weisco blues

[2-Stroke Tom]

Motorrad,
With no disrespect, didn't your bike overheat on your last desert race and cause a DNF? You're a talented guy with a wealth of knowledge and what you experienced is what I've personally seen for years with respect to the big bore two strokes. I'm not saying this to criticize your hobby or anything, I'm just saying that when people vary far from factory specifications/design to seek more power, they will be increasing their mean time between failures.

The vast majority of the people I knew and grew up with racing the KX500 were not pros, and most wouldn't even bother rebuilding the top end even once a year. When I used to help flag the racing courses back in the 90's several people in my club had 500s. Most would leave them at camp when flagging because there is a lot idling with very little air moving over the radiators.

Maybe I've been lucky, but I've put at least 150 gallons of fuel through the ex Team Green KX500 I bought and haven't even opened the top end and have never had a problem. It has an oem piston. With all of the bad things I've been hearing about aftermarket pistons, I may just use the OEM piston when I need to do a rebuild.

There is absolutely nothing wrong with using the OEM cast piston on the KX500. Like Polar-Bus, I have done a ton of top ends using the OEM piston without a single problem. The true test is that I raced on the same OEM piston for several seasons on one of my 250s. Sure, a forged piston is less likey to cause as much damage upon failiure, but if the cast piston is prone to breaking in your engine, you're likely to have other issues.

When Team Green desert raced the KX500, the stock OEM piston was used quite often. I realize that most people on this site are always going to try and seek more power, but there is a reason why so many pros who raced the KX500 kept the engine basically stock. You got to give the engineers credit who designed the motor (maybe I'm impartial because I'm an engineer!), because one of their major goals was realiabilty. Most heavily modified KX500 motors will never take the ruthless abuse of desert racing because they will either overheat, or simply not last that long. Yet, tons of "backyard" mechanics will insist that their mods aren't affecting realiability and only adding power. Their bikes will never be put to the test to prove this.

Very Very True...   I never had a problem with the cast piston in any of my bikes... (most of them have cast in them)

But.. when it comes to racing, and abusing motors,  it also helps when you are sponsored.. and have the option of putting in a new top end every race...

My setup see's alot of desert racing... and Bombing through the canyons with the sumo setup in between..   which I think the sumo stufff is TONS harder on the bike than desert race....

Wiseco has bit me good on that last piston of mine.

#1  rings were at .020 ish gap...
#2  Wrist pin clip grooves were machined .040" too close (going off memory)
#3  ring land machined wrong...


I still wont stray from forged though..

wossener here I come

[2-Stroke Tom]

A correction to my last post:

Motorrad,
With no disrespect, didn't your bike overheat on your last desert race and cause a DNF? You're a talented guy with a wealth of knowledge and what you experienced is what I've personally seen for years with respect to the big bore two strokes. I'm not saying this to criticize your hobby or anything, I'm just saying that when people vary far from factory specifications/design to seek more power, they will be increasing decreasing their mean time between failures.

The vast majority of the people I knew and grew up with racing the KX500 were not pros, and most wouldn't even bother rebuilding the top end even once a year. When I used to help flag the racing courses back in the 90's several people in my club had 500s. Most would leave them at camp when flagging because there is a lot idling with very little air moving over the radiators.

Maybe I've been lucky, but I've put at least 150 gallons of fuel through the ex Team Green KX500 I bought and haven't even opened the top end and have never had a problem. It has an oem piston. With all of the bad things I've been hearing about aftermarket pistons, I may just use the OEM piston when I need to do a rebuild.

There is absolutely nothing wrong with using the OEM cast piston on the KX500. Like Polar-Bus, I have done a ton of top ends using the OEM piston without a single problem. The true test is that I raced on the same OEM piston for several seasons on one of my 250s. Sure, a forged piston is less likey to cause as much damage upon failiure, but if the cast piston is prone to breaking in your engine, you're likely to have other issues.

When Team Green desert raced the KX500, the stock OEM piston was used quite often. I realize that most people on this site are always going to try and seek more power, but there is a reason why so many pros who raced the KX500 kept the engine basically stock. You got to give the engineers credit who designed the motor (maybe I'm impartial because I'm an engineer!), because one of their major goals was realiabilty. Most heavily modified KX500 motors will never take the ruthless abuse of desert racing because they will either overheat, or simply not last that long. Yet, tons of "backyard" mechanics will insist that their mods aren't affecting realiability and only adding power. Their bikes will never be put to the test to prove this.

Very Very True...   I never had a problem with the cast piston in any of my bikes... (most of them have cast in them)

But.. when it comes to racing, and abusing motors,  it also helps when you are sponsored.. and have the option of putting in a new top end every race...

My setup see's alot of desert racing... and Bombing through the canyons with the sumo setup in between..   which I think the sumo stufff is TONS harder on the bike than desert race....

Wiseco has bit me good on that last piston of mine.

#1  rings were at .020 ish gap...
#2  Wrist pin clip grooves were machined .040" too close (going off memory)
#3  ring land machined wrong...


I still wont stray from forged though..

wossener here I come

[alward25]

I don't know either, thought i might give it try to find out.  Put some time on it and then inspect it.  Just need to get it DLC coated, and an "experimental" sticker for the side panel.

I think I am am going to window a wossner and run it with the titanium pin.  Should lighten up a few things.

 I don't think a titanium pin will work with a needle bearing, even with a hard surface coating.
 

[don46]

I think I am am going to window a wossner and run it with the titanium pin.  Should lighten up a few things.

 I don't think a titanium pin will work with a needle bearing, even with a hard surface coating.
 

