Kx500 best gearing for top speed?

[Arrogant17]

I have a 2000 k5 with horrid crank and a stock cylinder, I have a fmf fatty pipe as well as I think a heavy flywheel, my power doesn't hit its just smooth, it tops out about 80, I'm running a 14t front sprocket and 49t rear, what would be the best gearing for top speed? I hear 15/43 is suppose to be insane but I don't want to buy new sprockets unless its for sure gonna get me around 100mph I hear the k5 should run around 110 stock with just changing gearing is that true? I checked compression today and I have nearly 2000 psi.any info would help, thanks

[sandblaster]

I'd like to see 2000 psi on a K5 top end... 
Top speed depends on many factors beside those you mentioned, so it's really hard to say (Excluding many so called stock mods).
My guess is that would be pushing it but possible..
With stock gearing, no way.
Check out gearing commander   http://www.gearingcommander.com/
My guess is 15/43 or higher
I haven't made a top speed run on my K5SM yet but I intend to find out.
Others on modded K5's have done well over that on this site.
And remember, saying you did it and proving it are not the same thing..

[Arrogant17]

Haha I definitely meant 200 psi, I love the k5 but I would really love to say I have a stock bike that runs over 100, so your best guess is I could probably use 15/43 or 15/47 and get a faster top speed then my 14/49?

[sandblaster]

Using a 15/42 I hit 95 in 4th.
Only backed off because I was in town and I didn't want to die  
That was verified by Satellite...
I did that with a V force 2 reed, pc2 pipe, my modded muffler, Wiseco piston, stock bore, 41mm carb, no other mods.
I had on stock wheels and knobs.
I have better tires now..

I'll be doing some top speed runs in about a month or so...

[ID KX500]

I've done 92 mph with14/48, stock.

[Motorrad]

200psi.

what motor mods are done.

[sandblaster]

I've done 92 mph with14/48, stock.

That put you at about 7800 RPM's with stock tires..

[Arrogant17]

Well looks like its time to try 15/43 and see what I can get , the only engine mod I have is a hot rod crank , wiesco piston at regular bore, v force reeds,

[Dutch-K5 Fan]

With 15/42 I hit 120miles on a beache race.
Only in deep sand it's to tall.



dutchy

[Motorrad]

Well looks like its time to try 15/43 and see what I can get , the only engine mod I have is a hot rod crank , wiesco piston at regular bore, v force reeds,

then your guage is wrong.?

[Arrogant17]

I don't think it is, it's a brand new gauge and its showing exactly 194 psi just to make sure the gauge is right I did it on my kx250 as well with a brand new topend and it's saying my 250 has 183 psi

[Polar-Bus]

I don't think it is, it's a brand new gauge and its showing exactly 194 psi just to make sure the gauge is right I did it on my kx250 as well with a brand new topend and it's saying my 250 has 183 psi

Even with running the optional thinner "race" head gasket my stock KX500 put out 170 psi per my gauge.

[Motorrad]

last time my bike read over or near 200.      I was running 15:1 compression and welded up kips releafs   (and higher port time, which hurts that number).   thin head gasket, and about .038" squish....................................    as per my snap-on  compression guage.

[Motorrad]

My bike now reads 195. 

and im 90mm bore, welded kips releafs, about .045" squish. and roughly 13.5:1 compression  thin head gasket

[sandblaster]

Most people I buy bikes from rave about how good their compression is...
If I ask the PSI I get the scared deer in the headlights look and something like, kick it over you can tell the compression is good, or something like, oh it reads 1548 psi and the bike shop said that was perfect...