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Spuds Porting and Tuning Thread


spudulike
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You would love mine then - it kicks back a bit - 220psi and an ignition mod - tends to hurt a bit now and then if not shown a fierce starting technique.

 

220psi!! Is it a diesel lol need to be superman to pull it over.

 

Am checking mine tomorrow is it your 357? , I'm sure my old 026 was 170psi

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220psi!! Is it a diesel lol need to be superman to pull it over.

 

Am checking mine tomorrow is it your 357? , I'm sure my old 026 was 170psi

 

The 357 has quite an easy pull to it even without using the decomp - it is the extra advance on mine that catches you out when it refuses to pull over - the saw has a pop up piston which gives it a little extra although 200 psi is possible with the standard piston and no base gasket!

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I took a look at the 560XP before I packed it up to send it back - you may remember that the stuffer had disintegrated and taken out the top end.

 

My findings were that the exhaust port can be widened and the shape can be significantly changed to increase flow.

 

The inlet port hasn't got a massive amount to be done although the manifold had a lip on it and could have been a better fit. I was impressed by the straight run from the carb in to the cylinder - no chance of impeding the flow there!

 

The uppers could be taken back a little but only on the top as they are very close to the air ports for the Husky version of Strato transfers.

 

I didn't look too much at the lowers but no doubt they could be flowed somewhat as well.

 

The muffler was pretty choked with baffle plates - getting rid should help a lot!

 

That's about it, didn't get the time to put the timing wheel on it or experiment with squish etc.

 

All in all, you can see why the saw pulls like a horse - straight inlet tract, transfers to the front of the saw for maximum velocity aided by the crank and an acute exhaust exit angle to aid scavenging - very nice design in this saw!

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Nearly 180psi👌[ATTACH]167830[/ATTACH]

 

Well that isn't too shabby:thumbup: My mod usually gains 15-20psi.

 

Go careful with that first pull as my modified saws have buggered up a large number of Schrader valves on Gunson compression gauges - best give the thing a few slow pulls to get some pressure up first!

 

A warm/hot reading will also register a lower compression than stone cold plus a machine that hasn't run for a long while will read less as the oil and fuel will have dried off from around the ring and piston lowering the sealing around the piston.

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