2 stroke tear down/rebuild

Related:
Create New Tag

12/3/2017 8:22 AM

Hey guys I’ve got a few questions about my rear down/rebuild. This is my first time tearing down a dirtbike engine. I’m pretty experienced and have built several Yamaha Banshee engines in the past with success. So I’ve been wondering...do I need to invest in a case splitting tool? Also do I need a crank installation tool as well? The Banshee cases come apart really easily. Just a few small taps here and there with a dead blow mallet and ta-da. Now obviously the YZ is a different engine. Next question is piston. I’ve always ran forged Wiseco Pro-lite pistons and that’s my intention for my YZ so I’ve been curious on either a Pro-lite or the new single ring Racer Elite piston? Just wondering what you’ve guys have experienced with these. I’ll be sending the cylinder & head off to Powerseal USA after Christmas to have the cylinder replated and the head fixed after I let Eric Gorr work on it. The head needs to be corrected for race/pump gas mix. Photo

Photo

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/3/2017 8:28 AM

Yes on both tools. The yz wont come apart without them. Unless you want to fuck up your cases.

The piston in your pic is what i used on my yz250 and never had an issue. Solid piston.

|

2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

12/3/2017 8:29 AM

After my first rebuild with case splitter and crank install tool, I will never do it without them.

|

12/3/2017 8:35 AM

definitely buy them... a set of Tusk ones will work just fine and arent too expensive.

|

12/3/2017 8:42 AM

Thanks guys that’s what I like to hear. Also anybody running the 8oz GYTR flywheel? I’ve thought about getting one of those also. I ride mx 95% of the time and I’m only 165lbs if that helps any

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/3/2017 11:33 AM

rmoto003 wrote:

definitely buy them... a set of Tusk ones will work just fine and arent too expensive.

This. I bought the Tusk tools a couple years ago. I’ve done three motors so far and the tools are worth their weight in gold. Good for a few other shop uses I’ve found too.

|

12/3/2017 12:12 PM

Again thanks for the info guys. I placed an order for the tools a little bit ago

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/3/2017 1:48 PM

Yes get the splitter and crank puller.

|

12/3/2017 3:01 PM

While you have it apart, check your kickstart shaft for cracks.

|

much ty. How to spot a paid forum poster/artificial forum traffic producer (see list of actions/phrases below):

Copius pattern amounts of phrases like “Anyone have”..., “Anybody know?”.... and their variations.

Thoughts?
Any help is appreciated!
Thanks in advance!





12/3/2017 3:53 PM

kzizok wrote:

While you have it apart, check your kickstart shaft for cracks.

Will do. By the way... I can have Powerseal USA do my head mod for $75 which is pretty a common price from what I’ve seen. Anybody else have a preference or experience with another company for the YZ head mod?

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/3/2017 4:54 PM

Looks like you need to replace the powervalve shaft seal.

|

Powerband in every gear !

12/3/2017 5:30 PM

FGR01 wrote:

Looks like you need to replace the powervalve shaft seal.

I had it disconnected so I could take the cylinder nut off

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/3/2017 6:11 PM

FGR01 wrote:

Looks like you need to replace the powervalve shaft seal.

eric513anderson wrote:

I had it disconnected so I could take the cylinder nut off

See the black spooge running down from the powervalve shaft ? That's not supposed to be there. There's a seal on the shaft that is supposed to keep that in the powervalve housing inside the cylinder.

|

Powerband in every gear !

12/3/2017 7:38 PM

eric513anderson wrote:

Will do. By the way... I can have Powerseal USA do my head mod for $75 which is pretty a common price from what I’ve seen. Anybody else have a preference or experience with another company for the YZ head mod?

I had mine done by RB Designs, he does great work.

Here is a before and after of mine: https://imgur.com/a/YvPx3

|

2019 TX300
'10 200 XC-w

12/4/2017 3:08 AM

eric513anderson wrote:

Thanks guys that’s what I like to hear. Also anybody running the 8oz GYTR flywheel? I’ve thought about getting one of those also. I ride mx 95% of the time and I’m only 165lbs if that helps any

I just bought the steahly 9oz flywheel weight for mine, have not ridden it yet but will report back when I do. Planning on this saturday

|

12/4/2017 3:32 AM

FGR01 wrote:

Looks like you need to replace the powervalve shaft seal.

eric513anderson wrote:

I had it disconnected so I could take the cylinder nut off

FGR01 wrote:

See the black spooge running down from the powervalve shaft ? That's not supposed to be there. There's a seal on the shaft that is supposed to keep that in the powervalve housing inside the cylinder.

Ahh gotcha. If I have Powerseal USA do the powervalve assembly/cleaning I can assume this will be taken care of? Might have to write that down for them to do

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/4/2017 3:33 AM

eric513anderson wrote:

Thanks guys that’s what I like to hear. Also anybody running the 8oz GYTR flywheel? I’ve thought about getting one of those also. I ride mx 95% of the time and I’m only 165lbs if that helps any

chump6784 wrote:

I just bought the steahly 9oz flywheel weight for mine, have not ridden it yet but will report back when I do. Planning on this saturday

Right on. I’ve heard nothing but great about the fww. My only concern is loosing the snappiness of the bike

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/8/2017 11:33 PM
Edited Date/Time: 12/8/2017 11:39 PM

eric513anderson wrote:

Thanks guys that’s what I like to hear. Also anybody running the 8oz GYTR flywheel? I’ve thought about getting one of those also. I ride mx 95% of the time and I’m only 165lbs if that helps any

chump6784 wrote:

I just bought the steahly 9oz flywheel weight for mine, have not ridden it yet but will report back when I do. Planning on this saturday

eric513anderson wrote:

Right on. I’ve heard nothing but great about the fww. My only concern is loosing the snappiness of the bike

Rode the bike today with fww and tuned suspension and there was just a slight difference as it pulled onto the pipe. Instead of a snap it was more of a surge but in saying that the difference was slight. There was still plenty of snap to break the back end loose and I'm 20 lbs heavier than you

The bike was tracking really well on flat corners. People were commenting on how well it was hooking up. I'm not sure how much was the fww and the suspension but i felt the fastest today than i have since i got back into moto.

