GS400 bored to GS448

[droyce]

Okay gentlemen I need some advice here.

Top ID of the sleeve is: 64.95mm
Bottom ID of the sleeve is: 64.67mm
Bottom OD of the sleeve is: 72.50mm

If I bore out the sleeves to fit the 69mm pistons, this leaves me with 1.765mm of sleeve at the bottom.

Is there any chance this is enough material to hold up? If not I have a pair of GS850 pistons w/ rings for sale haha.

[7981GS]

Typically 2.0 mm is considered safe. I would go for it myself.
If it worries you, run synthetic oil and an oil cooler after it is broken in.

Daniel

[Mekanix]

It might be more than you think. The bottom is tapered but the middle of the sleeve is a little thicker. you would have to take the sleeve out to see what i mean but I'm sure i have a picture around here to show you.

I would go for it.



See how the bottom of the sleeves are shaded? They are tapered a bit. Mine are a full 0.55mm smaller in the bottom than just above the taper. And then its consistent all the way up to the top.


So for you that means just above where you measured you have a little more meat.

OD would be 72.5mm + 0.55mm = 73mm

(73mm-69mm) ÷ 2 = 2mm sidewall where it counts, and .25mm less on the bottom.

[droyce]

Second shop said its pushing it, but should be okay. One week turn around. Now things are gonna get interesting

[pete]

I don't know why I haven't seen this before, but I need to see how this goes...

[droyce]

I don't know why I haven't seen this before, but I need to see how this goes...

Stay tuned Pete, It's slow going but I'll keep this thread updated.

[pete]

Stay tuned Pete, It's slow going but I'll keep this thread updated.

Good stuff, I'm always keen to see what people can do with these twins.

[droyce]

Pick up the block today, I'll post some better pictures later.

[droyce]

Cometic head Gasket

[7981GS]

For the final pic, instead of measuring the tapered lip, go deeper with the caliper to the thickness of the sleeve at the bore.

Eric

[droyce]

1.77mm, I was more worried with that thin tapered area breaking off under heat and stress.

[droyce]

I got the rings gapped and noticed this upon inspection. Any chance this tick mark could cause significant damage

[droyce]

Slugs in!

[Mekanix]

I got the rings gapped and noticed this upon inspection. Any chance this tick mark could cause significant damage

Not sure, can't really see it that clearly.

Slugs in!

I like it. your making more progress than me :P

[droyce]