CRF500L V2.0

Discussion in 'Japanese polycylindered adventure bikes' started by michaelkozera, Jan 4, 2019.

  1. Butters

    Butters Kwyjibo Supporter

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    Any thoughts on going to a smaller skid plate and using some form of case-saver to protect the sides? You have an ambitious weight target and it seems like that may be a way to save a couple pounds. I suppose you could also go to something like a Hyde-type skid plate as well, but I'm guessing you will be beating the ever loving crap out of this thing.
    #21
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  2. Cruz

    Cruz Lost but laughing.

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    Adapt an AXP plate to suit.
    Saves weight, quietens down the noise a bit, and slides over rocks and logs better.
    _20190107_180742.JPG _20190107_180806.JPG
    #22
  3. JMo (& piglet)

    JMo (& piglet) Unicorn breeder

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    Hi Michael - I'm presuming you know this, so my replies are really for anyone else reading...

    The reason dirt-bikes have a cradle style chassis [frame] is so that there is maximum rigidity combined with minimum weight - ie. the upper tubes can be made thinner [and thus save weight] because the overall frame shares the loads between swing-arm pivot and headstock.

    It's true that the CB500 engine is a semi stressed member in it's original application, but that is because the main frame above the engine in the CB is a far more substantial assembly (hence it's extra weight over the CRF250L chassis you used) to compensate for the fact it has to handle the majority of the loads between swing-arm and headstock.

    If you were to build a bike around the original main frame (or a similar design), then I would suggest what you're proposing would work (as it already does, on the CB500X), but the fact you've actually noticed even 'less than a few mm' flex in your current frame without the lower rails in place would suggest the backbone of the CRF250L chassis is NOT strong enough to do what you're asking/proposing?

    Certainly were you to ride that current frame and engine combo without any additional structural bracing (which would add weight of course), I can see the cast engine mounting lugs fracturing after any serious miles over rough terrain - they are not designed to handle that sort of loading without some additional support from a more substantial backbone frame above.

    So, yes - your conclusion in fabricating some kind of lower cradle to tie the forward and rear engine mounting locations together to help reduce any backbone flex I would consider essential.

    Just don't weld it on this time eh? ;o)

    Jenny x

    ps. Don't get me wrong, I applaud Michael for having taken this step initially - he's inspired some fabulous builds with his proof of concept... however, some of the methods suggested/employed I would personally question, particularly in regard to chasing minimum weight at the expense of engineering integrity.
    #23
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  4. totensiebush

    totensiebush re-tarded

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    I wouldn't have expected a lower cradle there to take any significant load when riding the bike. A piece of bent tube isn't very rigid, no matter how you apply the load. In comparison, an engine is almost infinitely rigid.

    I'd expect the load to almost entirely go through the engine with or without a cradle.
    #24
  5. michaelkozera

    michaelkozera Long timer

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    the CRF500L i made originally was never truly "production ready", not even close, it was more of a proof of concept/prototype.

    i will admit, not matter how reliable an engine is, it needs to be removable so this time around it will be.



    as for the rigidity/ strength of the frame. i will be visiting my friend this week, he has a cb500x. im gonna preform some "tests", mainly unscrew the front frame mount and measure the deflection and compare it to the crf500L deflection i measured. if i see similar deflection numbers then this will confirm my theory that the 500 engine is indeed the main support.

    another thing to consider too is the crf250l suspension has double the travel so more force can be dampened

    so the main question here is how strong (heavy) do i make the front subframe, IMO it obviously needs one....
    #25
  6. larryboy

    larryboy Stable genius.

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    It doesn't have to be heavy with 4130.

    :deal
    #26
  7. flipflopdog

    flipflopdog Youth & Talent, no match 4 Old Age & Treachary

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    Not pretty but very functional....
    #27
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  8. flipflopdog

    flipflopdog Youth & Talent, no match 4 Old Age & Treachary

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  9. OHjim

    OHjim Long timer

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    #29
  10. Butters

    Butters Kwyjibo Supporter

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    That is pretty much what I was thinking. I actually had DRZ case savers in mind since that is what I was familiar with. They were very light, but spread the impact over the whole case, as opposed to just the impact point. That, and another layer of metal can't hurt either.
    [​IMG]
    #30
  11. michaelkozera

    michaelkozera Long timer

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    #31
  12. Cruz

    Cruz Lost but laughing.

