First Port Job - Husqvarna 365 Build

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Huskybill said:
I smooth out the roughness from the carbide using the drum sanders. Then I use the buffer drums with lapping compound to polish the ports.
I use the coarse red, then fine white lapping compound then the finer simi chrome polish. I want the smoothest flow I can get. I don’t want rough ports.

https://www.amazon.com/ODOMY-Polishing-Grinding-Accessories-Attachment/dp/B07RS34SCB
Click to expand...
Semi-rough surfaces actually flow more air and are cooler than mirror finish surfaces. A sandblasted texture works well
 
She's ready. squish is .019 with a base gasket and Motoseal on both sides to ensure no leaks. Still have to compression test it to see what gains have been made there, but otherwise I just need to fire it up and hope she doesn't self detonate. I had a new 20" bar and chain lying around so I threw that on, and the high top is from my 372 and its there purely for looks haha!

Limited coil, no tach, tuning it by ear and feel. Ill see if it even starts, tomorrow.
 

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so I started it today, and it runs! right away the throttle response is noticeably much better, and the saw snaps up to speed. However when I hit WOT I noticed it was very lean, so I backed out the H screw a lot to hopefully hit a real rich sound and adjust from there, but then the saw started to act funny. It was fine as soon as I touched the H screw, but even after turning it back in the saw doesnt want to stay running. Its idling a little faster and as soon as you hit the throttle it falls on its face. If left to idle on its own it will idle for about 3 seconds and then die. I backed out the L screw a ton to compensate because it sure seems like a fuel delivery issue, but could I have an air leak? The fuel has plenty of oil so even if it ran lean for half a second at WOT theres no way it could've done damage from lack of oil. Itll start back up with the choke on, sometimes it won't though. I'm wondering if there is an air leak that only shows itself when the saw warms up?
 
sixonetonoffun said:
Is it the Zama carb? They often need to be rejetted.
https://www.arboristsite.com/community/threads/zama-carb-mod-cliff-note-version.275905/
Click to expand...
Thank you! I let the saw cool down, reset both jets to 1.5 turns out, restarted the saw and it idled great for a little bit. Then I started fiddling with things again and the saw acted up right away. I'm certain it's a carburetor issue, and then you share this link for me!! what a champ! thank you.

I may also swap the carb briefly for the RWJ4 on my 372 just to confirm that it is a carb issue, and the RWJ4 should be able to supply the fuel and air to get the full potential out of the port job. But those carbs are expensive so if I can modify the Zama I will do that instead.
 
After modding the carb, she still doesn't want to run. Drilled out the jets as per the link provided, added an air hole into the throttle plate also as per instructions, H seems fine, but as you can see in the video, its super boggy at low idle and really struggles to get above. once in the higher threshold she purrs though. My first thought is that its lacking fuel, but im kind of stumped. Any suggestions?
 
Artemis said:
After modding the carb, she still doesn't want to run. Drilled out the jets as per the link provided, added an air hole into the throttle plate also as per instructions, H seems fine, but as you can see in the video, its super boggy at low idle and really struggles to get above. once in the higher threshold she purrs though. My first thought is that its lacking fuel, but im kind of stumped. Any suggestions?
Click to expand...

Ill add that when its bogging real heavy, that's me holding it wide open throttle, and if I let off at all she dies immediately.
 
huskihl said:
Lack of fuel. It actually sounds like your impulse hose or circuit may have a plug or a hole in it
Click to expand...
Very likely. I replaced the impulse tube with some new pvc line, but i will do it again just to be sure. If the impulse line has a hole in it, won't it run crappy at all rpm and not just the low idle?
 
Artemis said:
I'm going to drill out the auxiliary jet more and see if that helps
Click to expand...
I'd go back and check the basics. Sometimes when you use line that is not fuel line it can create basic problems that are easily overlooked.

Had a buddy do that and the line got brittle overnight and broke off inside the tank.
 
Mufflermonkey said:
How did the other carb work ?
Click to expand...
I was just in the process of trying to use my walbro carb but thought I would give it another try with the Zama. I started it up with no air filter on and the fuel is just FLYING out of the intake. so the problem is that its obviously over fueling and choking itself out once it hits the lower rpm.
 

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