Stroking a Dolmar 7900

[mdavlee]

I take .060" out when I do a Solo hybrid. But, I take the exhaust up to 96.....so compression ain't crazy high. Transfers ain't as far off as you would think either. Intake comes in just right because you don't take anything off the base, and the longer stroke makes BDC further down the bore.

But.....I'm not sure if the deck height is the same between the Dolmar, and the Solo. I'm also not sure about the 7900 jug VS the 7910 jug as far as raising the exhaust that much. The 7910 jug has all that "extra" material due to the insert from the muffler into the port.

I’ve took them to 92 on exhaust. I like spacing them up and grind less with just .020-025” out.

 

[Mastermind]

Solo gasket thickness?

.018 I believe .

 

[Fruecrue]

She ran tonight, very briefly.
Had a couple sparks out the muffler which has quite a large opening in he front.
Could just be carbon, could be more.
Shut her down, doesn’t appear to be any damage.
That’s it for tonight.
Wife is having family over tomorrow to make Christmas cookies. With any luck she’ll kick me out to the garage.

 

[mettee]

It's alive!

 

[andyshine77]

She ran tonight, very briefly.
Had a couple sparks out the muffler which has quite a large opening in he front.
Could just be carbon, could be more.
Shut her down, doesn’t appear to be any damage.
That’s it for tonight.
Wife is having family over tomorrow to make Christmas cookies. With any luck she’ll kick me out to the garage.

Hopefully just carbon or something else SOFT burning off. This has been a really enjoyable informative thread.[emoji106]

 

[Wilhelm]

She ran tonight, very briefly.
Had a couple sparks out the muffler which has quite a large opening in he front.
Could just be carbon, could be more.
Shut her down, doesn’t appear to be any damage.
That’s it for tonight.
Wife is having family over tomorrow to make Christmas cookies. With any luck she’ll kick me out to the garage.

Make Your own cookies.

I'd rather run my Dolmar's today, but I won't be home all day.
I am helping out a coworker with his annual pig slaughter.
Not my favorite thing to loose a whole day on.

 

[Fruecrue]

Well... it’s alive.
Not without drama.
Looked into ex. Port this morning and saw this on the intake side.

Tore it down and found it was nothing more than oil streaking and marks from a hard previous life.

So it went back together, this time with the original stock muffler.
No start. Pop and flood.
Swapped carbs, checked spark, etc.

I pulled that cord and cussed until I had to leave for fear of putting a bullet in the saw.

Found intake block warped and boot starting to develop cracks. Swapped with my 7910.
No start.
Anger.......
Then went back to basics and found this.

Marked flywheel and crank, cleaned both and mounted flywheel. She ended up a couple degrees retarded but I left it for now. That will change when I do a Husky unlimited coil swap.
Put all back together, pull cord, smiled.
Apologized to Jesus for all of the things I said in the garage today.

 

[Fruecrue]

 

[Fruecrue]

First cuts. None too impressive.
My excuses are as follows:
Bad chain
Bad operator
Stock muffler
Retarded ignition timing
Etc., etc., etc.

 

[tickbitintn]

First cuts. None too impressive.
My excuses are as follows:
Bad chain
Bad operator
Stock muffler
Retarded ignition timing
Etc., etc., etc.

Nice!!
Baseline set and cookies made!!!
LOL

 

[tickbitintn]

My bro happy with da tree nine fo [emoji106]
His deceased 385 came home with me.
PTO bearing headed for warmer climates.

Sent from my XT1635-01 using Tapatalk

 

[mdavlee]

Well... it’s alive.
Not without drama.
Looked into ex. Port this morning and saw this on the intake side.
View attachment 151746
Tore it down and found it was nothing more than oil streaking and marks from a hard previous life.
View attachment 151747
So it went back together, this time with the original stock muffler.
No start. Pop and flood.
Swapped carbs, checked spark, etc.

I pulled that cord and cussed until I had to leave for fear of putting a bullet in the saw.

Found intake block warped and boot starting to develop cracks. Swapped with my 7910.
No start.
Anger.......
Then went back to basics and found this.
View attachment 151748
Marked flywheel and crank, cleaned both and mounted flywheel. She ended up a couple degrees retarded but I left it for now. That will change when I do a Husky unlimited coil swap.
Put all back together, pull cord, smiled.
Apologized to Jesus for all of the things I said in the garage today.

I fought one of those for around 2 weeks

 

[RI Chevy]

Damn keyways!!!!!

 

[huskyboy]

I dislike how a lot of newer saws have now went to a cast in key. Dumb idea imho.

 

[Dub11]

She ran tonight, very briefly.
Had a couple sparks out the muffler which has quite a large opening in he front.
Could just be carbon, could be more.
Shut her down, doesn’t appear to be any damage.
That’s it for tonight.
Wife is having family over tomorrow to make Christmas cookies. With any luck she’ll kick me out to the garage.

I never get kicked out to the garage, bs I tell ya.

I dislike how a lot of newer saws have now went to a cast in key. Dumb idea imho.

makes the assembly process easier for them and that's all that matters to them.

 

[Terry Syd]

Yeah, the cast in key is a really cheap way to put a timing key in an engine. To think that both Stihl and Husky use such an inferior system is surprising.

I've seen cheap Chinese saws with genuine machined keys that not only can be replaced if they shear, but you can tweak them. Try, say, a key with .20" off and then another with .25" off - go back and forth and decide which works better.

What I'd really like to see is a 'backing plate' for the coil where we could dial in the timing.

 

[mettee]

Hell yeah brother!

She sounds good, once you sort it out it's gonna crush it.

How bad was the chain?

 

[mettee]

First cuts. None too impressive.
My excuses are as follows:
Bad chain
Bad operator
Stock muffler
Retarded ignition timing
Etc., etc., etc.

At like 7 seconds you can see a spark fly in this video, I wonder if it's off the bar or what.

 

[mettee]

That monster torque snapped the keyway off.

 

[Wilhelm]

First cuts. None too impressive.
My excuses are as follows:
Bad chain
Bad operator
Stock muffler
Retarded ignition timing
Etc., etc., etc.

Chain can't be too bad, it is cutting without utilization of the saws spikes.
If deemed necessary give it a couple swipes, or simply utilize a new loop if You have one.

I see no operator fault.

Replace or mod the muffler, the saw will wake up a bit instantly.

Reset the ignition to true stock, or slightly advanced.

Try making cookies again.

Looks good for a first run.