I got an 04 rm125 last year to play with after I finished my kx125. The agreement with the fiance was inexpensive build to ride this summer as our wedding is in Sept. But she agreed after the wedding I could do another full build. So I've been stock piling parts 😆 🤣. I got a set of stock hubs and was thinking of getting them turned down. I've heard of plenty of people doing this and I even watched doc wob talking about a Pastrana build and he said the rear hub was factory on those bikes but the front was just stock turned down but they get to replace them every weekend if needed.
So my question is does anybody have any long term experience with turned down hubs? Any fatigue issues or failures with prolonged use? The front doesn't scare me much but looking at the rear that is a lot of material to remove.
Pics of my 125s just because
I haven't had any issue as long as the hub being turned down doesn't go past a skim cut and removal of the casting ribs.
Lots of kx hubs from fast team green riders were turned down and coated and never had an issue.
I did it to 2 KXs with no issues.
Got any pictures for reference? Imma go talk to the machine shop probably next week
Just feels like a lot of material to remove
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I wouldn't remove those ribs.....you're right.
Can you start smoothing it by hand and get it finished in a tumbler / ceramic polisher just to get it looking clean but keep the reinforcement? I know it won't get the shape you want but it'll loose the finish from casting.
That does look like a hefty bit of webbing to remove.
I have no experience so do not take my comment as saying it is or isn't ok 👍
Those look like "load bearing walls"... LOL
At first I thought you were just talking about the casting marks....I'm no engineer but I would NOT take those big ribs out and then go riding.
*Insert condom joke here*
Troy with TCR did a few sets for me some years back. Never had and issues. Give him a call
I am a degreed engineer. Don't remove those ribs. There are there for a reason.
Turn that ribbed condom inside-out so you get the enjoyment
I know I've seen others remove them. That's why I was curious about longevity though. In theory removing them creates the same profile as other hubs so i imagine it should be fine. But I would like to hear from someone that's done it to a similar hub.
Second to TCR/Troy and their work… he will be getting a set of 89 YZ250 hubs and another RM set for my 250 in the near future all for the turndown and coat (insert Lil Jon here) treatment.
Also, pics because RMARMY.
I would not remove them look how small the diameter of the center of the Hub would be when you're done compare that to a modern rear hub those ribs are there to save weight and add strength
A friend of mine did his RMZ hubs . He was riding the 450 Pro class locally and was fast enough on a good day to get into the local National's. I can not remember what they looked like before he did it, but they were smooth and polished after. His dad did it for him , the Dad used to build drag bikes and worked on Submarines welding. His Hubs held up fine for him ( at minimum a season of (2) 20 +2 motos every weekend from March -October And Unadilla and Southwick nationals) and I think they are still around on a Vet C class riders bike now. That was back on the 08-17 generation RMZ 450.
I wouldn't do it myself , but if You find a machinist that has experience doing it and says its OK to remove all of that material I would think about it then. Asking one of the people that others have suggested to ask would be a good start.
You may be a degreed engineer, but you're no English major
Bingo, I did the same with my Yamahas. Just make sure whomever is turning them to not go thin. IMO it is best to get them coated after to protect them a bit more and they simply look nicer. My coated hubs lasted 5 years and barely showed signs of a fade in color and held up well
I think most OEM's keep those ribs there to prevent breakage...and the hubs are already so light that the ribs being machined town would save minimum weight, and IMO wouldn't be worth the trouble vs. the lessened strength. But, then again...what do I know. Everybody wants to be "factory".
Pit Row
I don't think he's trying to save the weight, I think its the looks he's going for. But good point on the strength.
I just looked up photos of Hubs from that generation RMZ and the ribs on them were very minimal compared to yours. So I guess my post was pretty useless.
There not structural. Just casting left over. Confirmed this year's ago with Hewitt when running team green bikes. Does it add stiffness maybe but its not designed in.
Are the hubs really the weak link in the equation? Even after smoothing them down? I would expect the spokes to blow out long before the hub breaks.
Those certainly arent "casting marks" those were put in the casting for a reason, whether the hub will explode without them doubtful but certainly weaker. They will proabably do it but a machine shop will be annoyed when you bring them that as its going to be intermittent cuts which is annoying and kind of hard on tooling.
Bery true
That's where my mind went, I figured it'd be like the casting lines you see on a cast crank or camshaft on slower cars or road bikes, not a full bore web.
It may be ok and people have obviously done it, but I wouldn't and especially not if it's just for looks.
Hope it works out for you whatever you do man 👍
Technically the casting risers are designed in and would be accounted for in structural stiffness models since the manufacturing process does not specify a secondary machining operation to remove them.
In some cases you would be correct. This is not the case. The process to machine them off would be more money that's the only reason their not taken off. It's strictly left to reduce one step.
Again I have back in the early 2000's confirmed this with multiple people connected to KHI, i dont remember who i talked to in PC its so long ago, xtream team green- Bobby Hewitt at loretta's, Bruce Stjernstrom at red bud in 05. I was running a 05 kx125 and was curious after I saw sipes bikes hub turned down. Matt boni I was told had over 100 hours on his hubs and swapped those race wheels to each of his bikes. I never had an issue an issue with mine. Doing a 03 kx 144 and having tcr turn them down for me.
I can agree with you, because it seems you have the experience and info from a reliable source, BUT my question to you is what did those Kawi hubs look like before they were turned down? Did they look like the hub the OP posted, or like my YZ hub? There is a HUGE difference between those hubs...
I have a 2004 KX125 with TCR turned down hubs with coatings, no issues so far, been running them for 2 years. I dont remember if the web supports were as substantial as the Rm125 hubs though. I would proceed with caution.
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