KX Riders
Maintenance & Technical => KX500 Aluminum Frame Conversion (AFC) => Topic started by: mxaniac on March 24, 2014, 04:13:38 AM
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Based on the "my poor bike" thread it sounds like some broken frames have been experienced. Given the variation in weld material, motor mounts, head stays etc. all we can really do is look for any trends that exist. I thought it might make sense to start a "registry" if you will of any known breaks.
My 2006 450F based frame has broken.
DSPMOTO has had a 2006 based frame break.
Anyone else?
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Here was another one, looks like it was a 2008.
http://www.kxriders.com/forums/index.php/topic,10642.0.html (http://www.kxriders.com/forums/index.php/topic,10642.0.html)
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Here was another one, looks like it was a 2008.
http://www.kxriders.com/forums/index.php/topic,10642.0.html (http://www.kxriders.com/forums/index.php/topic,10642.0.html)
in the most cases they broke, because of wrong heat treating by the aluminium-welding ..thats a very important fact.. aluminium-frames are much more stiffer than steel-frames, that makes the modifying and welding a bit more tricky as the same work on steel-frames...
there were also some years of no modified honda oem-4stroke-al-frames that broke like glass...
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forgot about JHolt's breakage.
looks like in same place as yours. his headstay looks a bit weird. almost like the engine could rotate in the cradle, looks like a 2pt mount system rather than a 3pt that cant rotate.
can you shoot us a picture of your headstay?
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I still haven't had a chance, bit it is a cross tube between the original mount points with tabs to the head. Not as rigid perhaps as some have suggested it ought to be. I'm getting concerned about how much load might actually be on these engines, I doubt they were designed to be that much of a stressed member.
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have you seen Jfabs 'head bolt pattern to front tube' bracket? i wonder if something like that would help. care would be needed to be given in the design for easy engine removal, but to have another mounting point on something solid like the main down tube seems like it would help. so then you would have 2 anchors on extremely rigid structural material, then your 2 engine mounts on the bent tubing.
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What about this SR head?
(https://lh3.googleusercontent.com/-adbuS4fOLy4/UxxDD0DH2OI/AAAAAAAAAWk/UP98HOwG8Dg/s500/%2524T2eC16J%252C%2521zcE9s4g0vEfBR%2529pDEEjYQ%257E%257E60_12.jpg)
(https://lh5.googleusercontent.com/-PYq5YH6qvFA/Ux4jdGUSm4I/AAAAAAAAAZM/2dwyuNJjGjk/s512/107487_1454_107487-2648-17-paul-malin-mxdn-1991-2-1-.jpg)
Kawasaki used front and back headmounts. It's even in the place where many 450f and never 250f have the Original mount.
dutchie
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have you seen Jfabs 'head bolt pattern to front tube' bracket? i wonder if something like that would help. care would be needed to be given in the design for easy engine removal, but to have another mounting point on something solid like the main down tube seems like it would help. so then you would have 2 anchors on extremely rigid structural material, then your 2 engine mounts on the bent tubing.
I am gonna find a solution for that issue, an extra head mount on the front for my AF. I think I make it fully removeable, no welding.
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Already done it
(http://www.oem-cycle.com/forum/download/file.php?id=52)
(http://www.oem-cycle.com/forum/download/file.php?id=1428)
Even if you weld the mount on, you can still remove the engine.
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i may have to do one of these for some added insurance.
wonder if it will negatively affect vibration.
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I guess we'll find out.. :-o
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What about this SR head?
(https://lh3.googleusercontent.com/-adbuS4fOLy4/UxxDD0DH2OI/AAAAAAAAAWk/UP98HOwG8Dg/s500/%2524T2eC16J%252C%2521zcE9s4g0vEfBR%2529pDEEjYQ%257E%257E60_12.jpg)
(https://lh5.googleusercontent.com/-PYq5YH6qvFA/Ux4jdGUSm4I/AAAAAAAAAZM/2dwyuNJjGjk/s512/107487_1454_107487-2648-17-paul-malin-mxdn-1991-2-1-.jpg)
Kawasaki used front and back headmounts. It's even in the place where many 450f and never 250f have the Original mount.
dutchie
very rare factory gp-parts... i still dream to have one of the 3 1990/91 worksbikes or one of this engines ...
but watch out this cylinderhead is designed for the 1990-93 parallel cooling system that the production 125 and 250īs had... the 1990/91 kx500sr is similar in some points to the 1990/91 kx250 . and i still dont know, why its never gone into production...