I actually want to try an 11oz fww but the consensus seems to be 9oz for moto. If you are thinking about getting one i would,

|

12/9/2017 3:25 PM

Go to a 13 oz fly wheel... those YZ motors hit pretty hard... gear it down too... 48 tooth in the rear, 13 front.

|

12/9/2017 8:42 PM

PTshox wrote:

Go to a 13 oz fly wheel... those YZ motors hit pretty hard... gear it down too... 48 tooth in the rear, 13 front.

Gearing is pretty good for the tracks I ride on. The track I was riding on yesterday was really hard packed, kind of quarry based and I was able to hold 3rd gear pinned around flat corners that I usually had to look for a berm on. The tracks I ride on are fairly tight too, I don't want any taller gearing or I'd constantly be on the clutch

|

12/10/2017 7:40 AM

Going with a Wiseco pro lite piston and a flywheel weight is a bit counter productive. OEM in most cases is the best in terms of reliability and performance when it comes to pistons and cranks.

|

12/11/2017 9:24 AM

rmoto003 wrote:

definitely buy them... a set of Tusk ones will work just fine and arent too expensive.

This is what I did years ago and the tools work great. I've split many a 2-stroke cases with those tusk tools!

|

12/11/2017 10:35 AM

sdhuskyrider wrote:

Going with a Wiseco pro lite piston and a flywheel weight is a bit counter productive. OEM in most cases is the best in terms of reliability and performance when it comes to pistons and cranks.

I would take a forged piston over cast any day. Providing they are properly sized of course. OEM YZ 250 Pistons scatter from time to time...

|

Tomac and/or Anderson for 2020.....

12/11/2017 10:41 AM

sdhuskyrider wrote:

Going with a Wiseco pro lite piston and a flywheel weight is a bit counter productive. OEM in most cases is the best in terms of reliability and performance when it comes to pistons and cranks.

BobPA wrote:

I would take a forged piston over cast any day. Providing they are properly sized of course. OEM YZ 250 Pistons scatter from time to time...

Ya, I always used Wiseco in my last YZ. My buddy who is pro level will shatter pistons in his YZ if he goes more than 10 hours.

|

12/11/2017 11:11 AM

sdhuskyrider wrote:

Going with a Wiseco pro lite piston and a flywheel weight is a bit counter productive. OEM in most cases is the best in terms of reliability and performance when it comes to pistons and cranks.

BobPA wrote:

I would take a forged piston over cast any day. Providing they are properly sized of course. OEM YZ 250 Pistons scatter from time to time...

seth505 wrote:

Ya, I always used Wiseco in my last YZ. My buddy who is pro level will shatter pistons in his YZ if he goes more than 10 hours.

Careful with that 10 hour piston comment.....

|

2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

12/11/2017 1:10 PM

sdhuskyrider wrote:

Going with a Wiseco pro lite piston and a flywheel weight is a bit counter productive. OEM in most cases is the best in terms of reliability and performance when it comes to pistons and cranks.

BobPA wrote:

I would take a forged piston over cast any day. Providing they are properly sized of course. OEM YZ 250 Pistons scatter from time to time...

I won’t use a cast piston in a 2 stroke again

|

2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

12/11/2017 1:18 PM

The only time I ever shattered a cast piston is when the clearance was too loose. Never had an issue other than that. Ran them in watercraft at world finals a few times. Never an issue. From an engineering standpoint, swapping pistons with a different center of mass, weight distribution and thermal expansion coefficient is iffy.

|

12/11/2017 2:20 PM

BobPA wrote:

I would take a forged piston over cast any day. Providing they are properly sized of course. OEM YZ 250 Pistons scatter from time to time...

seth505 wrote:

Ya, I always used Wiseco in my last YZ. My buddy who is pro level will shatter pistons in his YZ if he goes more than 10 hours.

Acidreamer wrote:

Careful with that 10 hour piston comment.....

Haha, this is specific to yz250. Pros require their own special maintenance schedule anyway. Interesting enough, he sold that 250 and says his yz125 holds up better than that thing did.

|

12/11/2017 3:26 PM

seth505 wrote:

Ya, I always used Wiseco in my last YZ. My buddy who is pro level will shatter pistons in his YZ if he goes more than 10 hours.

Acidreamer wrote:

Careful with that 10 hour piston comment.....

seth505 wrote:

Haha, this is specific to yz250. Pros require their own special maintenance schedule anyway. Interesting enough, he sold that 250 and says his yz125 holds up better than that thing did.

My mechanic says the same thing, the YZ250's tend to break pistons and YZ125's are bulletproof. He told me I could go 30 hours safely on a cast piston but I'm far from pro speed.

|

12/11/2017 7:09 PM

sdhuskyrider wrote:

Going with a Wiseco pro lite piston and a flywheel weight is a bit counter productive. OEM in most cases is the best in terms of reliability and performance when it comes to pistons and cranks.

BobPA wrote:

I would take a forged piston over cast any day. Providing they are properly sized of course. OEM YZ 250 Pistons scatter from time to time...

Yep. YZ250 cast pistons are notorious for shattering on the intake side. Thanks to my stock piston grenading I was able to justify a full on Tom Morgan 295, new crank and bearings. Never again will I run a stock cast piston longer than starting it new at the dealer.

|