jx550 seca front end conversion

okay, I just got my front end from a xj650 turbo, two questions, first for those who have converted, do I use head bearings from the 650 or do I use the ones from a 550, I need to know as the new setup did not come with bearings, and I want new ones anyway, might as well do it right. Second does the headlight bracket from my round headlight off my 550 bolt right up, it looks like it should? And third, the 650 setup has a hose from one fork tube to the other, is this just to equalize pressure? My 550 didn't seem to have it. last it seems that the 550 isabout 1/2 inch shorter than the 650, so I take it I need to slide the forks up in the tubes?

 

I haven't converted but can answer two of your queries: The hose between the forks is not there on the 550 because it doesn't have "air" forks like the front end you got does; you would need to slide the forks up a bit to get the same geometry. Look at the axle to fork relationship, on the 550 Max it's in front of the fork tubes, on the 550 Seca it's directly at the end of the fork tubes. On the turbo it looks like they were similar to the 550 Seca, at the ends so it might not be an issue. You want to try to maintain the same geometery not just length so the amount you slide them up or down in the trees could depend on more than just overall length.

 

the whole geometry issue is fine, I deal with theat all the time with my dirt bikes. I really needd to figure out tthe steeering head bearings as it is the only thing between me and these new forks

 

also does anyone know who has done this conversion before?

 

As far as the bearings go.... If you're going to use the original bearings, use the matching bearings for the races that are currently pressed in the steering head (provided that they fit). Never mix and match old bearings and races, as they may have different wear patterns which could lead to premature failure.... On that note, I would recommend getting a tapered roller bearing set, so you won't have to worry about them for a very long time, and your bike will handle a bit better as the result. Ball bearings may "walk" sideways a bit when stressed, where tapered rollers don't have that problem.


my $0.02....

 

that is the plan I would never use new bearings with old races. At this point my initial problem is that the stem on the 650 is 1 inch longer, so I have to either remove the stem from the 550 and put in on the 650, or possibly make a nylon 1 inch spacer to go over the top bearing and under the top tripple, it looks like there is enough space with very little work to run it this way

 

no one???

 

I don't know if you can swap steering stems and I don't like the sound of the spacer idea. You cannot afford a failure in the steering head area it could be fatal.

 

hasn't anyone done this conversion before? I was under the impression that it was pretty normal?

 

If you do a search there are a couple threads.
look in mods
The ones I have read the new forks were a direct swap, no issues like you are having.

 

hey hound, what did you use as key words in the search, all the ones I found did not have positive ideas other than using a european left leg from a 550.

 

Hound,you may have been thinking about the conversion of a 650 Maxim to dual discs, and you can use teh 750 Maxim forks as a (basically) drop-in swap, the 550 Maxim and Seca models are more limited due to a number of issues..........first and foremost being there is no "comprable" model to a 550 that used dual front discs BESIDES the Euro 550 models.......550's, although they are beloved XJ's, are kind of like a chimps vs. humans things......related, but it was a long, LONG time ago, and things have changed quite a bit since then.

 

The 550 stuff swaps with other Yammies, just not so obviously. The XS 650's and 400's, the SR500, other chain drive bikes of the same era. Just not as easy to puzzle out is all. Cavi has another thread on this and I believe he found a Euro front end.

 

You are probably right.
I try to keep things straight.
AS for the 550 being the long lost link.
I often thought how odd it was the 550 Seca and 650 Seca shared the same look and the 750 was styled differently.
When the 650 and 750 were both the shaft drive, ie closer models in my book.

 

Genesis. Here's the FIRST Seca, all 398cc. Notice the family resemblance?

 

yes I found a euro fork, it will temporarily let me run dual front discs, I do plan on using the maxum wheels as I like them more, no problems there I hope?
Also, I do have a full front fork from a 650 if anyone wants to buy one.