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/cgi-bin/YaBB.pl General Category >> The Cafe >> Demolition Saw /cgi-bin/YaBB.pl?num=1365111993 Message started by rl153 on 04/04/13 at 14:46:33 |
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Title: Demolition Saw Post by rl153 on 04/04/13 at 14:46:33 I have a homelite DM 40 demolition saw. Its 2 cycle 16:1 gas mix . Its from the 90s. It idles ok, a little smokey, but when you press the gas trigger it dies.I don't know much about it ,someone gave it to me ,but I was able to download the manual.I put new gas in and some seafoam. Any other suggestions? Someone said the float was stuck .Thanks! |
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Title: Re: Demolition Saw Post by bill67 on 04/04/13 at 15:16:40 When you put Sea Foam in it takes some time for it to work.try again in couple hours,then again,Then in the morning if it doesn't run.If it has a choke put it on 1/2 choke when you give it the gas. |
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Title: Re: Demolition Saw Post by rl153 on 04/04/13 at 17:03:08 Thanks Bill!I might have left the choke on without realizing it. I'll check it tomorrow. |
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Title: Re: Demolition Saw Post by ZAR on 04/04/13 at 18:52:47 rl it's the ethanol in the gas causing your problem. With luck,the seafoam will get you through but I'm betting you'll have to strip the carb down and give it a deep cleaning. What's happening is the main fuel circuit is clogged and can't deliver enough fuel to match the air when you hammer the throttle. Our techs see that exact issue at least 10-12 times every week on 2-stroke equipment. |
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Title: Re: Demolition Saw Post by Boofer on 04/04/13 at 19:58:09 Check the air filter before you tear it down completely (If you can check it without tearing it down completely.) You may have a mud cake piece of crud in the shape of a foam filter. |
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Title: Re: Demolition Saw Post by Dave on 04/05/13 at 03:43:09 I doubt that the carb has a float. Chainsaws have to run right side up and sideways....carbs with floats can't do that. The carb has a diaphragm fuel pump and a diaphragm to control the fuel flow with a needle and seat......and these gum up and/or become stiff when the saw sits with fuel in it for extended period of time. Don't screw around with SeaFoam or even try to run the saw with old fuel and a cruddy carb. A 2 cycle engine is lubricated by the fuel/oil mix and if you run it lean it will not get enough lubrication and can sieze the piston. You also don't need to run a 16:1 oil mix anymore. That was written o in the days that we used to just dump 30 weight non detergent oil in the gasoline and makes lots of smoke while cutting. Today the modern 2 cycle oils are much improvecd and a 50:1 synthetic mix oil will work just fine in that saw when the carb is repaired. Listen to ZAR....he repairs these things for a living, and I did the same 35 years ago. The majority of saw repairs are done because the saws just sit for years between use. When you are done using the saw and you are not going to use it for a while, dump the fuel out of the tank, then start the saw and let it idle until it runs out of fuel. The factory manuals advise you to do that if you are not going to use the saw for more than 2 months. |
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Title: Re: Demolition Saw Post by bill67 on 04/05/13 at 05:33:06 Dave sorry Sea Foam didn't work for you.Every one I know use it and have good luck with it. I've never drained the gas tank on and vehicle or machinery.And being in the construction business over the years I've Had a lot of 4 and 2 cycle motors and diesels. |
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Title: Re: Demolition Saw Post by Dave on 04/05/13 at 05:40:45 5B5055550F0E390 wrote:
SeaFoam might work to clean up some things - but it won't work on hardened diaprhagms. Running a 2 cycle engine lean while tryig to clean out the carb is not a good idea, as a lean running 2 cycle engine will not get enough oil and can be damaged. It is not worth the risk. Sometimes you just have to do the right thing and make a proper repair. |
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Title: Re: Demolition Saw Post by Ed L. on 04/05/13 at 05:46:31 The saw probably has a Tillitson pumper carb on it, no float as Dave said. They are pretty easy to rebuild if you can find the gasket sets, I used to run Tilly's in the modified class for gokarts. If it smokes pull the muffler and see if it is loaded up with carbon. I had a chain saw the drove me nuts with that problem. Change the plug, two strokes hate dirty spark plugs. Since the saw is old I would inspect the fuel lines, the ethanol gas does funny things to them and can erode the inside of the tubing. |
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Title: Re: Demolition Saw Post by bill67 on 04/05/13 at 05:56:03 063D3027363A21273C343926550 wrote:
SeaFoam might work to clean up some things - but it won't work on hardened diaprhagms. Running a 2 cycle engine lean while tryig to clean out the carb is not a good idea, as a lean running 2 cycle engine will not get enough oil and can be damaged. It is not worth the risk. Sometimes you just have to do the right thing and make a proper repair.[/quote] Sea Foam has oil in it and its recommended for 4 and 2 stoke engines. I live in a boating and snowmobile area and a lot of them are 2 cycles and people here use Sea Foam. |
