KTM 380 - rebuild req'd? Help a 2T n00b.

[2TInstitute]

would have been 0.004mm not 0.0375mm(4 thou)

[Jeram]

would have been 0.004mm not 0.0375mm(4 thou)

Yeah I was trying to say one quarter of one thousandth of an inch. Aka .00025 inch, aka a bees dick

Your the one who got it honed for me tho, you'd know best what it was

[hybrid]

Yeah I was trying to say one quarter of one thousandth of an inch. Aka .00025 inch, aka a bees dick

Pretty sure that's just about a metric poofteenth.

[BRG1200]

Most bees are girls, so I can think of a more accurate anatomical reference, might convert to metric more precisely?

[mugget]

Thanks for the info Jeram. Good to know about the rehone possibility & properties of cast pistons Vs. forged. And yeah I will definitely be using taller gearing.

Don't get too technical on me though fellas, I'm new to all this 2T jargon. Metric poofteenths & bees dicks... *sheesh*

[mugget]

Just wondering if anyone can recommend a 2 stroke shop in Brisbane? For the honing, or other work if required (cylinder repair/replating)? Otherwise postage is not too expensive, so any recommendations on VIC, NSW shops would be good as well.

Cheers.

Edit>> Just found a shop 8 minutes away, I'll give them a try. Looking up some info about honing it seems like it's a really simple process, I think I'm worrying over nothing just because this is all new to me...

[Greasemeup]

Let us know who you used and if you were happy..

[2TInstitute]

You won't need to take the cylinder anywhere for honing. Just rub the cylinder in a diagonal pattern with red or green scotch brite scourers. Aiming for a 60deg cross hatch pattern.

Post some pics if your cylinder needs plating I have a trade account with NZ Cylinders. I never have plating done here.

[mugget]

Thanks 2TInstitute, I may be getting a bit ahead of myself, first I need to get some hydrochloric acid and see how much of the marks that will remove from the cylinder...

About the scotch brite pads - that seems to be an issue of great contention among forum users... that doesn't actually remove any cylinder material, right? That will just clean out old oil from the existing hone marks? Which is okay if the cylinder is in pretty good condition. But if there's any places where the hone marks are worn down a bit wouldn't you want the hone so that the cylinder surface is uniform, then it will hold oil to the surface better as well?

And back to the subject of pistons - I'm trying to find cast piston kits on eBay, it looks like the two options are either Moose Racing (~$240) or Vertex (~$190). Looking around online it seems like Vertex make good pistons? But just wanted to ask because I don't know anything about this & don't wanna cause myself extra dramas for the sake of $50...

Also Jeram, I was just wondering if there's any particular reason you mentioned Wossner over Wiseco? The local dealership can get Wossner pistons for ~$230. But I can see Wiseco pistons on eBay for around $160.
Actually doing some more reading online, is it true that Wiseco pistons are heavier & would cause more cylinder wear on cold starts? Also the excess weight stressing the connecting rod more?

Next question - top end gasket kits. I see some Moose Racing kits for $35-40, would you use these? Other option is to get a gasket kit from the dealership for $70-75.

Are the 380 SX engines the same aside from the gearing? Mine is actually listed as 380 EGS on the compliance plate. I think that is basically the Aussie version of the EXC with a larger capacity stator and larger fuel tank? I should be ok to use a 380 SX gasket kit for example?

[mugget]

Okay, I got to cleaning up the cylinder with hydrochloric acid, there was really only one small noticable aluminium deposit on the lower part of the cylinder, that cleaned up pretty well. Then I noticed some marking below the exhaust port, it was bubbling up real good just like I remembered ally does... But then I cleaned it up and... well tell me if I'm wrong, but I think it's pretty much rooted.

Old 380 cylinder... by mugget, on Flickr

Close-up crop:

Old 380 cylinder - crop by mugget, on Flickr

Sure looks like the nikasil has worn right away there...

What would you guys do?

I think I'll just take it to the local cylinder guy tomorrow and see what he says. Hopefully it can be repaired or patched easily? We'll see...

[hybrid]

Yeah that's no good. Needs to be re-plated or replaced.

[2TInstitute]

I would fix that in 5 min. Mugget you're NEVER going to remove any material with a scotch brite pad and why would you want that to happen any way. All your doing is restoring a bit of the lost cross hatch which is better than no cross hatch.

[mugget]

Thanks for the clarification 2TInstitute, that's what I thought.
I guess you're talking about fixing the general cylinder appearance in 5 min? Not the worn through Nikasil?
I got ahead of myself again... haven't got the cylinder replating organised yet because I've gotta take out the stubborn philips head screws, remove the power valve hardware. Gonna try a soldering iron on the screw heads and see if that loosens it up...

[2TInstitute]

No I could fix the whole cylinder in 5min

[mugget]

Please do tell of your secret methods!!

I have the cylinder completely stripped now, ready for anything that needs to be done. I have contacted Millennium Technologies and US Chrome in the States, so my only decision now is whether I send it overseas or drive up to Aurum at Naranga and give them a try.

But sounds like you have a 3rd, 5 minute option 2TInstitute?