[SOLVED] Chainsaw rope very hard to pull Solved

If the spark plug is hitting the top of the piston, the most likely culprit is the wrong spark plug is installed. A "hot" plug will usually have a longer nose, which could then make contact with the top of the piston if the engine isn't designed for it. The solution then is simple: swap the hot plug for a colder plug. Every spark plug carries a heat range, so look for a plug that's colder than what you have. Preferably, look for the actual plug recommended for that engine.

Some info about plug heat ranges:

If removing the spark plug allows it to easily spin over and it's not a physical interference between the plug and the top of the piston, then I would assume it's a high compression issue. So what would cause that? Well, for example, something being lodged in the combustion chamber that doesn't belong there, such as extensive carbon build-up or even a foreign object that might have come through the intake port. Can you remove the cylinder head and take a look?

Understood about using Sta-bil, etc. In my case, I can go years between uses. I'm not sure Sta-bil ideal for that long a period of inactivity. That would not explain why I can easily pull cord, with plug removed. It worked fine when I last used it, couple yrs ago.

I have not looked into the insides of the small engines. Does that one have any valves that open and close ? Maybe even some reed types ? They may be stuck or broken.

I doubt the Sta-bil would be good for years. In that case it probably is ok to let the engine run dry and just take the hit on no lubercation.

I bolught one of the roughly $ 100 700 watt generators from HF that is 2 cycle. I seldom use it, but do start it up every couple of months and run it for a while. Then put in a fresh batch of the alcohol free gas/oil and Sta-bil. I think some of the oil has some properties of the Sta-bil. Let that run for a short period of time. Found it hard to start even when new,so give it a shot of starting fluid and it cranks right up.

Actually, a hotter plug virtually NEVER has a longer "nose". The insulator is just longer and slimmer back into the body. Extended tip plugs are designed to run COLDER under higher speeds and hotter at low speeds and loads by virtue of getting the tip "out there" into the active flow.They are not only "extended tip" but "extended range" plugs. (I've been a mechanic since 1969 and taught the trade as well)

Maybe you are just getting old and feeble?? I have a little remington that is that way - as I've stated here before. Will almost tear your arm off if your hand is strong enough to not let go of the rope but once it starts it is a little BEAST!!! Compared to it the larger Partner saw is a breeze to start but the little fellow will give the big one a REAL run for the money - -

Since the saw has a SEALED tank the fuel in the tank won't oxidize or go rancid like it will in a lawnmower. I use SeaFoam in my saw gas and the last time I used the Remington it had sat for over 2 years with a FULL tank of Shell premium with 40:1 "smokeless" (yeah, right!!) semi synthetic two stroke oil and it started on about the 5th pull. Just remember to shake the saw a few times to make sure the oil has not stratified in the fuel. The Partner took a whiff of starting fluid to get it to kick, but then it ran fine. Haven't used either one for about 5 years - maybe I should crank them up and see if they still run in case a windstorm takes down more branches -- - - -

Yeah, I could have it wrong. I thought I knew about it from some limited experience back in the 80's but it probably faded since then. I was also relying a bit on this little table from the link I included.

Difference between Hot Plugs and Cold Plugs

Hot Plugs Have a long Insulator nose. A great surface area exposed to the hot combustion gases. Heat transfer to the engine head is slower. Its firing end heats up quickly.

Cold plugs Have a short Insulator nose. A less surface area exposed to the hot combustion gases. Heat transfer to the engine head is quicker. Its firing end does not heat up quickly.

He has the wrong thread reach plug. I am betting he has a 1/2" reach plug and it requies a 3/8" reach. In Champion that would be an L seies where he needs a J - in NGK it would be an H uffix instead of an N that it should have.

That 1/8" difference should be all it takes to keep the plug from hitting the piston.

I'm definitely older, but hopefully not that feeble :) I forgot to mention, I'm the original owner, and the spark plug is original. Original spark plug could be factor in running the engine, but I'm not getting that far.

I have a 25 year old Husqvarna that I have used heavily over those years. Last year it got extremely hard to pull. So I put it aside until June of this year.

I decided that on top of everything else I probably had a galled cylinder/piston situation. It turned out that piston and cylinder looked great.

BUT . . . what I did discover is that from where the carb attaches to the cylinder there is a port that runs inside the wall of the cylinder to its base, apparently to bring lubrication to the crankcase and ventilate the crankcase on the down stroke. I could see that lack of ventilation would make the saw extremely hard to pull.

SO . . . I first blew air through the port. No problem. No blockage. Then I examined the gasket and mating surface on the crankcase fully expecting to find a passage through the gasket and mating surface into the base. THERE WASN’T ANY!

WHAT I DISCOVERED is that all venting of that port through the cylinder relies on an extremely thin gap/channel between the gasket and cylinder base. It looked to me like that gap is no more than .020” wide.

NO MATTER. It was absolutely packed tight with carbon. So, I picked it clean with a dental pick. AND GUESS WHAT?

THE REASSEMBLED MOTOR PULLS EASY AND RUNS LIKE THE DAY I BOUGHT IT.

Now I am having the same issue with a month old Stihl MS171. Have loved that saw up to this point. Took off the carb earlier this week and you guessed it there is a similar port going from where the carb mounts down into the cylinder wall. I am guessing its for crankcase ventilation again. I haven’t had time to complete the investigation but obviously suspect it is the cause of the near identical symptoms.

I’ve had my ms290 for 14 years no problem and this just started. Pulls easy with plug out but you have to fight to pull it. with plug in. Was able to start it then could not restart. Now it won’t start at all but still pulled and jerks very hard. Pulled muffler off..ok..pulled flywheel off..ok..and by the way it does not have a compression release. I realize you have to tug on these saws but this is something that still has me scratching my head? Any ideas would be great. I want to save this saw.

I’ve had my ms290 for 14 years no problem and this just started. Pulls easy with plug out but you have to fight to pull it. with plug in. Was able to start it then could not restart. Now it won’t start at all but still pulled and jerks very hard. Pulled muffler off..ok..pulled flywheel off..ok..and by the way it does not have a compression release. I realize you have to tug on these saws but this is something that still has me scratching my head? Any ideas would be great. I want to save this saw.

Carbon build-up?

I was going to say that ... chances are this is a homemoaner who uses the saw to trim a couple of branches a couple of times a year . And it's never been run wide open since the day it was new , and "if one ounce of oil is good 2 must be better" . I'd bet that piston has enough carbon buildup to jack the compression ratio pretty high .

Of all I have read here and on many other websites, the closest I have to an answer is "If I install the spark plug by hand as thought as I can it will run fine. But if I put a wrench on it and tighten it literally a hair more it locks up. ..." I am going to try to loosen my spark plug, LOL May let you know (If I can find this webpage again?) :-) I cud understand if wrong 1/2" reach plug that should be 3/8 reach and "barely" touching piston top w/ carbon? Or if "plug thread leakage designed as compression release port" LOL

Or suck paper ball into cylinder if reed valve stuck shut?

YOU ARE MISSING ONE OF THE PAWS THAT ENGAGES WHEN YOU PULL THE ROPE. I HAVE ONE WITH THE SAME PROBLEM. TAKE OFF THE GAS TANK & YOU WILL SEE YOU ARE MISSING ONE