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Post by Urbanchainsawer on Jul 13, 2008 19:45:08 GMT -5
New member here looking for some help with my 101. I am also pretty new to the Homelite hobby. I've acquired a few really nice saws in a short period of time. All of them run great except for my 101. It's obvious that it doesn't have many hours on it, but there is a stumble when you gun it from an idle. Once it gets up to speed after the stumble, it runs like a bat out of hell. Sometimes, if I gun it too hard, it will die. I'm thinking a carb rebuild. What about an adjustment? I'm leary about cranking on the adjustment screws too much. Its a Walbro SDC 1. I've rebuilt Carter AFBs with great success, so I think I can tackle a Walbro. Any suggestions? Thanks in advance, Joe
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Post by lesorubcheek on Jul 13, 2008 21:15:10 GMT -5
Hi Joe,
The typical case of stumbling during acceleration means the Low speed screw is a bit on the lean side. Its safe enough to try a small amount of adjustment on it and see if that corrects the problem. Try turning it counterclockwise to open it, about 1/8 to 1/16 of a turn at a time and testing each adjustment. If you have to back it out more than a full turn and it hasn't made any difference, then odds are you'll have to dig a bit deeper.
Dan
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Post by mikevan on Jul 14, 2008 5:04:02 GMT -5
Joe, my 101 did the same thing this spring - Went from running perfect to what you describe in a matter of seconds. Got so bad, had to run it with the choke part way out before I fixed it. Get a complete kit for the carb, clean it real good watch which way the diaphrams & gaskets are, it'll only work right one way. You shouldn't have to pull the Welch plugs, I did, 'cause after my rebuild, it still hesitated just a little. Under one of those plugs is a tiny screen, it shows in the blowup pic. of the carb. There's also a diaphram under that screen, you have to be careful not to damage it, it's not in the kit. A fine wire pushed in all the tiny holes helps too. Mine runs great again now, a good feeling!
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Post by Urbanchainsawer on Jul 14, 2008 21:03:24 GMT -5
Thanks for the quick replies, fellas. Well I tried the low speed adjustment and it made no difference whatsoever. It looks like I need to dig deeper. I ordered the full carb kit to do a rebuild. I'm kinda looking forward to the experience. If there are any other tips out there, feel free to post!
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Post by lesorubcheek on Jul 14, 2008 21:39:12 GMT -5
Nothing's ever easy is it! Its a good idea to check out the fuel line and the filter while you're at it. Hopefully a good cleaning and a rebuild of the carb will set things straight.
Dan
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Post by bosshoss1 on Jul 15, 2008 20:35:18 GMT -5
i'm having the carb rebuilt on my super 77-i told the shop to put a shut off valve on the fuel line coming in from the gas tank.i think it can help to avoid carb problems in the future.
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Post by Urbanchainsawer on Jul 20, 2008 21:25:06 GMT -5
Carb kit has been purchased and carb has been rebuilt. Had a few minutes to make adjustments tonight. It fired quickly but died shortly thereafter. Will have to fine tune it tomorrow. I have excellent instructions to adjust it, but any tips will help. Just hoping that I don't end up  ! |
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Post by Urbanchainsawer on Jul 24, 2008 16:01:47 GMT -5
I had some time to mess with my 101. I achieved a nice idle following my detailed carb adjust directions, but it still tends to bog a tad when I gun the throttle. This is despite a complete carb clean and rebuild. It seems to do better when warmed up. Is this typical of the older saws or do I need to refine my adjustments? Once again, it runs like a bat outta hell when up to speed. Any detailed instructions would help.
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Post by chainsawwhisperer on Jul 24, 2008 17:48:40 GMT -5
JPW, It sounds like you still have a lean condition on the high speed adj.
Is the engine burbling/4-stroking at no load WOT?
How far out are your screws? CSW
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Post by mikevan on Jul 24, 2008 17:57:27 GMT -5
Joe, that little miss, hesitation, or bogging usually means 'not enough fuel when it needs it' Like Dan said above, I'd try opening the low speed screw 1/8 turn at a time, trying to put a little richer flow in there. If the saw idle starts going up, you can back off on the screw that adjusts the stop on the carb itself.
