Forum

[JTL]

Hi all,

About to replace my piston, but got stranded on the barrel removal. The two studs in the crankcase just below the barrel wount let go. Stud and nut are either corroded or very tight. The nuts are too soft for the 12 mm spanner. Any advice is modt welcome before I start to cruch the nuts or cut them of.

all the best
Jacob

[Gwilly]

[Gwilly]

Sorry not sure what happened there... get the best fitting spanner you can lay hands on.

good quality ring if it will fit over and clear barrel...

use heat from a butane blow lamp to heat nut. Careful not too much if its an alloy barrel instead of iron, you dont want to damaged/melt a fin... Remove flame and apply some penetrating release oil and allow to soak into the threads, be prepared for it to catch fire///?? ok all quite normal.. Now reheat and give it go with the spanner.. gradually increase pressure and feel for the give.. dont use openenders as they will spring open and slip for sure... Not sure if you can get a nut splitter in there, may not be enough room at the back... cheers gwilly

[JTL]

Gwilly, I'm afraid there is no room for a nut crusher in any of the four locations. I'd love to use the spanner, but my 12 mm spanner is too short for applying addequate pressure. And the nuts are made of very soft iron. By the way it is an iron barrel 2003 500 cc.
I don't have to save the studs and nuts. So if they are ruined from me working on them, it's ok. I just make some new ones in stainles.
My idea is to just cut the nuts with a Dremmel, and then extract the studs. But cutting the nuts is queit some work, and I might risk to do dammage to the crankcase. This is why I'm slightly reluctant to the cutting job. Anyway they have to go before I can pull the barrel.

Jacob

[Beezabryan]

If you no socket and only have a short ring spanner then why not follow Gwilly's suggestions and use some brute force & pig ignorance .... hit the spanner with an appropriate weight of thumping tool .... whack it clook & anti-clock to help break the rustiness ... have patience it may eventually give in to brutality .... if all else fails chop the nut with a small sharp chisel .... much better than Dremel and easier

[Alan R]

Hi JTL-------- Using a thin,sharp, flat chisel try cutting into the nut at it's thinnest point ie on the flat, with the blade parallel to the stud..Eventually you will break through into the stud--- albeit partially---- and the nut should now release its grip..........Just as an aside, can you tell us why you feel the piston needs replacing ?? I'm just being nosey, that's all ---------

[JTL]

Hi all

Brute force was what made me start this thread. My ring/fork spanner distorted one of the nuts when knocking on the spanner with a hammer. So instead of continuing knocking or cutting, I started asking all you very experienced guys for some advice. And it helped.

The thing with heat is for the very patienced people or when everything else does not work. I'm not really that patienced, so I had this thing with the Dremmel going on in my head. Not good. The thing with the thin sharp chissel is much better; like the nut chrusher. But best of all is the socket. After resting my head and using a fresh pair of eyes I just applied a heavy and steady pull with a socket and both nuts came loose. Problem almost solved. Now it is just a question of pulling the barrel, and it is stock. Or at least very hard to pull. Tomorrow I will give it a try again. Do you guys know of a place to gently knock with a wooden mallet to make the barrel come loose?

By the way, Alan R, I want to replace the piston because of worn out piston rings (heavy oil blow by). The bike has done nearly 18000 km with the stock piston. This is the first time the top end comes apart. I want to run the bike with a better piston and slightly higher compression, so now is the time to replace my piston.

all the best
Jacob (biking in Denmark)

[JTL]

Alan R, it is ok to be nosey and ask question, because only when answering these questions you get a chance to learn something new since most people continue to ask questions.
Jacob

[Alan R]

Hi guys----------- JTL, thanks for your honesty there.... Hitchcocks now do forged pistons both in Standard Compression Ratio OR at a slightly higher 8.5 : 1 .... I have one of these 8.5 pistons in my 500 and, with a suitably upgraded Mikcarb VM28 and 19t sprocket, it is a much livelier bike but still has the ability for slow running around town...........When removing the barell don't forget the two clamping bolts in the crankcase, just where the barrel enters it...

[Norm]

JLT, just make sure you have removed the small nut just above the tappet door, then if the barrel won't lift up gently with a piece of wood in the exhaust and inlet ports tap it up and it should come clear. There are several other options you can use and others will probably chime in if you don't have any jow with this method