Maintenance & Technical > KX500 Original

KX500 BIG BORE KITS

<< < (2/8) > >>

demographic:
Don't know if you have sidecar motocross over there but over here they take KX 500 engines and get a bit silly with them.
One of the lads that used to come on here (Scarykxer) has had his bored out to something like 570 cc

Bored out and I think they use a 2mm oversize CR piston as well which is 91mm in diameter and change the conrods to CR ones that are aparentely stronger.
I am not sure if they also offset the crankpin to increase stroke.

They also use the Maico engines (you lot might know them as the ATK intimidator engine but its a Maico all the same) and they are re badged as Zabel engines.

Think they are something daft like 700cc, don't fancy licking one of those over with my left foot though.

don46:

--- Quote from: maddoggy on June 26, 2007, 05:29:17 AM ---i'm not completely sure but i think a big bore kit would involve boring out the cyl. large and sleeving it to whatever the desired size. heres the problem. anyone whos worked on diesel engines alot knows about the problems associated with sleeves. they tend to wear holes in them from internal electrolisis(or harmonic induced cavitation). the wear occurs on the water side of the sleeve due to tiny bubble explosions that are vibration induced. knowing the revs on these k5s are high, in my opinoin, the sleeve wear on a 2 stroke would probably be worse than on a large low rev diesel. however, if a sleeve kit is chosen then change coolant at least 1 or 2 times per riding season. the sleeve wear is excellerated when running out of spec. coolant in the engine. my opinion only,  MADDOGGY

--- End quote ---

When the cylinder is bored it does not get into the water jacket, you shouldn't have to worry about electrolysis. Now you can use a new style cylinder, but if you desire to go more than 88mm you'll need to weld up the upper kips, or use an 86-88 cylinder. You don't have to install a cast iron sleeve, you can have it bored and re-plated. I have one that is 91mm, it works good, but, not sure if it's worth the work. I would have the Mods that Stewart has posted, I did a cylinder with the head, piston and 44mm carb mod, the thing hauls, it pulls a ton more gearing. Wiesco makes a 88mm piston, you could get your cylinder bored and re-plated to 88mm install the new piston and you'd be good to go.

There was a post asking if anyone had tried a PVL ignition with the Mods by
Stewart, I have and didn't like it at all. There is to much compression to spin the motor fast enough to fire, once running no problem, but getting running no way. The PVL works good on a lower compression motor. by my estimation my motor with the Stewart mods has 180ish psi of compression.

Rotorised:
This is all great info guys, cheers. I have recently taken my cylinder off to port a big bore, but have found it is allready sleeved, so now im thinking a 540 kit. I would like to run the same mods as some of the members here but i dont think it is possible as in Australia we only really have access to 98 octane fuel and would be looking at detonation. Has anyone here got any engine mods for this kind of fuel?

monster malibu:
Anybody ever dealt with KUSTOM CRAFT? They list a BBK for the KX500, it's a 540. I'm not sure about the BBK yet, but I'm still thinking about it. I like the idea of more power and speed.

monster malibu:
I can't be the only one that's interested in the big bore kit for the KX500. Somebody's got to have one? :?

Navigation

[0] Message Index

[#] Next page

[*] Previous page