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Post by Urbanchainsawer on Jul 24, 2008 17:58:48 GMT -5
Lean on my high speed adjust ? Or low speed? Someone mentioned on an earlier post that a stumble was typically lean on the low speed. Screws are + or - one turn out. I need to learn that 4 stroke sound. Remember, I'm new to the hobby!
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Post by chainsawwhisperer on Jul 24, 2008 18:18:50 GMT -5
jpw, sorry about the name goof-up.
I was referring to the high speed screw, but after reading the following posts I think I'm mistaken.
The burble sound that I mentioned usually indicates the proper F/A mixture.
At WOT, screw the H speed screw in to get the highest RPM, then back the HS screw out until the sound of the motor changes to a
slightly 'choppy' (burble, 4- stroking) sound.
4- stroking is just as it sounds, like the engine is firing every other stroke... due to the over rich condition at no load WOT.
This is ideal F/A mixture under load. CSw
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Post by chainsawwhisperer on Jul 24, 2008 18:21:52 GMT -5
I might add that you want to do this kind of quickly as holding WOT for an extended time is
not great for the saw. CSW
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Post by mikevan on Jul 24, 2008 18:42:56 GMT -5
One last thing Joe - The SDC 1 should have an accelerator pump body on the side of it, 3 screws holding it on? There's a diaphram under it too, I've seen different rebuild kits, not all of them have this part. You have to take the throttle plate off & pull the shaft out to get the cover off. The diaphram has a fine spring under it.
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Post by chainsawwhisperer on Jul 24, 2008 19:05:02 GMT -5
I wasn't familiar with the SDC 1, I did not know it has an accelerator pump.
I learn somthing new every day! Bad pump could be the problem.
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Post by Urbanchainsawer on Jul 24, 2008 19:20:00 GMT -5
You are correct. There was a diaphragm with a fine spring. The kit included this, so it has been replaced. I'm pretty sure that the word throttle is in WOT, but I can't figure what the WO is. Duh. I'm assuming that you mean full throttle.
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Post by chainsawwhisperer on Jul 24, 2008 19:44:32 GMT -5
Wide Open Throttle ;D
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Post by chainsawwhisperer on Jul 24, 2008 19:50:33 GMT -5
I boosted this from Turbocaster's post on AS. ALAP - (As Low As Possible) B&C – Bar and Chain BIL – Brother in Law BOX store - Home Depot, Lowe’s, Etc. BTW – By the way CAS –Chainsaw Addiction Syndrome CSM – Chain saw mill??? EGT - (exhaust gas temperature) probe FIL – Father in law FLEABAY - EBay FWIW – For what it’s worth GTG – Get To Gether I.E. Lets all get together and cut some firewood. HD – Home Depot IMHO – In my humble opinion IMO – In my opinion IPA - Isopropyl Alcohol IPL – Illustrated Parts List LOL – Laughing out Loud LP – Low Profile (chain) MIL – Mother in Law MTTF - mean time to failure NK – Narrow Kerf NLA – No Longer Available NOS - Not otherwise specified OCD -  OEM – Original Equipment Manufacturer OFR - OPE – Other People’s Experience??? OTD – Out the Door I.e. Out the door price OWB - P&C – Piston and Cylinder PB – 16 PB – Penetrating spray from Blaster Products PHO – Power Head Only PITA – Pain in the a$$ PM – Personal Message POS – Piece of (manure) PPE – Personal Protective Equipment RL – Red Light (on some models of Stihl 066) ROFL - Rolling On Floor Laughing SIL – Sister In Law WOT – Wide Open Throttle WTG – Way To Go YMMV – Your mileage may vary __________________ Turbocaster - Be safe and have fun! CSW |
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Post by mikevan on Jul 25, 2008 4:54:11 GMT -5
You only missed one - D.S.B. or, dreaded suck back - ;D
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Post by Urbanchainsawer on Jul 25, 2008 19:08:54 GMT -5
She's purring now, thanks to the pros on this site. It was a little lean on the high side. I now know the sound of the 4 stroke burble. And she flat out screams at W-O-T! I live in an urban area, unlike prolly most of you guys, and my neighbors think I'm crazy! They think I'm juggling chainsaws or something. At least passersby will know to steer clear if they have any thoughts of messing with my possessions. Thanks guys!
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