2018 XC300 Head Squish
 

Hi All,
Just a report on some motor work.Have been watching the head mod threads & decided to jump in while putting in a new piston & rings.
2018 XC300 112Hrs.
Head squish 2.4mm.
Had 1mm taken off & a little dome volume remove to keep compression down.
Wossner Piston(9gm lighter than stock).
Polished exhaust ports & matched to exhaust spigot.
New power valve bearings & clean/polish.
Power Valve 2 turns out.
Prework jetting-175main,NEDW#2,40 pilot,A/S 2.5out
Post work jetting-175main,NEDW#3,40 pilot,A/S 2 out
Result Pros-Pulls a gear higher(ie. switchback uphill corners don't need to change down),runs clean & bright,more torque,exhaust doesn't lubricate the swingarm.
Well,not yet.Did repack it so will see after a few more hours.
Revs its tits off at top end.
Can loft the front in any gear at any throttle position. Friken scary at times but so much fun.
Much easier to jet,responds to small changes.
Head Mod cost NZD$95!!! That is a Quarter Pounder Meal is other countries.
Result Cons-Should have taken 1.2mm off the squish but was being conservative.
Throttle Control is VERY important now.

1mm is very safe for low revving engine. 0.8 might have been ok. But keep compression below 13:1, or less on shitty fuel.

Glad you are happy.

Need some plug reading input.The electrode tip has a white ring.Haven't seen this before.What does it indicate?

Probably nothing more than that the sparks are jumping from the corner of the electrode.

Plug looks very good to me...

Thanks all,happy with the general colour.

That plug doesn't tell me a whole lot. Looks a tad rich but looking at the end is rather misleading. If you really want to know how well your jetting is you need to see the bottom of the center electrode insulator and do proper plug chops.

I cut a plug pre squish mod. Will do another & post up

Top Plug-Prework jetting-175main,NEDW#2,40 pilot,A/S 2.5out
Bottom Plug- Post work jetting-175main,NEDW#3,40 pilot,A/S 2 out
Squish reduction has made it more sensitive to small jetting adjustments.
I'm not chasing jetting nirvana & but I think I am getting into half clip adjustment & maybe one main size richer? Feels great so probably just ride it.

Looks maybe a little lean on the main but pretty good everywhere else.