobe and holding the drill be accomplished single handed?
2/ Is, even a powerful drill capable of taking the revs higher than low/mid rev range?
3/ Because operation rotation is clockwise, would it be necessary to fully torque up the flywheel nut to prevent the drill from undoing the flywheel between every adjustment? This would require the extractor to be used .

I understand your predicament re the neighbours . Its not just about whether the neighbours would complain its more an issue of being considerate and treating your neighbours as you expect them to treat you... with consideration.

I usually make sure that my immediate neighbours are ok about my testing /tuning my bike and scooter because I know how annoying noise can be especially on weekends or when you have someone ill or babies sleeping etc.
It also depends where you live. If you live in a quiet cul-de sac of retired senior citizens most people would be considerate about noise or nusience ... If however you rent a property on a busy social housing estate then there is probably so much noise going on day and night that it wouldn't be an issue

Have you looked at the flexible drives you can use with electric drills ? this sort of thing but better obviously
http://www.ebay.co.uk/itm/915MM-36-LONG-FLEXIBLE-FLEXI-DRIVE-DRILL-SHAFT-EXTENSION-KEYLESS-CHUCK-/390822998670

If you want precise cheap rpm control look at the simple cheap electric motor controls used on electric bicycles or wheelchairs. No need to reinvent the wheel or use expensive industrial componants.

The reason engines get hot is mostly due to the heat from detonation although friction is a contributory factor. if you kept the testing to short periods and used a fan I doubt you would have any significant heat /friction/ wear problems but you can always stop and let things cool down if needed

[Meds]

Have you considered the dynamic balance between the motor and the engine
Using an electric drill allows the prime mover ( drill) to float to the engine and you have control over the alignment, and therefore the vibration.
A fixed engine-motor configuration will require some sort of flexible drive otherwise the imbalance will be taken up in the bearings of the motor and engine.


On a much simpler note
Some modern bench grinders have flexi drive connections and standard 240v speed controller may do the trick.
Try googling pedal operated speed controllers

[dickie]

Have you considered the dynamic balance between the motor and the engine
Using an electric drill allows the prime mover ( drill) to float to the engine and you have control over the alignment, and therefore the vibration.
A fixed engine-motor configuration will require some sort of flexible drive otherwise the imbalance will be taken up in the bearings of the motor and engine.


On a much simpler note
Some modern bench grinders have flexi drive connections and standard 240v speed controller may do the trick.
Try googling pedal operated speed controllers

You're right meds, I'd advocate the use of a flexible coupling. And if the intent were ever to spin the electric motor at 2500/3000rpm whether through the crank or layshaft I'd make a board with fixing points to make sure that each motor was correctly aligned. It's quite easy to isolate any misalignment by using the right couplings.

A bench grinder would run it up, but you don't have the ability to control the speed, which you don't absolutely need (you don't need to do any of this really but........)

I'm not really sure what you mean by 'standard 240v speed controller', but a sewing machine is very low power and basically uses a resistor to slow the motor down. I estimate that a typical motor loses about 1bhp (0.76kW) at higher engine speeds so you'd need a motor around this size, but preferably a little larger to allow some margin. I'd look for 1.1kW. if you don't want to run it too fast you could use a much less powerful motor (0.25kW) as drive train losses are pretty much proportional to speed. If you ran it through the crank rather than the layshaft you could get away with an slightly smaller motor as you wouldn't be spinning the gearbox.

Blah, blah, blah.

to my mind you have 3 options

1. use petrol and air to run the motor
2. a drill with less control through the crank
3. used motor, cheap inverter and a mate who knows inverters

[solostax]

Hi and thanks dickie, johnyxs, and meds for the latest developments.

I believe that dickie's idea of driving the rear hub is the way to go and I enclose a picture of the engine in the jig (solid and secure).

Imagine an electric motor (from washing machine or wheelchair?) bolted to the workbench directly below the layshaft. Fit suitable v belt pulleys to the motor and layshaft.

Now incorporate johnyxs's idea of readily available rpm control electronics as used in electric bicycles or wheelchair scooters and I think Meds wise caution regarding mis-alignment

vibration causing imbalance stress to bearings, could be addressed.

So if this project moves on I think the cost so far would be minimal .

The next consideration on the menu which coaster and myself share is that of top end lubrication.

I also share johnyxs's sentiment regarding nuisance to neighbours and reiterate that this topic is a major motive for this project.

In the event we can produce plans for a cheap workable tool I would feel rewarded .

P.S. Tried to upload Pictures but max allowable resolution keeps reducing unable to upload any.Anyway please visualize my description of engine in jig !

[Meds]

Try something like this
Cebek R-10 Electronic Module (Pre-Assembled)230Vac 1500 Watt motor speed controller allow you to adjust the speed of single-phase "universal" AC motors as used in power drills, vacuum cleaners.

Or

A fan electronic speed controller.

Most are are simple voltage control devices, incredibly wastful of energy but cheap and cheerful.

[solostax]

Thanks meds.
Loooked at the ac controller and I believe 1500w is equivalent to 2 HP ,which I guess would be adequate to spin up an engine from the layshaft /gearbox
end,(with spark plug removed).
Still need some thoughts on top end lubrication!
Regards

[johnnyXS]

I shouldn't have thought that it would take more than 30 seconds at a time to check the timing and adjust it but if you were concerned why not simply put a squirt 3in1 or gun oil down the spark plug hole

[solostax]

Ok thanks johnyxs.
About the lube question ,I'm in agreement ,and think that some proportion of oil squirted down the bore should remain for a long time as it is not being burnt.
Cant help but vaguely remember some TV ad about Shell ,Castrol ,Duckhams or whatever brand emphasizing their oil's molecular structure clinging/sticking
to an engines metallic surfaces despite being highly stressed...was it Magnatec?
I guess this is happening to the under piston rings portion in the cylinder.
Anyway ,got some real inspiration from yourself and other contributors on this subject and now have some confidence in constructing a prototype.
All the best
solostax