front fork mod

I have a 82 xj750 and wanted to know if it was possible to shorten the front fork? A guy I work with said something about preloading the front end to shorten the shocks. Not sure what he ment by that. But I want to shorten the front by about 2". Anyone ever done this? Any advice appreciated.

 

in another threadhttp://www.xjbikes.com/forums/threads/wanting-disk-in-the-back.72172/
it was stated a seca 750 fork tube would fit a 550 seca with the 750 being longer and extending above the triple tree. it was done for the dual disc setup. so the inverse should also be true
why do you want to shorten the forks?
way back we used to put extended forks with out raking and it caused oil issues. if you shorten your front end your oil may all spill forward leaving your transmission low on oil and crank case high. this may not be good.....
another link
http://www.xjbikes.com/forums/threads/new-guy-with-a-1981-xj550-seca.72284/

here is a list of
Fork tube dia


37 Yamaha XJ-650 LK "Seca Turbo" (83)
37 Yamaha XJ-900 RK "Seca" (83)
37 Yamaha XV-920 RH/RJ "Virago" (81-82)
37 Yamaha XJ-1100 J "Maxim" (82)
37 Yamaha XS-1100 E/F/G/H (78-81)
37 Yamaha XS-1100 LG/LH (80-81)
37 Yamaha XS-1100 LG/LH "Midnight Special" (80-81)
37 Yamaha XS-1100 SF (79)
37 Yamaha XS-1100 SF (79)
"36(mm) Yamaha XJ-650 RJ "Seca" (82)"

 

The 550 forks will be undersprung for the 750. I woud not reccomend that swap.

What I would recommend is new springs from Progressive.

Adding preload to the front will not shorten the forks. It will just make the springs behave as if they are already partially compressed. The shocks can be shortened, but that requires shorter springs and longer preload collars. This also will make for quite a harsh ride, so I would not do that unless you are going racing.

 

XJ550 Seca fork tubes are 35mm OD, all of the XJ750 (except the XJ750-X and the XJ750RL) are 36mm, and the XJ750X and RL models are 37mm. The XJ550 Seca models are the "baby fork tubes" of the entire XJ series, which is very odd.

 

But the swap can be done despite the different tube diameters. A 1mm difference can be made up with shim stock. I still would not reccomend the swap.

 

So a front end swap would be best if I want a "shorter shock" and less of a rake.

 

rake is the angle of the forks. droping the front end would give you a steeper angle , tilting you forward. think of it as pivoting off of the rear axle. or putting your front tire in a hole. putting a shorter shock on the rear of the bike would drop your rear end of frame the bringing you back closer to the original angle. to short of a shock may have you bottoming your fender to the tire.
rake was changed by cutting frame and rewelding head stock (where your vin tag is) it to a different angle
so a shorter shock is the easiest way to change and can be returned to oem standards in the future.

take a look at this link poster went
to shorter shock
http://www.xjbikes.com/forums/threads/aftermarket-shocks-and-lowering-bike-advice.68105/page-2

any mods you do will make have to be considered carefuly.
rear wheel travel, fork travel possibly need a spring change to compensate for the weight difference in bike you have, compared to weight of 550. bottoming out on frame and front end travel could lead to big time loss of control
.
I agree with K-moe on this would not suggest it. Yamaha knew what they were doing when they designed the bike.

 

sorry i misunderstood what you meant by shorter shock did not grasp you were talking about the front forks as being shocks in your post

"So a front end swap would be best if I want a "shorter shock" and less of a rake."

 

Thanks for the advice fellas. I'm planing on doing a front end conversion and possibly a virago mono shock rear end. Maybe a Seca 900 rear wheel. Been doing a bit of research and getting on here asking advice is helping me along. I have an idea of what I'm after. And sorry if I post a bunch of blogs. Only post them if I can't find what I'm looking for.Plus I feel it gives everyone a chance to chit chat and pass knowledge around.

 

Well change.......

I'm still up in the air about the mono shock conversion. I LOVE the look of it but I'm trying to build a budget friendly streetfighter/ cafe. My main focus is on mechanical then cosmetic.

 

To go mono-shock = mods +$
To swap to 900 Seca rear wheel = mods +$

 

Yeah. I figured eitherwould cost some money. I'm willing to spend a bit of money to get it where I want just not trying to go over board. I've been reading a forum on here "project shadow warrior". I like what he did and his tenacity but it's a bit to extreme for me. But I like some of his ideas.

 

I think that what you really want to do is an R6 front end swap.

Monoshocks look sexy. but they don't perform any better than an equivalent dual setup.