*I just ported my 1973 stihl 015 saw and I went a little too crazy on the exhaust port so now this thing runs but the timing is so delayed that it wants to die if your not on the throttle. So after following your steps I advanced the timing and now this saw is a little monster, Thanks man!*
Another option is to find a coil that fits your saw that has gradual timing advance built into it, that will keep the starting easy and advance at higher speeds. Although, with some advancing coils, they have a rev-limiter as well and the advance works with the rev limiter circuit, I’ve removed the rev limiter on some saws and had the advance stop working, which lost me power at the top end. I usually make my own timing marks on the flywheel using math to figure out the degrees on the outer face of the flywheel, then you can watch to see if the advance kicks in.
Good evening Sir, it's very precise business doing that in deed !!! Keep up the good work and have yourself and your loved one's a great Merry Christmas !!! Cheers and Joyeux Noel !!!
I've always filed the flywheel keyway instead on all saws. The warning is one of those lawyer-induced "hot coffee" warnings. The flywheel key is perfectly safe to file. The reason the flywheel can burst instead of bend is because it is cast aluminum-magnesium alloy. Just be careful with it and don't ever drop them or hit them directly with a hammer. That'll screw them up badly. I also sandblast them after I work on them because it helps clean out all the little holes and brings it back to original balance. By the way, the 10 milligrams of metal shaved off the inside will make no difference in balance at 13,500rpm.
I’ve tried this many times and I think I’ve overdone it. I usually take off half he width of the key; if you have hard starting or the saw rips the pull cord out of your hand, you’ve over done it. A flywheel like any circle is 360 degrees, you only want the flywheel to move 1/8” or so at the outside diameter. I’ve gone up to 3/8” which was way too much, possibly 20 degrees 😂
After after looking for someone on RU-vid that knows what their doing with saws. I was pleased to find you. I greatly appreciate your 660 clone build videos. I just stopped bye here because you mentioned advancing the timing to the cloned 660. But i saw what it did in the shootout with the real 660. Now im not sure it needs any help. I had a 395xp total stock. And it blew me away how much raw power it had. But always had a few stihls and like them so I bought a clone 660 to play with. Ill have to check the squish and maybe port it a little. Thank you. 👍👍👍👍
Thanks for the kind words! I'm glad that my videos helped you! These clone saws are great to play with since the parts are cheap. I've heard that a 395 is a healthy saw. I'd do some basic stuff to the 660 first, muffler mod, check squish, and timing advance. I'm not sure the air filter is good on these saws either. The clog up and are hard to clean. I'm going to run the clone 660 against the real one again when I find a nice piece of wood to test them. Have a good weekend.
The old vise grips in a vise trick. Works every time 60% of the time. Thanks for the info I am trying to run some better fuel then the ethanol blended shit they sell everywhere. With that most of the fuel I can find that doesn't have ethanol is some kind of specialty fuel that has a higher octane rating and to get maximum performance this is going to help me out some. The fuel I intend to run is 100LL Av gas with a 50:1 Klotz R50 premix. If that doesn't work any better I am going to have to dig into the dirtbikes VP. I really don't want to especially because of the price. The only upside I have noticed is the smell with the VP hopefully the lead adds a little more of that good ole cancer that seems to make things run better .
Hello I filed my key down 0.22 thousands, I'm not going anymore its put back together, just wondering if you know ruffle how many degrees I changed from the 0.22 thousands? Should still be safe ?thanks alot
Here are a couple of videos. MS170 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Dp-wb8g8tdg.html MS390 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Dp-wb8g8tdg.html
If I’m putting a 390 short block in an old 029 saw would you recommend advancing the timing? I had planned to only run 94 or 97 octane in it to eliminate pre-detonation
You could, but it does not net a big gain. Here is a test I did. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Dp-wb8g8tdg.html You don't really need high octane, 92 is more than enough. I run 87.
When you advance the timing , making the ignition module SEE the firing position just a tab bit SOONER than factory specifications has it at , the air fuel mixture is ignited just a hair sooner and this gives the engine a little more power and a tiny more burn time in nano seconds , but it can cause detonation at wide open throttle or near w.o.t. and possibly make the saw harder to pull to start or even jerk back on the pull rope during attempted starting , is this not correct ?? And may get worse with kick back using a higher octane fuel ??
I know some of my saws allow for a slight change in the coil, as the holes are wallowed out a bit. Is it safe to say this will also achieve a similar result if i reposition the coil counterclockwise just a hair?
