2-stroke rebuild thread

   #1  

JC

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Squirrel Karma.

Beautiful weather forecast for the weekend so I took the S3 up to TWOS in Suches , GA for some camping and riding! My group of 4 fast riders had nailed down a 9:30 am ride on Saturday. 2 Ducati's, a Polaris Slingshot and my S3.

We decided to head up to Tellico Plains, TN for lunch, via the very twisty path! Massively fun on the S3! I was bouncing the lil 400 off red line in every gear. We are all intercom linked and everyone was commenting on how my engine over the intercom sounded like a 500cc GP race from the 80's. Lol! Well, about halfway up to Tellico, on a tight road called Cutcane, I was running 2nd behind a Ducati leaving behind the other Ducati and Slingshot. A squirrel jumps in the road from the right and stops for my buddy in front. I was thinking "don't do it Mr Squirrel', but he did it! Bump Bump and I called out over the Com "squirrel down!" Guys behind confirmed.

About a mile from lunch, I went into a false neutral shifting from 2nd to 3rd. I clunked it up into 3rd and the bike felt like it was jumping in and out of 3rd into a neutral. Deceleration was fine but under power it kept jumping in and out of 3rd. 1st 2nd 4th and 5th will pull to redline just fine but 3rd is unusable!

So Mr Squirrel got his revenge from the Beyond! I rode back to camp skipping past 3rd and resigned myself to the new Winter project of going through the transmission to repair so the ol S3 can be ridden next spring.


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   #2  
OP
OP
JC

JC

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Spare engine is split so I can familiarize myself with the gearbox before I dig into the good engine!


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   #3  

Austin_F

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looks like i need new glasses, picture is blurry to me.
 
   #4  

hagrid

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Holy McFuck!

Is that rust on the crank?
 
   #5  

hagrid

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About a mile from lunch, I went into a false neutral shifting from 2nd to 3rd. I clunked it up into 3rd and the bike felt like it was jumping in and out of 3rd into a neutral. Deceleration was fine but under power it kept jumping in and out of 3rd. 1st 2nd 4th and 5th will pull to redline just fine but 3rd is unusable!
You have a bent shift fork, most likely since it just crept up on you.

Second bet is a mangled passage in the shift drum.
 
   #6  

Master-Cylinder

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Or it's just the gear dogs are worn out on it. Gonna spend the money to have them undercut while you're in there?
Use Permatex Ultra Grey for case sealant.

Lest we not forget to look at the little pins on the shift drum. And everything else.
 
   #7  

CZLoco

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What's an S3? I'm guessing it's not a Samsung.
Thanks for the ride report.
Glad the only casualty was a squirrel.
I can't imagine running over a squirrel without crashing.
 
   #8  

Master-Cylinder

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What's an S3? I'm guessing it's not a Samsung.
Thanks for the ride report.
Glad the only casualty was a squirrel.
I can't imagine running over a squirrel without crashing.
You must be the mayor of SquaresVille daddy-o.
 
   #10  
OP
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JC

JC

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Transmission is immaculate. Forks not bent. Dogs are clean.....then I removed the output shaft and then locator pin at the end of the shaft is flush with case. The entire shaft has moved sideways throwing off the engagement of third gear.


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   #11  
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JC

JC

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Holy McFuck!

Is that rust on the crank?
On the dead, spare engine. I kept the spare for the sealed tranny that you see. Good thing I did, too!

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   #12  
OP
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JC

JC

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What's an S3? I'm guessing it's not a Samsung.
Thanks for the ride report.
Glad the only casualty was a squirrel.
I can't imagine running over a squirrel without crashing.
S3 is what Kawi called the first 2 years of the 400 triple.

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   #14  
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JC

JC

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I have fixed a few of those pins that are pushed in flush. How long ago were the cases apart?
My guess would be late 80s. The triples guys are saying I have to back drill the case and push them back out.

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   #15  

NTRYDR

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What's an S3? I'm guessing it's not a Samsung.
Thanks for the ride report.
Glad the only casualty was a squirrel.
I can't imagine running over a squirrel without crashing.
Kwacker two stroke triple..Formerly known as a toddler..till they made a 250 that looked almost the same..I had a Blue Meanie..
 

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   #17  
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JC

JC

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1 pin out! 1 to go!


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   #18  

Master-Cylinder

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1 pin out! 1 to go!


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Is that a glop of JB Weld? I'd probably cross pin it so it can never slide in again. Honda did that on the RS250 piston ring locating pin to keep the piston ring from jacking it out of the top of the piston.
 
   #19  
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JC

JC

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That's sealant left from splitting the cases. That will all be cleaned up before bolting together. The drilled holes will be back-filled with jbweld. Here's all 3 pins that are now back out.


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   #21  

tinhead

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Nice job! Some shop somewhere is crying over what they didn't get to charge you for that job. :cool:
 
   #22  
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JC

JC

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Is that a glop of JB Weld? I'd probably cross pin it so it can never slide in again. Honda did that on the RS250 piston ring locating pin to keep the piston ring from jacking it out of the top of the piston.
My guess is that whoever split the case before did not line up the pins with the shaft locating holes so the pushed in when tightening the cases.

I'm not too worried about the pins dropping because I had to get a small sledgehammer to pound them back out. But I'll back fill with jbweld anyway.

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   #23  

BilletMan

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My guess is that whoever split the case before did not line up the pins with the shaft locating holes so the pushed in when tightening the cases.

I'm not too worried about the pins dropping because I had to get a small sledgehammer to pound them back out. But I'll back fill with jbweld anyway.

