Need a non-limited 7900 coil

[Haywire Haywood]

Anyone know where I can get a non-limited 7900 coil? I did a search but no luck. Dean tells me that I'm going to need one.

thanks,
Ian

 

[Former Saw Builder]

I have some here but I don't know what they used on the 7900 ask Dean if one of the Husky 385 (Black) coils will fit that Dolmar if so I have one for ya.

 

[Haywire Haywood]

From what I've been hearing, nothing out there is a drop in for the 7900. EHP used a 372 coil but the spark plug wire comes out in the wrong place and runs too close to the muffler for a work saw. Heat issues there. I believe I also read that he had to mod the flywheel somehow to correct a timing problem. I've almost convinced myself to abandon the 7900 and go with a 372XP instead.

Ian

 

[rahtreelimbs]

Is it that big of an issue???

The 7900...............even modded................rarely, if at all, see past 13,500 in the wood!!!

 

[Freakingstang]

The coil that Ed uses is not the 372, unless he has changed....either way, there is no drop in no limiting replacement coil that fits (that I have found). You can make many of them work, but most require the flywheel to be retimed or the case to be modified.....

 

[Haywire Haywood]

Is it that big of an issue???

The 7900...............even modded................rarely, if at all, see past 13,500 in the wood!!!

This is most likely true. What worries me is false tach readings running WOT unloaded while trying to adjust the H. I've heard of folk mistakenly leaning saws out too much due to that. I may be picking nits here, but that's my concern.

Ian

 

[Haywire Haywood]

The coil that Ed uses is not the 372, unless he has changed....either way, there is no drop in no limiting replacement coil that fits (that I have found). You can make many of them work, but most require the flywheel to be retimed or the case to be modified.....

Maybe I read his post wrong then, or maybe he switched to another coil after first trying the 372.

Ian

 

[Lakeside53]

This is most likely true. What worries me is false tach readings running WOT unloaded while trying to adjust the H. I've heard of folk mistakenly leaning saws out too much due to that. I may be picking nits here, but that's my concern.

Ian

Sure it's a concern, but you'll quickly figure it out. You can detect when it's happening; you just need to change your technique a little - seting mixture using the WOT method is only an approximation anyhow, so justs err slightly on the rich side. It won't affect your cutting, and unless you're racing, does it matter all that much?

 

[Jacob J.]

The coil Ed used was a 272 coil and he had to move the flywheel around quite a bit to find the sweet spot. I think it he ended up almost 90 degrees off the stock timing.

 

[BIGBORE577]

I'm having a similar issue with my 7900. However maybe it's the type of tack I'm using. I have a Dixson analog with the induction pick up not one where you attach the wire to the saw. If I back the the H screw 1-1/4 turns, 2 turns or 4 turns it still jumps off the rev limiter. I just don't know how much is safe. Once it hits the limiter I have to start over again. I can sneak up to about 13k before it jumps off and there is just a little left in throttle travel. Does any of this make sense or should I invest in yet another tach?

 

[rahtreelimbs]

FWIW I find the best way to set a 7900 is to set it rich...........12,500..........or so. Then start cutting leaning out a little as you go using the 2 stroke - 4 stroke method. Then recheck your setting with the tach.

 

[BIGBORE577]

FWIW I find the best way to set a 7900 is to set it rich...........12,500..........or so. Then start cutting leaning out a little as you go using the 2 stroke - 4 stroke method. Then recheck your setting with the tach.

The problem is I've backed out the H screw 4 full turn and I'm still hitting the rev limiter at approximately 13k. Again, maybe it's the old school tach but I don't have this issue with any other saw. I would tend to think after backing out the screw 4 times I should be below 13K