Let's Talk 262 Timing and Performance

[drf256]

I'm not looking for fuel economy.

Neither am I.

I just dont see the point of pushing 20% of the mix out the exhaust.

Where the balance is is the question.

Plus theres torque at RPM, etc.

So a lower transfer with a free flowing muffler should give better torque and still good RPM

 

[jmssaws]

All you can do is raise the exhaust and I wouldn't do that

 

[jmssaws]

I run lots of saws with short blow down and don't notice fuel out the exhaust,all I notice is more power,but this is a husky were talking about so I don't know.

 

[295 tramp]

I have no porting experience at all, but I have rebuilt several 262xp's from early to latest models. Usually all the parts from the same saw. Sometimes basket cases get a mix of what ever was in my stash. The best performer has been and I still have is a regular mahle jug with CR no base gasket, hda 87, muffler mod and alittle advance timing.
Most definitely a fuel hog but hotrods aren't ugos

 

[exSW]

I'm not looking for fuel economy.

That's good cause all I've done to mine is put a beer can base gasket in to drop the squish to .018. I ran it fat for several tanks (new ring) and have since leaned it out some more. It's a real good saw to take if you want to burn a tank or two just to say you did something. I've yet to touch the muffler.

 

[Redfin]

A wise man told me 40* primary angle is a good rule of thumb for these things.

I had a Mahle with no base sitting at 106/117/70. It makes sense with that much primary the trans needs to be high but what is the thinking with the intake that high to begin with.

 

[drf256]

Are you sure its really 106/117 and your wheel didnt slip John?

 

[Mastermind]

Without a base gasket I can believe 106.

Numbers are tough to get spot on. I run a ring up the bore to check them, even when checking stock numbers. A light thru the port even throws it off....

 

[Redfin]

Are you sure its really 106/117 and your wheel didnt slip John?

Thats what they were Al. I do what Randy says with the ring. Part of the reason im so dang slow.

 

[SixGun]

Great Thread

 

[drf256]

I'm surprised, but I have had to raise it up a bunch when I've taken .026 off the base to get to 103.

 

[David Young]

love the discussion.
has anyone ccd the 254 vs the 262 case?
I know they have the same stroke but the 262 has a longer conrod.

 

[Redfin]

Onto the intake. Why 69*?

That's 16* less intake than exhaust. One would expect a large carburetor would feed the engine better with less time/area. The intake is relatively wide from the factory though. Much wider than any Stihl jug I've seen.

I'm wondering if the move from the 87 carb to the smaller bore 120 was the factory fix for pollution. Flowing less air would prevent the higher transfers from ejecting more unburned charge out of the exhaust port. The charge in the case would be less.

This model just feels undercarbed to me. More so than other saws I've tinkered with.

The one I built was a bit rpm challenged. More than one would think with these jug numbers.

Have you tried more intake on this saw?

 

[drf256]

Have you tried more intake on this saw?

It drops to 72ish with .026 off the base and no gasket.

I was thinking of taking it to 75 or 150 duration. Moving the transfers to around 118 (124 dur)

 

[exSW]

How much(if any)taper is there to the squish on a factory 262 jug?

 

[drf256]

How much(if any)taper is there to the squish on a factory 262 jug?

A bunch actually.

As you cut the band, you can see it.

 

[beaglebriar]

Tons of good info here. Now I think I will be keeping an eye out for a 262!

 

[tickbitintn]

i think a 262 just got harder to find.....
i would like to find one also....

 

[exSW]

Just don't give sh!t until you luck out. Worked for me.
#1
#2

 

[Mastermind]

I may or may not have a few 262s.....