Huztl FarmerTec 070 Build Thread with upgrade info and completed saw

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i had a plunger fall into the cylinder once. It's not a big deal. pull the spark plug, flip the saw, and in a shake or two the plunger came out.

This doesn't help the installation, but bringing the cylinder to TDC seems to keep the plunger from dropping all the way into the chamber. This is somewhat what Ted described above.
 
Awesome information. I just caught up.

Years later I still am preaching the role a carb plays in oiling a saw. Plus, it shows I been to high on the tune. Enjoyed reading this. Thanks

I had a conversation with a guy that complained strongly the saw was too slow. I tried to steer him to the 660. Folks need to understand slow can be powerful and this might help with that.
Here are a couple service bulletins I found posted on a different site. They go into detail on carb tuning for the 070/090. I thought it made for a pretty good read.

chainsaw kits and packing lists
http://thechainsawkitguy.com
http://YouTube.com/c/the1chainsawguy
 
My plans for the decomp is to make a plug, then drill it out and tap it to install a modern stihl decomp button. Kinda like a homemade time-sert. I'll use a small enough id sized washer underneath to catch the plunger if it ever fails. Also I don't have to worry about holding the damn thing down with my thumb when pulling the rope.

Actually I tried that fix, but went back to just put the correct decomp valve back in and has worked perfectly. Thanks
 
What about it didn't work?

I could say if I persisted could have made it work. My plan was to use a Husky valve with the OEM style knob. The Husky type is close to a long reach spark plug as far as threads go. I was going to use a plug then drill it and tap it the same as the Husky valve, but one of the issues cam up with the plug is that it is not straight. The bottom part of the plug is much more narrow with less material to work with. After spending a hour or so I thought why am I spending time on something that might not work well. Went to the trusty desktop and ordered several. Now the decomp is nearly bullet proof with out spending much time on it. Thanks
 
My decomp valve was leaking and I didn't feel like waiting on an order. I went down to the hardware store and grabbed a 14mm x 1.50 bolt and went at it.
20181230_142857.jpg

I noticed there's a pretty good sized hole left exposed to the combustion chamber. 20181230_144834.jpg

It calculates out to the equivalent of adding .0215" to the squish band which lessens compression some. I decided to machine down the smaller bolt on the right in the picture above to match that area perfectly to eliminate it. The copper washer also needed opened up a little on the inside to fit the plug. I'll make another plug out of aluminum to replace it if it creates a hot spot. 20181230_030515.jpg


Here's the piece I cut from the end of the 14mm bolt to finish it off. 20181230_030253.jpg 20181230_031640.jpg


The increase in compression is a noticeable difference.

I'll eventually be cutting the base to increase compression enough to need a decomp, so another piece of that 14mm bolt will work perfectly for machining a time-sert to fit a modern decomp.
 
My decomp valve was leaking and I didn't feel like waiting on an order. I went down to the hardware store and grabbed a 14mm x 1.50 bolt and went at it.
View attachment 693570

I noticed there's a pretty good sized hole left exposed to the combustion chamber. View attachment 693577

It calculates out to the equivalent of adding .0215" to the squish band which lessens compression some. I decided to machine down the smaller bolt on the right in the picture above to match that area perfectly to eliminate it. The copper washer also needed opened up a little on the inside to fit the plug. I'll make another plug out of aluminum to replace it if it creates a hot spot. View attachment 693585


Here's the piece I cut from the end of the 14mm bolt to finish it off. View attachment 693587 View attachment 693588


The increase in compression is a noticeable difference.

I'll eventually be cutting the base to increase compression enough to need a decomp, so another piece of that 14mm bolt will work perfectly for machining a time-sert to fit a modern decomp.

Nice! That's what I was thinking of doing.
 
hmm that's what I did too but I was having doubts it will seal the side hole well and work in a long time ( see where the copper washers are showing, I added a few there ).

now looking at a new cylinder, this hole is not there !!! the decomp valve failure blew that hole ! without that side hole, I have a lot more confidence in a simple DIY plug technique.

BTW, instead of cutting the base to increase compression, maybe it is possible to just make the tip of the plug extend into the cylinder a little more :)
 

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hmm that's what I did too but I was having doubts it will seal the side hole well and work in a long time ( see where the copper washers are showing, I added a few there ).

now looking at a new cylinder, this hole is not there !!! the decomp valve failure blew that hole ! without that side hole, I have a lot more confidence in a simple DIY plug technique.

BTW, instead of cutting the base to increase compression, maybe it is possible to just make the tip of the plug extend into the cylinder a little more :)
It can't leak like that because there isn't a break in the mating surface below the side hole. Using more than one washer shouldn't be necessary.

Since it's on the way to becoming a gtg/race saw I'll cut a little off the base to get higher compression than what I can get with a longer plug.
 
It was not leaking much and was even running like that with the lower piston ring already broken (compression was low but it was running ) but the ring failed completely
soon after that. It is difficult to tell now how much of the compression loss was due to this hole vs the ring failing and cylinder damage in other places
 
I just ordered a FarmTec 070 kit but have not received it yet and have no experience with this type saw. Bedfords' videos have been most helpful getting ready. I have seen in another chainsaw thread (Stihl 070/090 pulling clutch... Houston we have a problem) where somebody overtightened the clutch nut so the clutch was always engaged, and then couldn't remove the clutch off the Spieth adapter sleeve to fix it. Question - is it possible the FarmTec clutch carrier was made wrong with the "bead" on the wrong side?? I ask this because on page 18 of the 070/090 service manual I have it says to slide the adapter sleeve on the crankshaft, the next step is then to "fit the clutch in position". Putting the Spieth adapter sleeve on first would allow the clutch carrier to come off easier for future repairs because of the taper. What do you all think?
 
I just ordered a FarmTec 070 kit but have not received it yet and have no experience with this type saw. Bedfords' videos have been most helpful getting ready. I have seen in another chainsaw thread (Stihl 070/090 pulling clutch... Houston we have a problem) where somebody overtightened the clutch nut so the clutch was always engaged, and then couldn't remove the clutch off the Spieth adapter sleeve to fix it. Question - is it possible the FarmTec clutch carrier was made wrong with the "bead" on the wrong side?? I ask this because on page 18 of the 070/090 service manual I have it says to slide the adapter sleeve on the crankshaft, the next step is then to "fit the clutch in position". Putting the Spieth adapter sleeve on first would allow the clutch carrier to come off easier for future repairs because of the taper. What do you all think?
First welcome. What I show and write on my website gives you 100% of what you need to know. I have to say people wing it a lot and then whine. Do not change the assembly instructions
Buy a Stihl clutch nut. Do not use the nut that comes with the kit. Tightening it down damages the threads and then it's hard to get it off or you break the crank. It took me 6-7 weeks to get mine. I waited. Will answer any of your questions.

Did you read the comments under the videos, I don't recall anyone saying they had that problem. Again you have to be Ridgid in how you approach the assembly. You are building a massive saw.

It's hard to absorb everything,
d162f7e20144194bcf934c0f5e006f84.jpg


chainsaw kits and packing lists
http://thechainsawkitguy.com
http://YouTube.com/c/the1chainsawguy
 
I ran into that problem a year or two so I ordered several German valves very high quality. If you have trouble with your you can always contact me. I for saw some issues if I made an insert to house a more modern decomp valve. That is why I decided to stay stock never had any problems. Thanks
 
Thanks for the response Bedford, I'm going to get spare clutch nuts on order. Can you tell me what problems you had with the FarmerTec carb that caused you to replace it with the OEM Tillotson carb? Does the Tillotson take care of those problems?
 
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