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That's totally plausible. That is exactly what happened....You're an engine detective! An engine Columbo!
 
   #24  
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That's actually a fun job once you know what to do and are confident in your abilities. A lotta folks might be intimidated by that. What size hole did you make to drive the pins back out?
 
   #25  
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When I was 15 years old, I talked my dad into taking me to look at this bike's identical twin, which was for sale slightly used, locally. At the last minute, we recruited my older sister's boyfriend to come along with us, since he had an M/C endorsement... so he could ride it home for me (legally) if I bought it.

I rode the bike, and loved it, tried to beat the guy up on the price a little bit, but he wouldn't budge. We may have been $50 apart. I walked away, figured he might change his mind if he saw us heading toward the car. Worst case, I sleep on it, come back the next day and give him his asking price.

Long story longer, the next fucking day, my sister's boyfriend shows up at my house on that bike! Cocksucker said, well you turned it down, so I decided to buy it! I'm still a little pissed, and that was, like 4 decades ago! :screama::fu:
 
   #26  

Master-Cylinder

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Seeing your 400 makes me want to get the RD out and take it for a spin.
You gonna leak/vacuum test the engine once it's back together?
By the way, your trans repair job is kicking what's his name's Ford engine swap.:up:
 
   #27  
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JC

JC

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That's actually a fun job once you know what to do and are confident in your abilities. A lotta folks might be intimidated by that. What size hole did you make to drive the pins back out?
I used a 3/16 drill bit. I probably could 've used a 1/8.

Once I seal up the cases I'll pull the cylinders and probably hone them and install new rings. The engine's a runner. I'm not worried about the crank.

On the ford swap thread I think I suggested a used engine swap like I just did on my Isuzu Rodeo engine.


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   #30  
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JC

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Ready to bolt the cases back together!


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   #31  

BilletMan

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NEW SEALS!! PLEASE!!
 
   #33  
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JC

JC

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NEW SEALS!! PLEASE!!
'Afraid not. This engine runs good. Now that the spare cranked is out, I'll have that reconditioned and ready when needed. Next up is replacing the right cylinder with one that has good exhaust studs- I've been running with the right pipe held on with baling wire! Lol! I finally found a cylinder with good shape standard bore.

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   #34  

BilletMan

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Goddamnit, I was hoping MC would hurry up with feeding the ducks and turtles and back me up on this! Shit man, the seals are a few dollars, I woulda sent you some....you're old school, you KNOW the importance of good crank seals in 2-strokes! Shaking my head.....
 
   #36  

BilletMan

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He'll put in new seals after the top end melts down! :lol:
EXACTLY!! There's a guy who knows... Kinda crazy how you can take an old engine THAT far down and not toss a few seals in it, eh?!
 
   #37  
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JC

JC

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Goddamnit, I was hoping MC would hurry up with feeding the ducks and turtles and back me up on this! Shit man, the seals are a few dollars, I woulda sent you some....you're old school, you KNOW the importance of good crank seals in 2-strokes! Shaking my head.....
Rebuilding the crank is not a few dollars. And when the engine's running fine I'm good with the seals when all I have in the bike is $50 and oil & gas & Tires. I'm gonna get it back running and flog the hell out of it!

New seals will go in the spare crank.

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   #39  

BilletMan

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Just change the seals on the outboard ends of the crank...you know, the ones that leak air and seize your engine. I'll bet there aren't rubber lip seals between the cylinders. It probably has labyrinth seals....A few bucks...
 
   #40  
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JC

JC

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2 end seals, a seal between each cylinder. All 4 are still pliable. I feel fine about using them. And I'm on a tight budget. Deal with it.

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   #41  

BilletMan

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The ones on the ends are the only ones that matter.....leakage between cylinders won't make it run lean....whatever dude, carry on! I'm out...
 
   #42  

Master-Cylinder

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I'm with Billet, new fucking seals on the ends. One end could suck air and seizes up, the other could suck oil and then seizes the trans, then the cylinder.

Honda sent out a bunch of bad primary side seals for the RS250 once. During a practice session it sucked the oil out of my trans and it started squealing! Corner workers were just getting ready to black flag me because they thought I was on fire or aboot to blow up, there was that much smoke!
 
   #43  

Master-Cylinder

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The ones on the ends are the only ones that matter.....leakage between cylinders won't make it run lean....whatever dude, carry on! I'm out...
My RD uses a labyrinth seal. The RS250 had a single lip seal in the center. If you pressure test one cylinder, it blows into that cylinder. If you pressure test the other cylinder it doesn't leak into the previous one. So, it uses crankcase pulses to kept the cylinder/crankcases sealed from one another.

I was looking at a RGRacing RS250 crank on the net yesterday, pure billet porn! But then it had better be for $2,000.00! Comes in a fitted aluminum case!:eek:
 
   #47  

BilletMan

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This topic is FAKE NEWS!! "Rebuilding" generally encompasses disassembly, cleaning, careful measurement and inspection, and renewal of worn components. That's obviously NOT what's happening here. I'll bet he'll try to reuse the old gasket sealer!

So for engine "rebuilding" topics, rumble phish's topic wins!!
 
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   #48  
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JC

JC

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Quit yer whining!

There is only 3000 miles since the seals were put in. Wiggle on the rods and crank are nice and tight. Seals are in good shape and the engine runs strong. The tranny was the reason for this work.

Now while I have the engine out of the frame I'm replacing the right cylinder that has a broken header bolt.


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   #50  
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JC

JC

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And these are my December birthday present.


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