stihl 361

oregonlogger

Has anyone taken out the decompression valve and plugged the hole? If so how did it change the performance?

25inch361

I still have mine....why would you want to remove it?

rogue60

Taking out the decompression valve and plugging it will have zero effect on the performance of the saw..unless it was leaking in that case the saw will have more power

nmurph

Plugging the decomp hole will decrease the combustion chamber volume and increase compression. I do know that you do not find decomps on racing saw just for this very reason. Maybe someone knows something the racers don't know.

25inch361

I just wonder if you would be more likely to break off a plastic starter pawl trying to start it all the time at 100% compression....

Rob Chace

pluging will not NECESSARILY decrease the cc volume. However if doing so does decrease cc volume comp ratio will increase. Alternatively if you plug it and decrease cc vol. then comp ratio will (obviously) fall.

you may also introduce a hot spot by plugging it.

Tony Knight

G'day 25inch361,

We never use the decomp anyway, haven't broken anything yet (3 x 361's).

If you did increase the cubic capicity through removal, I'm tipping it would be minscule, if I needed even a little more torque I'd reach for a '460'.....

Cheers

Tony

rogue60

Im not sure how plugging the decomp can increase compression,the only way you can do it is flush with the combustion chamber,The same as the stock valve.Some valve's are in a few mm from flush you could pick up a hair of compression but nothing you could feel using the saw.. Having anything protruding into the combustion chamber will result in problems with the flame front as it spreads out from point of ignition.thats why so much R and D is put into the shape of combustion chamber's...who knows how high compression is on most race saw's, id say they take the valve out as it leaks under these conditions and its a part you dont need as such and it could fail, so they bung it...

nmurph

I omitted the need to have a bolt cut that will flush up with the cylinder wall. It does raise compression in the same way that decreasing squish does. You can lower the squish by .01" and raise compression by several pounds. As in any motor, gains are usually small for any one change, but the cumulative effect of several changes show up on the clock. On a stock 361 I don't see the need for a decomp. If you need it, then use it. There is some truth to assumption that reducing the pulling effort will increase the life of the starter parts.

ScottyAFoster

The decomp plus are available from Stihl to replace the decomp assembly. Why remove it if it aint broke. Do not use it and you do not need to plug it