Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => McCulloch => Topic started by: Rich73Kelly on September 08, 2015, 03:04:12 pm
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As I stated last week, I would start new threads with my saws disabilities .... so, here, first, the PM605 ... I bought this saw at a pawn shop last spring for $50.00. It started a little hard there but started and ran so, I took it home. It is a damn good running saw once I get it started !!! Is it something internally with the saw or, am I trying to start it wrong? First, I am left handed so, I probably DO start the saw different than most. With the saw sitting on a flat surface, I choke it and start pulling. I can pull and pull 20, 30 times, turning the choke off and back on and once in a while it will fire but, won't stay running. Once it does start and gets warmed up, it will run all day ... even after running out of gas, I just pull a time or two and it fires right back up.
Now, this isn't funny ... after taking pictures to post here, I read the starting instructions below the switch. "3 Activate throttle latch" ??? Do I need to give it throttle while it is choked to get gas in the chamber ???Is this all I am doing wrong?
Can someone give me some input here? Are they stubborn to start or, is there something I can tweak?
Apparently, the size of my pictures is too big. I will look for a pinned post on resizing photos but , for now, in case there isn't one, "total size 2700KB, maximum individual size 337KB" ... my photo edit program resizes in megapixels. How does one convert 337kb to megapixels? I am using Adobe Photoshop Elements.
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Check valve diaphragm is stiff from old age .Lets the gas dribble back out of the carb if it sits for a while .Rebuild it,cheap less than 10 dollars .FWIW I had to rebuild the carb on one of my PM 610's only lasted 25 years before it went south . ;)
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Al, are the kits still available? If so, where would I look? How do I locate the carb #?
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Apparently, the size of my pictures is too big. I will look for a pinned post on resizing photos but , for now, in case there isn't one, "total size 2700KB, maximum individual size 337KB" ... my photo edit program resizes in megapixels. How does one convert 337kb to megapixels? I am using Adobe Photoshop Elements.
IMO just upload pics to a free photobucket account and it resizes automatically. Then just copy and paste the IMG code here for pics to show. www.photobucket.com
For embedding I just set my editing software to 72 and make pics about 8x10 using megpixels too. Thats seems to put them in the 180KB range.
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Let's see if this works ...
http://i389.photobucket.com/albums/oo333/Rich73Kelly/P9071339.jpg
or ... (http://i389.photobucket.com/albums/oo333/Rich73Kelly/P9071339.jpg) (http://s389.photobucket.com/user/Rich73Kelly/media/P9071339.jpg.html)
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It's probably just your starting technique. The instructions on that decal are a bit lacking...
Yes you have to set the throttle lock. Squeeze the trigger, pull the little black nib sticking out of the top/front of the rear grip rearward, then release the trigger. The throttle latch should then stay set until you pull the trigger again. Be aware that when the engine starts with the throttle lock engaged that the chain will start moving.
Pull the choke and the pull the rope repeatedly until you get the first 'pop' from the engine. Do NOT pull again after that 'pop' with the choke all the way out or you will flood it.
Push the choke in 1/2 way and then pull the rope repeatedly until it starts. Ease in the choke the rest of the way, release the throttle lock with a pull of the trigger, and keep the engine running with slight 'blips' of the throttle until it warms up.
Being left handed shouldn't matter. I'm left handed and I'd start that saw by holding the handlebar down with my left hand while pulling the rope with my right (with the toe of my right boot on the 'boot plate' at the bottom rear of the saw.
When the saw is hot. Don't use the choke. It should restart without the throttle lock......but may require the lock to be set. The saw is also likely to not be tuned correctly. That'll make things difficult too....
In warm weather you can often skip the 1/2 choke step during your initial cold start. Instead, after that first 'pop' at full choke, push the choke fully forward before pulling the rope again.
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Al, are the kits still available? If so, where would I look? How do I locate the carb #?
I think it most likely has a Tillotson model HU if I recall correctly,yes available.Numbers will be on the side of the carb,might be hard to see .
