How do I remove gudgeon pin? It won't move.

[nudedaytona]

No the missing part is at the bottom (crankcase side) of the piston. Basically there's two parts where the piston extends over the conrod towards the crank, and the piston is missing a portion of one of these. I can take a photo. I'll take photos of crankcase, piston and cylinder and post on here.

[FROSTY:Me]

Geeze All I do is squeeze em out nice n easy like with a modified g clamp.
G clamp goes round piston and just turn the handle -no bashing thumping or distorting going down

[FROSTY:Me]

After removing piston, I spent about 10 min eyeballing conrod and turning crank. It looked straight to me, but I gave it a few whacks back the other way just to be sure. It still looked straight, and it lines up with an etching at the bottom of the crankcase, so hopefully that's a case of no harm no foul there.

SHUDDERING --Im sorry dude but the idea of giving a conroad a "few whacks" with a hammer gives me the heebee jeebees.

[nudedaytona]

I tried with the g clamp. I had one g clamp that was too small and one that was too big. If I had known that a clamp pulley system would work I would have done that first, but I wasn't born in a workshop.

Tapping it out seemed the best way to go, and they don't tell you how to do it in the manual.

The conrod looks like a sturdy wrench, the kind you'd use to bash someone over the head with or to undo a really big nut, so it's hard to see how I could have bent it. I guess we'll see once I get new piston

[Subike]

After removing piston, I spent about 10 min eyeballing conrod and turning crank. It looked straight to me, but I gave it a few whacks back the other way just to be sure. It still looked straight, and it lines up with an etching at the bottom of the crankcase, so hopefully that's a case of no harm no foul there.

OMG!!
you really dont know do you?
I think more than one rider in here has seen the wong end of a fractured conrod hanging out the sump of bike.......not a pretty sight,
I wish you luck when its running again, that it hangs in there

[nudedaytona]

Yeah I didn't know no need to piss your pants. I'm not a mechanic by any means, but I think that one of the good things about doing you own work is that you don't need to explain yourself to everyone who has an opinion.

it's hard to see how a few whacks with a rubber mallet (not a heavy post hammer ) could have hurt it, and it looked straight to me.

[Subike]

Yeah I didn't know no need to piss your pants. I'm not a mechanic by any means, but I think that one of the good things about doing you own work is that you don't need to explain yourself to everyone who has an opinion.

it's hard to see how a few whacks with a rubber mallet (not a heavy post hammer ) could have hurt it, and it looked straight to me.

Fair enough bud... sorry to assume the worst senario on you.
I hope you learn heaps with this experiance, good experiance is hard earnt.
Art least your asking the right people for advice, even if we do rib you a bit.
Hope the reassembly goes without any more big hassels.
Make sure you clean everything twice, including your hands whilst assembling.

[zxcvbnm]

Muriatic acid is the stuff to get the aluminum of the nikasil, just remember the rest of the barrel is aluminum to.

[speedpro]

Caustic soda to clean the alloy from the piston off the bore. Been there, done that, it's other use is as a drain cleaner. I use "Wipe out" crystals mixed with water to make a real strong brew and then dab it on using a cotton bud or similar. It'll make the alloy fizz but doesn't affect iron liners or nicasil/chrome. It can take a while - be patient.

[speedpro]

Back in the old days we used to clean out 2-stroke pipes, H1s and H2s etc, with it as well. Jam a spud in one end, mix up a brew and pour it in. Leave as long as you dare then rinse out real well. It softens the carbon and what doesn't just wash out will blow out the first time you give it the gas.

[FROSTY:Me]

Back in the old days we used to clean out 2-stroke pipes, H1s and H2s etc, with it as well. Jam a spud in one end, mix up a brew and pour it in. Leave as long as you dare then rinse out real well. It softens the carbon and what doesn't just wash out will blow out the first time you give it the gas.

A good trick for two stroke race bikes -everyone behind you has a coating of black glugg all over their visors

[speedpro]

Except that the mixture dissolves all the oily deposits leaving just a dry dust once it's poured out and drys

[speedpro]

By the way - standard conrods are tough as hell, they will not just fracture. Check out my avatar. That is a standard rod with a 90deg twist and a 90deg bend. The piston was shrapnell, the little end cage was in the pipe, and the gudgeon pin was just sitting in the cases. The rod is bent and twisted but there is no sign that it is going to part.

[nudedaytona]

Sorry forgot about photos. Will do that after work and post tomorrow.

[quallman1234]

Before buying a standard sized pistion, you might wanna get the cylinder measured up to decide if you have to go to an Oversized pistion etc.

The max tolernce between the cylinder and the pistion for my RG150 is 0.120 (MASSIVE!) you probabaly don't really wanna have anything greater than 0.6-0.8 over as your get some pistion rattle/ scoring on the barrel.

A simple vernier will kinda do the trick but what you want is a barrel measurey thingy!

Not sure how much new pistions are for RS250's but a RG150 one including guegon pin and circlips is 210$ per pistion so that give's you an idea. Don't buy geniune as it will probabaly be stuipdly priced!

Good luck, also note there's a technique of putting the pistion back in (etc lining up the clips) so ask on here first before you get too far ahead of yourself and snap a ring!