661 Stroker

[MG porting]

So none of you mf'ers know what you're talking about? Impressive..

No they were out thinking themselves it happens I do it to myself from time to time lack of sleep or just to much other stuff going on in the brain it happens. Lol

 

[beaglebriar]

No they were out thinking themselves it happens I do it to myself from time to time lack of sleep or just to much other stuff going on in the brain it happens. Lol

Meh....these guys know I'm kidding.

 

[MG porting]

Meh....these guys know I'm kidding.

Lol.

 

[huskihl]

The limited coil on a 372/390 starts to advance around 3200-3300rpm and retards at idle to make starting easier from what I have seen. It’s a pretty abrupt change and if you have the idle set too high it makes the idle wonky as it goes in and out of advance. Not sure what stihl coils do or if the advance works the same.

I always thought that was the A/C kicking on and off...

 

[Redbull661]

Oh dammit maybe Im bakkerds?

coil is on upside down...so your retarded!

 

[Redfin]

Thank you Captain.

 

[huskyboy]

I always thought that was the A/C kicking on and off...

It’s the turbo man!

 

[Lightning Performance]

Nice work....time to chase the gremlins!

 

[Wolverine]

I always thought that was the A/C kicking on and off...

I raffed!

The limited coil on a 372/390 starts to advance around 3200-3300rpm and retards at idle to make starting easier from what I have seen. It’s a pretty abrupt change and if you have the idle set too high it makes the idle wonky as it goes in and out of advance. Not sure what stihl coils do or if the advance works the same.

Hmm, so that explains that. The HU365sp can be a bear to tune and I’ve experienced said wonk.

 

[Bigmac]

Interesting, all of my cr250 ignitions retard at high rpm
I have been seeing gains in high rpm hp an torque with less timing above 9k on my alky banshee, I gained 5hp above 9k and gained over-rev when I pulled 5°, I also lost power under 9k, I need a programmable cdi to get the best of both worlds. That was on a dyno, I know it’s not a saw but it is changing my thinking about two stroke timing. My Trx250r’s gain power with the cr250 ignition, and the cr ignition has less timing everywhere than the stock ignition, again showing less timing with rpms is a good thing, at least in my bike applications

 

[Lightning Performance]

Interesting, all of my cr250 ignitions retard at high rpmView attachment 198534
I have been seeing gains in high rpm hp an torque with less timing above 9k on my alky banshee, I gained 5hp above 9k and gained over-rev when I pulled 5°, I also lost power under 9k, I need a programmable cdi to get the best of both worlds. That was on a dyno, I know it’s not a saw but it is changing my thinking about two stroke timing. My Trx250r’s gain power with the cr250 ignition, and the cr ignition has less timing everywhere than the stock ignition, again showing less timing with rpms is a good thing, at least in my bike applications

Good combustion chambers tend to need less lead on the ignition timing. That generally applies on most liquid fueled engines. Gas might want even less than alky up above 6k

 

[huskyboy]

Good combustion chambers tend to need less lead on the ignition timing. That generally applies on most liquid fueled engines. Gas might want even less than alky up above 6k

More compression = likes less timing advance?

 

[MG porting]

More compression = likes less timing advance?

All depends on what octane of fuel you're running.

 

[MustangMike]

Gas octane and oil ratio will have an influence, but higher compression will always increase temp and reduce burn time.

 

[Bigmac]

Good combustion chambers tend to need less lead on the ignition timing. That generally applies on most liquid fueled engines. Gas might want even less than alky up above 6k

I agree, my testing and research has shown me that a fair amount of initial timing is helpful to get the motor on the pipe, and then a gradual reduction in timing with an even bigger reduction at peak power will extend the power longer. That’s reed valved piped motors

 

[Redfin]

Fitted a coil before I left for Kevs gtg. No mtron but limited.

 

[Redfin]

Fitted an unlimited coil at Kevs and sorted the timing.

 

[MustangMike]

Looks good, but is it stronger??? That saw was already awesome!

 

[Shanesaw80]

Fitted an unlimited coil at Kevs and sorted the timing.

Wow that things a beast!!

 

[Lightning Performance]

Were they both 40mm?
Fast chains?