Jump to content

Which replacement crank? 450EXC

Recommended Posts

Hi everyone,

I have a 2006 KTM 450EXC that has started to really show a lot of metal in the oil.  I removed the ignition cover and flywheel and the crank feels pretty locked in there (no end play that I can tell).  I assume the crank has spread and is eating the main bearings.  I was told that the best course of action is just to completely replace the crank assembly with an OEM replacement from KTM (other than going to a full billet crank).

Question is, it seems KTM no longer manufactures the 2006 crank, but 2007 still seems available.  I have heard most of the RFS cranks interchange easily.  Is there a recommendation right now to go to a newer crank?  If so, do I use the main bearings from a 2006 or from the year of crank I go to?

 

Thanks for the help everyone.

Share this post


Link to post
Share on other sites

Why not get the crank rebuilt by a pro. I know they use one of several rod kits. If the crank halves are good it would be than getting a complete crank. I think DJH uses the stock rollers for EXC's and ball bearings for the SX or Motard use bikes. For trail & dual sport use, this should have enough longevity. Think I'm 20K on the '05 crank rebuild.

Share this post


Link to post
Share on other sites

DJH rebuilt my crank a couple years ago due to crank spread that ate my main bearings.  He replaced the rod bearings and welded the crank.  This is the preferred method of repairing them.

Share this post


Link to post
Share on other sites

Hmm,

I read on here a lot of people were having spread issues again after about 4hrs on the DJH welded cranks.  I called thumper racing and was told that if it's tight in the cases it's best to just replace the assembly.

I assume that it will probably be around $400 all said and done to have the crank shipped out and repaired (including the cost of parts).  A new crank is $550 I believe.

Definitely will to hear from people who have had success with welding the crank.

Share this post


Link to post
Share on other sites

The crank ,cant spread if the pin is welded to the throw weight, unless the weld breaks.  Those crank assemblies also have to be shimmed properly for clearances in the cases, which is an added hassle.

Share this post


Link to post
Share on other sites
1 hour ago, Burnrider said:

Never read that so IDK- looks like you did the research. 

Well I can't really vouch for what I read, just kinda throwing a feeler out there because I've heard it both ways.

 

Does anyone know if a 2007 crank will even fit?

Share this post


Link to post
Share on other sites
15 hours ago, Dforez said:

Hmm,

I read on here a lot of people were having spread issues again after about 4hrs on the DJH welded cranks.  I called thumper racing and was told that if it's tight in the cases it's best to just replace the assembly.

I assume that it will probably be around $400 all said and done to have the crank shipped out and repaired (including the cost of parts).  A new crank is $550 I believe.

Definitely will to hear from people who have had success with welding the crank.

I have about 80 hrs on my DJH welded crank and my bike runs awesome.  You have to make sure you have adequate end play in the crank when it's reassembled.

I'm curious why Travis said that it's best to replace the assembly if it's tight.

Share this post


Link to post
Share on other sites

Never tried this but here's a link to a few photos and a video of my crank issue.  The video is the sound the bike made before the repair.  I rode the bike about 50 miles in BFE Nevada with that sound.  There's some shots of the inner bearing race showing the skidding of the main bearing and the welded crank.  There's also a shot during the end play adjustment.

https://photos.app.goo.gl/igHvUV0OGn42iJxa2

Share this post


Link to post
Share on other sites

Cobra,

That is really helpful! My motor is still in pretty good shape, it doesn't sound or feel off, so if your crank was repairable then I'm sure mine is fine.

Travis said that if they get more than 0.004" of spread then the crank pins get too ovalized and need to be machined.

I almost have the crank out for inspection but I'm just having a bit of trouble getting cases fully split. I'll get it.  

How long did DJH take to get your crank turned around? Do you have contact info for him?

Share this post


Link to post
Share on other sites
10 hours ago, Dforez said:

Cobra,

That is really helpful! My motor is still in pretty good shape, it doesn't sound or feel off, so if your crank was repairable then I'm sure mine is fine.

