I recently picked up a 73 1.7 (was originally told it was a 1.8.... didn't think to check the engine stamp to verify. but I got it for a song).

I also and looking at picking up a big bore kit (94mm by Kolbenschmidt) for trade. The original plan was they should bolt onto the 1.8 and be a pretty easy setup.

With the 1.7, I understand I will need to have some head work done to accept the larger cylinders and pistons.

Here is my dilemma: one of the pistons has a chipped skirt. The cause of the broken piece is unknown.

Click to view attachment

Click to view attachment


I realize it MIGHT work to just use it as is, but as the person who is offering these in trade so rightly stated: " Emotional side of me says I don't like putting an engine together with something I know is not quite perfect"

So I figure my options are to
a) get all the piston skirts machined off to match
b) inquire on the classified section if anyone has a single 94 mm Kolbenschmidt they would be willing to sell (hopefully cheap since its only one!)

Anyone have input on the first option to machine off all the skirts to match?
Thanks as always!

Toss it and get another.

A perfect situation where JB Weld might come in useful.

JB won't hold up in an environment like this. You need to user Crazy Glue or maybe Gorilla Glue if you have lot's of water in the oil (it's activated by water).

it's a paper weight!

the weight of the piston is now different to the others and will throw of the balance of the rotating assembly. that is the really big problem !

the other issues would be the stability of the piston would be off also and it would rock in the cylinder enough to gall the walls.

if this guy thinks it would run ok with it.... I question the rest of the parts.

I am pretty sure I have a set with one bad piston.
The wrist pin would not go in on just one.

Let me check.

Big bore is usually a 96mm piston (or larger), not a 94. Sure about the piston size? Or are you just getting stock 2.0 pistons and the seller is calling them "big bore."

Zach

Ya think?

Why not just bench grind it flat and then do the other side?

I thought this was an April fool's joke.. Seriously?

I'm gonna go out on limb here & be politically incorrect & say screw the paperweight, make it an ashtray.

or a cupholder!

You and I are on the same page ......................

Reply to my own reply.

It's called "blueprinting an engine".

I read it in another thread....

Maybe if I was stranded on a deserted island, I'd consider the glue

Butt plug...

Actually, it is blue printing...you will need to reduce the other three and keep it under 1500 rpm...oh just short shift.

Seems as though most people didn't read the full post. My bottom line question was can I machine off all the slipper skirts so all the pistons match. If that wasn't clear, then that's on me and my bad. I have seen several new big bore kits that have pistons that do not have those slipper skirts so it seemed like a valid question.

Consensus seems to be, "bad idea"

Additionally, I am doing all of this on a budget. Would love to have the cash to send an engine out to one of the guru's on here and have them do it for me, but for now, that's just not in the budget. And in case you didn't notice the "Newbie" designation, I still have a lot to learn. And I enjoy learning so its great to ask about these things to try to figure out what I can, or am willing, to do myself.

I am all for being sarcastic, and can take and dish with anyone.... just wish some of you might have added something valuable to say along with it. Even if its "no clue"

Next time I will be less likely to ask, which sucks.

Bad idea.

How many times do you want to rebuild it?

Just install it like it is. It will make a cool slapping sound. People may even think it's a rod knock. But you'll know better, laughing all the way with your self machining pistons and bent crank...

To your questions:
$200 will get you a new set of 94mm AA pistons, cylinders and rings.
$230 for a new single piston and cylinder from Mahle (German). I think KS that you have are NLA.
Either choice is better and cheaper than what you try to do.

http://www.europeanmotorworks.com/vw/type-...-cylinders.html

You could put a WTB ad here in the classifieds, I'd bet someone might have one
KS piston or a full set of Mahle 94mm pistons. I see used sets all the time on Samba or ebay but typically people try to sell them for too much. You can certainly get
a new set for a good price.....AA has 94mm sets for budget builds and the afore-mentioned European Motorworks has 96mm pistons and cylinders for not much more.
I would never put a broken part back in an engine, too much risk.....and since you are budget minded, why spend more on another rebuild when that broken part fails.

I checked my stash and I have:
94mm piston & cyl set - all good
93mm piston & cyl set - one piston with very tight wrist pin
90mm pistons only - all good

So I dont have just one oddball 94mm

I got a couple of Harley pistons as ashtrays ......
1 900 Sportster , 1 61cui Panhead

Jack

p.s. yeah make an ashtray out of it , or paperweight....YMMV

Heck man, I've got a used one I'll send you for the price of postage, or a set of 4 for 50 bucks.

I agree. And I'm sorry if you got a browbeating over what was/is a valid question. Don't let the naysayers rule your curiosity friend.
Actually, back in the day when we were making go fast Triumph dragster bikes, it was fairly common to chop the skirts thus reducing piston mass to gain some piston speed. If you chopped off all the skirts so that each piston weighed the same this would work. Durability and or longevity? Well that's quite hard to say.
And remember this....there are no dumb questions, just dumb answers.

So you say the piston diameter is 94mm? It started life as a 1.7?

Check this out:

engine calculator

plug in 94 and 66 for the stroke and hit the displacement button.... 1832cc? you know 1.7 was a 1679 cc with 90mm pistons and the 66 mm crank.

2.0 liter has the 71mm crank... plug that in with the 96mm pistons....

You can go to 1911 with the 66mm crank like you said with a little head work. But they are off anyway, so touch them up.

& if you machine 1, you have to machine them all (balance). How this will hold up I have no clue. I'd take Curt "the cabinetmaker" up on his offer & pay for postage. Seems to be the easiest/cheapest solution by far.

Hey man,

Dont take people too seriously around here. If there are two ways to take a comment, and one is joking and the other is mean, 99.99% of the time we all mean the former not the latter.

Your question will become humerus to you once you stick around and learn a few things. Dont be put off.