Front end conversion.

[nj1639]

Bump, anyone know of a 35mm triple tree that will bolt on to the early frames?

Like Leo with his 1100, the '77 XS 750 Standard model in 36mm is or should be a direct swap for the earlier trees and it doesn't have the leading axle. Brake caliper is the same but the rotor is smaller in diameter...........will raise you up about 1 3/4 inches in the front though.

 

[acebars]

I've just come back to this conversion again, the 34mm stock forks are terrible I can compress them fully just by leaning on them with just some of my weight !

I'd like to use a pair of EX-500 / GPZ500S forks as they have the look I want and can be modified for what I'm after. I understand they came in 35mm early and two 36mm later types.

Is it correct to presume that late 80s-90s 35-36mm forks will perform much better than 70s forks of the same diameter?

Also wanted to double check the XS750 steering stem accepts a 36mm fork and fits the early frames without modification?

One last thing '75 36mm Yamaha TT 500 forks look perfect although they maybe a little long, my only concern is they are for offroad use, is using forks designed for offroad inadvisable on a road bike?

 

[jd750ace]

While the EX/GPZ forks will be easier to find variety in parts for, they are KYB forks as well, and the performance will be similar, if not slightly better due to the more modern internal bushing design. Having owned a 1991 EX500, and put over 36,000 miles on it, I'd say it's going to be a push. Spring it for your weight, and work with the fork oil weight and height, and it will probably be passable, but it's a 35mm fork born to a bike that was over 100 pounds lighter than the XS. I'd say it's even money if it gives you the flexibility in design you need and you're going to go through them anyway. I've never been impressed with anything smaller than a 41mm fork, but I'm a 240 pound gorilla that rides the front of the bike pretty hard, so your results may vary.

 

[acebars]

Thanks jd750ace, yes I had that original reservation about the EX500 forks (especially the earlier 35mm forks) and as you correctly pointed at the bike is lighter.

Going 36mm would be easiest given I'm told the XS750 steering stem is a straight swap, and the later EX500 forks are 36mm and would be suitable for modifying. I checked out the '76 Yam TT500 36mm according to the reviews they are poor performers so the search continues for anything else.

The worst forks in my experience I've used on a medium size bike are the 34mm early XS forks, close to that 35mm Honda '73 CB450, a much better improvement 35mm '75 CB500t forks and a large jump above that 35mm XS650 forks, it's interesting that same diameter forks can have such disparity in the same decade.

Failing all this I may come full circle and go the 41mm R6 forks as suggested here with some triple tree/stem hunting. Just trying to find some detailed dimensions so I know what I'm dealing with to see if it's possible to modify/retrofy them like I'd like to.

 

[acebars]

Well I've come to some decisions I was wondering whether you guys could help me a little more with what I'm looking to do, this being the first time I've ever done something like this.

I was thinking of going 36mm XS750 but I've decided to go for later EX-500 / GPZ 500 forks which are 37mm which is enough for me. The lower yoke / triple trees are also perfect for what I want to do but I will have to swap out the stem. Couple of questions:

-Is it possible to swap out any stem for another? Or will I have issue trying to swap out the early XS650 stem onto a a GPZ 500 lower? I can only imagine different stem diameters and such.

-The top yoke is unsuitable from the GPZ500 as it doesn't have handlebar risers and also the bolt to tighten up the top yoke to the stem which I require, is there anyway around this? Perhaps welding the risers on from the early XS650 or something? Is it possible to use a different top yoke or is this difficult to match up?

I'll have to outsource this work because it is beyond my capabilites so any suggestions would be appreciated!

 

[acebars]

Bump. Anyone any suggestions/ideas?

 

[weaselbeak]

Anything is possible. Take the whole triple tree mess to a machine shop and show them what you want. Don't forget your checkbook if the machinist isn't your son.

 

[acebars]

Anything is possible. Take the whole triple tree mess to a machine shop and show them what you want. Don't forget your checkbook if the machinist isn't your son.

So it's never the case that one stem is too narrow to fit another yoke?

Also is it possible to use a different top yoke or is this a no-no?

 

[weaselbeak]

So it's never the case that one stem is too narrow to fit another yoke?

Also is it possible to use a different top yoke or is this a no-no?

Stem diameters can be played with depending on bearing availability. See what ID and OD you need to do what you are attempting and then call any bearing company (I use Motion Ind) for a cross reference. They've made a lot of choices over the years. I even found some very weird Guzzi trans bearings, in my hands in a couple of days.

 

[acebars]

Yea I'd like to keep the early XS650 stem my concern is the GPZ500 lower may not accept it or something like that, some very good bearing companies in the UK so I'm sure that won't be an issue.

That and the top yoke, wondering whether it's possible to use another top yoke, that or weld risers to the GPZ500 + other changes.

 

[Airwolfie]

Here is one possibility, look at my thread so you can get some ideas on what to do..........

http://www.xs650.com/forum/showthread.php?t=30130

Pretty straightforward swap, I just had to think about it, and with the help of another forum member, I managed to do it!

 

[acebars]

Right slowly coming around to doing this now planning parts etc.

I've acquired a good set of 37mm 1998 EX/GPZ 500 forks for the grotesquely cheap price of £12 (circa $20), which is a happy medium for me as I need to keep the fork lowers thin (which is what they are on the EX/GPZ 500) and 37mm is a lot better than 34mm, but any wider makes them too large for the look I'm going for.

I'm a little concerned that the GPZ500 forks may have been designed too light, they were made for a 185kg bike and I'm making no weight savings on the XS650

That has me thinking perhaps it would be better to buy a set of GL1000 1975-79 forks, they too are 37mm but were made for a 250kg bike. GL1000 forks are a lot more expensive at around £80 usually and the fork lowers are chunkier.

What do you guys think? Is it worth the effort?