for sandblasters front mount, i would say : its better to lift up the mount on the frame, as high as possible to get more space to the head and using also brackets like on the rear mount... :wink:
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It is my view that a bad head stay mostly causes this...we need to think about lateral force aswell as longitudinal ....a cross braced staggered firmly anchored headstay seems to be the answer,the plate method is just too springy for my liking and FORGET using side mounts period...I'd also be using radius tube for the under cradles...I use this on Hondas and kawasakis and not had a problem...I run a telescope join on the upper part of the y with a staggered/castellated join and a round plug weld in a hole on the upper to y join.....I also like to leave a 5mm gap in my telescope joins and sink a weld right down into the root then a dresser weld over the top ....I'm not an engineer or fabricator but this system has worked time and time over for me
(http://i1049.photobucket.com/albums/s398/ylwgtr2/IMG_2798_zps26494e14.jpg)
(http://i1049.photobucket.com/albums/s398/ylwgtr2/IMG_2801_zpsfebc170b.jpg)
(http://i1049.photobucket.com/albums/s398/ylwgtr2/IMG_2647_zpsa992b4ae.jpg)
(http://i1049.photobucket.com/albums/s398/ylwgtr2/IMG_2612_zps6f62b279.jpg)
(http://i1049.photobucket.com/albums/s398/ylwgtr2/IMG_2715_zps95ae49c3.jpg)
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I can say yes! here is a good design to fit preparation for welding.
Mister, Ylwgtr...
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Looks top notch.
Are you going to use a front head stay as well?
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Very nice work. That head stay is beef
I wouldn't run stainless hardware there though.
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I'm unsure who's questions are for who here but I'll answer just incase there for me....I don't use stainless bolts anywhere....I design my parts to take genuine bolts from either one of the four jap brands...I dummy up with whatever I get my hands on but assemble using OEM bolts,the ones in the pics are s**tty steel ones(not stainless anyway).Also I don't run front headstays on any of the jobs I do
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I'm unsure who's questions are for who here but I'll answer just incase there for me....I don't use stainless bolts anywhere....I design my parts to take genuine bolts from either one of the four jap brands...I dummy up with whatever I get my hands on but assemble using OEM bolts,the ones in the pics are s**tty steel ones(not stainless anyway).Also I don't run front headstays on any of the jobs I do
Cool. they look like stainless on my phone...
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Most stainless fasteners are 18-8, equivalent to a Grade 2 U.S fastener. Don't confuse stainless fasteners with strength. You can get very high strength fasteners in stainless but most are not.
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I like things looking like the manufacturer built them thats why i like OEM stuff....nothing worse than a dirty unflange hex bolt in my books washer or no washer
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just found this... looks like wrong heat treated and cracked direct at the welds between rails and y-part...
(http://p.vitalmx.com/photos/forums/2013/10/03/33349/s1200_KX_2_stroke_broke_in_half.jpg)
and this pic from 2009 with the broken honda-frame..there is also a video on youtube, where you could see the bike running and little bit later it was happened... name of the video: 500 2stroke day at apex ..
(http://p.vitalmx.com/photos/forums/2013/10/03/33364/s1200_broken500afframe.jpg)
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Correct, you want DIN 6921 fasteners in 10.9 or 12.9 grade.
I like things looking like the manufacturer built them thats why i like OEM stuff....nothing worse than a dirty unflange hex bolt in my books washer or no washer
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I'd like to have some strain gauges and accelerometers on a bike. Pretty hard to analyse when you don't know what the inputs are. Head stay comes up again and again, if that is the case I would assume High Cycle Fatigue is the culprit.
just found this... looks like wrong heat treated and cracked direct at the welds between rails and y-part...
(http://p.vitalmx.com/photos/forums/2013/10/03/33349/s1200_KX_2_stroke_broke_in_half.jpg)
and this pic from 2009 with the broken honda-frame..there is also a video on youtube, where you could see the bike running and little bit later it was happened... name of the video: 500 2stroke day at apex ..
(http://p.vitalmx.com/photos/forums/2013/10/03/33364/s1200_broken500afframe.jpg)
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So a quick disclaimer, anything I state is merely a subjective opinion and should not be relied upon for anything other than entertainment purposes. Use of such opinons for any other purpose could result in serious death or injury. Sorry about the ridiculous disclaimer but the world is what the world is.
I modelled up a crude representation of the KX450f frame with the Y moved up in the configuration I used for my conversion to the KX500 engine.
(http://i58.tinypic.com/2pqu8nn.jpg)
Based on this model and a very simplistic analysis I've reached the OPINION, which I refer you once again to my disclaimer regarding the appropriate use of, that thin wall square tubing is woefully inadequate even with a very rigid head stay in the region directly below the Y.
(http://i62.tinypic.com/sya6wg.jpg)
I'm unable to submit recommendations due to liabilities so I'll leave you to your own conclusions.
