Husqvarna 298 tuning issues

[Ditchbanger08]

Looking for some advice on the old Husqvarana chainsaws. Have a 298 that I plan to use for a milling saw and im having some issues with tuning it. When I try to set the H it seems it wants to constantly lean out after couple seconds of full throttle. So obviously it acts like its leaning out, so I richen it up to bring rpms to where I need them but it will still want to race even when I max out the screw. Its odd since it wont run lean when I first hold wide open throttle but after few seconds. Didn't know if I should look to replacing diaphragm baffle for fuel pump even though it appears to be fine or possibly replace entire carb? Once I richen all the way up it then will throw everything off and then cause it hard to restart the saw. Main symptom is the H adjustment though...if I were leaking air somewhere wouldn't it affect the saw through all rpms? I have removed and cleaned the carb as well. And also the saw leaks bar oil when not running and uses a lot when running. Is there an adjustment, I cannot find one. Im running a 36 inch bar on the saw and shooting to run max rpms around 11,500 rpm. If theres any advice for this saw id greatly appreciate it. Thanks

 

[Deleted member 117362]

1 to 1-1/2 turns out, usually is a starting point. But I would vacuum check that saw for an air leak, before running.

 

[Ditchbanger08]

Ok thanks for the quick reply. 1 to 1-1/2 turns out on both screws? And probably a dumb question but is there an easy method to vacuum check the saw? Ive never done this to one, so figured id atleast ask if theres a clever way before turning it into an all day job...thanks

 

[Deleted member 117362]

Start at 1 on H and 1-1/2 on L. You need to block off intake and exhaust ports, make my own plates and rubber gaskets. Been able to clean intake and exhaust, really clean, and block off with a few layers of duct tape. Not the best method. I took a spark plug and knocked out insulator and cemented a hose into base, so able to draw vacuum from spark plug hole on 2 series saws. Should be able to pull around 7 pounds and hold, may have a very slow leak down. You will need a Mini vac or similar. Another method is to use carb cleaner and spray by cylinder base, flywheel bearing (as best you can) and near clutch side bearing. Careful not to spray close to carb intake. If saw stops from sucking in cleaner, you found a leak, also not the best method, but works. Hope that helps and someone will be along to add information, I am sure.

 

[BobL]

Here is my setup
A: tubeless tyre valve - just go to a tyre shop and ask - I was given a couple for no charge.
B: on/off valve. Any air tight tap will do.
C: -10 to 20 PSI pressure/vacuum gauge.
D: Adapter plate to attach pressure line to cylinder inlet port.
E: Alternative Adapter to attach pressure line to spark plug hole - if this is used the inlet port must be blocked. This is not the best way because it does not allow you to pressure test while moving the crank (yes you should do this).
F: 14 x 1 mm blocking bolt for a compression release valve
G: Blocking plate and rubber gasket for exhaust port. Hole in the middle is not required. Easiest way is to slip a bit of rubber between exhaust and port and retighten exhaust bolts

For vacuum as opposed to pressure test, the car tube will need to be removed. You can then open up the pump and flip the rubber seal. or just suck with mouth - you can easily reach the vacuum normally required for most testing ie 6 PSI and then close the tap. Taste of crankcase gas not very nice so I keep a beer handy to rinse my mouth!

 

[fatfred]

Also having trouble tuning my 298. Ran fine before i rebuilt the carb. Low was 1 and high was 1.25 before. I got it to idle for a good minute or 2 with the choke all the way out but once I put it in it dies every time.

To answer your question about the oiler...you have to take it out and adjust one of the screws on the top. I read other places if you remove the oiler you should replace the O-ring and seal. The V-ring on my oiler was broken into pieces so I have a new one coming in the mail now. I don't think that would cause a vacuum leak if the seal to the crank case is good though. Good luck with yours!

I think this oiler manual applies to the 298 but not 100% certain. Screw labeled CS controls oil output.

Looking for some advice on the old Husqvarana chainsaws. Have a 298 that I plan to use for a milling saw and im having some issues with tuning it. When I try to set the H it seems it wants to constantly lean out after couple seconds of full throttle. So obviously it acts like its leaning out, so I richen it up to bring rpms to where I need them but it will still want to race even when I max out the screw. Its odd since it wont run lean when I first hold wide open throttle but after few seconds. Didn't know if I should look to replacing diaphragm baffle for fuel pump even though it appears to be fine or possibly replace entire carb? Once I richen all the way up it then will throw everything off and then cause it hard to restart the saw. Main symptom is the H adjustment though...if I were leaking air somewhere wouldn't it affect the saw through all rpms? I have removed and cleaned the carb as well. And also the saw leaks bar oil when not running and uses a lot when running. Is there an adjustment, I cannot find one. Im running a 36 inch bar on the saw and shooting to run max rpms around 11,500 rpm. If theres any advice for this saw id greatly appreciate it. Thanks

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