560xp "flat spot"

[TGB]

In real terms, it is giving too little fuel at low revs, this is the prime cause of that early to mid range bogging before the high speed circuit kicks in.

 

I know what you do to a carb to get rid of it but no idea on an autotune:confused1:

 

Would this solve the problem:

 

Sounds like the same thing.

[spudulike]

Would this solve the problem:

 

Sounds like the same thing.

 

It could be worth trying if you have a pop off pressure gauge and a couple of spare springs - If you bugger up the spring then just fit the standard one again.

[Stubby]

Would this solve the problem:

 

Sounds like the same thing.

 

Cunning wizardry

[spudulike]

Cunning wizardry

 

Not really, you are just lowering the pop off pressure that is needed to open the needle valve thus making sure the correct level of fuel is metered in to the carb.

 

Most small carbs have very high pop off pressure and have noticed many larger ones and ld school carbs pop off much earlier!

 

I test carbs this way but havent experimented with it as to date, I havent needed to.

 

The Yanks tend to be quite resourceful in their approach!

[Stubby]

Not really, you are just lowering the pop off pressure that is needed to open the needle valve thus making sure the correct level of fuel is metered in to the carb.

 

Most small carbs have very high pop off pressure and have noticed many larger ones and ld school carbs pop off much earlier!

 

I test carbs this way but havent experimented with it as to date, I havent needed to.

 

The Yanks tend to be quite resourceful in their approach!

 

Cunning wizardry is my way of saying more resourceful in their approach !

[GardenKit]

I am a little surprised that the same result cannot be achieved by raising the metering arm just a little, but still don,t quite see how it helps.

 

After all, the fuel required to overcome the flat spot is already sitting in the metering chamber, The normal problem is that insufficient fuel can get past the L screw, hence screwing it out a little to let more through.

 

I am struggling to understand how, having more available in the chamber, helps it through the L jet.

 

I will get there though.

[SawTroll]

anyone else? had mine a month or two now but only realistically started working it hard this week,8 tanks a day in large ash coppice.starts,runs and cuts like a dream,just has a very slightly annoying flat spot when revved from idle,keep it spinning its fine but just that fraction of a second is bugging me! guess it'll wear in? thanks

 

Such a "flat spot" is exactly what that saw shouldn't have - rather the opposite, with the RevBoost!

 

Take it back to the dealer, something is wrong (likely with the carb).

[SawTroll]

TBH, if you have a workable 'flat spot' then your tuning is not far out. Its just very slightly weak. The merest tweak out on the L screw will probably do the trick. Turning it in will get it to the point where it just will not pick up.

 

The saw is an AutoTune, so manually adjusting the "L" side isn't an option.

 

This could be about a faulty carb, or a faulty run-in - back to the dealer, as I already said.

The dealer can reset the AutoTune - and if that doesn't help, the carb likely is faulty (warrenty issue).

[wyk]

The saw is an AutoTune, so manually adjusting the "L" side isn't an option.

 

This could be about a faulty carb, or a faulty run-in - back to the dealer, as I already said.

The dealer can reset the AutoTune - and if that doesn't help, the carb likely is faulty (warrenty issue).

 

It sort of does. Dunno if it's been mentioned earlier, but I think the 560, and I know the 550, have idle bypass screws. In practice, on a ported saw, they sort of work a bit like the "L" screw when you adjust them. Snelling has used them to good effect to adjust out flat spots from idle in 550's.

Edited January 15, 2014 by wyk
thaipose

[CHC]

I had the same problem. Mentioned Otto the dealer and said about washing the air filter and it worked so that might be worth a try