Romper
ArboristSite Lurker
I’m afraid I fall into this category. Lesson learned. Thanks for the input.
029 woes
- Thread starter Romper
- Start date
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a air leak will not cause low compression but a crappy cylinder/piston/rings sure will
A air leak will cause a lean condition that will ruin a piston/cylinder though
A air leak will cause a lean condition that will ruin a piston/cylinder though
Bent rings or a bad ring land will make it come up low. A low spot in the cylinder wall will also have a lot of blowbye.
It's just the rings going away. If you put OE or OE quality rings on very crappy pistons no issues. The sooner people understand quality hardware is likening to "the rubber that meets the road." BFG compared to X brand rof lmao.
Rings
Bearings
Wrist pin
Pin Clips
Gaskets
Rubber bits including the carburetor inside
Fuel and impulse hoses
Duckbills
Check valves
Orings
Clutch springs
Starter cord
Starter paws, clips and bolts
Worm gear, learned the hardway
Oil pump gear
Ignition system
Did I miss anything but better filters and inlets?
That is a solid list.
I built piles of 029/290's.
The bolt mistake is running in new thread set by not paying attention to the the original threads. The ones already "fixed" often needed a new threads installed and fine threads on a smaller bolt size and no more issues. The second problem is nobody oils the threads in the case and the bolts under the caps when torque is applied to the bolt. I've never used an AM top end on one and never had a comeback. Setting the factory threads deeper when its apart will save you on broken bolt issues and use oil. I buy Caber, Husky, Stihl, Makita, or Dolmar rings. The seals are available anywhere and several widths fit so no worries there. Not much else to that long block. I buy good pin clips like rings and new Stihl wrist pins. Port the intake and exhaust wider. Add intake time to get 77 if needed. Lift the the transfer ports a bit if they want more power or notch the piston 0.025- 30 on both sides at the primary port opening and lay it back to nothing up top.
Igntion timing is all over the map on 1127 so find 30 degrees btdc and put it there. 28 on an 039 OEM jugs is good with a 25-28" bar highly NOT recommended. They require an oil control bolt mod. The rest is almost stock but the usual stuff we all modify. Adding bigger carb added nothing to my 039 OEM cylinders with or without the decomp button. 029S runs the best stock with the least vibes. 310 is as fast as 390 ported to me. 029S has the most aggressive port timing and the least ignition advance in my findings. After reviewing all the AM cylinders two 029/290 ones are maybe worth using. The 390 AM is a failure in every brand for performance. I'd buy used ones before aftermarket types.
It takes about fifteen minutes longer to strip one if the bar bolt gets stuck. Weld a nut on itand replace it. Wont move... weld another nut on it ;-). The rest is just a tool. Set your mind to taking the crank out as fast as possible and it will go faster. Getting the tank handle off takes the same time as pro saws.
Why?
You can use shop air or bicycle pumps. HVAC pumps and old compressors work for vacuum or pressure. Hand pumps I've owned all broke over time. Shop tools never did. Air pressure operated HVAC pumps are cheap and work well. Spend the money on leak down kit gauges or build a set. Tiny old fridge compressors and air brush stuff even works. Tap the inlet and outlets. Use valve stems for check valves so you can replace the Schrader valves. Also makes a nice pressure or vacuum release. No hand pumps. Soapy water in a bottle finds it most times. I've had seals pass both tests but still suck air if old and hardened when running.
On many Stihl chainsaws with the rubber intake I use my thumb to block it off. Or you could use a rubber cork. Hardware stores sell several different sizes.
Romper
ArboristSite Lurker
OK since I don’t mind doing things over, I might just put a set of OEM rings in with the Chinese junk and see about compression.
OK. I have lost track.
You have two of these saws.
At the start, both with AM top ends, both did not run and had low compression.
Both got replacement top ends.
Saw #1. 117 pounds after new parts. Stopped running.
Saw #2 ran after new parts. But doesn't now, and shows low compression.
Is that correct?
You have two of these saws.
At the start, both with AM top ends, both did not run and had low compression.
Both got replacement top ends.
Saw #1. 117 pounds after new parts. Stopped running.
Saw #2 ran after new parts. But doesn't now, and shows low compression.
Is that correct?
Romper
ArboristSite Lurker
Saw #1 starts good. Have not put it in wood
yet.
Saw #2 still at 75 psi. Starts with carb cleaner seems to run good but doubt it will do any good in wood. This is the one that I might try a set of OEM rings. What do you think???
yet.
Saw #2 still at 75 psi. Starts with carb cleaner seems to run good but doubt it will do any good in wood. This is the one that I might try a set of OEM rings. What do you think???
There are people who commonly buy Caber rings for use with new cheaper AM pistons...thinking, say, the Hyway pistons are better than the Hyway rings. I have used a few Hyway rings without problems.
As someone earlier pointed out, compression often improves as saw is used (after getting new rings). Maybe Saw #1 will be fine. What is its compression?
Many people think a saw won't run at 75 psi.
Did you try the sandpaper method on the OEM jugs? Many cylinders look totally scored when they are actually smeared with aluminum from the piston.
Roy
As someone earlier pointed out, compression often improves as saw is used (after getting new rings). Maybe Saw #1 will be fine. What is its compression?
Many people think a saw won't run at 75 psi.
Did you try the sandpaper method on the OEM jugs? Many cylinders look totally scored when they are actually smeared with aluminum from the piston.
Roy
I think you need to try a different compression gauge..
Compression gauges all break eventually so no need for them. You know when the numbers don't add up by pulling on the starter.
Romper
ArboristSite Lurker
Thanks for the info. I think my gauge is good. It has indicated as high as 140 on other saws
Romper
ArboristSite Lurker
Very informative. Both these saws had aftermarket jugs when I took them apart. They were for sure shot. I plan to run both saws in wood to break them in, check compression again and go from there. Likely Caber as you suggest. Thanks again!!
thompsoncustom
ArboristSite Guru
did you perform the compression test right? some saws are more forgiving then others.
Sorry...my mistake. I thought you decided not to use the original' jugs.
Good plan.
I have no idea if cheap rings are your problem. But, I do know Caber rings are first rate. There are counterfeit Caber rings...so, use care about who you buy rings from.
Roy
Romper
ArboristSite Lurker
Yup usually a little heat in the saw with the throttle wide and choke off
Romper
ArboristSite Lurker
I suspect all of the typical on-line saw shops which sell Caber rings sell the real ones. I avoid ebay and amazon for such things.
Wolf Creek, Duke's, Sawsagain, and such. And...
https://www.hlsproparts.com/searchresults.asp?searching=Y&sort=2&cat=122&show=30&page=4
I guess there is a difference between normal Caber and f-cast Caber rings. You can google the difference...I don't know the difference off the top of my head. It does seem the F-cast are easier to find.
Roy
Wolf Creek, Duke's, Sawsagain, and such. And...
https://www.hlsproparts.com/searchresults.asp?searching=Y&sort=2&cat=122&show=30&page=4
I guess there is a difference between normal Caber and f-cast Caber rings. You can google the difference...I don't know the difference off the top of my head. It does seem the F-cast are easier to find.
Roy