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Excellent work, thanks for posting!
I agree with your analysis...
I would like to ask you a favor.
Along with the back head stay, could you model in a head stay at the front like the pics below?
(http://www.oem-cycle.com/forum/download/file.php?id=1294)
(http://www.oem-cycle.com/forum/download/file.php?id=1293)
It may well be that thicker walled tubing is needed, but I would sure like to see the front head stay with the stress analysis ran on it..
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It may well be that thicker walled tubing is needed, but I would sure like to see the front head stay with the stress analysis ran on it..
Can you get your engine in and out? With all the cases on? If i recall correctly the water pump is always part of the problem getting it out.
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Never tried it with all the case covers on.
I have tried it as you see it and no problem.
I'll see if I have some extra case covers around and try it.
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awesome job modeling the frame. very impressive!
+1 on adding a front head mount and re-running the stress test. I'm really hoping on that showing some different results and taking some load right below the Y as that seems where most are breaking.
I'm running square tubing on mine :| , so making a front mount right now to give me a little insurance. + heat treating it also.
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For the purposes of discussion only one could surmise the front head stay significantly reduces the stress in the problem area, but not enough to be considered the only fix.
(http://i62.tinypic.com/245dpur.jpg)
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awesome. thank you for doing that.
odd that by the way the stress is showing, it almost looks like its a shear force between the headstay and the top motor mount. like they are moving separately (headstay mount is moving more forward than the top motor mount).
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That would be correct, it is. I'm simulating a high load on the steering head such as when you overshoot the tabletop and land on the front wheel, not that I would ever do that but you know hypothetically.
Here is a deformation plot, in this model I've boxed in the high stress area with 5 mm plate.
(http://i62.tinypic.com/2ccxykw.jpg)
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Very nice.
I guess it's time to up the tube thickness...
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Just to be clear, that last plot is showing exaggerated displacement and not stress.
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wonder if putting a strip of alum the width of the rail on the inside of the rails between the Y and the top motor mount to beef it up would help. basically just re-inforce the area showing failure.
i'm doing a front headstay as we speak, glad to see that it may take some of the load off.
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Well for entertainment purposes mind you I modelled up fish plates between the rails and on the side of the rails towards the engine tiening the Y together with the motor mounts and it greatly reduced the stress in that area. Combined with the front head stay and a rigid rear one things are starting to look iffy instead of disasterous.
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Cool!
But we need pics :lol:
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Can you get your engine in and out? With all the cases on? If i recall correctly the water pump is always part of the problem getting it out.
Yes :-D
Remove the fuel tank, carb, rad hoses, chain, the rear head stay, mounts bolts, exhaust, ect.... Push, pull, twist, shake it a bit, then start over, do this 2-3 times and out it comes... piece of cake.
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Can you get your engine in and out? With all the cases on? If i recall correctly the water pump is always part of the problem getting it out.
Yes :-D
Remove the fuel tank, carb, rad hoses, chain, the rear head stay, mounts bolts, exhaust, ect.... Push, pull, twist, shake it a bit, then start over, do this 2-3 times and out it comes... piece of cake.
sounds a little easier then how the motor comes out of my beta lol....
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I went with this for the front stay:
(http://i57.tinypic.com/209r0x1.jpg)
Very tight.
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I like it.
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I've heard about people heat treating or stress relieving, but my question is, what every bodies opinion on doing the frame rail mounts along the bottom with the two top mount front and back. I am done with my frame I have both front and back top mounts and am deciding if I need to heat treat it. With the front top Mount you are basically making the motor part of the frame, not allowing the weight and pivot of the motor itself directed towards the fabricated y yoke. Hope I am not asking a repetitive question. What does everybody think?
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i'll say this....
service honda doesnt heat treat
and i just found out lately that their whole rail design is 2pc SOLID machined pieces. not bent tubing.
the VAST majority of the distributed weight is on the swingarm pivot and the top engine mount on the frame rails (below yoke).
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Has anyone considered that by moving the "y" section up we have actually exposed the frame rails to a high stress point?
The point most of these breakages is occurring is in an area that the standard 250f or 450f would have the main large spar still in place.
With my build I put a lot of effort into the rear head stay to ensure it was positioned to provide the best load sharing opportunity possible.
I am a firm believer that those that use a 09 or later frame need to mount the rear head stay from the spar not from the side.
Don't forget that the 09 onwards 4 strokes share the load of the top of the motor across the rear and front of the head so the strength isn't required in the rear so much.
That's my $0.02
I hope my theory is right as I'm about to start riding my build in the coming weeks, I will be monitoring the frame each ride.