1988 bike
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Have actually managed to find a second hand mb barrel with more life In it, just waiting for it to arrive, cylinder head cleaned and powervalve cleaned and polished. Loads of bits came from fowlers in prep for rebuild. Need overflow hose from rad to expansion bottle if anyone has one lying around (discontinued). Helmet lock ordered from Japan, genuine Yamaha ignition lock changed to 4 wire plug and earth, carb stripped and cleaned, waiting for frame to come back and frame parts I have ordered ordered to arrive from France and them can get those powdercoated and plated.
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Removed swingarm bearings so that's ready to go for refurb, and finally removed rear shock lower bolt. Removed seals and found worn ball joint that seems to be pressed in to shock lower. Any advice if repairable or should I be looking for another rear shock?
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My mistake, ball joint held I by 2 spring clips in recess of shock lower. Saw them when I enlarged pic posted. Have got the 2 clips out , heavily corroded, ball joint stuck fast. Left soaking on release spray, but still left with trying to find replacement unless find a nush that fits?
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Removed swingarm bearings so that's ready to go for refurb, and finally removed rear shock lower bolt. Removed seals and found worn ball joint that seems to be pressed in to shock lower. Any advice if repairable or should I be looking for another rear shock?
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@oldman they are not serviable as far as I am awake.
Thanks Calum, ordered one from Portugal (second hand) that looks good without rust for a reasonable price. Other 3bn barrel arrived today freshly rebored @1.25 over standard, and has been tuned. No id marks to say who did it , messaged seller to see if he knows. Mick Abbey marks his work as far as I am aware so doubt its him. Be good to know though and a bonus it's done. Will post a pic up later.
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@oldman they are not serviable as far as I am awake.
Thanks Calum, ordered one from Portugal (second hand) that looks good without rust for a reasonable price. Other 3bn barrel arrived today freshly rebored @1.25 over standard, and has been tuned. No id marks to say who did it , messaged seller to see if he knows. Mick Abbey marks his work as far as I am aware so doubt its him. Be good to know though and a bonus it's done. Will post a pic up later.
@oldman What engine are you fitting this to?
3MB barrels and 3BN barrels are not interchangable!
The 3BN has a larger bore, therefore shorter stroke. If you fit this onto an engine designed to have a 3MB cylinder, you could risk the piston hitting the cylinder head.
It is very minimal, but they are different strokes.
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@oldman What engine are you fitting this to?
3MB barrels and 3BN barrels are not interchangable!
The 3BN has a larger bore, therefore shorter stroke. If you fit this onto an engine designed to have a 3MB cylinder, you could risk the piston hitting the cylinder head.
It is very minimal, but they are different strokes.
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@Calum it's the 88 bike engine, same as the barrel that came off, 89 bikes changed to accommodate new carb amongst other things, is that right? Matching frame and engine nos so original engine
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Will not need to though if it's an 88 engine? Just need to make sure crank is correct for stroke, will check part nos to be sure.
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Checked fowlers for part no, con rod for 88 listed as separate item, later years checked a(89 and 1990) and shows discontinued with no part nos? Have ordered a genuine 88 one to be sure but any info you have useful? Original barrel was already 1.75 over hence the replacement
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It's definitely an 88 bike and engine, the barrel was consistent with engine and I did have a spare 3mb barrel but sourced like for like. Cant be sure con rod in engine is correct hence ordering correct one from fowlers. Could be whole crank differs from later bikes but don't know (yet) will check clearances as built, lucky to find a matching barrel to be honest
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It's definitely an 88 bike and engine, the barrel was consistent with engine and I did have a spare 3mb barrel but sourced like for like. Cant be sure con rod in engine is correct hence ordering correct one from fowlers. Could be whole crank differs from later bikes but don't know (yet) will check clearances as built, lucky to find a matching barrel to be honest
@oldman Yeah this.
The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.
It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.
As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!
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Have the original powervalve fortunately, the manual is. 4 or. 04 difference I think from memory, Will be checking when assembling .
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@oldman Yeah this.
The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.
It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.
As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!
@oldman Yeah this.
The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.
It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.
As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!
Hello Calum,What's the difference with the powervalve? Have measured and dry assembled and seems no different than one that came with bike, bar original has no grooves for seals and diamond style pulley shaft on end? Frame back but waiting for rack, grab rail, footrest hangers, suspension spring, etc.
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@oldman Yeah this.
The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.
It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.
As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!
Hello Calum,What's the difference with the powervalve? Have measured and dry assembled and seems no different than one that came with bike, bar original has no grooves for seals and diamond style pulley shaft on end? Frame back but waiting for rack, grab rail, footrest hangers, suspension spring, etc.
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OK, thanks Calum. Replacement shock arrived and it's worse than the one I need to replace sadly. Lower ball joint corroded and worn and corrosion on plunger shaft has damaged the seal, very little damping going on. Will keep looking for a decent one.
