Topic: most economical front end upgrade for 75 550k?

[thehammer]

ive seen alot of people put gsxr forks or forks from various other streetfighting donorbikes, and im wondering . . . are there any badass modern forks that are readily available, and can be put together with the triple tree and head tube spindle of a cb550? are the gsxr forks all i would need, or would i need the entire gsxr frontend? probably going to need brakes from the donorbike as well?
Not very well versed in crotchrockets, but want to modernize my cb550k, also wondering about rear struts but im not as concerned with those, although if anyone has any favorites, i want a pair just a little longer than stock.

any ideas are appreciated

[BlindJoe]

so you want modern suspension in the front but a hunk of metal in the back? seems a bit odd

[thehammer]

thanks so much for your input. as i said, any cool ideas about the rearend are welcome too. even pictures of your old lady's rearend.

[traveler]

economical?  1.  Progressive springs, 2.  10W30 Pennzoil oil in the forks, 3.  fork stabilizer.

~Joe

[thehammer]

yeah, of course the stock fork is good ENOUGH but i want an upgrade. making a trip to the MC graveyard on monday to poke around for inspiration. maybe i can find a good set of forks from a newer suzuki or kawasaki that can be rebuilt and bolted on to cb550. also gonna keep my eyes peeled for rear struts that would raise my rearend a bit, and that i can get new from progressive.

[traveler]

....you said "economical".....progressive springs in the front is NOT stock.  Stock is mushy/crappy.  Progressive springs, with GOOD 10w30 oil (pennzoil) will make it "act right".

If you want a modern fornt end...cool....but again, you said economical....your stock front end is more than sufficient unless you are a trained professional rider.

If it didn't work, it wouldn't be on my racer....enough said.

~Joe

[Zaipai]

Joe brings up some good points. However I believe what he wants is more of an updated look in the front and possible in the back if he can do it cheap enough. Search the forums I have seen some cool mods done by a number of 550 owners.. Not sure how cheap it would be however you can at least get some idea's and maybe take it to the MC graveyard and work some thing out..

.: Scott :.

[raymond10078]

I have a 78 CB750A.  I also had that question.  I wanted to use the same triple tree - so I figured out what fit this way:

I went to bikebandit.com, and found my axle.  Then, I cut/pasted that number into their search box, and then clicked on the "Fits Machines" link.  This will give you a LONG list of bikes that share the same axle.  The point here is that the same axle means - same width.

Then, I went here:

http://scandalon.com/2009/06/motorcycle-fork-diameter-chart/

to find which bikes had the same fork sizes.

Between the two pieces of info, you can determine what "front ends" will directly swap into your triple trees.

If you don't want to keep your triple trees (I did so I knew for sure that my gages would fit), then your options are greater, but I can't help you there . . . .

[hondaface75]

I imagine you might want to be concerned with wheels too then? Especially with the upgraded brakes? I havent done any of this I'm just throwing it out there.

[Duke McDukiedook]

Most economical would be to just get some new fork springs.
This is a thirty year old bike, if you want something more modern just buy a more modern bike.

Pairing modern front end with struts in the rear is kinda negating what you are trying to do to your bike, yes?

[Alan F.]

I'm unsure if the OP used the word 'struts' to mean shocks or what we know as solid steel pieces that bolt on in place of the shocks and hold the swingarm at a fixed position.

 

[thehammer]

....you said "economical".....progressive springs in the front is NOT stock.  Stock is mushy/crappy.  Progressive springs, with GOOD 10w30 oil (pennzoil) will make it "act right".

If you want a modern fornt end...cool....but again, you said economical....your stock front end is more than sufficient unless you are a trained professional rider.

If it didn't work, it wouldn't be on my racer....enough said.

~Joe

Traveler, upon some further research, i see that dennis kirk sells these springs for pretty cheap. In fact I think I may go this route with some progressive rear shocks although i havent decided on the length of the rears yet. you are right, this is the most economical way, and it will be good enough for my purposes . . .

Kandrtech . . . you get a gold star. great resources . . .

Alan, no, Ive got the original struts still. soft tail

Zaipai, couldn't have said it better myself. Mostly going for aesthetics here. not about to spend a boatload of cash on racer parts.

