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Bigger Front Forks

Discussion in 'The Garage' started by BigMacDouble, Feb 5, 2021.

  1. BigMacDouble

    BigMacDouble XS400 Enthusiast

    So the stock forks i have look to be suffering from some really bad rust pitting above the oil seals. I'm assuming this will cause some leaks but they're only sparse except for below where the steering head mounts.

    Is it possible to fit what i assume is xs650 forks on (35mm in diameter vs 33mm on xs400) I have a like new pair with oil seals i can put together but this would mean strecthcing out the steering head mounts so not sure if the bolts will thread in nicely . would this also cause issues with the front wheel? I know there's no fender mounts on the non stock ones but i can make something work down the line.

    If this is only cosmetic maybe i could just throw those big fork gaiters on top? Bikes gonna be mostly black anyways.
  2. xschris

    xschris a lifestyle not a trend Top Contributor

    The xs650 stuff will not work with the xs400 stuff. You need to get another set of sohc xs400 tubes.
  3. BigMacDouble

    BigMacDouble XS400 Enthusiast

    Are the stock ones i have fine or is it too much pitting? I can just throw some gaiters on top
  4. xschris

    xschris a lifestyle not a trend Top Contributor

    If pits are in the seal travel area they will need to be replaced.
  5. amc49

    amc49 XS400 Addict

    You just have way too much pitting there. I've seen a few that when sanded will not hurt much but that many..........consider each one as a file to grind on your seal edges, they might last minutes.

    Some people bore the triples out to the bigger needed ID but that means the remaining material must still be thick enough to be strong, often a problem on smaller bikes as they make the clamp area thinner on those.

    Pic the upper and lower triples where they clamp.
  6. xschris

    xschris a lifestyle not a trend Top Contributor

    xs400 triples are way too small for xs650 35mm fork tubes and forks.
  7. amc49

    amc49 XS400 Addict

    Smaller bikes commonly are. Bigger ones can do it.
  8. BigMacDouble

    BigMacDouble XS400 Enthusiast

    I should really just buy a 650 at this point . Got these 650 I assume triples that have room for 35mm forks .

    would these fit a 400 frame?

    Attached Files:

  9. xschris

    xschris a lifestyle not a trend Top Contributor

    For what you would need to do to get the xs650 forks to fit, just replacing the 33mm xs400 tubes what be far easier.
  10. BigMacDouble

    BigMacDouble XS400 Enthusiast

    It’s about the journey not the destination Chris.
  11. xschris

    xschris a lifestyle not a trend Top Contributor

    I guess take as long as you want then. Hope you get to where you need to be in the end.
  12. BigMacDouble

    BigMacDouble XS400 Enthusiast

    What would be the issue with these triples? Would the standard bearing races not fit ? the 400 triples are on my frame and torqued so i dont want to take it off to check
  13. Bear Hands

    Bear Hands XS400 Member

    I had the stanchions from my TDM900 rechromed a couple of years ago. I had to phone around to get the best price but basically they come back as good as brand new, probably better than buying pattern parts.
    I think I paid around £100, but the cheapest I found after a quick google is £145 now. Certainly easier than fitting the "wrong" forks.
  14. amc49

    amc49 XS400 Addict

    Re-chroming likely won't work there, it requires still having almost a perfect surface with no dents before starting as it is only a very few thousandths thick. The pits there (at least some of them) are going to be deeper than that; they have gone way off into the parent metal.

    You could chrome it but it will simply be chromed dents.

    Verify your chrome guy too, a lot of them have dropped out of business due to air emission issues. We had 3 here now none.
  15. Bear Hands

    Bear Hands XS400 Member

    Personally, I am not an expert on plating. My advice would be to contact a company who IS. I used Dynasurf: http://dynasurf.co.uk/motorcycle-forks/ but I have also heard very good reports on Philpots: http://www.pittedforks.co.uk/
    They will centreless grind the stanchions back and apply new HARD chrome (not the blingy show chrome favoured on Harleys...) to oversize, then they grind the new layers back to factory tolerances, so it is possible to recover forks which initially appear too far gone.

    As I said, talk to specialists, dont rely on opinions on forums.
    Gra900 likes this.
  16. NA3S

    NA3S XS400 Enthusiast

    SR500 triples will fit the XS400 neck and will allow you to use the 35mm XS650 forks.


    Doing so will give you a stiffer front end as well as allow you to run the cheap MikesXS emulator valves.


    If you go with 35mm XS650 or SR500 forks, be prepared to contend with their 17mm axle vs the 15mm XS400 axle. 17x42x13mm 2RS bearings would work along with a new 17mm ID inner axle sleeve and most likely some misc spacers to center the wheel.


    As for brakes, you'll be far better off using one of the MotoLanna adapters to fit a single Brembo caliper and 320mm floating rotor to your 35mm, either XS650 or SR500, forks.

    Last edited: Feb 14, 2021
    Robsteeler66 likes this.

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