piston fun :(

[rapidray]

You can't use the 750 pistons in the 1000 because the compression height is WAY different. Ray.

[Shaughn]

Hey FT,

I don't know spit about piston swaps, but I noticed what
looks like a fair amount of scoring in the bore of your #1 rod.
Is that shallow enough you to take out with a hone? The wrist
pin is scored too, but noone seems to mention that. Is that kind
of wear typ. when you get these apart? Or is that a sign of a lubrication
issue?

[knotzilla]

I bet money it was broken before installed into the bore.

By the way the piston pin circlip opening HAS to be at 12 o clock or 6 o clock.otherwise they will pop out. that does make a mess of the cylinder.

just a tip for those who do not know.

I installed my circlips with the opening 180 degrees from the opening in the piston. Isn't that what the factory manual states?, Ted

[first timer]

Hey FT,

I don't know spit about piston swaps, but I noticed what
looks like a fair amount of scoring in the bore of your #1 rod.
Is that shallow enough you to take out with a hone? The wrist
pin is scored too, but noone seems to mention that. Is that kind
of wear typ. when you get these apart? Or is that a sign of a lubrication
issue?

I am not sure, Ray, Trip, Bueller? Anyone care to comment, I don't have enough experience to comment.

[reddirtrider]

Circlips

I'e never heard of, or ever paid attention to circlip positions. The only thing that's really important is to make sure they are seated in the groove properly.

I can't imagine the small mass difference of the opening having any effect.

[trippivot]

no failures eh? ever? yeah like we all believe that. the tip I gave away freely is true. bad information is the easiest to get.
if the circlip is at 12 and 6 it works like a self lock inside the groove-both ends pushing outward together. anywhere else and the flex of going up and down will pop it right out of the groove one side against another-like a spring. try squeezing one like a c and then squeeze one right on the opening. my point will stick right into your finger. it is a true engine building detail.

20 years and never worried about where the circlip opening is? next you probably like to put the top ring opening gap at 12 and 6 o'clock too??

which is also a no no it is called the thrust surface...

this has been trippivot's believe it or not-

why? a circlip in a groove, installed correctly will not pop out just because its not facing the right way. where did this information come from? i have been building bike engines for over 20 years now and have never worried about where the circlip sits and have had no failures yet!

[Agemax]

no failures eh? ever? yeah like we all believe that. the tip I gave away freely is true. bad information is the easiest to get.
if the circlip is at 12 and 6 it works like a self lock inside the groove-both ends pushing outward together. anywhere else and the flex of going up and down will pop it right out of the groove one side against another-like a spring. try squeezing one like a c and then squeeze one right on the opening. my point will stick right into your finger. it is a true engine building detail.

20 years and never worried about where the circlip opening is? next you probably like to put the top ring opening gap at 12 and 6 o'clock too??

which is also a no no it is called the thrust surface...
this has been trippivot's believe it or not-

believe it or not mate, upto you, you are talking crap. a circlip in a machined groove, fitted properly will not pop out, it is not under any stress or thrust unlike a piston ring, which i agree should be fitted in the correct position.

[first timer]

Can we get back on track here. Go start a circle clip thread . What has been done has been done, I need to figure out the extent of damage and the remedies. The current topics are:

1. How bad is the scoring of the small end surfaces and is it a problem and how to fix it.

2. Will the pistons labeled pistons 2 in the photo link work as a replacement for the current pistons (ie. pistons1 image)? Pistons2 came out of a 1000 kat but the tops look differant.

For what it's worth I'll install my clips at 12 o'clock to be safe and install my rings like the book sez.

[reddirtrider]

no failures eh? ever? yeah like we all believe that. the tip I gave away freely is true. bad information is the easiest to get.
if the circlip is at 12 and 6 it works like a self lock inside the groove-both ends pushing outward together. anywhere else and the flex of going up and down will pop it right out of the groove one side against another-like a spring. try squeezing one like a c and then squeeze one right on the opening. my point will stick right into your finger. it is a true engine building detail.

20 years and never worried about where the circlip opening is? next you probably like to put the top ring opening gap at 12 and 6 o'clock too??

which is also a no no it is called the thrust surface...

this has been trippivot's believe it or not-

I choose not.

If your circlips are so worn out as to be influenced by the acceleration of the piston, then you've got problems of a different sort. It's called bad components.

I don't suppose you have a link that you can post that backs up your claims? I'd accept some from top notch engine builders.

[first timer]

1. How bad is the scoring of the small end surfaces and is it a problem and how to fix it?

2. Will the pistons labeled pistons 2 in the photo link work as a replacement for the current pistons (ie. pistons1 image)? Pistons2 came out of a 1000 kat but the tops look differant.

[reddirtrider]

Can we get back on track here. Go start a circle clip thread . What has been done has been done, I need to figure out the extent of damage and the remedies. The current topics are:

1. How bad is the scoring of the small end surfaces and is it a problem and how to fix it.

2. Will the pistons labeled pistons 2 in the photo link work as a replacement for the current pistons (ie. pistons1 image)? Pistons2 came out of a 1000 kat but the tops look differant.

For what it's worth I'll install my clips at 12 o'clock to be safe and install my rings like the book sez.

I've been loosely following this, so here's my opinion.

1) It looks as if the bad piston was installed that way. I don't see how a chunk can break off and not harm the cylinder, nor be found somewhere in your engine.

2) It also appears that all of the pistons are not the same. This is bad. The issue isn't just realted to diameters, skirt lengths, and wrist pin locations, but the mass of the pistons must be matched.

3) The rod small ends can be easilly reconditioned if they don't look good. You'll need to pull the crank, which is probably a good idea anyway. You've gone this far anyway, do it right and split the cases.

Once the motor is completely dissassembled you can install new oil seals, which you probably need anyway.

4) Get a new, matched set of pistons. Pitch the others or use as ashtrays.

Install the circlips whatever way makes you feel comfortable. lol