Project TS420 Concrete Saw

[Automender]

More testing today yielded a good purge bulb and fuel hoses but still wouldn't pull enough vacuum to prime the carb. Not sure of what the item is called but the check valve that is in the venture but it leaks vacuum when I use the primer. I can't get access to the part because it is covered but a plug, not a welch plug but a solid metal one. Ordered an aftermarket carb from Amazon and it will arrive tomorrow. Didn't want an aftermarket carb but didn't want to layout $130 for an OEM, aftermarket was $25 with fuel, air filter and sparkplug. See it it works!!

 

[qurotro]

You can try tapping it out.

 

[Automender]

I tried to soak the carb in mineral spirits and used my ultrasonic cleaner for 30 minutes but the main jet valve is still leaking when I pull a purge vacuum.

I received the aftermarket carb today and pulled a purge vacuum and no leakage. Quality seems really good on the outside and I will install it and give it a try. Good reviews on Amazon. But I understand these things are a hit and miss on function.

 

[Automender]

You can try tapping it out.

Once I get this AM carb and saw fired up I will try pulling out the plug and see if I can get the jet/check valve out and fixed. I figure I can solder up the plug to fix the hole I used to pull it. I don't think I can find a replacement jet/check valve.

 

[Automender]

Played with the saw today for a short time. Compression test showed 125 psi which seems decent with new rings and cylinder. Saw started after I realized I had the choke in the open position, didn't pay attention to the markings on the cover. It was at a high idle but ran good and it had not lag as I increased the throttle. I was not able to lower the idle to a point where the blade would stop. It was too cold today to play around with the idle screw and lever. I did try to adjust idle mixture drop the idle speed but that didn't seem to change much. Started with H and L screws out 1 1/4 turns out. Todays run was just to make sure coil was good.

If I can't get the idle down with adjustments then I could have an inlet boot leak at cylinder or carb. I didn't vac/pres test with the boots on but boots were in great shape, no cracks. I have a Husky 970 and it is a lot easier to work on than this saw. Everything is compact and hidden and the top shroud contains the throttle, choke and stop switch so taking it off makes it hard to run.

 

[Automender]

Tried to get the idle speed down today. Didn't matter if I removed the idle throttle screw or adjust the mixture screws, the idle was too high to get the clutch to disengage. Saw would rev up smooth and drop down quickly to a point where the blade would just about stop but then speed up again.
Sprayed some carb cleaner around the inlet boot and idle dropped much lower. I pressure tested the saw but not the inlet boot so I need to retest the saw with a plate instead of the carb. Also could be the carb leaking.

 

[Automender]

Getting closer to pressure testing to find out the high idle issue source. Made a test plate from 1/4 inch aluminum and a old carb inlet tube. I drilled a hole and heated the plate and inserted the tube and when cooled it was in really tight. I added a little epoxy just for good measure. Maybe tomorrow I will slip a inner tube piece of rubber in between the muffler and the cylinder. Should have made this plate when I did my first pressure test
.

 

[Automender]

Decided to pressure test today but had problems putting the intake boots back in to the carburetor plate. I just pulled the boots off the cylinder and was going to pull them into the plate and then push the boots on. I found a nice little crack in the bottom boot. I had ordered a bottom boot because the old one didn't seem to have a thick flange to give a good squish to the lower carb face. I replaced the boot and decided not the pressure test the saw. I also removed the spacers on the boot clamps so I could tighten them a little more. Popped up on the third pull and fired up on the first pull without the choke. Idle was low enough to stop the blade and I tweaked the idle mixture a little to make sure it was a little rich. Need to do some cutting to really get it right.

 

[Shane¹]

Glad you got it figured out. Sounds like you are just about ready for another project now

 

[Automender]

Glad you got it figured out. Sounds like you are just about ready for another project now

Picked up a 2013 Husqvarna 440 Xtorq yesterday for $50, one owner. I know it isn't one of the great saws but it's a good start to learn. Starts cold, but owner said frustrating to start warm. Compression was 120 psi and leaks bar oil. Not sure what is the factory compression is but it doesn't have a decompression valve.