Yamaha 130 V4 Project Build.

[Mr. Demeanor]

The early 200 Ex is at 1.69 or 43mm
My early 150 ProV is the same 1.69 with the addition of a 10mm or call it 3/8 notch.
The 225 Excel is 1.57
These numbers are from engines I have measured.

So with yours at 1.62 that was a hotter tune than the 200 was, interesting.
Looking forward to what power you have with another 1.5 or 2mm port height.

I edited my above post as you were typing. Hydrotech says 1.55 max. and 61mm wide. That would be 2.8mm higher. That will almost eliminate the relief notches.
Let her eat lol

I think mine are a little higher than stock. He didnt really raise them but just cleaning up prob brought them up a little.

[Mr. Demeanor]

Gordons saying maybe go 1.58 with a nice chamfer edge to get to 1.55 ad leave the intake side alone to keep it reliable. Kind of seems to be the consensus. I like making m long river runs and coming back to the dock under my own power

[Umassot50]

if your going to have the heads redone take the blend radius out of the transition from the squish to the bowl. a sharp edge here can make more power. yes sharp. like machine the squish band. machine the chamber. dont touch the edge. i maybe scotch brite it the smallest amount. tough to turn a squish and chamber on twin heads like those though.

[Mr. Demeanor]

Well that took awhile but I pulled the powerhead yesterday and disassembled it today. Still love having a powerhead I can lift off, fully dressed, by myself without a hoist.
Everything looks fine except that piston. A little scuff where the piston pushed out above the ring where the screw burried itself. The ring still moved but it sure was close to sticking it. The screw damn near top pinned the piston. Its actually right above where the pin is which is probably why the ring didnt get stuck.
Block is over at Teds ready for a little exhaust port work and then Ill be breaking it in again. Thinking of maybe top pinning the pistons while its apart.

[Mr. Demeanor]

Just about ready to put it back together. Ports are raised to 1.550 from stock which was 1.620.
Should be a pretty big change in power curve.

Any thoughts on replacing the throttle plate screws with stainless steel rivets? This is the one that came out. Rivet should end that possibility but Ive never seen rivets used here so wondering if theres a reason.
I would have to drill the threads out of the hole to fit a 1/8" rivet so theres no going back once Ive done it,

[Dave Strong]

Loctite and stake the threaded end they won't come out.

Dave

[baja200merk]

Put screws back in and tig them to the shaft.

[Mr. Demeanor]

Loctite and stake the threaded end they won't come out.

Dave

Thats the other thing I thought about. Get some nice button heads and slot the threaded ended so I can spread it Kind of like the stock screws were. I think a Dremel cutoff wheel is thin enough to make a slot narrow enough.

[Dave Strong]

Don't think stainless is a good choice in this case due to how hard they are. Used to rebush QJet pri shafts back in the day the non stainless screws are much easier to stake.

Dave

[Mr. Demeanor]

I think the stock screws were brass.

Just picked up the block from Ted and the ports look great. Almost all the exhaust notch is gone now. Off to Flagship tomorrow to get honed.

[DoktorC]

I got rid of my exhaust notches using excel sleeves...

[Mr. Demeanor]

That'll work !

[Mr. Demeanor]

So the screw took out the threads in the shaft when it came out or, the threads were damaged when I removed the original staked screw. Either way, there's no thread to put in a new screw and not much there to go oversized. Think I am going to try rivets as some of the other threads are probably in the same shape.
I may have to add a little epoxy to the center of each rivie to close it off although I wanted to a hole in the plate like the Merc carbs anyway.

So now I have the air bleed holes I wanted although not exactly where I would have put them but Ill see how it works. I used a ball end allen wrench to spread out the other side of the rivet and make it pretty flush. Used steel rivets.

[CharlieN]

I am surprised you did not use solid rivets or at least Cherrymax rivets.

[Mr. Demeanor]

I am surprised you did not use solid rivets or at least Cherrymax rivets.

I wanted as low profile as possible on both sides.