Thanks guys

[Zaipai]

I say go with Kandrtech's idea, it seems to be the best route, and if you find some front end at the yard, or local paper all the better..

.: Scott :.

[Motoguy23]

If you read the thoughts of hondaman he has a section dedicated to 500's and 550's and in it he tells you to put on airvalve in the top of the fork caps and fun 10 lbs PSI and put 3 washers that are the same inside diameter as the forks ontop of the spring.

I had a 1990 XR200 growing up and I remembered that those fork caps had the air valve built in already and that they were 35mm. Just ordered the caps from bike bandit ($160 or something like that) and now I'm waiting and hoping they didnt change the threads in the forks.

RE:  I ordered the fork caps from bike bandit and when they came I took off the old ones and the threads on the XR200 caps were much more fine and the caps were little too large in diameter maybe for like a 36 or 37mm fork instead of 35mm.

[Zaipai]

If you read the thoughts of hondaman he has a section dedicated to 500's and 550's and in it he tells you to put on airvalve in the top of the fork caps and fun 10 lbs PSI and put 3 washers that are the same inside diameter as the forks ontop of the spring.

I had a 1990 XR200 growing up and I remembered that those fork caps had the air valve built in already and that they were 35mm. Just ordered the caps from bike bandit ($160 or something like that) and now I'm waiting and hoping they didnt change the threads in the forks.

That's a good idea I had forgotten about. Thanks for the tip.. However for thehammer hes going for the look, not the performance so I think for him the only solution is to find some bolt ons that will give him the look he is after.

.: Scott :.

[thehammer]

ive heard about the air conversion . . . im not sure thats the way i want to go. i know alot of people say it works good but I'm a little worried about adapting my fork to air using the same seals. just seems like air would leak out. what worries me most is that leaks wouldnt be visible, and it may be dangerous on long trips. later on i'll check out hondamans technique, but right now i am skeptical.

[bwaller]

I've run 6psi in my 750 forks for twenty five years. (prog. springs too) If the fork tubes & seals are good they are nearly airtight.

Too much air increases stiction but I find a small amount helps these dinosaur forks, progressive springs or not.

[ieism]

Progressive springs will make a noticable difference. That and some modern dual compound tires will be a better investment than a bolt-on fork from another bike IMO.

There is a tread somewhere on upgrading the stock forks, but you'll have to seach. I remember there was an idea to use these damper valves:
http://www.mikesxs.net/products-19.html  

[OldSchool_IsCool]

I put CB750 forks, disk, caliper & fender on my 550 over the winter.  Looks about the same but much better stopping power.

[Retro Rocket]

Pairing modern front end with struts in the rear is kinda negating what you are trying to do to your bike, yes?

Terry { Terry in Australia} has a 41 mm FZR Yamaha front end on his new 750 and i think Koni's on the rear with more modern wheel sizes and brakes and he said {and he has owned a lot of these bikes} that it is the best handling Honda he has ever ridden. If you do some sensible mods like modern forks coupled with some frame bracing and good rear shocks you can almost bring these bikes into the future handling wise. There will be detractors to this way of thinking but most street riders only have enough ability to use about 20-25 percent of modern sportbike suspension on the street anyway so an upgraded "old school" bike with updated suspension can compete in the modern world quite well.

Mick

[thehammer]

thanks for the encouragement, rocket. any bike with 35mm fork tubes will work for a donor front end.

So now Im thinking that since the back tire needs to be changed, and the spokes and probably the wheel bearing are junk, Instead of investing in new spokes, I'd spend a little more money on mag wheels to avoid ever having to replace spokes and to be able to run tubeless tires.

I'm going to the mc graveyard tomorrow to look for a bike that has 35mm fork diameter, mag wheels (with chain drive i.e. not comstars ), mounts for dual front calipers and disks . . . the best i can find. a longer swingarm with a smaller back wheel?

I really doubt I'll find donorbike that suits my needs exclusively. so for now my plan is to replace the front springs with progressive springs. change the seals and the oil . . .

there are a few choices of fork seals. anyone have a favorite? NOK anti-stiction seals are 14 bucks from dennis kirk and they look to be beefier than the leak proof brand seals that are 27 bucks ??

good to hear the 750 fork will work, that'd be cool.

Does anyone know the timken part # for the head tube tapered roller bearings and also the swingarm bearings?