picked up a pair of CS-750EVLs...

[JUSS10]

cedarshark, once I get one running and usable, I will likely tear in to the other and start another thread. Maybe we can bounce ideas and info off each other. I will say, these are well built saws but also seem a bit more complicated than my other saws sitting around.

 

[cedarshark]

cedarshark, once I get one running and usable, I will likely tear in to the other and start another thread. Maybe we can bounce ideas and info off each other. I will say, these are well built saws but also seem a bit more complicated than my other saws sitting around.

Sounds good. Like any saw there is a procedure to go through to effectively get them apart and together. I would think modifiedmark has done this before and can provide some direction on how to solve my problem and hopefully avoid it in the future for both of us.

 

[Modifiedmark]

I have done them before, but it has been some time since I was into one. I remember the throttle linkage being a PITA though.

I have the service manual for it if you want to send a email address to me. One thing to be said on these old Echo's, they had excellent IPLs and Manuals for them.

 

[JUSS10]

Seeings you already have my email, can you send me the service manual?

Thanks!

Justin

 

[cedarshark]

I have done them before, but it has been some time since I was into one. I remember the throttle linkage being a PITA though.

I have the service manual for it if you want to send a email address to me. One thing to be said on these old Echo's, they had excellent IPLs and Manuals for them.

I would sincerely appreciate the service manual....pm headed your way. Thanks a lot !

 

[Modifiedmark]

You guys should have them now.

 

[cedarshark]

You guys should have them now.

Got it. Thanks loads ! Worth its weight in gold. You are a life saver !

 

[cedarshark]

I pulled the carb off my 702 this aft and thought I would offer the following hints as your 750 is very similar:

1) My linkage rod had fallen off and diappeared in a black hole. Removing the recoil cover opened up that side of the saw and the rod was easy to recover. Pay very close attention to the orientation of your throttle rod. It will only work 1 way. If yu still have the rubber grommets that are on the choke and throttle rods, be very careful when you remove them to take carb out. The grommets hold the rods in position and prevent the rod ends from falling off the attachments points.

2) The carb will come off the saw with the box. There is a small gasket on both sides of the box. Be careful and dont tear them. Although I believe they can be made, there are very small holes for the impulse.

3) Mine has the Tillotson HS166A carb. I thought I had a kit but I dont. I cleaned the carb up and pulled it apart to inspect the gaskets and diaphrams. They appear old but in ok condition so I reinstalled and put the carb back in the saw.

4) Removing the recoil cover will expose your fuel line from the tank to the saw. It will also give you the chance to clean that side of the cylinder that you cannot reach from the clutch side. Mine was packed with sawdust/oil. The fuel lines appear to be OEM and I decided to test the whole line as I do not know the age. I unplugged the filter in the tank, plugged off the fuel line end that attaches to the carb and pressured it up to 7 psi. It held that pressure for 5 minutes so I decided to leave it alone. You will note that the carb end of the fuel line is "belled" and also serves a seal for the hole where it enters the carb box. This could be a problem if replacing the OEM line with tygon. I dont know if aftermarket preformed line is available...but need to look.

Although I have not been completely thru this saw, I am very impressed with the design and build quality. I think having the air intake on the opposite side of the saw that produces the dust and dirt is a VERY good idea. The manual oiler(in addition to auto) and the external idle adjust screw is very handy and not seen on the best of pro saws on the market today. At 16.5 lbs, its heavy.

I will do a compression test tomorrow and try to fire the saw up. Good luck with your project.

Many thanks to Mark for the service manual. As he said, it is very well written and helps a lot.

 

[JUSS10]

Thanks for the heads up cedarshark. I may dig in to the saws some more tonight. Been building a log splitter and that has been occupying my time!

Is the compression test with the relief valve open? I would assume that's the case due to the low numbers in the manual, just curious if thats true or not.

 

[cedarshark]

Thanks for the heads up cedarshark. I may dig in to the saws some more tonight. Been building a log splitter and that has been occupying my time!

Is the compression test with the relief valve open? I would assume that's the case due to the low numbers in the manual, just curious if thats true or not.

The decomp valve on the saw stays closed. keep pulling the starter rope until the compression gauge will go up no further. I normally will pull one a dozen(or more) times to get an accurate reading.

 

[JUSS10]

hmm, the numbers seemed low for the decomp valve closed but maybe larger bore engines have lower compression? the manual says 105 PSI, for your saw, it says 70. That just seemed really low to me.

 

[cedarshark]

hmm, the numbers seemed low for the decomp valve closed but maybe larger bore engines have lower compression? the manual says 105 PSI, for your saw, it says 70. That just seemed really low to me.

Saw won't run at 70 psi compression. Even 105 is low, but the saw should run. Did you get the compression numbers from the service manual ? I have not read that section yet.

 

[cedarshark]

Just reviewed page 30 of the service manual and you are correct...normal reading for a cs702 is 70psi and a normal reading for a 750 is 105. I have no explanation for this, as I am accustomed to my Stihls having 130-160. They wont run at 70psi. I will know later today. If mine runs, I will do a comp test and let you know. Maybe these old saws just dont run the higher number you see on the newer ones.

 

[JUSS10]

yeah, thats right from the manual.

 

[JUSS10]

I'll try mine too, but i don't really trust my compression gauge anyway. I just wondered if that was the reading you were supposed to get with the valve open since the compression is supposed to be "too high" to start with it closed otherwise there wouldn't be a reason for a decomp valve, right?

 

[cedarshark]

yeah, thats right from the manual.

It will be very interesting to verify these numbers. Maybe that is the reason these saws last forever ? I bet modifiedmark can tell us if these numbers from the manual are bogus or not.

 

[cedarshark]

I'll try mine too, but i don't really trust my compression gauge anyway. I just wondered if that was the reading you were supposed to get with the valve open since the compression is supposed to be "too high" to start with it closed otherwise there wouldn't be a reason for a decomp valve, right?

No, the decomp valve is just for starting purposes to make the saw easier to pull over. After it starts, you close the decomp valve. Did the manual mention doing the test with the decomp valve open ?

 

[cedarshark]

If I can pull start an 044, I can check this cs 702 with the valve closed.. If the saw is throwing 130-150 psi with the decomp closed, I think we can assume the service manual infers the test should be performed with the valve open.

 

[JUSS10]

True, I didn't have an issue starting it with the decomp valve closed, especially if its that low of compression. makes you wonder if you could shave a little off too up the compression on the saw to boost a little power... anyway, let me know what you find!

 

[cedarshark]

True, I didn't have an issue starting it with the decomp valve closed, especially if its that low of compression. makes you wonder if you could shave a little off too up the compression on the saw to boost a little power... anyway, let me know what you find!

You might be able to remove the cylinder base gasket after you check the squish to raise the compression. I wouldn't do it until I had good compression numbers on the saw with good rings.