McCulloch Chain Saws

[Jethro 2t sniffer]

I would hazard guess that its a timing related change in the ports or in the cranks key?
Only because I run my 10-10A saws for firewood and dropping small 8-14" trees ( crazy I know, when I have a bunch of bigger saws) but whenever I have had to install an electric chip in one I absolutely notice a change in performance, rpms and torque . Whatever advanc they put in the chips is a go sweet spot for the 10-10 I've found. I've been half tempted to try one in my PM60 but it was such a SOB to get straight with the points I'm probably not gonna mess with it.
Compression is the only other factor that I can think of if all things being the same.

I'd like to know if these chips and the factory electronic ignitions have an advance curve like a dirt bike does and also if modern saws have that too. Like is that part of the change in power that we see in a modern saw.

In modern mx bike ignitions some have different modes for a different delivery.

Is there a hi performance chip out there we all should be hunting down?

Bike cdi boxes are alot bigger too maybe thats why

Is there an ignition off a modern saw we should be trying to fit?

 

[Goinwheelin]

I have a chip in my pro 10-10A and it’s pretty snappy compared to my 10-10 with points, but it’s also fresh rings and the exhaust is all opened up and port matched so that has an effect. Would be cool to see a comparison between the two.

 

[Jethro 2t sniffer]

I have a chip in my pro 10-10A and it’s pretty snappy compared to my 10-10 with points, but it’s also fresh rings and the exhaust is all opened up and port matched so that has an effect. Would be cool to see a comparison between the two.

The exhaust port on the 54s seem tiny did you take out bridge?

 

[mogulmasher]

Yeah my sp81 is chipped too and seems pretty snappy. However, same story for me, I cleaned ports up a bit and opened exhaust up a little so don't know.

 

[PogoInTheWoods]

I have a chip in my pro 10-10A and it’s pretty snappy compared to my 10-10 with points, but it’s also fresh rings and the exhaust is all opened up and port matched so that has an effect. Would be cool to see a comparison between the two.

Like I recently mentioned in the Mac thread over on OPIE, it would be interesting to do some timing comparisons between the 7-10 and PM700 ignitions to see what the advance difference may be (between the points and electronic designs). May as well throw a chip in the mix, too -- though I don't think there is an inherent curve designed into the typical MegaFire type chip. I'd guess the 'snappiness' of a chip over points would simply be faster triggering of an electronic system over a mechanical one, though that's just a guess without doing any research and I could be entirely wrong there.

 

[Goinwheelin]

The exhaust port on the 54s seem tiny did you take out bridge?

I didn’t take out the bridge I just turned them into squares matching the gasket then opened up the muffler to match.

Like I recently mentioned in the Mac thread over on OPIE, it would be interesting to do some timing comparisons between the 7-10 and PM700 ignitions to see what the advance difference may be (between the points and electronic designs). May as well throw a chip in the mix, too -- though I don't think there is an inherent curve designed into the typical MegaFire type chip. I'd guess the 'snappiness' of a chip over points would simply be faster triggering of an electronic system over a mechanical one, though that's just a guess without doing any research and I could be entirely wrong there.

It would be cool to see that done with the same saw and same B&C combo in the same type of wood and see if there is a difference.

 

[PogoInTheWoods]

No bar and chain necessary. You'd just need to establish timing marks at 26 degrees BTDC on each saw (using the same flywheel for both saws) and fire up a timing light and a tach to see the results at various RPM's for each type of ignition.

 

[Goinwheelin]

I’m talking performance wise in use.

 

[PogoInTheWoods]

I'm talking establishing timing curve differences (if any) between types of ignitions and how that info may be extrapolated to explain any actual performance differences among them.

 

[heimannm]

I did check a McCulloch electronic ignition coil/module when I was working on the SP81E. The original two piece ignition did not have any advance that I could determine. The newer coil (same one is used on 10 Series and 600 Series with a longer lead) did display some advance evident as the RPM increased. I only had my cordless drill to spin it so I probably only went up around 2,000 RPM but from say 600 to 2,000 there may have been 3-5 degrees movement. The newer coil also provided a visually better spark than the original two piece. For what it's worth, some of the early PM850 saws also had the two piece system based on the IPL's that I have looked at.

McBob used to tell us that in Australia, all of the saws with two piece ignitions were changed over to the newer one piece units when he was working in the McCulloch factory there.

The two piece system had the coil under the saw and the trigger unit attached where the electronic coil mounts.







Mark

 

[Goinwheelin]

I'm talking establishing timing curve differences (if any) between types of ignitions and how that info may be extrapolated to explain any actual performance differences among them.

I know Poge but we gotta see some chips fly as part of the experiment right?

 

[PogoInTheWoods]

I vaguely recalled that timing experiment in the thread on OPIE..., primarily in relation to the performance difference discussion (perceived or otherwise) between the 7-10 and PM700. What happens in the actual power band timing-wise would tell the real tale.

Regarding the chips flyin', that's the subjective part. Absolute timing numbers would establish the objective reasons for how many chips and how fast they fly. LOL

 

[Maintenance supervisor]

Someone just did a 70cc dyno ,so I pm'ed them and told the I'd freshen up the cherry pm700 next time they do it.
Just a side note .
The little electric chips do work well. I believe that some of the differences in off brand creamsicles had the same series saw with 3 different ignitions (064) one having a higher timing advance.

 

[2broke2ride]

Tonight's project...... really debating whether I want to spend $30 on diaphragms for this flatback or just convert to a Tillotson. I have plenty of parts saws here but I have been told that the flatback gave a performance edge over the Tillotson and being that this is a Super 250 I don't really want to stifle it's power.

Sent from my SM-G981U using Tapatalk

 

[mogulmasher]

Fix the flatback.

 

[edju1958]

I got the SP81 in the mail today that Vinny rebuilt for me & I put a NOS spike on it that I found just laying around.I'm supposed to get the 28 in.bar & chain tomorrow,so I'll try to post pics.

 

[vinnywv]

I hope you like it, if not my offer stands. Ha haaaaa

 

[sawfun]

Flatbacks performed noticably better for me, I just hate the priming issue.

 

[2broke2ride]

Flatbacks performed noticably better for me, I just hate the priming issue.

This one has a choke, no priming issues.

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[heimannm]

Another vote for the flat back. I find the ones with a choke are very reliable.

Mark