Dolmar 7910 Breaking in Brand new Saw

[farmerdoug]

I have a new saw that I am about ready to break in. (I have not started it yet) A few questions about the process:

• I have a tachometer to measure the rpm's wide open and make sure they are at maybe 12,500 RPM's, or would you go right up to 12,800?
• Do you run a brand new saw wide open for this measurement with the bar out of the wood?

I was thinking of running a tank through the saw before setting the High rpm setting.

If I were to leave the bar in the wood and open it up, would I get the same measurement as if I let it run free with no resisitance?

This is the link that I read for the process and I thought it was very beneficial. http://www.madsens1.com/saw_carb_tune.htm

 

[mdavlee]

I'd tune it put of the box for sure. It could be way too lean.

 

[Onan18]

Max RPM is spec'd no load, i.e. bar and chain out of the wood. I would check it for sure, like Mike said a lot of new saws are way lean out of the box.

Joe

 

[Czed]

I heat cycle them for a few minutes after fattening up the hi/lo with a little extra oil in the mix 40/1 for me then tune in wood we all have our processes lol

 

[Czed]

I can say i bought three new saws set too lean but we are all at different altitudes.

 

[farmerdoug]

This is all very helpful - Thank you!

 

[Adirondackstihl]

I'm a fan of heat cycles in any 2-stroke as well

 

[farmerdoug]

When referring to heat cycling:

• Are you warming up the saw and then let it cool down and then warm it up again a few times?

When you rotate the carb adjustment screw clockwise you are making it more lean and when you rotate it counter clockwise you are fattening up the mix. Just wanted to verify this. Thanks!

 

[Adirondackstihl]

When referring to heat cycling:

• Are you warming up the saw and then let it cool down and then warm it up again a few times?

When you rotate the carb adjustment screw clockwise you are making it more lean and when you rotate it counter clockwise you are fattening up the mix. Just wanted to verify this. Thanks!

Yes & Yes

 

[Czed]

There's no science to it i turn the idle in a little lo and hi i back out 1/2 to 3/4 or so let it idle 5 minutes shut off then when cool do it again been doing this 30 years dirtbikes atvs chainsaws etc.
Everyone's different but it seems to seat everything better.
I know guys new saw first hit full throttle no load just wfo for a minute or two lol

 

[KenJax Tree]

Just gas it up and beat it like it owes you money

 

[Simondo]

Just a point on the max rpm...the 7910 is "coil " rpm limited to 12800 rpm .
You will need to go ...way rich ...then come up to the rev limiter and back into the rich again if you start doing any significant adjustments . A tach will give odd readings from the interference from the coil rev limiting side over the rev limiter.

 

[TJ the Chainsaw Mechanic]

Fire it, let it idle awhile...and cut some wood with it. Might fatten the H and L a bit for the break in period though. Perrty much what I do.

 

[Czed]

Lol See we all do it differently.

 

[farmerdoug]

This is very helpful - Thank you all for your input.

 

[TJ the Chainsaw Mechanic]

Lol See we all do it differently.

Makes the world a funner place. haha
Guys at stihl told me, fire it....hit wide open throttle a few times to quickly prime the fuel system and lube the moving parts, let it idle awhile so everything gets nice and hot....then go cut wood. Technically a saw is "broken in" after 12 tanks. My 460's have had like 50+ tanks through them and piston and cylinder still look new. Little bit of cold scoring, but machine marks plainly visible. Different manufacturers probably have different ways...Last I checked Echo's even have a Longer break in period than Stihls.

When an engine is new or cold...I always prefer keeping the RPM's low. Just me; when I warm up my truck in the morning, I idle it at 800 RPM for 5 minutes. Saws I idle for a couple minutes usually hitting the throttle hear and there. Pistons expand faster than the cylinder. And during break in when tolerances are tight....that can be the difference of scoring or no scoring. Just my experience.

 

[Czed]

Rings are better quality now years ago you didn't know how long they would last.

 

[TJ the Chainsaw Mechanic]

Rings are better quality now years ago you didn't know how long they would last.

lol Maybe that's why they used 4 on my 305 v6, 3 compression and one oil. Those engines have been known to top 300,000 easily.

 

[Wilhelm]

Congratulations on Your new saw!

I own a Dolmar PS-6400 & PS-7900, both great saws.

I never "knew" that a saw should be broken in, thus the ones I bought new got fueled and ran.

Nowadays I'd probably set a new saw a tad rich and ad more oil to the mix, like 32-40:1 (I run 50:1).

I wish You to enjoy Your Dolmar PS-7910 for years to come!

 

[farmerdoug]

Thank you! I am trying to upgrade from being the guy that just runs a saw, to a guy that takes care of his saw. Dolmar is not common where I live. I have been put out by local dealers just wanting my money and not really helping, so I am making a jump to being responsible for my own saw and then mailing it back east to a saw builder who specializes in Dolmar. My new saw program allows me to have a backup saw, so shipping a saw out for a while will be okay. Thanks for all your help!