OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Reel Lawn Mowers, Atco & Villiers etc. tecumseh kirby ignition timing and parts

Hi Folks
I've had a look through your site and tried to search your archives however I haven't been successful in finding the information I'm after regarding setting the ignition timing on my little 3hp kirby / tecumseh 4-stroke engine. It's a HK30 model. Whilst its easy enough to set the points gap as the cam lobe is a separate part from the flywheel, does anyone know a method for setting the ignition timing with any reasonable level of accuracy?

It would also be wonderful to hear from anyone who can advise where I might be able to go for parts for these little engines? I have another one that I believe is in need of a replacement conrod.

Cheers guys

dune,

Click HERE to view the conrod you are looking for.

Here is some information from the workshop manual in the parts list and manuals area of the forum.

To adjust points
- Adjust points gap to 0.45 � 0.50mm (.020�) as follows
(see Breaker point setting table).
- Turn engine to bring cam heel to widest opening point.
- Insert feeler gauge and with the aid of a screwdriver
fitted in slot �A� (Fig 11), gently close points until a �drag�
is felt on the feeler.
- Tighten points securing screw.

Many thanks for that lightning fast response there Bruce. Good to know those conrods are available. It makes spending time with the 'spare' engine worthwhile now.
Yep, I've got the points gap under control but thanks for that info too. What i'm up to now is the ignition timing. There is quite some adjustment there, and I'm wondering how folks actually set it given that it all happens behind the flywheel?

I kind of suspect that an expedient way of doing it would be with the head off and then measuring the opening of the breakers in terms of 'milimeters before top-dead-centre'??? In other words...if there even is such a measurement for this, could it possibly be in mm from othe top of the piston to the top of the cylinder?

Alternatively, do folks just set it in approximately the middle part of the adjustable range and reckon that's good enough given the fairly low state of tune of these charming little units?

Cheers again Bruce, and hopefully any others who can shed some light on this for me.

dune,

We usually just set it to the centre of the slotted holes unless you really want to get tech with it.

Maybe grumpy can put some light on it for you.

Dune, because these small cheap engines do not have an ignition advance mechanism to get their timing more or less sensible across the rev range, they tend to be severely retarded except at idle. Since we usually don't expect them to idle often or well, it would make sense to advance their ignition timing from the standard setting, if it were not for one problem: they would end up with excessive advance when starting, and would kick back. That would not just be unpleasant - it would be dangerous.
I suggest that if you want to do some experiments, you try advancing it a bit from the mid-point position and watch for the first signs of kick-back. However remember that at any time the engine might forcefully pull the rubber starter cord handle out of your hand, and you wouldn't want it to dislocate or break any fingers when it does that. The old round knob that Victa used long ago was unlikely to hurt you that way, but the T-shaped ones used nowadays could be more of a problem.
With electric starters, you can hear the kick-back and retard the ignition, but with a hand-pull you can get bitten before you know you're on dangerous ground. If you want to experiment, be careful.
One of the built-in factors that protects you against kick-back is the flywheel: the heavier it is, the less risk of being hurt. On the other hand if you try to start a vertical-spindle mower engine without the blade-plate fitted, you may get hurt even with standard ignition timing, because those engines rely on the inertia of the blade plate to keep from kicking back.

Thanks again Bruce, and thanks very much for the insight there Grumpy. It seems these little engines may not have as much scope for pepping up as I'd hopped. Given the originally ultra low state of tune and .... build quality... (the innards of my old Victa motors looked light years stronger and better made), plus the fact that they're supposed to run with a govenor I shouldn't be surprised. I do however intend to continue with these little guys in their application... no rush and it's all good fun. I really appreciate you gents taking the time to help me out.
Cheers again.

If you are looking for a cheap, tiny engine that has reasonable horsepower per litre, you might try looking at the ones used on Honda postie-bikes over the years. 50-110 cc, depending on when they were made, they are OHV with centrifugal ignition advance, and put the mower engines completely in the shade both for output and durability. They are also dirt cheap, so long as you don't mind taking a whole bike and tossing away what you don't want. At farm clearing sales they seem to be in the $50 range.