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Author Topic: Tight Gudgeon (wrist) pin on Bullet 500  (Read 870 times)


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  • 2003 Bullet 500 4 speed
Tight Gudgeon (wrist) pin on Bullet 500
« on: January 15, 2013, 10:22:24 am »
Hi all,

I am in the process of a rebuild on a 2003 bullet 500, I have had a previous post on here regarding the subject which started with a soft seize and piston slap in the original motor.  I then had massive issues getting off the head which had been 'glued on' somehow, this resulted in a broken crankcase, (long story short), I now have the bike back up to requiring just the top end putting back together.

I have had the barrel bored out to 0.20 oversize and picked up an oversize piston to suit from Price parts in the UK, the make of piston kit is JP from Australia.  (Tho original bore had marks from the soft seize).

The concern I have now is that the new piston kit had a tight wrist pin on fitting, once in the rod it is tight to the point where I have to move the piston itself manually on the rod, it will not rotate under its own weight on the small end.
The small end in the rod looked good with no burrs or marks.

Is it normal to have a tight fit from new like this...I did have the barrel on and when spinning the motor with my hand it all moved smoothly.

Any input welcome please?


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Re: Tight Gudgeon (wrist) pin on Bullet 500
« Reply #1 on: January 15, 2013, 10:37:16 am »
Point a hair dryer blower on the piston to heat it up a little bit, and if it moves around at around 75 degrees F or a little higher, it will be okay.
The aluminum is very active to temperature changes. They usually free up with a little warmth.

If it is really stubborn, you can take it in to a shop and ask for the pin bosses to be lightly honed for a slip fit at room temp. Don't over-do the hone. The pin bosses are going to expand in a hot motor.


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Re: Tight Gudgeon (wrist) pin on Bullet 500
« Reply #2 on: January 15, 2013, 09:06:01 pm »

I did as you suggested and it free'd the pin up nicely, after a few minutes of heating at the pin area the piston rotated much better.

Barrel and head back on ready for installing back in the bike....watch this space.

thanks for the help.