"careful- it's an easy way to damage/ruin your engine" -- Could you elaborate on this? Do you mean IF you over-did it so badly that you caused significant enough pre-ignition to actually damage the rod and/or bottom end? Can't imagine a lil knock would be an engine-killer (unless you just kept running it) Would LOVE your elaboration, have the same chinesium *66 as you (2, actually) that I'm tuning & building "for high performance at-work" so longevity is as-important as power is, however I find it impossible to believe that - even after porting and all that - that my unit's OEM-spec'd timing just happens to be "optimal"...but I've no idea how much to remove, or how to gauge, what I've done -- I WAS gonna just order 2 or 3 of those cheap lil flywheel-keys, figuring I'd do one at like 10thous removed and the other around 25thou removed, try them both, then make the 3rd one closer-to the one that I liked better / that felt better.... but my understanding was a slight 'bad timing' adjustment here was NOT going to damage anything (except the over-worked flywheel key you'll need to replace, of course :P ) so now I'm hesitant to begin that A/B testing I'd wanted to, thought it was pretty risk-free so need to know if there's more worries than just knock/pre-ignition when advancing timing! (BTW, do you happen to have any idea - & ability to explain in a basic way - how the coil "knows how to fire properly"? I of course do not mean m-tronic firing, but the same ole coil fired, magneto-driven mechanism that's been on chainsaws for half a century now, I find it VERY hard to believe that the old units had different timing BASED UPON what RPM the engine was at...BUT, from what I've learned of it, it seems you'd want to be aiming your timing to be ideal for "optimal cutting RPM", not simply idle-RPM....) Thanks a ton for any insight, and thanks so much for all these videos, great content & lucky me the 660's are all I care/think about right now, going on 2mo and I still have at least another of "working the platform" before I call them 'done' (I just finished & proved my proof-of-concept muffler, with big baffle-plate that's curved and shoots the exhaust-pulse right back at the exhaust-flange, creating a lil cyclone in the rear half, with the excess escaping under the baffle-plate's bottom & out a hole in the front plate, both passages are *more-than* enough to be considered as high-flow as anything!) One problem is it does mean the muffler will get hotter, but I'm running a big aluminum heat-shield plate as a muffler-gasket (was blown away to see there wasn't one on this saw, or any heat-shielding except some chintzy aluminum stick-on under the muff, thankfully I've learned the great lesson that you can use red Permatex, or their Motoseal, depending what degree of stiffness you want, as a heat shield!! My 355t has had such a shield (red perma) on the side of clutch-case for >1yr, to protect / isolate it from the muff that's right beside it, but I also painted the entire "muffler reception area" of the 660 with the gray Moto and man that stuff works well there, even at the muffler mounting junctions it didn't burn-off at all!!) Thanks again for taking the time to post all these, so darn helpful!!
If the timing is over advanced it will ruin the piston and it is also hard on the bottom end. On a saw like this, most do around .020 off the key but you are on the right track by buying some to play with. Who know what the timing is on a Chinese ignition module. It may vary. You can use the keys to test on other saws. The timing is based off of the placement of the flywheel magents and the electronic ignition module. Some saws have an advance and others don't. I'm glad you like the videos. Check out the videos I did on the MS290 with the cross cylinder. I did testing after each mod to see how it performed.
"If it sounds like popcorn" LOL yeah if someone doesn't stop running it ASAP they *almost* deserve the damage (*almost*, :P ) but yeah man I'm so eager to hear how "this can damage your saw" because I can't tell if you mean there's inherent risks to the tinkering of these woodruff-keys, or if you mean the secondary consequences of over-filing and over-advancing the timing to the point that pre-ignition is occurring (which is far worse than knock, I don't know if knock would be influenced at all here since knock is post-spark combustion of areas outside-of the actual flame-front that's produced by the plug, whereas pre-ignition is pops occurring while the piston is still on the compression/upward stroke, before TDC, *far* more damaging to the connecting rod &bottom end than knock but sadly pre-ignition is what you're facing w/ overdoing timing-advances!) Was so stoked to get 2-4 of the keys, play around, going modest enough, doubt I'd ever have hit any preignition and, for my optimal, it won't be "close to" pre-ignition it'll be more like "SLIGHTLY noticeable, just a touch faster responsiveness" (which is why I"m doing it -- my understanding is the actual power gains are not so significant but maybe i'm wrong on that?)
Yes, if it sounds like popcorn. You can ruin the piston and it would be hard on the bottom end. The gains won't be huge, but is easy to do so why not do it. Not all saws like a timing advance.
This isn’t a very good idea because you’re risking wearing the engine out faster. It is the same reason why you shouldn’t be messing with the governor on a lawn mower. On top of that I wouldn’t be doing it on a really expensive piece of equipment like this one.
By advancing the timing, you are squeezing a slight amount more of power out of it. If done properly, I doubt that most you would notice a shorter engine life.
Meanwhile there are fellers out there with port jobs on 1500 dollar saws and zero complaints. Modification usually has the most risk when people do it with a certain level of ignorance. Ignorance can be cured by learning. Newer choked up equipment can GAIN lifespan with some modest and responsible modification by running a better air fuel mixture and decreasing heat retention. Your advice is misleading, at best. Just my humble opinion.