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    The RG covers work well and weigh very little.
    _20190109_062328.JPG
    #32
  13. michaelkozera

    michaelkozera Long timer

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    looks like alot of corrosion over the last 150,000km. makes sense since i ride all year round here in calgary. and they salt the roads 6 months a year......

    [​IMG]
    #33
  14. michaelkozera

    michaelkozera Long timer

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    looks like i was totally wrong.

    i had a chance to go to my freind house and have a look at his 500x, we removed the front engine bolts and measured the deflection using 175lb's of seat weight (me).


    the crf500l deflected 3mm +/-0.5mm
    the cb500x deflected 1.5mm +/- 0.5mm

    so clearly the cb500 frame is far beefier then the crf250l frame (obviously). so looks like a steel subframe will indeed be needed. damn.
    #34
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  15. flipflopdog

    flipflopdog Youth & Talent, no match 4 Old Age & Treachary

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    Did you keep the two original sections from the 250..??? I used them with much success, worth a thought.
    #35
  16. michaelkozera

    michaelkozera Long timer

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    all tacked up ready for welding:

    this front section is now made of 100% stainlesssteel.
    [​IMG]



    ended up reusing the old dual pipe splitter, rusted sure, but it will do.

    [​IMG]

    new mufflers weigh ~800g lighter, each. that plus the thinner stainless steel pipe metal, equates to about 1.5kg (3.3lb) in weight reduction.


    [​IMG]
    #36
  17. michaelkozera

    michaelkozera Long timer

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    #37
  18. michaelkozera

    michaelkozera Long timer

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    had an issue with the oil pan, turns out when i welded it it warped and its no longer flat.

    so i had to get creative. using my CNC would work , however thats lot of work and a high chance of damage/failure.

    so plan B:


    wet sand paper on glass, since glass is very smooth/flat, i was able to get a perfectly flat and smooth mating surface.

    [​IMG]

    [​IMG]

    took about 2 hrs of sanding, about 2mm of material.



    [​IMG]


    so smooth.

    [​IMG]






    now onto the subframe and skid plate:

    made the subframe removable

    [​IMG]

    and welded the skidplate frame/cage to the subframe.

    both the skid plate frame and the subframe add to each others strength. once this get all welded up i will be mounting the aluminum skid plate to this subframe/skidplate cage.

    the mounting screws and bolts are just temporary for now.

    [​IMG]

    [​IMG]


    [​IMG]



    the aluminum skid plate will also wrap around the steel tube to add additional strength. and its 1/3 the weight of the old subframe!

    and as a bonus, this new setup gave me an additional 1/2" of clearance. i did a fast measurement and got roughly 12" of ground clearance now.
    #38
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  19. michaelkozera

    michaelkozera Long timer

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    got the exhaust finalized. sound meaner then it did before for sure, abit louder too. but necessary for the weight savings. still not obnoxious IMO:

    #39
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  20. michaelkozera

    michaelkozera Long timer

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    getting the skid plate all together:

    this is the main plate, 7mm thick 6061, made to take the main hits, 6 screws to mount it on, and its removable so you dont have to take the whole front sub frame off to do oil/filter change.

    [​IMG]

    this outer aluminum sheets are 3mm thick.

    [​IMG]

    put some vent holes and slits for heat dissipation:
    [​IMG]

    now thats one mean skid plate:
    [​IMG]


    and best part,

    old skidpalte/subframe weighed in at 6380g (~14lb's)

    new skidplate/subframe weighs just 3850g (8.5lb's) and impressive 5.5lbs lighter!

    Also. Very mad max looking. I like it. Dont know if i should paint it black or just leave it polished aluminum.


    300lb's wet here we come!
    #40