Husqvarna 61 carburettor issue.

[Myce]

Good day everyone, I've lurked here for a couple of years and as much as I thought I was a good amateur mechanic, I have learnt so much from this site, so thank you.
I have an problem with a 1997 Husqvarna 61 grey top and am reaching out for some advice please. Bought well second hand, cleaned up, changed mismatched bar and chain then decided to investigate carburettor. Cleaned out and fitted Tillotson 23 kit. Levelled pin height as per manual..no fuel getting through at all. Checked pin top to diaphragm...all good. Lifted pin by about .75 mm. Saw starts straight away but will not rev above about 5000 and is 'burbling.' Have I made it too rich with such a small adjustment or is it too lean? Appreciate any advice, thanks guys.

 

[Mad Professor]

Clogged fuel filter/screen in carb, or hole in fuel line/impulse line?

 

[Myce]

Clogged fuel filter/screen in carb, or hole in fuel line/impulse line?

Really appreciate your reply, thank you. Saw was running ok ISH before I stripped down carb. I've obviously got something wrong when rebuilding the carb and I think it's associated with the needle height. Am I too rich or too lean if it's not pulling up to max rpm?

 

[Mad Professor]

Really appreciate your reply, thank you. Saw was running ok ISH before I stripped down carb. I've obviously got something wrong when rebuilding the carb and I think it's associated with the needle height. Am I too rich or too lean if it's not pulling up to max rpm?

Check the carb parts are correct and oriented in the correct positions. Some kits service several carbs.

Also look over fuel line, often removing an old one will produce a crack that is hard to see, and/or loosen the fuel intake elbow on the carb.

 

[Myce]

Check the carb parts are correct and oriented in the correct positions. Some kits service several carbs.

Also look over fuel line, often removing an old one will produce a crack that is hard to see, and/or loosen the fuel intake elbow on the carb.

Thanks for that, I'll have a look tomorrow evening. Again, appreciate all advice. This site is a phenomenal font of information. Thank you all..

 

[Old2stroke]

Good day everyone, I've lurked here for a couple of years and as much as I thought I was a good amateur mechanic, I have learnt so much from this site, so thank you.
I have an problem with a 1997 Husqvarna 61 grey top and am reaching out for some advice please. Bought well second hand, cleaned up, changed mismatched bar and chain then decided to investigate carburettor. Cleaned out and fitted Tillotson 23 kit. Levelled pin height as per manual..no fuel getting through at all. Checked pin top to diaphragm...all good. Lifted pin by about .75 mm. Saw starts straight away but will not rev above about 5000 and is 'burbling.' Have I made it too rich with such a small adjustment or is it too lean? Appreciate any advice, thanks guys.

Are you saying that you adjusted the control lever to be .75mm above the correct height? Did you pressure test the fuel inlet after doing that?

 

[Myce]

No pressure testing done; I'm not that advanced! I set the control lever at the height specified, from memory a fraction below 'deck height' with a generic carb height tool and the saw would not start. Checked why and no fuel getting through. I raised the lever around .75mm. Started straight away but will not reach full speed, just seems to be 'burbling' on WOT at around 5000 rpm. Unsure if enough fuel or too much.

 

[ballisticdoughnut]

Make sure on the metering side of the carb you have the diaphragm on top of the gasket. Gasket, diaphragm, cover. Not diaphragm, gasket, cover. Hope that makes sense.

 

[Old2stroke]

No pressure testing done; I'm not that advanced! I set the control lever at the height specified, from memory a fraction below 'deck height' with a generic carb height tool and the saw would not start. Checked why and no fuel getting through. I raised the lever around .75mm. Started straight away but will not reach full speed, just seems to be 'burbling' on WOT at around 5000 rpm. Unsure if enough fuel or too much.

The "burbling" at WOT is commonly called "4-stroking" and is the sound made when a 2-stroke is running too rich. There is a narrow range of adjustment of the control lever, higher and lower than nominal, that will allow the carb to operate like it's supposed to. You may have exceeded the range. Have you tried adjusting the H screw? As mentioned, could be faulty assembly of the carb components or even a difference in the size of the nub on the new diaphragm. What is the initial setting of the H screw?

 

[Myce]

Make sure on the metering side of the carb you have the diaphragm on top of the gasket. Gasket, diaphragm, cover. Not diaphragm, gasket, cover. Hope that makes sense.

Good advice thanks and checked out ok as I had a diagram of carb rebuild just in case it had been 'tinkered with' before. You never know what you get with second hand purchases!

 

[2StrokeFondler]

Do you still have the old diaphragm? If so, check that the metal dimples are the same height. Had a Jonsered 630 where the new kit had a different style diaphragm. Had to change the metering lever too, otherwise it wouldn't fit right.

 

[Myce]

The "burbling" at WOT is commonly called "4-stroking" and is the sound made when a 2-stroke is running too rich. There is a narrow range of adjustment of the control lever, higher and lower than nominal, that will allow the carb to operate like it's supposed to. You may have exceeded the range. Have you tried adjusting the H screw? As mentioned, could be faulty assembly of the carb components or even a difference in the size of the nub on the new diaphragm. What is the initial setting of the H screw?

My thoughts exactly, thank you. It sounds if running very rich. I did briefly try the H screw but as we were out cutting I didn't spend any time on it, just picked up another saw. I'll look at again at the weekend and drop the needle by fractions. Good call about fuel lines after being disturbed as well; I will check.
Thanks again everyone for the advice, really appreciated.