Fist top end replace on first bike a success?

Joined
Jun 9, 2001
Messages
124
Likes
0
#1
I think I successfully replaced my top end (new rings and piston) tonight. I have to say the most difficult part of the whole job other than the amount of time was aligning the rings with the piston alignment pin and holding the rings in place while sliding the cylinder over it. I assume they stayed aligned because the cylinder slid on super easy and I rode the bike for 15 min and every thing seems great. Does this mean I'am in the clear or does it take an hour worth of riding for the rings to fully expand and then if they are not perfectly aligned trouble strikes? Also I used Wiseco piston kit, is this as good as the OEM piston and rings? The other pain was installing the circlips. Has anyone ever had a problem with the circlips falling out and doing major damage to the top end? Thanks for answering all my top end replacement quesions it all proved to very valuable advice.
 
Joined
Dec 10, 2000
Messages
1,490
Likes
1
#2
Lets start at the beginning.

If the rings were not in place and aligned with the pins, you would have known something was wrong the first time you turned the engine over.

A Weisco piston is agood product, as good or better than stock, but they can seize veryeasily during break-in if done improperly, and you are doing it in a kinda risky way. The first time you started the engine, you shouldn't have ridden it, only warmed it up and then shut it off to cool down completely. But that is done now, so just make sure you ride it gently 2 or 3 more times for 15 minutes or so and cool it down completly between each ride. The piston needs these heating and cooling cycles to break in properly. Also always be sure to completely warm it up before each ride.
 

bigred455

"LET'S JUST RIDE"
Joined
Sep 12, 2000
Messages
782
Likes
0
#3
Sounds like you are good to go.No i never had a circlip pop out,you know when they are in correctly you will here them snap in the groove.I will visually check them to make sure they are sitting in the groove all the way.I also push on the wrist pin both ends to ensure myself(COMPULSIVE DISORDER) Their is 1 thing i have noticed though i put my circlips in at the 12:00 position on a oem piston 00 kx 250.Every time i take my top end apart the clips are sitting at 6:00.
 
Joined
Dec 10, 2000
Messages
1,490
Likes
1
#4
Originally posted by bigred455
i put my circlips in at the 12:00 position on a oem piston 00 kx 250.Every time i take my top end apart the clips are sitting at 6:00.
Sounds to me like you should start putting them at 6:00 from the begginning. You know the saying, "If you can't beat 'em, join 'em.";)
 
Joined
Mar 17, 2000
Messages
531
Likes
0
#5
Good deal Spanks

I too am doing my 1st top end rebuild in my 1st bike , and found the bore wear limit to be out of spec. I shiped the cylinder out 2 weeks ago to be re sleeved and probably have to wait another 2 before it is done .:(
 
Joined
Dec 10, 2000
Messages
1,490
Likes
1
#6
Are you having it sleeved or replated? Sleeving is not a good choice, I hope you meant replating.
 
Joined
Dec 10, 2000
Messages
1,490
Likes
1
#8
Phew! Replating is what you want, not sleeving. Plating is a very hard coating electro-plated onto the aluminum casting, and is very durable and long-lasting. Sleeving a cylinder means they machine the jug to accept a steel liner, and they are by far inferior to plating. The steel liner wears at about the same rate as the piston and rings, requiring it to be re-bored at every top-end rebuild.
 
Joined
Mar 17, 2000
Messages
531
Likes
0
#9
Thanks for sorting that out for me . One question if you don't mind . Will the bore be the same as new ? I have new OEM piston and rings that I would like to use .
 
Joined
Dec 10, 2000
Messages
1,490
Likes
1
#10
Yes, they will plate it to the stock bore size, and the plating will be a much higher quailty than the OEM stuff.
 

MADisher

Grand Data Poohbah
Joined
Apr 30, 2000
Messages
377
Likes
0
#11
Are you saying the cylinder doesn't need 'replating' every time ? If it's scored, and I venture to guess in most cases they are because most folks wait too long, and the cost of replating is substantially higher.

A sleeved cylinder doesn't need bored every time, just probalby honed a bit to clean it up. And it depends on the sleeve, they are often hardend and some, I'm told nearly as hard as the plating. I could be wrong though. Wouldn't be the first time.
 
Joined
Dec 10, 2000
Messages
1,490
Likes
1
#13
Originally posted by 88RM250
Are you saying the cylinder doesn't need 'replating' every time ? If it's scored, and I venture to guess in most cases they are because most folks wait too long, and the cost of replating is substantially higher.

A sleeved cylinder doesn't need bored every time, just probalby honed a bit to clean it up. And it depends on the sleeve, they are often hardend and some, I'm told nearly as hard as the plating. I could be wrong though. Wouldn't be the first time.
When I bought my current bike, at the first tear down I discovered the previous owner had aparently blown the engine, and had the cylinder sleeved. The piston-to-cylinder clearance at that time was about .06" at the top and bottom of the cylinder, and about .09" in the middle, obviously needing rebored. So, off to the shop it goes, and it gets reassembled, with a new piston. At the next tear-down, prompted by a loss of compression after only about 30 hours, I find the clearance to be nearly as much as it was the first time. No more of this crap! I bought a new cylinder, and it has been rebuilt 9 times without replating, and it is just now worn to the spec limit. Is a sleeve as good as plating? not by a long shot in my experience.
 

bigred455

"LET'S JUST RIDE"
Joined
Sep 12, 2000
Messages
782
Likes
0
#14
Originally posted by spanky250
Sounds to me like you should start putting them at 6:00 from the begginning. You know the saying, "If you can't beat 'em, join 'em.";)
.

Spanky,smart i like,smart ass i don't.LOL good one.
 
Joined
Oct 14, 1999
Messages
4,005
Likes
0
#15
Hardest part was......

Goldman:
..the most difficult part of the whole job other than the amount of time was aligning the rings with the piston alignment pin and holding the rings in place while sliding the cylinder over it
No, I haven't done this on my (prettymuch) new KDX..but it's worked on any other 2-stroke I've done topends on (yamahas). Put the piston in FIRST. With the cylinder on a bench and upside down it's MUCH easer to get the rings in correctly. Then, with the pin boss just below the bore, put the whole mess back on and install the pin. You can use a couple of blocks of wood to hold the cylinder in position when it comes to putting the clip in.

Now I suppose I'll find out that the pin hole isn't even visible using that method on a kdx?
 
Last edited: