Give Your Spree More HP

Post by **noiseguy** » Sat Nov 11, 2006 12:47 pm

OK...

On the head; it will should be fine. If you want to check it out, tape some electrical solder onto the piston, reassemble with the head and head gasket, torque to spec, and rotate the engine by hand a few times. Measure how much the solder got "squished." A .020" running clearance will be fine, I've heard of guys running down to .010" cold... but I've never tried it. The '84/85 Honda replacement piston is domed anyway; the dished version was just used for production in those two years.

The '86 head has a taller dome. You should be able to get higher compression with this head and a domed piston IF you have the head machined down. That said, the domed piston + the '84/'85 head might actually have higher compression with no modifications. Looking at the two, I'd guess the '84/85 head has much lower chamber volume.

On the A or B jug, you are supposed to replace the stock A jug with another A jug, or B jug with another B jug. Why? The parts (the engine case actually) are running on opposite ends of the build tolerance. On these small engines, they hand-sorted parts to get the last .0010" on them; they would measure the case and use an A or B jug depending on where the hole landed in final machining. Very common in a variety of moped/scoots in the 50cc range. I'm not sure how much difference it really makes, but there you go.

Hope this clears things up.

darat · Post by **darat** » Sun Nov 12, 2006 12:59 pm

so you can take off .010 of a spree head.

Post by **noiseguy** » Mon Nov 13, 2006 11:08 pm

You can take .020" off. If you've ever run a Spree without a head gasket (on purpose or not) you've removed that much. I pulled .017" off mine and have run it that way quite awhile. That's an '84 head with the stock dished piston.

I *think*, but am not sure, that you can remove even more than that with a domed piston and the '86/87 head. But I've never verified it personally, it's based on comments I'd read elsewhere. I'd love someone to check this out for me and post back with results.

darat · Post by **darat** » Tue Nov 14, 2006 10:44 am

since mine is a 86 how much can i take off.. p.s i was thinking about putting a elite 80 engine on my spree over the winter.

Post by **noiseguy** » Tue Nov 14, 2006 7:44 pm

I have no idea. You'd have to measure it with solder and a micrometer as described above.

martin@spree · Post by **martin@spree** » Wed Nov 15, 2006 5:10 pm

hello again guys the best way to know what works or not ...is to try it all thats how we found the best triks,,,,,milling the heads always works but in the other hand there will be overheating problems...i saw a trick that workd whith a head milled almoust all the way it consisted on making a aluminium gasket for the lower part of the cilinder where you have a paper gasket.. a cuarter or an inch... not letting the piston reach the to the top so WALA... PRESTO...no clearence eachues and more comprecion ...ps you will need longer bolts.

Post by **noiseguy** » Thu Nov 16, 2006 9:38 pm

You can make copper base gaskets or, if you're really brave, use a thin layer of heat-resistant RTV in place of a base gasket (I'm not a big fan of doing that though, RTV always ends up everywhere.)

The stock base gasket is .020" once compressed, so if you make up a .010" copper gasket instead, you've increased compression without shaving the head. Same on the head gasket, replacement of the head gasket with a .010" copper gasket added to the base gasket decreases the clearance by .020" overall.

Not a bad way to do this on a budget, without special tools.

Post by **noiseguy** » Thu Nov 16, 2006 9:44 pm

martin@spree wrote:i saw a trick that workd whith a head milled almoust all the way it consisted on making a aluminium gasket for the lower part of the cilinder where you have a paper gasket.. a cuarter or an inch... not letting the piston reach the to the top so WALA... PRESTO...no clearence eachues and more comprecion ...ps you will need longer bolts.

What you're doing by lifting the jug is raising the port timing, then compensating for the lowered piston with a super-shaved head so that you keep compression up. Port timing is a whole other can of worms. You'd want to combine that with lowering the bottom of the exhuast port, methinks, but I haven't experimented with this at all.

darat · Post by **darat** » Thu Nov 16, 2006 11:38 pm

u should try it...

xela_p2004 · Post by **xela_p2004** » Fri Dec 22, 2006 3:32 pm

Well My 86 spree has a 84 head and a dome piston and I use 93 octane, I also have a racing pod filter and have elimiated one chamber off the muffler making the scavenging effect much quicker. Iam currently using a 78 main jet and the spark plug looks like a dark red color. The take off of the scoot is quick but still all these mods did really little for my top end, just my accerlation. When I first started with a 86 head and dished piston the scoot had a slow take off and maxed out at about 32mph, now it blasts off but comes to quickly to a max at about 35mph. I need more top end what else can I do? I also have a 2.75 rear tire vs the 2.50 tire. Tired a bigger tire but didnt work. Accerlation isnt a big deal for me, but top end is. Any other ideas anyone?

MySpree · Post by **MySpree** » Fri Dec 22, 2006 5:47 pm

shave your inner pully

Kenny_McCormic · Post by **Kenny_McCormic** » Mon Dec 25, 2006 5:42 pm

shave the head .028 add .010 to the base this should get some power and REALLY high revs

darat · Post by **darat** » Tue Dec 26, 2006 1:03 pm

Kenny_McCormic wrote:shave the head .028 add .010 to the base this should get some power and REALLY high revs

ok the peguin thing is crazy.. i just noticed that it tells me my ip address and what internet i am useing. wow thats messed up..

Kenny_McCormic · Post by **Kenny_McCormic** » Tue Dec 26, 2006 8:31 pm

you can have one to if you want they are pretty customizable got to danasoft.com

antoniobustamante · Post by **antoniobustamante** » Wed Dec 27, 2006 2:48 pm

i have a really goofy question. i've seen people argue about that whole turbo on a two stroke thing, and i don't care to go there. but what if a person were to come up with a way to apply just the right amount of vacuum to the exhaust side?w/no boost on the intake. kinda like an artificial expansion chamber. I know this wouldn't be easily accomplished. maybe an electric pump of some sort. I'm just wondering what would happen. no back pressure would be very bad I'd imagine. Just Curious