Modifying Strato/X-Torq saws...

[parrisw]

you need to do some reading on port time area and port mean time, jennings is good for this. it's hard to exlplain.
macking the ex port wider gives the port more time area so the ex gas gots out faster. so you don't need as mutch blow down.
does that help?

Yes, thanks, that makes sense, I guess I did know that. I'm just thinking out loud here. It helps me to understand things to just talk about it. Sometimes hard to think about it.

 

[2stroked2smoke]

Here's a video of my 562 that I've matched the strato and intake timing, opened exhaust to 65% and raised the exhaust port 2-3 degrees. It runs pretty good. I was planning on cutting firewood today but it flippin freezing out. I was planning on cutting up a bunch of bigger wood to really let the autotune settle in but I ended up just making about 10 cuts in a 12 inch log to set it before I made the video. Good chance the saw will run better with some more run time.

 

[mweba]

So...What do you think? Impossible to tell from the video but the revs don't "sound" any higher. Not being critical, just trying to decide if mine remains stock

 

[2stroked2smoke]

So...What do you think? Impossible to tell from the video but the revs don't "sound" any higher. Not being critical, just trying to decide if mine remains stock

I'm not overly impressed yet. It kinda feels like I might of lost a little bit of torque. Like I said though, I haven't run it enough to really let the autotune settle in. It COLD out there. That wind is vicious. I keep ya updated as I cut more with it. I have a new 562xp coming next month. When I get that one I can compare them side by side.

 

[blsnelling]

Doesn't sound like the RPMs are there yet. What did you do with the transfers? Sorry if I missed it.

 

[2stroked2smoke]

Doesn't sound like the RPMs are there yet. What did you do with the transfers? Sorry if I missed it.

I didn't do anything to the transfers. I just raised the exhaust port 2-3 degrees to increase my blowdown to 14 degrees. I matched the intake and strato port opening timing and I widened the exhaust to 65%.

 

[weimedog]

Seems to me the RPM's in his video are defined by how hard he's pushing in the cut, the question for me would be a before and after time in the cut. (Different pressures at equal chain speeds might realize different chip size therefore cut time is the base assumption. ) So really can't tell much from the vid..at least I can't:msp_sad:

 

[2stroked2smoke]

OK, wasn't happy with the saw losing torque. The changes that I made shouldn't have made that much difference torque wise. Got to wondering if the engine was using more fuel now and maybe the carb was maxxed out on adjustment on the auto tune. I dissassembled the carb and raised the lever that operates the needle and seat so more fuel was available. Bingo! The saw revs and cuts better than it ever has. Makes me think that this setting was off from the beginning. I had a hesitation on acceleration when this saw was new. Upon terry's advice I shortened the spring under the lever. This helped but was probably just masking the real problem. Nobody else seams to have had this problem so hopefully this was just a fluke.

 

[mweba]

Did you check squish? Seem to remember the triple five being closer to a smoosh

 

[2stroked2smoke]

No. I had no intentions of changing the squish so I never measured it.

 

[blsnelling]

No. I had no intentions of changing the squish so I never measured it.

Why not? You're missing a big piece of the puzzle not changing the transfers. Did you alter the strato ports?

 

[Andyshine77]

Setting the squish can make a pretty big difference. Sounds like the pop off pressure was too high and the lever was too low, AKA normal for a new saws these days.

 

[funky sawman]

OK, wasn't happy with the saw losing torque. The changes that I made shouldn't have made that much difference torque wise. Got to wondering if the engine was using more fuel now and maybe the carb was maxxed out on adjustment on the auto tune. I dissassembled the carb and raised the lever that operates the needle and seat so more fuel was available. Bingo! The saw revs and cuts better than it ever has. Makes me think that this setting was off from the beginning. I had a hesitation on acceleration when this saw was new. Upon terry's advice I shortened the spring under the lever. This helped but was probably just masking the real problem. Nobody else seams to have had this problem so hopefully this was just a fluke.

How much did you raise the inlet needle lever?

 

[2stroked2smoke]

How much did you raise the inlet needle lever?

About .015 It doesn't take much to make a big difference

 

[funky sawman]

WOW:msp_ohmy: .015" that is alot, I dont normally move them more than .005, but if that worked for you and your idle is stable in any position, COOL

 

[Terry Syd]

Good catch on the metering lever height. When you get the new stock 562 it would be interesting to see if it is set low. Obviously your mods took the demand to the stock set-up carb past the point that it was capable of tuning for - that's a good sign.

It will be interesting to see the comparison of your modded 562 with the stocker.

EDIT: I just remembered that when I bored out the stock carb on the 450 that it wouldn't flow enough fuel. I checked the metering lever height and instead of being level with the carb body it was down below it. I had to raise the lever up about .5mm or .020". That fixed the problem. I'm wondering if the metering lever height should be checked on all these Husky stratos.