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Title: Re: Demolition Saw Post by rl153 on 04/05/13 at 06:16:24 I put like 1/3 ounce of seafoam to a pint of gas. that's a little more than called for on the can . Should I have used more or less? Also, if I used a 16:1 fuel /oil mix and ,will that be a problem?Thanks everyone for the great answers. |
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Title: Re: Demolition Saw Post by bill67 on 04/05/13 at 06:24:19 7A73607F787327242F2F160 wrote:
Thats about the right amount of Sea Foam,If it says 16-1 thats what I would use. |
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Title: Re: Demolition Saw Post by rl153 on 04/05/13 at 14:26:00 I changed the plug and sprayed carb cleaner in the air intake . At full throttle it runs strong, but now it wont idle . There is an idle screw a lo screw and a hi screw on the carb,How do you adjust these screws to make it idle . I tried turning the idle screw all the way in ,clockwise ,but it still doesn't idle .I think I'm almost there. Thanks! |
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Title: Re: Demolition Saw Post by rfw2003 on 04/05/13 at 15:12:11 Don't listen to bill67 on the Snake oil cure all of SeaFoam, Do the right thing and pull the carb and clean it properly and replace any hoses that have become brittle or are starting to deteriorate. Your clunk pickup also sometimes it's a stone type filter for the clunk pickup may also need to be changed as well in the fuel tank. bill67 thinks seafoam and klotz oil will magically cure anything when it comes to engines, he even claims that if you use them you will never have to change your oil. ::) If something like that had truly been invented all other brands would now be non-existent and engines would last forever, which we all know is not true. If after cleaning your carb and adjusting it properly plus the air filter cleaning if it's foam or replacing if it's pleated paper, it still doesn't run properly then your issue could be a little more involved meaning the reed valve has gotten stiff or cracked, which could cause the same symptoms. I had this happen on a weed eater type engine once that I had converted to glow fuel for use on large scale R/C airplanes. It's a fairly simple fix but you gotta tear down the engine to replace the reed valve. R.F. |
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Title: Re: Demolition Saw Post by bill67 on 04/05/13 at 15:38:32 Ruff Ruff how many motorcycles and snowmobiles have you owned. |
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Title: Re: Demolition Saw Post by rl153 on 04/05/13 at 15:42:04 thanks RF,but my mechanical knowhow is limited. since i sprayed carb cleaner into the intake the throttle is very responsive.i cleaned the air filter too. i just can't tear the carb apart.any further suggestions would be appreciated. |
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Title: Re: Demolition Saw Post by rfw2003 on 04/05/13 at 16:02:48 32393C3C6667500 wrote:
Motorcycles over the years probably 20, snowmobiles 0 I live in TX things that use 2 stroke engines I couldn't even begin to estimate how many I've owned. R.F. |
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Title: Re: Demolition Saw Post by rfw2003 on 04/05/13 at 16:12:40 535A4956515A0E0D06063F0 wrote:
well pour in cleaners which are just diluted solvents and external sprays without tearing it apart can only do so much for cleaning. Those any position carbs are actually very simple to rebuild. If you take it in to one of the small engine repair shops, they can identify which carb it is, and get you the right kit for it. Just take your time while pulling it apart and either take pics or draw diagrams to help put it back together. also alot the the rebuild kits include instructions with them. The shop can also tell you which mixture screw is for the high speed circuit and which is for the low speed circuit, and what the base setting to start with should be. R.F. |
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Title: Re: Demolition Saw Post by Charon on 04/05/13 at 16:55:57 I have been waiting for years for someone to devise a repeatable test for SeaFoam and other comparable additives. Personally, I think they are useless despite the apocryphal stories of the magical cures wrought by them. I suggest you type into your favorite search engine the term "MSDS" and your favorite product. In the case of SeaFoam you will find it contains naptha (lighter fluid); Pale Oil (SAE 20 oil); and isopropyl (rubbing) alcohol. Which of those three do you think is a better solvent than plain old gasoline? |
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Title: Re: Demolition Saw Post by houstonbofh on 04/05/13 at 21:00:09 032821322F2E400 wrote:
Does not have to be better, just different. Water is called the universal solvent, but not for glass. But hydrofloric acid will dissolve glass, but not plastic. I have been working on engines for many years, and have a LOT of friends in the business. The two that are consistently mentioned, but for different applications, are Techron and SeaFoam. (Techron is gold for mechanical injection pumps, like in the 80s Bosch FI systems) As far as apocryphal stories, how many does it take to be evidence based knowledge? |
