More power mods/motors

[Zac]

So I run a simple setup, stock motorized, ngk plug, mz65 clone and nt with better air filter, with a 44t sprocket. How can I get more top end without sacrificing low end? I have tons of low end, I can go up any hill, accelerates crazy fast, but one it tops out, I'm not too happy with the speed. Any mods to get more top end out of my bike? Or for future build what would be a good all around power motor?

 

[Sidewinder Jerry]

The first thing you need is a tachometer. You need to know what your engine is currently doing as is. Then when you start doing performance mods you'll have a baseline to know how effective they are. Performance mods will be things like porting, crank balancing, expansion chambers, carb adjustments etc

 

[Chainlube]

So I run a simple setup, stock motorized, ngk plug, mz65 clone and nt with better air filter, with a 44t sprocket. How can I get more top end without sacrificing low end? I have tons of low end, I can go up any hill, accelerates crazy fast, but one it tops out, I'm not too happy with the speed. Any mods to get more top end out of my bike? Or for future build what would be a good all around power motor?

What you need is a motorcycle.

 

[Zac]

The first thing you need is a tachometer. You need to know what your engine is currently doing as is. Then when you start doing performance mods you'll have a baseline to know how effective they are. Performance mods will be things like porting, crank balancing, expansion chambers, carb adjustments etc

Porting I can do, but have no idea about balancing a crank. What does that do

 

[Sidewinder Jerry]

Porting I can do, but have no idea about balancing a crank. What does that do

Lowers the vibration in the engine.

 

[Zac]

What motor should I get for my next build? I've been getting pk80s, they're pretty good, but how would a phantom 85 compare?

 

[noah9988]

What motor should I get for my next build? I've been getting pk80s, they're pretty good, but how would a phantom 85 compare?

I've had a wildcat pk80 for a long time. Abused it, holding it wide open, 9k rpm, running it lean, putting timing in it, nitro, whatever (not all at once). I've never had a catastrophic failure. The main thing that happens to it is cylinder scoring, which I'm not really sure why it happens, but whatever. It doesn't vibrate much, always starts up fist revolution without choke.

I've now had two phantom 85s have catastrophic failures within 30 miles. One of them the ring caught the exhaust port and ruined the cylinder and piston. Bottom end was fine but the holes drilled into it for the studs where crooked and wasn't useable. The second one, which blew up yesterday, the piston tore itself in half (see pictures). The bottom end is full of piston bits and metal shavings. Might be saveable but the case surface was extremely uneven as well. Both my engines would rattle my teeth out at 6k rpm.

IF you get a phantom, you NEED to tear it down, balance the crank, replace the bearings, surface the cases, put an aftermarket chainsaw piston in it, and clean up the ports. Even if you do that there's no guarantee that the holes will be drilled straight in the case, a piston ring won't snag, or some other weird factory defect. Sure, the thing will absolutely rip, especially if you put something like a pwk carb and pipe on it, but it's not worth it. If you want speed, just get a minarelli.

I don't know what their reputation is and I don't want to get in trouble with damien, but southerncustomcc has a prebuilt minarelli with a preadapted mz65 pipe for $450. After what I've been through and wasting so much time on this junk I'd much rather spend the extra money on that minarelli.

(Venting ends)

 

[FrizzleFried]

I swear ... I am just SOOOOO freakin' exited to get my Phantom in to a frame (which I am still waiting on powder coating)...

Is my sarcasm evident?

I wonder if Bicycle-Engines would take my brand new never used Phantom back for trade on one of their now in stock Zeda 80's...?

...but then I am stuck with a piston I can't use... and clips for said piston as well.

>argh<

I'm just not experienced enough to dive in to the bottom end. That said, mine seems to be aligned at least.... so that's a start.

 

[noah9988]

I wonder if Bicycle-Engines would take my brand new never used Phantom back for trade on one of their now in stock Zeda 80's...?

You could certainly ask, wouldn't hurt anything.

 

[FrizzleFried]

Oh... and I wonder. If I use the solid piston... and it breaks... will Bicycle Engines cover the warranty or am I forced to use the inferior windowed piston to get said warranty? I probably should have inquired about that PRIOR to purchasing that chainsaw piston... but holy crap... if I can PREVENT issues by using it ...

...so tore.