Post 750 Kat Shock Rebuild

[Tmod]

Just posting this info if anybody has any questions on whether that post 750 shock can be rebuilt and/or revalved. Yes it can have both done as shown in the images below.

That is the stock piston you see there as I did not install a Racetech Gold Valve in this one.

Notice new charging cap on reservoir.


Compression valving:


Rebound valving:


Side view of valving:


Tmod

[JayBell]

can you be kind enough to explain "shock valving" as you mean it here?

that looks sweet!

[Robgsxf750]

Damn. I wish I knew what I was looking at.

[Black_peter]

can you be kind enough to explain "shock valving" as you mean it here?

There is only one way to mean it..
Do you see what looks like a stack of ever smaller coins?
Those are spring valves. They cover the oil port of the shock. As the fluid (shock oil) is pushed through the port (by the movement of the shock) they "peel" back. Since they are stacked, in order to push a larger flow of fluid you have to peel aside more springs. How you stack them and what stiffness they are determines the "valving" or at what speeds the oil is controlled at.

Tmod did you install new springs?
Did you change the valving any?
I have one of these and would love to mess about with it..

[ThAzKat]

Well explained BP!

how much time do you have in this tmod?

[Black_peter]

Well explained BP

I could go on...

[Tmod]

Tmod did you install new springs?
Did you change the valving any?
I have one of these and would love to mess about with it..

I left the stock spring intact as it is rated at 10.9 kg/mm
Yes the valving is completely different
Go for it.

Tmod

[steves]

So... when people say "not economically worthwhile to rebuild" what's your take on this?

[Tmod]

So... when people say "not economically worthwhile to rebuild" what's your take on this?

Well I personally look at it as you can buy one from Ebay and not really know the condition of the unit purchased, Or you can have it rebuilt and know you have a fresh shock.

Also if you purchase one from Ebay they are stock valving and if the unit purchased was for some other bike it may not be valved where it should be or sprung correctly. Granted the stock spring may be too stiff for some or not stiff enough for others. The piston that is used on this shock has higher flowing ports than a gsxr shock and would be more sensitive to how it was valved.

As far as being economical it takes all the same parts as a 2007 gsxr shock with the exception of the cap I made for the reservoir. Same seals, same bushings, same valving, same bladder.

For people that already have this shock to me it is a no brainer as they already have a decent shock that is just valved wrong for their application.

Hope that answered your question if you were asking me.

Tmod

[Black_peter]

I guess to expand Steve's question.. Not including the original shock, how much $$ do you have in it?

[Tmod]

I guess to expand Steve's question.. Not including the original shock, how much $$ do you have in it?

I would say right about $20.00~25.00

But I made the reservoir cap and have all the equipment to service them.

I reused what shims I could and added new ones where I needed them.

Tmod

can you be kind enough to explain "shock valving" as you mean it here?

that looks sweet!

Too add a bit to BP's post if you notice the rebound orifice is not a one way flow, Look at the shaft end and then the shaft where the rebound is called out and you will see that the oil can flow in either direction equally. This is why when you dial up the rebound your compression gets stiffer as well. Please keep that in mind when adjusting your shock.

Tmod

[JayBell]

I finally got off my arse and installed Tmods Revalved shock in my 2001 Kat 750(pictured at beginning of thread)

I'm a bigger guy, at 6'4" and 220lbs and found the rear suspension to be pretty mushy, and slow to compensate for rough conditions.

I left it set as I got it, so the preload isn't right...yet, but I installed it, and took it for a ride on some roads I usually avoided due to an uncomfortable ride, and bottoming out issues.

I have the rebound set at "2" and the compression damping on the reservoir set at 1 turn out from full soft, so I have 1.5 turns left to harden the compression damping.

you'll have to forgive me here, as i really dont know the proper vocabulary for what I'm feeling as i ride, i'll just describe it.

this shock is at LEASt twice as responsive as the old shock... it cycles faster between bumps, and feels like it takes the bumps much more softly... not a "bang" like the old shock... which on a real bumpy road would feel like its skipped or chattered across bumps.

also, the bike does not bottom out like it did on certain areas, Tmod left the bumper up against the bottom of the shock, and after a hard ride, its still above the spring keeper seat, meaning I have yet to bottom the bike out to push it all the way down

its a lot more firm feeling on smooth roads, and you can feel the shock functioning... not a mushy dead feeling like the old one... you get some feedback from the rear, without it feeling harsh. things like wide expansion joints in roads are a mild "blip as they go by.

also, the bike does nothing squirmy or goofy in hard cornering... it seems to soak up some bumps that previously felt wierd, like the tire was skipping a bit.

thats all I can really think to say...I'm not sure how to properly evaluate the shock from a suspension experts standpoint... its just a tangible "much better feel " than the old factory stock model.

I'm going to set the preload properly, then re-evaluate

if ya have a specific question about it, maybe I can answer the feel I get.

[jdm5770]

That's good to know; thanks for posting. I'm probably going to have to do that soon.

[JayBell]

ok, got the preload set about 32mm (1.25") and it feels the same... so above is a valid description of the shock actions.

[Tmod]

JB,

How far from bottoming out is the bump stop?

Have you hit any potholes? And if so big ones little ones? How did the shock react to those?

Any square edged obstacles? How fast were ya going when ya hit them?

After hitting a bump or something along the lines of railroad tracks does the suspension want to buck you off? As in too fast of rebound?

When you adjusted the preload did you need to tighten or loosen the adjuster and how much?

I am sure there will be more questions but that will do it for now.

Thanks!!

Tmod