[B]Dolmar 112 points ignition timing....help...anyone?[/B]

[Gregford]

I hope someone else out there can help on this one.

I recently gave this saw a new set of rings and put it all together and found it had no spark. So I took the flywheel off and adjusted the points to .016" (with the aid of a 4mm spacer) so that they actually open.

Unfortunately it ran pretty ragged, so I got out the protractor and made some timing marks and stuck the timing light on it. The timing is about 20 degrees BTDC if the points are set at .016". This doesn't seem excessive. My old Canadiens run at 35 degrees BTDC and my Husky 380s run at 26 degrees BTDC. Unfortunately, the Dolmar still runs ragged at this setting. I have tried adjusting the points gap down to retard the timing without much success. Of course, it may not be an ignition problem, but I'd like to set the timing/points gap to the original specs so I know that they aren't the problem.

I consulted Mike Acre's site which suggests aprox. 2mm BTDC for the timing of many similar Dolmars, but how do you measure this? On the crank? On the outside of the flywheel?

Anyone?

 

[TRI955]

I have one of these 112 Dolmars but I have done very little to it. I didn't even know that it had points, I just assumed it was electronic ignition. I'll help if I can in anyway.....

 

[Gregford]

Okay - all sorted...

Ran a check lamp across the points, reduced the points gap by 0.001" graduations until the points didn't open, then checked the gap (0.008" with a 4mm spacer) and added 0.016" to the measurement and opened the points to 0.024". Big fat spark but it still didn't run right so I removed the coil and condenser and got them tested. Both stuffed, so I got another 2nd-hand coil and condenser, installed them and bingo - the 112 runs like it should.

So for anyone doing one of these from home, when you take the flywheel off you must insert a spacer between the points heel and the crankshaft. A 4mm Allen key gives a slightly smaller radius than the points cam, so you have to set the points wider than normal. 4mm Allen key + 0.024" gap gives you a points gap of 0.016" when the flywheel is back on.

Guys who do this for a living either have the special spacer from Dolmar, or cut the centre out of a second flywheel, but for someone from home neither of these options is viable.

I suppose it would've been better to get an electronic coil, but after spending so much time getting the points gap right, I was reluctant to see all that effort wasted.:monkey:

 

[pioneerguy600]

Ran a check lamp across the points, reduced the points gap by 0.001" graduations until the points didn't open, then checked the gap (0.008" with a 4mm spacer) and added 0.016" to the measurement and opened the points to 0.024". Big fat spark but it still didn't run right so I removed the coil and condenser and got them tested. Both stuffed, so I got another 2nd-hand coil and condenser, installed them and bingo - the 112 runs like it should.

So for anyone doing one of these from home, when you take the flywheel off you must insert a spacer between the points heel and the crankshaft. A 4mm Allen key gives a slightly smaller radius than the points cam, so you have to set the points wider than normal. 4mm Allen key + 0.024" gap gives you a points gap of 0.016" when the flywheel is back on.

Guys who do this for a living either have the special spacer from Dolmar, or cut the centre out of a second flywheel, but for someone from home neither of these options is viable.

I suppose it would've been better to get an electronic coil, but after spending so much time getting the points gap right, I was reluctant to see all that effort wasted.:monkey:

The coils on the 112 have a bad habit, the copper grounding wire will break somewhere inside the black jacket, its not always visible and sometimes it will break off just under the coil sealing surface, this will cause the same problem that you encountered.
Pioneerguy600

 

[Gregford]

The coils on the 112 have a bad habit, the copper grounding wire will break somewhere inside the black jacket, its not always visible and sometimes it will break off just under the coil sealing surface, this will cause the same problem that you encountered.
Pioneerguy600

Thanks for that. Mine was arcing from the plastic coil insulation across to the coil frame. Maybe it just needed the crack(s) filed out and refilled with resin but to be honest, I much preferred just buying another coil.