357xp play thing

[wisecobandit]

Well decided to pull apart the 357xp (2002) this afternoon. Never had any issue with it, it never had the recall even and still runs the plastic clip on the inlet manifold etc.

Anyway i divulge, reason was to me i felt the compression was down a bit, my compression tester doesnt work on chainsaws so had to use the "lift by the pull start" method and it would slowly wind out to the end of the cord.

So armed with a new meteor piston/rings on spuds recommendation stripped it down etc. Was amazed how clean the cylinder was tbh given its age and work. Some blow by on the piston but apart from that all good. Gave the cylinder a quick port, took a few pics midway but phone went flat so couldnt take finished port pics but gives you a rough idea. Also widened the inlet/outlet slightly.

All bolted back together in time to watch the rugby. Fired up 3rd pull afterwards but couldnt run it to long given living in a built up area etc so just gave it a quick tweak on the fueling but no chance to cut anything yet.

Anyway 2 things...

Compression doesnt really seem to have increased any given its had a new piston. (need to get a compression tester for 2 strokes) and secondly on the pull start it certainly recoils the starter cord after "the pull" almost like the vaccum of the engine pulling it back in. Neither im to worried about if im honest.

[spudulike]

Good on you for trying, hope it works out, you can drop the base gasket safely on a 357 and gain 15psi so a little more torque.

 

The 357 has a pretty good recoil so although it doesn't feel like much compression, it probably has more than you imagine - the piston and ring will bed in and roughning the bore will help this.

 

I found that widening the lower transfers wasn't a good idea as it lowers the transfer velocity and may cause issues with scavanging and max torque but see how it goes.

 

I use the gasket as a template to blend the transfers to the crank openings, assume you have done the same.

 

How wide are the ports - you have to be careful not to exceed the maximum safe spec - this is pretty wide as the skirt allows it but too far and the ring may snag!

 

I am guessing you have radiused/bevelled the port edges - failure to do this well will cause serious issues!!

 

Let us know how it goes.

[wisecobandit]

Hi mate,

Yeah i smoothed/bevelled the edges etc to prevent rings catching. Ive only widened the ports by 1mm or so both sides i didnt go mad. Didnt raise or lower the heights as didnt want to change the timing as such although i did clean them up as some rough casting marks.

The transfers i matched to the gasket. I was tempted to leave out the base gasket but decided for now to have one in there. Can always pull it at a later date once i have a compression tester that works as would be god to see the difference it makes.

I didnt have a hone that fitted tho roughed up the bore slightly with some very fine emery paper just to try help a bit of bite.

[spudulike]

OK - 1mm is well within the maximum allowed size, you won't get any problems with that - you could have probably gone further.

 

If you leave out the gasket in future - use some high temperature liquid gasket - do not take it out and not seal with anything -you will get airleaks and the saw will seize!

[wisecobandit]

Just didnt want to go to mad on it and run out of time and rush it. i done 1mm or so off each side so basically 2mm overall on each port.

The muffler is still OE and not modded as i need to order a new one. The original is getting thin now so cant see wasting my time on it and blowing holes etc welding in a new pipe so at the moment i wont get the full advantage until thats sorted.