I have a slightly used cylinder and piston removed from my Zen 26; and I thought I would try my hand at porting.

I guess these questions are for Scott S. or any one else with experience since I have none in this field.

Will modifying the porting; without modifying the port timing make any significant difference?

Why the "Caution Note" on modifying the exhaust transfers?

If just the porting mods are made to the cylinder will this require the machine work on the top of the piston to prevent seizing?

Should the squish clearance be changed after these porting mods are made or should it be left stock. Changing the squish will also change the timing; right.

How effective? "Power incresse"; if these mods are made and the timing is not changed?

Approximately how much wall thickness is there to work with or is the biggest gain in the transfer volume due to the widening of the passages by removing internal material and not decreasing the thickness of the wall area of the cylinder.

Would you recommend performing the porting mods on the cylinder and piston first, using stock squish clearance; assembling and trying the engine then if everything works out for the better going back and making the timing mods?

Thanks,
Jim

Jim,

Not going to get long winded here ... so here's a quick overview.

To gain more HP from a 2 stroke engine it needs to turn more RPM, be able to flow greater quantity of air/fuel threw it's internal ports & passages, Exhaust timing must be raised to better take advantage of the boost & scavenging attributes a tuned pipe offers.

The "How Too" article address's ALL these issues, tho it is not spelled out what each modification does.

*Dropping the cylinder down decreases squish clearance and will add some torque and exhaust port duration decreases slightly, intake duration is increased slightly adding some rpm potential.
That alone won't do squat really ... Because once you do the other mods of raising Ex port height the compression gain of a lower cylinder decking are negated any ways. But gains of a tighter squish remain.

The BIGGEST gain one can make on a STOCK Zenoah running a pipe would be to raise Exhaust timing and increase intake duration !!
Internal port work increases flow potential and that is where the real HP gains will be found, tho aforementioned mods must be in place as well.

Scott