KDXRIDER.NET

Can the crankshaft seals in a 2002 KDX 220 be replaced without splitting the crankcase?

Sadly, no.

That said, some people have ground/machined off the stops that keeps the seals from being replaced externally. I know the next time I'm rebuilding a KDX bottom end I will do it as well.

If you do decide to do that, I’d suggest building some retainers for the seals to replace the ones that are ground off. Crankcase pressure can push the seals out if there’s nothing to hold them, and that would make for an inoperable engine possibly far from home.

Slick_Nick wrote: 12:35 pm Mar 04 2023 If you do decide to do that, I’d suggest building some retainers for the seals to replace the ones that are ground off. Crankcase pressure can push the seals out if there’s nothing to hold them, and that would make for an inoperable engine possibly far from home.

You know, I've wondered about that. I know at least one member here who did exactly that, made some seal retainers. However, was/is it necessary? Plenty of bikes out there, like my '11 GasGas I'm putting all new seals in right now, that have nothing to keep the seals from pushing out. Some are on much higher strung bikes (just did crank seals recently on "The Squirrel's" '98 CR250 265cc big bore) which having nothing holding them in as well. I wonder if the KDX, with it's relatively low compression, vs something like a CR250, would actually push them out. Hmm, I might have to test that out down the road just to see how much pressure it would take to push them out or at least cause a leak.

Don't they make seal lock adhesive of some sort?

Don't KDX seals have a metal body as well? Most other bikes are butyl all the way through.

I honestly don't remember it's been so long. Like KDXGarage said I think there are some special sealer/adhesive that can be used just to make sure.

My other engine, a Honda 250 2 stroke has no retainers and no issues. I’ve read before to put blue loctite on the outer edge of the seal right before you install it. Retainers wouldn’t hurt but I don’t think they’re necessary.

Funny enough, I was dealing with this exact thing last night and was doing a few searches in the forum. As stated, you have to split the cases. grinding off the tabs I think would work though. There is not really enough room to machine in a proper retaining ring in my opinion. And not a real easy process to mill or turn in a ring due to the case shape and setup and how you'd hold the case half. Could be done though

BUT after tapping in the seals last night, I'd guess it would be perfectly fine without a retaining ring. As SlickNick said, they are a metal OD. And do not go in or out easy, they were tight! (tapping is a bit of an understatement) So I'd be very surprised if crank case pressure would blow em out.......... that being said, I'll let someone else try first :)

As a side note, I also unfortunately found out that the OD of the crank seal are the exact same OD as the output shaft seal ............... How I found this out was I wasn't taking my time putting the cases back together on the weekend, and had a extra seals kicking around on the bench, and accidently installed two output shaft seals in each case half, then dropped in the main bearings.

While doing a test fit without the crank in, I couldn't initially figure out why the little sleeve that goes on the transmission output shaft wouldn't fit properly. I HAD PUT THE CRANK SEAL IN THE OUT PUT SHAFT BORE AS WELL............ slow down, triple check, etc, my bad

I also decided to bite the bullet and order the crank installer tool. Was going to get the TUSK version but it was 2 weeks out. Got an amazon copy, will be arriving tomorrow. Will update if some wants to know how well it works. Would have built one, but throwing cash at it was just easier and quicker....... and yes I know hot/cold will work, but one can never have too many handy tools.........

I’ve got all those tools if you wanted to borrow them instead of buy. I’m in Panorama Hills NW.

Thanks Slick_Nick, greatly appreciate the offer! I'm down in the SE in Riverbend. I may take you up on it if this amazon one is a piece of crap though! It's showing up tonight and I'll give it ago. Will let you know, but again certainly appreciate the offer! That's the great thing about most of these enthusiast forums. Many guys willing to help out as they share the same interests.......

Happy to help. I’ve rebuilt a bunch of KDX engines feel free to reach out if you need any assistance.