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Title: Re: Demolition Saw Post by Dave on 04/06/13 at 02:55:25 OK......I was going to avoid posting on this again....as I believe that trying to run this engine without cleaning the carb is a huge mistake....however I will tell you how to adjust the carb on a 2 cycle engine. (And so that Bill believe my credentials I have worked on chainsaws since 1973, and I currently own 3. I have probably repaired a couple of hundred chainsaws, along with 2 cycle tillers. hedge clippers and weed wackers. Most of the problems have been from sitting with old fuel in them, as these are seasonal use items and sit more then they are ever used). A 2 cycle engine needs to run rich when no load is on the engine, and it will run cleanly when a load is applied. The sound you are looking for is called a "burble" or "4 stroking" in the trade. If the engine currently is running - just start with the current settings on the carb. There will be 3 screws and one should be marked (L) which is the low speed mix, one should be marked (H) which is the high speed mix, and the idle speed may not be marked or might be marked (A). You should adjust the idle mix just like you do for a 4 stroke engine....you turn the screw in until the engine speed drops, then back it out until the speed increases and then just a bit more until you hear the engine tone change to rich.....then turn the screw back in until the engine runs smoothly again. Then adjusting the high speed screw is painful, as it requires that you run the engine with the throttle wide open.....although it doesn't have to be very long. The engine should not run smooth at full throttle with no load.....it should run rich and hav a "burble" sound. You can pull full throttle and adjust the (H) screw in until the engine speeds up - then adjust the screw out until the engine just starts to burble and run rich. The engine should have this sound until you put the saw into some wood and start cutting under a load. Small branches and light loads should still have a bit of a burbling sound -but when you start cutting with a good load the engine should run clean and strong. Here is a link to a the adjustment from Madsen's, which is a very reputable shop. The page includes sound clips for the idle adjustment and for the high speed adjustment. You can hear what the sound should be when adjusted correctly. http://www.madsens1.com/saw_carb_tune.htm |
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Title: Re: Demolition Saw Post by rl153 on 04/06/13 at 08:39:49 Thanks Dave, I appreciate it. |
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Title: Re: Demolition Saw Post by justin_o_guy2 on 04/07/13 at 08:36:07 I, Too, thot "All fuel additives are created equal. None do a thing." Then, I poured Sea Foam into my back hoe. It was making a hard clacking sound that made me think something was gonna come thru the block, but, I knew it was an injector. In about 5 minutes, the sound was much diminished. After that, when I fueled up, if I forgot to add it, it would clack. I recently had the injectors re-worked & no longer need the Sea Foam, but I have some around, because it works. |
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Title: Re: Demolition Saw Post by Dave on 04/07/13 at 13:53:53 JOG. I am not opposed to SeaFoam, Lucas and other type fuel system cleaners while the engine is still running and the fuel system is relatively clean. I am opposed to using it as a cure all. One member here last week suggested a fellow use it in his bike that had actually "stopped" running and would no longer start...and later we discovered the fuel tank was rusty and had holes in it. I am also opposed to using it in a chainsaw that has sat for an unkown length of time and more than likely needs the diaphragms in the carb replaced. A 2 cycle engine cannot run lean for very long.....the fuel/oil mix is the lubricant and when it runs lean......it can sieze very quickly. If someone wants to use SeaFoam or another cleaner in an attempt to freshen up their fuel system or try and cure a recently acquired symptom......it is probably a cheap fix if it works. I don't believe is a cure all....and cleaning the fuel system is a sure fire way to get rid of any junk that has gotten into your fuel system. You just need to consider the symptoms and condition before you dump the SeaFoam into the tank. |
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Title: Re: Demolition Saw Post by rfw2003 on 04/07/13 at 14:00:46 0C373A2D3C302B2D363E332C5F0 wrote:
That's what I've been trying to relay as well, fuel additives/Oil additives are maintenance items to be used on something that is still running, They are not a magical liquid that will make a non-running engine run properly or fix a mechanical issue that requires you to replace parts. I myself in my cages use a fuel cleaner additive once a month to keep the injectors clean. I will not go into brands here but it's not SeaFoam as I refuse to pay that kind of price for something that will do the same job and is made of the same exact stuff for a much lesser cost. R.F. |
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Title: Re: Demolition Saw Post by bill67 on 04/07/13 at 14:29:21 Come on RFW tell us what your using,I don't think $7 a can is a lot for something that will make a motor start that want start.And it only takes a ounce or so. |
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