Tips + Maintenance

You built it now what?

Break In: This is, besides the pressure tests the most important build step in the saw you just built. Yes the piston, rings need to seat, but we can not forget the aftermarket main bearings sitting under them. A Stihl owners manual tells you not to run the saw "full throttle off load" (meaning out of wood) for first three tanks. not even once. That goes double for us because our main bearings are aftermarket. My advice is to listen, you will damage them and that later will come home. So put that in context and follow the points below. Make your tune fat. Keep the trigger at half.

  • Heat cycle, idle it, for two minutes, and then let it cool 15 minutes. Repeat that 3 times, never race the engine. Then continue in wood until you use up 3 tanks, cut small wood so you go in and come right out and never race the engine. When you reach that milestone go for it, (still don't race the engine, because the main bearing instantly overheat)
  • After breakin, after running the saw for a long period of time, allow it to idle to cool down for a few minutes.

Use on E10 or Better Fuel. Canned fuel would be best for the occasional user. Use 91 octane or higher and use the best synthetic oil at the correct ratio. Use 32:1 when milling. If you are using gas with ethanol in it pour it in your car or garden tractor after 4 weeks, it will not hurt either. Put a tag on your fuel can and date it and keep the can closed.

Every three months remove the clutch bearing and grease it. If it fails it could damage your crank surface. While you are in there check your worm gear and the wear on the sprocket. Check the screws holding the oiler and look closely at the clutch wear, replace as needed. if you have been using long bars they require more slip and put more stress on the clutch springs.

If you are out cutting for the day have more than one air filter with you and replace when needed and clean later, a dirty filter robs power and can cause lean conditions. It is terrible for dust and debris to get past that filter and wind up coating your bearings. Bet you thought it would get burned off. Nope. It also can actually block the impulse channel and cause a lean condition. You built it. Show it some love.

Your carb does more than deliver fuel. It carries the oil, the life blood of the saw. So having the best fuel, fresh fuel mixed with the best synthetic oil using a carb properly tuned using a clean fuel filter (pickup) in excellent condition. If you can find a carb with a larger jet, I recommend that. So your fuel filter, fuel hose and a properly sized and tuned carb is the best insurance for long term ownership. Kit saws are great, do more than the minimum.

Video below of me breaking in a new top in. This only got me past a 1/2 tank. Still need 2 1/2 tanks more run through it. A new top should be at 32:1




Don't overlook your clutch area. You should clean it out from time to time and grease the bearing. The clutch threads go in the opposite direction you normally remove something. An excellent grease is the gearhead grease you use on your string trimmer gearhead. Its clings well. The drum should be replaced when 20% of thickness is gone. I cant find the thickness listed anywhere of that part. While you have the clutch removed check the brake band and clean your oiler and check for issues....see below.


The brake band needs to be replaced fairly often...because you use it every time right? Maintenance on that part should be when you are inspecting your saw on whatever schedule you determine is best for your health and safety and to get the most from your investment, the band should be replaced immediately when the thickness of the band is 0.6mm or less. If the brake band thickness is greater than that use a strip of #120 emery cloth and rough the contact surface and your brake will operate optimally until your next checkup.

If you have more than one saw and are new to chainsaws Oregon and Stihl makes a low cost tool that will help you quickly identify chain size and type, bars groove sizes and file sizes. Puts you in the driver's seat. It's about the size of a business card. Very handy to have in your tool box. Just a few dollars. It makes it stupid easy to pick chain hanging on the wall is you are chain savvy so you are certain you selected the right one. Here is a Oregon video of it in use.


Tips on Tuning MS660

Clean filter, adjust fuel and oil levels and warm engine up and check chain tension. as you go +- 200 rpm

Walbro WJ-76 L no limiters. Close and open to 1.5 Counter Clockwise on both H& L (FarmerTec both 1 turn out)

Adjust LA to 3000 rpm

Adjust L to max engine speed, if over 3400 rpm start from scratch

Adjust the LA to bring back to 3000

Adjust the L to bring back to 2500

Adjust the H to 13000


Tips on Tuning MS440





Tips on tuning a MS270 no limiters

Clean filter, adjust fuel and oil levels and warm engine up and check chain tension

Close H & L and open High CC 1 1/8 - Low CC 1 1/4 as you go +- 200 rpm

Adjust LA to 3300 rpm

Adjust L cc/c max engine speed, if over 3700 rpm start over from scratch

Adjust LA to 3300 again

Adjust L to 2800

Adjust H to 13500






The FarmerTec Cylinders in my opinion are not suited for Caber rings. They are too hard for the coating or lack thereof in their cylinders. by JS

For the 070 Pressure test you also need the gun and nipple. plus the exhaust block off and a sealing plate and the intake flange you can find that information and part numbers on page 39 of the shop manual which you should have.

Intake items needed Exhaust items needed

the digital display reads for the exhaust is 45mm and the intake is 25.5mm. Washers if shown you need for space..

Here is instructions on installing/replacing the bearings. Remove and replace on the professional saws. The illustrations are from the MS660 but are very similar for the other saws that use a magnesium case. Kits come with the bearings and seals installed.

MS660 PTO Side w/heat


MS660 without heat




Clutch Side MS660 w/heat


Clutch side continued


MS660 Clutch side no heat


This video demonstrates me using the seal puller for my first time. Its much more elgant to use once you use it. To get the profiles in the seal you simply push it in. Who knew? This will work on any of the professional saws.