I agree, the titanium Rod I have has pressed in steel sleeves, I haven't had it out since it was installed but my later this summer

[Motorrad]

Motorrad,
With no disrespect, didn't your bike overheat on your last desert race and cause a DNF? You're a talented guy with a wealth of knowledge and what you experienced is what I've personally seen for years with respect to the big bore two strokes. I'm not saying this to criticize your hobby or anything, I'm just saying that when people vary far from factory specifications/design to seek more power, they will be increasing their mean time between failures.

The vast majority of the people I knew and grew up with racing the KX500 were not pros, and most wouldn't even bother rebuilding the top end even once a year. When I used to help flag the racing courses back in the 90's several people in my club had 500s. Most would leave them at camp when flagging because there is a lot idling with very little air moving over the radiators.

Maybe I've been lucky, but I've put at least 150 gallons of fuel through the ex Team Green KX500 I bought and haven't even opened the top end and have never had a problem. It has an oem piston. With all of the bad things I've been hearing about aftermarket pistons, I may just use the OEM piston when I need to do a rebuild.

There is absolutely nothing wrong with using the OEM cast piston on the KX500. Like Polar-Bus, I have done a ton of top ends using the OEM piston without a single problem. The true test is that I raced on the same OEM piston for several seasons on one of my 250s. Sure, a forged piston is less likey to cause as much damage upon failiure, but if the cast piston is prone to breaking in your engine, you're likely to have other issues.

When Team Green desert raced the KX500, the stock OEM piston was used quite often. I realize that most people on this site are always going to try and seek more power, but there is a reason why so many pros who raced the KX500 kept the engine basically stock. You got to give the engineers credit who designed the motor (maybe I'm impartial because I'm an engineer!), because one of their major goals was realiabilty. Most heavily modified KX500 motors will never take the ruthless abuse of desert racing because they will either overheat, or simply not last that long. Yet, tons of "backyard" mechanics will insist that their mods aren't affecting realiability and only adding power. Their bikes will never be put to the test to prove this.

Very Very True...   I never had a problem with the cast piston in any of my bikes... (most of them have cast in them)

But.. when it comes to racing, and abusing motors,  it also helps when you are sponsored.. and have the option of putting in a new top end every race...

My setup see's alot of desert racing... and Bombing through the canyons with the sumo setup in between..   which I think the sumo stufff is TONS harder on the bike than desert race....

Wiseco has bit me good on that last piston of mine.

#1  rings were at .020 ish gap...
#2  Wrist pin clip grooves were machined .040" too close (going off memory)
#3  ring land machined wrong...


I still wont stray from forged though..

wossener here I come

My cooling issue was 100% radiator related..   stock vs modded wouldnt have made a differance...  as it all came down to me being Cheap and trying to save my old radiators

Id argue that the mods I have made... are what saved me from having to push it back...

I will also say the CYL I got off of Destry abbots bike... was NOT STOCK.. on porting...
and the CYL off my Jeff ward bike... that was owned by Doug Hass (dyno tuner for kawasaki).. was also... NOT STOCK...
as well as the CLY that is for sale here local... that I have had my grubby hands on... that was off JEFF HEALEY's practice bike.. was.. also.. NOT STOCK

[81cr450]

Ohh Ohh OOooo factory cylinder for sale how much? & is it as sweet as the others youve had youre grubby hands on.

Sorry to go sideway but... Factory  Cylinder

[Motorrad]

Ohh Ohh OOooo factory cylinder for sale how much? & is it as sweet as the others youve had youre grubby hands on.

Sorry to go sideway but... Factory  Cylinder

guy wants $100...   and its....... TRASH...    lots of things broke... and continiued to go up and down in it.....


Could it be saved?    yea... probably..

its not as bad as my Destry abbot CYL we brought back to life was

[Foxx4Beaver]

well lets see here....after 9+ hours of doing searches about top ends on here dating from 03 til just a couple days ago,and a 40 minute phone call with JoJo Keller,I've found that the "majority" of guys still choose Wiseco.I myself have yet to have any problems with them,been using them for 32 years.I even have an 81 KZ1000 with the Wiseco 1400cc big block kit that I installed in 98 and have 28k miles on it and it still rips just as strong as it did since I installed it.I recently re-rung my KX5 roughly 15 hours ago(Wiseco)and had no problems,compression was at 175 right after I installed them,now it's at 170....and that's on a jug with 4 seasons on it.Should get a hair more when I throw on the new jug.I'm not doing my rebuild til mid March or so,so I'll be watching this thread and any others closely.I see Motorrad,Alward,and a couple others are thinkin Wossner.I've never tried them,but if you guys like them,then I'm on board too.

As for OEM cast...ugh....I found 21 posts of pics of cracked/shattered cast pistons on here,and NOT ONE of forged.Not saying there is'nt any posts of forged pistons grenading,but after 9 hours of searching,I had had enough.
After talking with JoJo,he also swore by Wiseco and forged in general.He used Wiseco through-out his whole racing career...EXCEPT in 1984,he said he chose to run his YZ490 with the OEM cast at Southwick for practice...and on his final lap,his bike locked up...cast piston shattered.He said after that,he came up with the motto..."you'll come in last,if ya run cast".
Not that he was ever the king of motocross or engine building,but it's from someone with a ton of experience.Then there's several posts from Stewart,who replyed several times..."cast won't last"...and coming from someone that has dedicated EXTENSIVE hours of building and testing the KX5 motor as much as he has....I'll listen to him long before I listen to someone trying to suggest I run cast!!!...in any of my toys!

So for the guys that swear by OEM cast and have never had a problem with them....I say Good for you,and best of luck to ya.
ALL the proof that I or anyone else will need,is right on this site.

Foxx