Travis said that if they get more than 0.004" of spread then the crank pins get too ovalized and need to be machined.

I almost have the crank out for inspection but I'm just having a bit of trouble getting cases fully split. I'll get it.  

How long did DJH take to get your crank turned around? Do you have contact info for him?

PM sent

Share this post


Link to post
Share on other sites

I understand that 4 stroke rods spread out and the way to measure wear is to insert a feeler between the rod and crank halves? Is this correct? Can someone tell me the acceptable tolerance? Thanks 

Share this post


Link to post
Share on other sites
11 hours ago, The Creature said:

I understand that 4 stroke rods spread out and the way to measure wear is to insert a feeler between the rod and crank halves? Is this correct? Can someone tell me the acceptable tolerance? Thanks 

The service manual has all the inspection criteria in it.  You can download it for free from Beta.  Beta used the RFS engines for quite a while.

Share this post


Link to post
Share on other sites
On ‎4‎/‎18‎/‎2019 at 7:38 AM, Dforez said:

Hi everyone,

I have a 2006 KTM 450EXC that has started to really show a lot of metal in the oil.  I removed the ignition cover and flywheel and the crank feels pretty locked in there (no end play that I can tell).  I assume the crank has spread and is eating the main bearings.  I was told that the best course of action is just to completely replace the crank assembly with an OEM replacement from KTM (other than going to a full billet crank).

Question is, it seems KTM no longer manufactures the 2006 crank, but 2007 still seems available.  I have heard most of the RFS cranks interchange easily.  Is there a recommendation right now to go to a newer crank?  If so, do I use the main bearings from a 2006 or from the year of crank I go to?

 

Thanks for the help everyone.

The year model you have, since 2012 has been beefed up a lot in that area. No needle bearings as mains, but very large ball bearings, cranks that don't separate, no endplay shimming to deal with. Lower rod bearing that's double the life of what you have. that's just a few things.

If the bike runs, Have you considered that you might have an opportunity here, since the bike is still running.

 

Share this post


Link to post
Share on other sites
14 hours ago, Spud786 said:

The year model you have, since 2012 has been beefed up a lot in that area. No needle bearings as mains, but very large ball bearings, cranks that don't separate, no endplay shimming to deal with. Lower rod bearing that's double the life of what you have. that's just a few things.

If the bike runs, Have you considered that you might have an opportunity here, since the bike is still running.

 

To be completely honest, I don't think I'm following you.  What exactly are you implying?

Share this post


Link to post
Share on other sites

If you were implying that I sell the bike, I have thought about it.  The only issue is that with the bike being worth 2500-3000 and a newer EXC, even used, commanding $8000, I just don't see it saving me money to upgrade.  I've ridden the bike very frequently for the past 7 years, and it's only ever needed 1 top end.  If I can get another 7 years out of the bike for $2000 then I'm still winning in my mind.  Especially seeing as I just spent $1000 for custom suspension.

Anyway, I have thought about upgrading, I just couldn't believe how much the newer bikes were going for.

Share this post


Link to post
Share on other sites

I think what Spud is alluding to is that you have an opportunity now to upgrade your current crank with superseaded (better longevity) parts at the same time as you have your crank inspected and corrected. Prior to 2014 many engines had lower rod bearings and mains that were good, but lackluster for longevity - here is your chance to fix everything with updates in place of just restoring what you have.

Share this post


Link to post
Share on other sites

Oh I see,

I would love to make those upgrades.  Would anyone be willing to point me in the right direction? Perhaps to some other thread where it has been discussed?

Share this post


Link to post
Share on other sites
5 hours ago, Dforez said:

Oh I see,

I would love to make those upgrades.  Would anyone be willing to point me in the right direction? Perhaps to some other thread where it has been discussed?

I don't think the lastest updates works on that model, but that's not what I meant.

Your chance to upgrade to newer model, was what I meant.

Some of that older stuff, the way its built, Stuff has improved, like the things Inroost mentioned.

But I can understand not wanting to shell out 8 grand.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×
×
  • Create New...