top end re-build - Motorcycle-Journal Forums

MikeFry · 02-28-2006, 09:56 PM

when your bike needs a new top end does that always include resleeving the cylender or, is just replacing the piston ok too?

Shea · 03-01-2006, 09:28 AM

I know in cars, a top end rebuild it only the heads and possibly carbs, it doesn't include pistons. Not sure about a bike though.

MikeFry · 03-01-2006, 01:38 PM

Quote:

Originally Posted by MikeFry

when your bike needs a new top end does that always include resleeving the cylender or, is just replacing the piston ok too?

i mean on a two stroke rm 125, sorry if i confused anyone.

JoelAZ · 03-01-2006, 06:40 PM

I have to assume from what you've said that the bike has an iron sleeve. If this is the case, you can just oversize the piston and bore it over. If however, you have a plated aluminum cylinder, this requires a new jug...

Dave2122 · 03-01-2006, 08:24 PM

What year RM 125?

All modern MXers use a hard coating called Nikasil Carbide that does not need anything done to it unless the surface was damaged. It is harder than Diamond so it is very tough. If you have a modern 90's RM then you need only replace the following

1 Piston
1 Ring set
1 Wrist Pin
1 Wrist Pin Needle Bearing
2 C clips
1 Head Basket
1 Base Gasket
New Coolant with Distilled Water at 50/50
New Spark Plug

MikeFry · 03-01-2006, 08:41 PM

Quote:

Originally Posted by Dave2122

What year RM 125?

All modern MXers use a hard coating called Mikasil Carbide that does not need anything done to it unless the surface was damaged. It is harder than Diamond so it is very tough. If you have a modern 90's RM then you need only replace the following

1 Piston
1 Ring set
1 Wrist Pin
1 Wrist Pin Needle Bearing
2 C clips
1 Head Basket
1 Base Gasket
New Coolant with Distilled Water at 50/50
New Spark Plug

1997, from the dude i bought it from he told me that the person that owned it before him rebuilt it a year before he bought it, i bought it from him a year after he bought it.

digipoi · 03-01-2006, 08:52 PM

^You could just get away with changing the rings and gaskets. Usually all I ever have to do and I only do it because my powervalve gets gummed from riding slow trails or with my family.

But like Dave said, thats all you really need and a piston is not that expensive either if you wanted to do the whole thing. Chance em'

MikeFry · 03-02-2006, 09:10 AM

one more thing, if i order a piston from dennis kirk or rocky mountain mc, it doesnot come woth a new cylender sleeve only the rings, circlips, piston, and ithink wrist pin. how to i get a cylender sleeve?

Dave2122 · 03-02-2006, 11:28 PM

You dont need anything other than what I listed. The cylinder is Nikasil and does not need any replacemnt or honing or boring or anything. the only time you have to do anything is when the motor siezes and you damage the Nikasil in the cylinder. If this happens you get it replated.

MikeFry · 03-03-2006, 01:43 PM

i got it all sorted out now, thanks!

02-28-2006, 09:56 PM	#1 (permalink)
MikeFry Where Am I ? Joined: Feb 2006 Posts: 34	top end re-build when your bike needs a new top end does that always include resleeving the cylender or, is just replacing the piston ok too?

03-01-2006, 06:40 PM	#4 (permalink)
JoelAZ Seat Tester Joined: Feb 2006 Bike: Still under consideration Location: Phoenix, AZ Posts: 88	I have to assume from what you've said that the bike has an iron sleeve. If this is the case, you can just oversize the piston and bore it over. If however, you have a plated aluminum cylinder, this requires a new jug... __________________ -Joel mmMMmmMMmm.... tasty!!! (\__/) (O.o ) (> < )<-- This is Bunny. Copy Bunny into your signature to help him on his way to world domination.

03-01-2006, 08:24 PM	#5 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	What year RM 125? All modern MXers use a hard coating called Nikasil Carbide that does not need anything done to it unless the surface was damaged. It is harder than Diamond so it is very tough. If you have a modern 90's RM then you need only replace the following 1 Piston 1 Ring set 1 Wrist Pin 1 Wrist Pin Needle Bearing 2 C clips 1 Head Basket 1 Base Gasket New Coolant with Distilled Water at 50/50 New Spark Plug Last edited by Dave2122; 03-02-2006 at 11:29 PM.

03-01-2006, 08:52 PM	#7 (permalink)
digipoi Seat Tester Joined: Sep 2004 Location: Honolulu Posts: 84	^You could just get away with changing the rings and gaskets. Usually all I ever have to do and I only do it because my powervalve gets gummed from riding slow trails or with my family. But like Dave said, thats all you really need and a piston is not that expensive either if you wanted to do the whole thing. Chance em' __________________ 2004 RM250 2004 DRZ125L 2006 TTR-90E 2004 JR50 1993 RM250 1990 KDX200

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03-01-2006, 09:28 AM	#2 (permalink)
Shea Third gear and cruising Joined: Feb 2006 Bike: Buell XB12Ss Lightning Location: York, Pa Posts: 521	I know in cars, a top end rebuild it only the heads and possibly carbs, it doesn't include pistons. Not sure about a bike though.

03-02-2006, 09:10 AM	#8 (permalink)
MikeFry Where Am I ? Joined: Feb 2006 Posts: 34	one more thing, if i order a piston from dennis kirk or rocky mountain mc, it doesnot come woth a new cylender sleeve only the rings, circlips, piston, and ithink wrist pin. how to i get a cylender sleeve?

03-02-2006, 11:28 PM	#9 (permalink)
Dave2122 Sprocket Pilot Joined: Sep 2004 Bike: Which one of the 9? Location: USA Posts: 887	You dont need anything other than what I listed. The cylinder is Nikasil and does not need any replacemnt or honing or boring or anything. the only time you have to do anything is when the motor siezes and you damage the Nikasil in the cylinder. If this happens you get it replated.

03-03-2006, 01:43 PM	#10 (permalink)
MikeFry Where Am I ? Joined: Feb 2006 Posts: 34	i got it all sorted out now, thanks!

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