Xj 550 Seca fork tube interchange

Thought I'd run this about to see if anyone knew offhand......

Are there any fork tubes from other Yamaha models (IE: RZ350, 400 etc.) that will interchange with the 35mm tubes that I have on my 82 XJ 550 Seca that will use the stock fork clamps and lowers/sliders?...What I am looking for here is a fork tube that has screw in fork caps instead of the snap ring thingies that retain(?) the plug/forksprings that I have now......I do not want to preform a complete fork swap with another set from a different model, just a tube replacement........A pair of tubes a bit longer that could be trimmed to remove the counterbore and then threaded would work also........Or....if there are a set an inch or shorter that are already threaded that would work also as I am running the std tubes up a bit tru the top clamp already......

Having a set made is an option but if a stock set can be interchanged then this should not be necessary..........

 

Try this.
http://forums.sohc4.net/index.php?topic=64343.0

 

Thanks!..............good link........

Should take awhile to research this one......Takes a lot of the guess work out of where to look.............

 

this one is always helpful too http://www.yamahapartshouse.com/yamaha- ... ibrand=YAM

 

Excellent!......

Now I can cross reference different models....Thinking that a set of 80-83 XT 250 tubes may be in order....35 mm, screw in fork caps.....33" long tho so lower tube can be trimmed to size ( need 30" from top of tube to c/l of axle) ....Checked about on the Bay and there are quite a few of everything and the price is right....Would prefer a straight across replacement but will do what is necessary to get the threaded fork caps.....Just need to figure out what is needed either for core or replacement...............Thanks!

 

I have a Yamaha with the screw-in top cap and I have found that neither way (screw-in, circlip) is all that easy. The screw-in cap is very easy to cross thread if you don't take your time (while simultaneously compressing the fork spring with the socket wrench - grrr) and the circlip method can have its own set of challenges (rusted solid; simultaneously pressing the plug while using a small screwdriver to grab the end of the circlip). The one advantage of the circlip method is that you use 2 different tools (plug compressor and circlip grabber) so multiple attempts are somewhat less frustrating.

The trick with either fork is to get the front wheel completely off the ground before getting the fork cap off.

 

I have to admit I hit the roof when I saw the circlips.....WTF!...have not seen those damn things since the early 70s in a mini bike.........None of my Britt bikes, HDs or GSXRs had a damn circlip holding the forks together......Cheap way of doing it I guess....still....its gotta go.......After having them both rusted/froze solid from water getting in there and the whole mess as one so to speak ( penetrating oil ,drill the plug, tap & slide hammer made short work of that) I'm not going tru that again....Fork tubes have quite a bit of rust outside that pitted the chrome too so a different pair are in order.......Know what ya mean about the fine threads tho...real easy to cross thread if not careful....But circlips?.....Not an option

 

To each his own. I find the circlips just slightly easier. Just make sure the inside tube top and plug body are rust free (lightly sand if not) and lube both with grease prior to reinstall. I also put a thick coat of grease on top of the plug after the circlip is installed to help keep any stray water out (since the dust cover doesn't seem to).

Also easier to get a set of OEM tubes for replacement than making something else work :wink:

 

The early RD(Z) 350YPVS 31K model has forks that will fit aswell as SR500, XS500, XS650, Honda XBR500, NS125, Aircooled Yamaha RD250E,400E are all 35mm like your XJ mate.
Not sure about the length though.

Hope this helps.

Cheers
Col.

 

Hi Col................

Have been researching the forks and what I want/need is available just need to narrow it down as to what units may be a straight across replacement......Several dirt models have the extra length needed to trim to length and machine the lower tube. The SR500 & RD units have been getting a real hard look.Need to look into the Honda option tho, Thanks for that!.......The 30 1/2 inch overall length can be a bit shorter if need be as I run the forks about a inch up tru the top crown......This mod may seem a bit silly to some but the circlips just are not an acceptable way to retain the fork springs to me. Threaded caps will also give an option for fork preload/assembly as I do not care for loose preload spacers in the least...........

 

Hey Bart,
one thing I would also consider to make the swap easier would be looking at the wheel bearing sizes of the bike you choose to pinch the forks from. It will make life alot easier if any spacers that you may need to make are only for the width to centre the wheel.
It may be possibl ewith the RD or SR that it is a straight swap. Pretty sure the RD/SR has the same width of spindle as the XJ.
You could also look at a complete front end changeover using FZR etc. by checking out the steering head bearing sizes that way yo get a better fork, wheel option & brakes??
I may go down this road once I have tried my XJ out on the road if the current set up isn't upto it.. ;-)

Cheers
Col.

 

Col...

FZR 600 front end looks real appealing.......38mm tubes, very light weight, better fork valving, readily available & reasonably priced.......If I end up going down the Vintage track bike route that may be the way to go....At this point tho I think that the 35mm units should get the job done ( track day maybe but day in/out rider for most part)......Looking at a brake set up kinda like yours cept for using a early R1 monoblock dif. bore caliper I have on the shelf........Not sure bout the dia of the disc...Looks like a FZR 600 disc (298mm dia) may work out but not sure bout the bolt pattern being the same as the OEM Seca wheel.........

Where I am at this point:


Still lots to do.....fab battery & air box, sort forks, tuck the pipe in,finish the seat & sorting the ele. etc.but for most part real happy how things are going......Fighting the natural urge to NOT make this into full blown Vintage Race project.......for now.........

 

Bart,
the bolt pattern is the same I'm sure. 6 bolt definatley. On a previous race bike RD350 aircooled I used a disc from a TDM850 on the wire wheeled hub from an RD. My mate also racing a RD with cast wheels used the same model Aprilia RS125 disc I'm using on the XJ.
You will only need to make up a bracket for the caliper & possibly space out the disc to suit depending on what disc you decide upon.

Loads of options for you ..
Cheers
Col.

 

Bingo!................ .......Thought someone on the forum would know that info......I think the offset is bout the same as what I have now...The monoblocks are a real compact unit too...With a pair of sintered pads and the F model ( Teapot) master cylinder I have laying about it should be about all the stop action the forks/axle can transfer........Several FZR 6 rotors on the bay for a good price now.......Happen to have a pc of 3/8 S-7 laying about and just the right size it looks ( tough to work with, but.....it does not flex/move)......Well off to the Bay.....worse that can happen is I spend 25.00 on a rotor and it won't work out....best case is I'll have the price of a master-caliper seal kit & the rotor for a front brake that should be a good upgrade & its all stock OEM parts................Should be interesting to see how it compares to the rebuilt stock rotor/caliper/master that is in place now...........