Milling the head of an 86 spree

mccain · Post by **mccain** » Sat May 02, 2009 11:08 am

Can someone please tell me if milling the head down will improve the low rpm torque. I just don't want to go through the expense of a motor swap or a bore kit.

Thanks to this forum I've gotten my free spree up to 34mph (from 28mph) on flat ground but I lost some bottom end.

Kenny_McCormic · Post by **Kenny_McCormic** » Sat May 02, 2009 12:48 pm

Have you opened up the intake mani yet? Lapping the head and jug flat(if warped) and using a THIN layer of high temp silicone will make you lose ~.020" for free.

mccain · Post by **mccain** » Sat May 02, 2009 2:06 pm

Im not sure what to do to the mani, when I look inside I see something that looks like it's completely blocking off the intake. When I push on it with my finger it opens up. Since I didn't know what it was I decided to just leave it there.

p.s. When I looked in the exhaust mani I didn't find any washer either, I looked in the head pipe too.

ALOW1 · Post by **ALOW1** » Sat May 02, 2009 2:19 pm

mccain wrote:Im not sure what to do to the mani, when I look inside I see something that looks like it's completely blocking off the intake. When I push on it with my finger it opens up. Since I didn't know what it was I decided to just leave it there.

Those are the reeds, you have to have them otherwise it will not run.

mccain · Post by **mccain** » Sat May 02, 2009 3:10 pm

"the reeds" Thanks! Is there any other removable restrictions after the reeds?

Kenny_McCormic · Post by **Kenny_McCormic** » Sat May 02, 2009 9:38 pm

If you look at how the manifold is machined it has horrible flow, smooth out the round-square transition with a dremel.

mccain · Post by **mccain** » Sat May 02, 2009 10:35 pm

I'll take a look at the intake tomorrow, this would be my first porting experience. I've done a bit of reading about porting over the years so I feel confident I won't screw it up. Do I need any last minute advice?

Post by **noiseguy** » Sun May 03, 2009 12:35 pm

Milling the head improves performance across the torque band. I'd run the high-temp gasket material 1st, then have the machining work done if you like the improvement.

Kenny_McCormic · Post by **Kenny_McCormic** » Sun May 03, 2009 2:15 pm

noiseguy wrote:Milling the head improves performance across the torque band. I'd run the high-temp gasket material 1st, then have the machining work done if you like the improvement.

Why bother if the silicone holds?

mccain · Post by **mccain** » Sun May 03, 2009 3:59 pm

Well if I can take away .020" for next to nothin' then I don't think im gonna' pay someone to mill a perfectly good head down.

I got this scooter for free and my goal was to see how much I could improve on it without spending more than the bikes worth. So far im up to $170, that includes new clutch tire tube and several other little things. I can't wait to see what the porting and high temp silicone does for it.

Post by **noiseguy** » Sun May 03, 2009 10:10 pm

Kenny_McCormic wrote:
noiseguy wrote:Milling the head improves performance across the torque band. I'd run the high-temp gasket material 1st, then have the machining work done if you like the improvement.
Why bother if the silicone holds?

I'm not a huge fan of silicone.

scooterwerx · Post by **scooterwerx** » Mon May 04, 2009 10:09 am

see if you can get hylomar, the s*** is crazy....it works great in a pinch for a trackside head gasket! im sure it would awesome for a permanent on for a small engine.

Kenny_McCormic · Post by **Kenny_McCormic** » Mon May 04, 2009 3:41 pm

Hylomar, thats the stuff I was thinking of. Im not a big fan of sillycone, but it has saved my * a few times.

circusracer · Post by **circusracer** » Mon May 04, 2009 9:29 pm

mccain wrote: I can't wait to see what the porting and high temp silicone does for it.

Dude, I have three sprees and I have done as much as possible and the gains are very small. Make sure you have the #68 jet in the carb after all your changes. What year is your Spree?

mccain · Post by **mccain** » Mon May 04, 2009 11:10 pm

Mines an 86 with 4300 miles on it. My moms boss gave it to her and she gave it to me, so I nick named it the Honda free. All I had to do was rebuild it.

I flooded the motor with the 68 jet, I'll try it again after I port it.