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Having used a model 610 for 8-9 years selling fire wood this is what I found .You should periodically remove the recoil and chain guard and blow out the chips that accumulate under the cylinder .Because it will stop the air flow from the fan and if ran long and hard on a shutdown the ignition model will fail .
Once it cools down,like 45 minutes it will start but until you could pull your arm out of the socket and it will never start .
Also because it uses a diaphragm,impulse type of oiler they eventually could leak which will draw chain oil into the crankcase .Given enough time this will carbon the screen and clog the ex port .If it isn't too bad you can still run it but be on the look out for a new pump which could be from 25 to 45 bucks new .I just pulled the screen .These things often sell so cheap you can find one for parts for less than the price of the pump .
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Many of these had Walbro HDB carbs. K10-HDB is the kit for them. Some had Zamas.
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Aaron (Eccentric) well, ruled out starting technique .... I set the choke, set the throttle lock, pulled and pulled ... couldn't get that first pop ... checked the plug, a bit damp but, not wet ... I am now curious if some moisture might have got in the tank ... it has bee quite humid the past couple of weeks ... maybe I should even consider getting a NEW plug! Does someone recall what the recommended plug and gap are ? It has like, a U8JY or something close to that now ... Is it possible the flywheel or coil contacts are rusting and weakening the spark ??? I am not sure if these are similar to a conventional lawn mower engine.
Al, I am still not ruling out carb issues ... Would it be wiser to replace or, rebuild? Either way, I would need to find the parts. According to the manual I found online two years ago, the 650 was the only one with a Walbro (HDB-7A) and the rest have a Zama C-25. I haven't had the saw far enough apart to look so, I am not sure if this info is correct. I don' know of an impulse oiler either, as you can see in the photo I posted, the green push button above the power switch is the oiler.
You also mentioned to pull the recoil and chain guard to blow things out ... I did this last year ... Speaking of the recoil, ... is there a sticky somewhere about rewinding them? I took mine off back in the spring because the rope pulled out and wouldn't go back in without taking it all apart .... yup, had to rewind and seat the spring. Untied the rope at the pull handle and restrung it. I don't know how tight to wrap the spring for proper recoil and it still locks with the cord pulled. It's getting to be a royal PITA having to remove it and rewind it every time it decides to do this. I have even found the rope between the recoil and flywheel.
Also, this manual recommends 40:1 fuel mix, is this acceptable or, should I go with like, 32:1?
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You need about one more wrap on the drum passed fully retracting the cord.If you get the tension too tight it will bind the drum .
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I think that is where I set it this last time ... now, can you answer me this? What should be the "standard" length of the rope? I seem to bottom out the length of the rope while pulling, thinking it's not long enough ... it already seems to fill the drum while wrapped.
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All the saws in that series have both manual and automatic oilers. The diaphragm pump is at the top of the powerhead. In front of the Carb box, and visible when the AF cover is removed. The saw could still be flooded an/or fouled by old/contaminated gas.
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Alright, guys, ... I opened up the PM605 today. Yes, it does have the auto oiler. Never realized this ... and yes, it has the Walbro HDB carb witt a 6B under the HDB.
(http://i389.photobucket.com/albums/oo333/Rich73Kelly/P9221378.jpg) (http://s389.photobucket.com/user/Rich73Kelly/media/P9221378.jpg.html)
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It's almost like we know what we're talking about.... 8)
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Alright, I found a gasket kit and am going to go get it today. Any issues or quirks I should know about before opening it up? How tight should the different bolts/screws be? Just snug or, be sure they're tight? I am not going to tamper with the hi and lo screws if I don't have to. The saw ran fine when it would start.
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Never fear the carb .Just screw the things tight and count the turns ,remove ,blow out the carb,put it back together .Do the same ,tight then back them so many turns .Nothing should change very much if any .You're not going to learn any younger .
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Al, young is but a state of mind at my age! Lol ... over 60 already! I have rebuilt several automotive carbs through the years but, none were aluminum, which I am assuming this one is. I figured tight enough to seat the gaskets but, at the same time I don't want to strip anything either.
