How many degrees timing advance MS 400?

[wilfrie]

Hello! As a tree climber I do like my Stihl MS 400, but I would like to increase the bottom power (torque) a bit more. I opened already the stock muffler, but I would also do a timing advance, since I read it does help as well on a 400.

My question is, how many degrees of advance is save & perfect for the MS 400? I read people do from 4 to 8 degrees on comparable saws (like the 362 or 462), but I couldn't find many information about timing advance on the MS 400. Most people seem to do 5 or 6 degrees, but would e.g. 8 degrees add extra wear to the engine? And has anyone already tried different degrees of ignition advance to find the optimal benefit, since there should be a kind of an optimum technically?

So I hope you can help me and already many thanks!

 

[lehman live edge slab]

So you haven’t done any yet you asked weeks ago already an I told you how to advance it and about how much using the fan blades on flywheel. If you think what I told you was too much or too little then start with less advance and add to it after you try it. Your going to get probably several different answers on how much and still need to decide what your going to use for the number

 

[Mastermind]

7mm at the outer edge of the flywheel.

 

[lehman live edge slab]

7mm at the outer edge of the flywheel.

I told him 1/4” about on outside edge couple weeks ago so pretty similar

 

[Mastermind]

Yep. Same Same.

 

[wilfrie]

Thanks for the replies. I understand that the 5mm you mentioned in your personal message Lehman, the 1/4" (6,35 mm) and 7 mm are in the same scope. But since 1 degree corresponds to 0,9082 mm, those differences in milimeters do matter, because they corresponds almost to different degrees. So e.g. 5,4 mm corresponds to 6 degrees and 7,22 mm to 8 degrees advance. And since the amount of degrees of ignition advance might matter, in terms whether there is an optimum and from what degrees detonation (popping) of the engine occurs, I am interested in experiences of others with different degrees? And from there I can deduce how many millimeters of change in the outside of the flywheel that means.
Or does the difference between 5 and 8 degrees timing advance not matter at all by the MS400 with respect to a power optimum and detonation occurance or extra engine wear?

 

[huskihl]

It’s not an “optimum power” thing. More timing advance typically adds lower rpm power but also holds back some unloaded or less loaded rpm. If you’re cutting 6–8” wood all day, any more timing advance could be hurting it. If you’re cutting 24 inches of wood, then more is probably better

 

[lehman live edge slab]

Another way you could gain some torque is drop a tooth on your rim depending what your running or kind wonder how .325 would run with an 8 pin on a 400.

 

[wilfrie]

It’s not an “optimum power” thing. More timing advance typically adds lower rpm power but also holds back some unloaded or less loaded rpm. If you’re cutting 6–8” wood all day, any more timing advance could be hurting it. If you’re cutting 24 inches of wood, then more is probably better

Ah oké, and do you mean with 'any more timing advance could be hurting', more than 0 degrees? And what do you mean by hurting, and how bad is that? How many degrees timing advance would you advise if you cut mostly between 16-20" mainly hard wood?

 

[huskihl]

Hurting the power for that size wood, not hurting the saw.

I would do what was mentioned before, somewhere between 6 and 8MM of perimeter rotation further counterclockwise. When you are looking at the inside of the flywheel with the key on bottom, you would need to file away a portion of the left hand side of the key

 

[farminkarman]

The last ms400 I did has 10 degrees of timing advance…that translates to a little more than 3/8” of movement at the OD of the flywheel.

 

[wilfrie]

I've done the timing advance on my MS400 for about nine months, and it made a huge difference! Significantly stronger, and a pleasure to work with. I did a 6.5mm movement of the outer flywheel side counterclockwise, which corresponds to 7 degrees advance (along with a muffler mod).

I've noticed, however, that the saw is getting a lot hotter than before. If I put my hand on the plastic cover above the cylinder, it's really quite warm. I was wondering if you recognize this, and how much harm it can do? Does it actually cause more wear on the cylinder and piston, or does it increase the risk of seizing? Would I be better off reversing the ignition by one or two degrees, or can it handle all that just fine? Since some people advance the ignition by 8 or even 10 degrees, doesn't that seem to cause any problems? What are your experiences?

 

[lehman live edge slab]

I've done the timing advance on my MS400 for about nine months, and it made a huge difference! Significantly stronger, and a pleasure to work with. I did a 6.5mm movement of the outer flywheel side counterclockwise, which corresponds to 7 degrees advance (along with a muffler mod).

I've noticed, however, that the saw is getting a lot hotter than before. If I put my hand on the plastic cover above the cylinder, it's really quite warm. I was wondering if you recognize this, and how much harm it can do? Does it actually cause more wear on the cylinder and piston, or does it increase the risk of seizing? Would I be better off reversing the ignition by one or two degrees, or can it handle all that just fine? Since some people advance the ignition by 8 or even 10 degrees, doesn't that seem to cause any problems? What are your experiences?

I do a 1/4-5-16” outside diameter which is what you did roughly on a couple 400’s and a bunch of 362’s for a tree service and the 362’s still going after 7-8 years

 

[mainer_in_ak]

Hurting the power for that size wood, not hurting the saw.

I would do what was mentioned before, somewhere between 6 and 8MM of perimeter rotation further counterclockwise. When you are looking at the inside of the flywheel with the key on bottom, you would need to file away a portion of the left hand side of the key

Do u remember a 67 cc saw with actual torque? Ignition are so aggressive on the 680/620/7310, u dont have to mess with em.

Still in production and will over oil a 32" bar.

 

[two4spooky]

Okay, familiar with basic performance modifications here and rebuilding saws but have never done any timing changes.

Viewed from the left side of the saw with the flywheel stil attached(outside viewing in), to advance the timing and increase low-end i would file the key to allow the flywheel to rotate further clockwise relative to the crank shaft. Outside viewed in with the crankshaft still attach, 5 to 7mm further forward as measured on the outermost portion of the flywheel, flywheel moving in a clockwise direction

Or do I have this backwards? Outside viewing in with the flywheel still attached, I would want the flywheel to be retarded(counterclockwise) by 5 to 7mm?

Thanks, trying to understand this modification. Just trying to learn

 

[tree monkey]

i like 10deg

 

[lehman live edge slab]

i like 10deg

Hi Scott, guess I can go a bit more than I am than.

 

[Outback]

Spooky. Your backwards. The saw rotates counter clockwise when viewed from the flywheelside. You want to make the fly wheel go further or "advanced" in its position counter clockwise relative to the crankshaft so the spark happens sooner.

 

[two4spooky]

Spooky. Your backwards. The saw rotates counter clockwise when viewed from the flywheelside. You want to make the fly wheel go further or "advanced" in its position counter clockwise relative to the crankshaft so the spark happens sooner.

Ahh... having a blonde moment. Of course, flywheel rotates counter clock wise while saw is running. PTO side rotates clock wise. Just a brain fart. Thanks for that

 

[Outback]

The part that gets me is when you take the flywheel off and your filing it because its upside down or backwards depending on your perspective you have to file it like its moving the opposite direction. I think my brain is just one giant fart sometimes.