Husqvarna 450 Tuning

[Skippydiesel]

My Husky 450 has a high RPM problem.

History;
The saw was not staying in tune - often requiring a "field" adjustment.
Still had original carburettor parts so decided on a replacement kit.
Fitted kit - saw now start much better BUT problem with high end RPM

I use a digital tacho to tune my saws - Low speed all good - High speed seems to be "missing" at full throttle and tacho stops reading properly.

If I progressively increasing throttle, it accelerates smoothly until the last 1/4 of movement. Tacho is reading about 12400 RPM at this point. Squeeze a little more saw starts to vibrate/miss & tacho drops out.

Going for cheapest fix, a put a new spark plug in - no change.

I suspect the coil - What does the Brains Trust think???

 

[huskihl]

Limited coils mess with tachs once above the limiter. Not sure if that’s what’s going on, but richening the H screw might bring it down so it will read

 

[Chevboy0167]

"The saw was not staying in tune - often requiring a "field" adjustment."

Possible air leak?

 

[Skippydiesel]

Limited coils mess with tachs once above the limiter. Not sure if that’s what’s going on, but richening the H screw might bring it down so it will read

Limited???

The tacho "reads" my Stihl saws without any problems

 

[huskihl]

Limited???

The tacho "reads" my Stihl saws without any problems

Coils on some saws are rev limited to a certain rpm. Some aren’t. All tachs go haywire at or around the rpm that the coil is limited to. Your Stihls may not be limited, or you may have them tuned below the limiter

 

[Vintage Engine Repairs]

Coils on some saws are rev limited to a certain rpm. Some aren’t. All tachs go haywire at or around the rpm that the coil is limited to. Your Stihls may not be limited, or you may have them tuned below the limiter

This^^

Limited coils mess with tachs once above the limiter. Not sure if that’s what’s going on, but richening the H screw might bring it down so it will read

and this ^^