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2-Cycle tune-up


Resaw's Avatar
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03-16-04, 06:53 AM   #1  
Resaw
2-Cycle tune-up

Hi,
In my quest to keep my machines in well working order, i need some help in tuning up my engines. The particular machine that needs tuning is a Homelite 45cc 18" Chainsaw that i bought last fall, and it is now broken in enough, to not be running at top notch. I think the carborateur needs tuning. Hi-speed/idle-speed mixture needs adjusting. Let me give you the symptoms. and what i've tried.

Symptoms. Starting the saw is no problem. Warm it up, no problem. What it does is, after running it wide open, and perhaps setting it down to idle for 20 seconds. I go to pick it up again, and pull the throttle, and the thing stalls out. Also, another symptom. If it idles after a good wide open run, it slowly fades and stalls. I've tried to adjust the throttle screw, that limits the idle. But it doesn;t seem to help! It doesn;t even seem to change the idle set speed at all! Which is kind of confusing to me. I've tried fiddling with the mixture adjustments some, but, i can;t seem to get it right.

So i ask for some expierienced help. Anyone know what my problem would be? And how to fix it?

By the way, the adjustment screws have those stupid plastic limiters on them that don't alow you to turn very much. I know on one of my other machines i took them off and there were screws underneath the dumb limiters.

Basically what i am getting at is--i need some guidelines for tuning my 2-strokes. I have 2 Zama carberateurs on my machines, and the Homelite....i don't know the carberateur type. And one other unknown, (it's a Craftsman hand blower)

Thanks in advance

 
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03-16-04, 07:16 AM   #2  
Hello: Resaw

Check the air filter. May need cleaning or replacement. Also clean out the air circulation system. May be restricted causes slight over heating problem.

Also the exhaust system. Muffler or spark arrestor may be restricted. Check fuel filter too. Fresh fuel helps 2. Plug may be fouling, clean and replace or replace it.

May be some binding in the centrificul clutch too or chain drag. Chain may need more oil while in use or chain may be too tight.

Those fuel adjustment limiters are there to prevent or limit lean fuel mixtures which leads to a hot running engine. Also to keep the fuel mix to air ratio correct. Very important not to allow a too lean fuel to air mix, since the engine does not have a governor.

Another possibility is the ratio of oil to fuel mix. Too much oil causes two cycles to run too hot. Lab tested and proved. Known fact too.

May have a slight fuel leaness if the machine was not used for a long period of time or stale fuel, etc.

Regards & Good Luck. Sharp Advice.
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03-16-04, 09:11 AM   #3  
Resaw
Good tips Sharp.

Also on this particular saw....It spews oil like crazy. I think it uses way too much oil for the bar. It makes an unnescesary mess on the clothes you wear when operating( i know, they're just work clothes, but it also makes the saw a bit of a pain to clean). I have never seen a saw make such a mess. Is there anyone out there who has the same saw and knows what i am talking about? It's a 45cc Homelite 18" bought last fall. Agh! I want to know if there is a way to adjust the Auto Oiler to a bit less free flowing? ( i know i know, no such thing as too much oil in this aplication, but for goodness sake!)

Thanks

 
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03-16-04, 10:22 AM   #4  
Resaw

Are you using bar and chain oil or plain motor oil? Bar and chain oil is thicker and stays put on the bar far better than motor oil or plain generic oil. Oil is not created equal.

Specialized and formulated oil for bars and chains works best. Provides more than just lubrication. Also helps to cool the chain to reduce chain stretch and reduce wear on both bar and chain.

 
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03-16-04, 12:25 PM   #5  
Sharp Adice is right. Clean all those passage ways and see if that helps. I would clean your carb too. I also agree that you are probably using the wrong oil for your chain oiler.

 
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03-16-04, 10:22 PM   #6  
Hello Resaw!

Sounds like the engine is leaning out. This could be due to a variety of reasons. Check fuel lines for cracks, check to be sure the carb bolts are tight. The fuel may be stale, carb may be restricted or have some varnish buildup inside, or it may need adjusting. At full throttle, you want to turn the high speed screw in until the engine begins to race wild, then back it out until it just starts to flutter. That's where you want it. The other possibilities mentioned in the previous posts are valid as well.


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God bless!

 
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03-17-04, 11:09 AM   #7  
Cheese, I was leaning towards the other side of the problem...sounds to me like it is getting rich when it is sitting there idling...but I have been wrong before....lol..Nonetheless...it sounds to me like the carb needs tuning for sure.


Check out this link
http://www.madsens1.com/sawtune.htm

 
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03-17-04, 12:29 PM   #8  
Resaw
Thanks DennisG!
That link was perfect for what i needed to know. A great guideline lesson for tuning two strokes. Can i apply these guidelines on that site with my other two stroke equipment? Blowers, and weed wackers?

Also, i spent some time at the garage today, and i got into the saw a bit, cleaned the air filter ( i swore i checked it recently) But that sucker was clogged! Which was causing it to run rich. Checked the spark plug, it was ok, i could tell it had been running rich though. it was a little blackish, instead of powdery brownish color....if that makes any sense? Now about those fuel set screws on my carb, it has those plastic gaurds on it....will that prevent me from tuning the engine properly?

One other question, an 18" bar, what kind of tension should my chain be? I've heard alot of opinions. And i know they can;t all be correct.

One last question....is there anything i can do about the Oiler? I have been using bar and chain oil, and it uses 1 tank of oil, for aproxamately 1 tank of gas, and the tank isn't that small. I literally sprays oil from the bottom of the chain, where the chain makes it's way around the roller tip.

Thanks for all your guys' help in here. I have learned A LOT!

 
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03-17-04, 12:35 PM   #9  
That website has great information. I think we can all use it one time or another.

 
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03-17-04, 01:19 PM   #10  
Resaw, those plastic caps can be dealt with, but typically don't need to until you modify the engine. If you want to eliminate that issue pull off the carb and grab a dremel tool, and grind off the little plastic bumps on them...that will give you free range...but I didn't tell you that...lol..

Now for your oiler, if you are slinging oil off of the tip when you cut, and running approx. 1 tank of oil to one tank of gas, this is good. Don't mess with what is working. A very good chance that this machine also leaves a puddle of oil under it when left alone. Very common, put cardboard under it.

Chain tension is a difficult one as there are many opinions...what I typically do for my everyday use saws, is, when it is tightened i pull up on the top of the chain, and if I can fit a coin between the bar and chain...I call it good. If your oiler is working good (which it sounds like it is) then a bit of overtight won't hurt too much. Too loose and you will start throwing chains.

 
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03-17-04, 02:00 PM   #11  
Resaw

Good advice by Dennis regarding chain tension on the bar. The bar has to be help up before thightening it to the saw.

Than the chain adjusted so no more than half a drive link is visable above the bar rail when lifted in the center of the bar.

That is the OEM chain adjustment recommended setting for chain tensioning. To loose and it could jump off the rail. Too tight and it will stretch too much from excessive heat.

A quarter used for the coin is about right for chain tensioning per Dennis' instructions.

As mentioned prior, bar oil does more than just lube the chain. Best to leave than as is. Same applies to those fuel adjustment screws. When the fuel is correctly mixed, the engine running correctly, those settings are best left as is.

 
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06-13-08, 09:33 AM   #12  
throttle

this has bin so helpful. i got chainsaw used, didnt run. thanks to u all its running now but now its time for a tune up. how does 1 adjust the L,H & T? also, what is the ratio of gas & oil? i tryed 30 to 1. little smoke but after 30 mins it acting like over heating. im geussing still rich in oil.

 
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