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The 600 series all tend to start like that, you lock the throttle until initial pop, then off with the choke, and pull until it starts with a few throttle blips there running, however i have noticed that keeping the on off switch good and clean keeps the spark strong which helps with the starting. Last but not least these saws are usually pretty high compression setups and they really like the high octane fuel, mid to high 90s, or even flat out race gas, these saws also when tuned properly actually produce very good cutting power regardless of what the nay sayers wine about.
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No i fix these saws alot in the shop and many of the 610 or timber bears i see do indeed have the walbro carb, i see a few now and again with the zama and tillotson carbs. My experience has been that the tillotson carbs always seem to be the better of the bunch. I ofter switch these to a tillotson as well as any other saws that i can, the tillotson carbs seem to be the best for starting, rebuilding and tuning. I often wish i had tillotson carbs for all chainsaw applications.
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Mikehonda, caught a notification for your reply in my email this morning. I appreciate your replies. As you can see, my last reply was back in September. It starts getting too dang cold to be outside puttsing (for me, anyway) with a bull headed saw. I put it away til spring. As I stated earlier, I did find a carb kit, I just haven't installed it yet. I also bought a new plug and will be putting that in.
I never thought about the switch being dirty. As stated earlier, once it's running, it runs great. Will just spraying it with contact cleaner do the trick?
As far as fuel selection goes, the highest Octane readily available is 91 or 92. This is the only grade available, short of racing fuel without Ethanol in our area. I have already opted to using this in my other small engines (lawn mowers, snow blower, etc.) I will be doing the same with the saw.
One other question with you being a new response on this thread, what is your input on my pull cord issue? As you probably know, the casing is molded plastic and the cord wrap is aluminum. There is no noticeable wear on either so I don't feel this is the issue. Is there anything, you feel would work to stop the cord and recoil from binding?
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Those damned starters can be as fickle as a teenaged prom queen.Don't oil them because all that does is attract little wood chips causing all kinds of problems.
Take the whole thing apart and make certain all the crud is blown out . What often is the problem is the tension on the bolt holding the starter drum in place .If it is too loose or too tight it will cause issues.You want just about one wrap of the drum passed full cord retraction on the take up spring .
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Al, I hear ya on "being fickle" .... I took it all apart last time it bound up ... blew everything out, wiped everything down, including the spring, and put it all back together, only to have it bind up with the cord dangling all the way out again after ten or fifteen pulls. Is there a torque spec for that drum bolt? I tried not going too tight cause it's going into plastic but, I know it's snugged up. As far as lubing it goes, I figured oil would just attract dirt. Could I maybe spray it down with Silicone spray and let it air dry? I am about ready to find a different recoil assembly!
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It's been a long time since I had one apart .It seems to me it's nothing more than a carriage type bolt and either a flat washer or a spring washer and a nut which I think is a nylock type .
It could be the spring itself getting wound up all over like a coiled snake .
Find you a friendly saw shop with a big "dead pile" usually a non runner will be cheaper than buying the parts to fix one with problems.
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I hope this stays in this thread ... I failed to post in the spring ... my bad ... I did get the carb rebuilt. Put it back together, gaped and put the new plug in, put new gas in, ... 4 or 5 pulls, it pops, push the choke in, one or two pulls and she's running ... every time !!! Now, I just wish I could master keeping the chain sharp! lol ...
Oh, and as far as the issues with the recoil go, haven't had any. This may have been due to me pulling too fast and the recoil not keeping up ??
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That series was pretty dependable if kept in tune .One note is periodically check for bolt tightness because given enough time they will rattle the bolts loose .It's all metric sized .
For no more than they bring on the used saw market it's a lot of saw for little money .A little heavy for their size maybe but still in all a good firewooder .The only reason my three are shelf queens is because I have better saws in my stable .A lot of plastic parts in them but they are still tough as a nail .I've seen them run for years with engine damage that would have killed the average saw engine .
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the choke plate must lay tight to the carb body on these or your gonna pull your brains out. however probably the longest lasting chainsaw in the world if not one of them.