High Quality Chainsaw Bars Husqvarna Toys

How to tweak and tune for good starting

davidwyby

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Some of my stock saws like my 2050 always start quickly. If I can get the choke off fast enough, it’s running in one pull. Also, my @Mastermind 6100 usually pops on the first pull and roars on the second after opening the choke. Same with my @Benwa 2159/357xp. My 395 and 266 are not so quick to start.

@Armbru84 was telling me about the lengths he went to to get a good strong sparking coil for the 3120 I bought from his as it was his race practice saw. I know @Lightning Performance has stated his saws have to fire right up or they go on the bench.

So what are some things to check tweak tune for good starting? Something I read somewhere on here by @Terry Syd was that coil to flywheel spacing can be adjusted for more spark.

Thanks
 
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Maintenance Chief

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My neighbor is 82 years old and loves his 026 pro but it was getting a little difficult for him to start. I rebuilt the carb and cleaned the whole intake tract but still it was difficult for him because of age and shoulder surgeries.
Slightly richer low setting fixed that saw for him and regapping the coil to factory specs.
My Super 1050A Homelite saws can really be a bear to start without fattening up the low jet also(100cc no decomp) . I believe thats because the bigger cylinder has alot of space to get a little bit of mix.
The carb diaphragms should be nice and supple also.
 

Nutball

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I prefer choke switches that are separate from the power switch. I often open the choke only 1/3 from closed after priming with full choke. This usually starts with one pull instead of 3-4 extra. It helps if the saw doesn't spool up enough when it hits on full choke to flood it in the slightest.
 

Sagebrush33

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How many heat ranges of plugs are available for the same saw, in general? In other words, when a saw is extensively ported, ignition timing changed, and other P&C magic, where does one look for a hotter plug.
 

kneedeepinsaws

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Proper L screw tuning is key IMO.
A well tuned L screw and a saw that is mechanically sound will only start cold with the choke fully closed and the engine pops over then dies.
If it runs with the choke on there is a problem. If your using 3/4 or 1/2 choke there’s a problem, if it starts without the choke there is a problem! :)
 

Lightning Performance

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A fresh plug that’s indexed and gapped properly seems to start easier as well.
I posted a bit from here earlier but the site won't cooperate.

These three above are all right on point.

Shut of a 1050 with the choke might help those next mornings restarts.

My saws are tuned so fat on the low they tend to load up when cold at idol. Indexing the plug and reducing the ground strap to open up the spark gap can help a bit with that. Also burns cleaner at high rpm imo and cools better hot in this heat with dry air with it fat middle throttle and idol. I boiled pump gas last week in my 6401 not ported with a 24" 7pin. Boat gas fixed that in a snap. No more "funny" running issues.
How many heat ranges of plugs are available for the same saw, in general? In other words, when a saw is extensively ported, ignition timing changed, and other P&C magic, where does one look for a hotter plug.
Big mistake there.
You want to go colder not hotter.
Try a 6 vs a 7 or 8 heat range.
And... the heat range has nothing to do with cold starts.

My 066 runs any heat range from 6-8 just fine.
It only takes four slow rolls to prime it up. Then starts on one pull with no choke and no high idol. If not it ran out of gas last time out. Takes about ten rollovers to get it primed up. Two pulls, kill the choke and Bob's your uncle. Nothing left but time for pain!

I set my coil gap at 0.008, no exceptions. If it rubs you need bearings.


*f-word autocorrect
 

Lightning Performance

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There's merit to spark heat and what color it is.
Finding the precise spot of where the field collapses in relationship to the windings could effect spark intensity. Amps is what your looking for when the field collapses not voltage. Voltage is made in the primary.

Did he try grinding down the plates to how close you can go before the point of diminishing returns?... doubt it but another thing to consider on a weak mag coil.

For automobile mag distributors that was all figured out long before I was born. I'd bet Mr. Andreas and his team did a good enough job not to worry about that very much. New stuff is even better one would hope. Maybe... not the tiny bits but the big picture should be better overall to keep a standard setting imo.
 

Sagebrush33

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Do you index for the gap to face top of piston?
Use a
washer for indexing or just buy half dozen plugs and see what is closest?
Chris.
 

davidwyby

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So something I’ve been cogitating on…the L. There’s kind of a balance or back and forth between the mixture screw and the idle speed screw. You can set the mix right in the middle for best idle and then adjust the speed, sometimes go back and adjust the mix some more.

But I’ve noticed you can do that and then set the mix fat to where it slows it down and then bring it back up by adding air with the idle speed screw. Is there any advantage or disadvantage to balancing the two one way or the other? If we tune fat and bring back up with more air, is the mix still any fatter? Does one way or the other help starting or throttle response? My gut wants to say go fat and open the throttle with the idle speed screw.

Thanks
 

Duane(Pa)

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You're right. In my experience, if I tune for a smooth idle with the L screw, I get a lean bog after cutting for a while. Inevitably retune fatter L and adjust idle screw to make things right. Then, since I’m a fool, I do it all over next time out :D
 
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Ketchup

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So something I’ve been cogitating on…the L. There’s kind of a balance or back and forth between the mixture screw and the idle speed screw. You can set the mix right in the middle for best idle and then adjust the speed, sometimes go back and adjust the mix some more.

But I’ve noticed you can do that and then set the mix fat to where it slows it down and then bring it back up by adding air with the idle speed screw. Is there any advantage or disadvantage to balancing the two one way or the other? If we tune fat and bring back up with more air, is the mix still any fatter? Does one way or the other help starting or throttle response? My gut wants to say go fat and open the throttle with the idle speed screw.

Thanks

Every carb is different but there are several models I tune that way. If there is a lot of bog when you hit the throttle it seems like the fuel isn’t keeping up with the increase in air. So give it more fuel. A cut out in the butterfly can help instead of extra Idle.

That said, I find saws start easier at a higher idle. It’s easier to get the mix right on the L if there is more air moving through.

Just my gut though.
 
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Woodslasher

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Every carb is different but there are several models I tune that way. If there is a lot of bog when you hit the throttle it seems like the fuel isn’t keeping up with the increase in air. So give it more fuel. A cut out in the butterfly can help instead of extra Idle.

That said, I find saws start easier at a higher idle. It’s easier to get the mix right on the L if there is more air moving through.

Just my gut though.
My old saw repair book has a section on carb tuning, one of the troubleshooting bits says "If the saw bogs when accelerating, the low speed mixture is too lean and must be adjusted richer"
 

49er

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Anyone have any thoughts on the metering springs and how they affect cold starts?
 

49er

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I have a set of springs and a friends Husky61 that is hard to start. I think I will experiment a little with a weaker spring.
 
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