Topic: HONDA CB550 changing to taller shocks - Will this cause a problem with handling?

[kyle750]

The stock Honda shocks on the CB550 are dead and gone and need to be replaced - someone sprayed them grey and they are ugly    I have a set of aluminum body older KONIs for the CB750 model 7610-1296.  The stock shock is 12.5 inches and the CB750 is 13.25 inches so 3/4" inch taller.  Will the added height create a problem with front end handling?  As the CB750 KONIs  have stronger springs (designed for the heavier bike) I am quessing they will also add more weight support but also create a more firm ride.  As a riding style I actually prefer a very stiff ride and I can't stand bouncing up and down like a pogo stick.

Quick fitment check but not bolted on yet. Waiting on a floor jack from a neighbor as I will need to raise the back end before removing both shocks.  Also new shock bolts ordered. 

[kyle750]

I can also buy a set of 7610-1302 KONI shocks from a good KONI friend in Europe I met on a facebook group.  The 1302 were used on both the CB350 and CB500/CB550 at 12.5 inches height.  The only difference is the CB500/550 1302 use a stronger spring (for the added weight of the larger bike). 

[seanbarney41]

Longer shocks in back may be a problem.  The cb550 turns very easily in stock form and raising the rear will make it turn very quick.  Will it be dangerously unstable at speed?...not sure

[newday777]

The longer shocks will effect the turn in to corners some, how much I'm not sure either.
As discussed when you got those aluminum Konis they have adjustable damping on the bodies, which is what is great about them(adjusts up and down rate of speed).
The springs are what handles the weight of the bike and load of rider and passenger, and added gear if traveling.

[rotortiller]

Attempt to fit the shocks, evaluate potential mechanical interference and interactions at the higher position then decide to go further. If it looks good take it for a cautious ride. If it has an issue then now you know. Some of the stuff people do chopping or ratting out these bikes can be quite excessive. There are many lowering kits are available for modern bikes with short people, so deviants have had success. If it does not prove suitable for whatever reason then at least you gave it a try. Think of all the wheel diameters guys have grafted etc.

[kyle750]

Thanks for all the replies.  On a related topic about altering the height of the back with longer shocks I noticed there is something just not right about the back end.  On the center stand and the back wheel raised off the ground the back end looks low - very low. The front end is much higher.   The tire is a 18 3.25 so very small.  Here is a photo of the bike on the side stand and you can see the back end is entirely too low.

[kyle750]

And here is a photo of the bike on the center stand with the back end raised off the ground.  To my eye the back end is entirely too small. It just looks and feels wrong!

[bryanj]

Surprised the back wheel is even off the ground with the longer shocks BUT i think its supposed to be a 3.50x18 rear tire and that will make a difference

[kyle750]

Both photos are with the stock shocks (not the longer shocks)

[Deltarider]

Looks normal to me. Rear is supposed to be 3.75-18* though, front 3.25-19.
*3.75 is hard to find. Rear rim will accept 4.00. I always had a 4.00.

[kyle750]

Looks normal to me. Rear is supposed to be 3.75-18* though, front 3.25-19.
*3.75 is hard to find. Rear rim will accept 4.00. I always had a 4.00.

I think you are right.  On the front a 3.25 looks perfect but on the back a 3.25  looks ridiculously small.   I can see how a 3.75 would be the way to go but if it is a hard to find size tire I might have to go with the 4.00 which is the same as the CB750. The big beefy 4.00 back tire looks perfect on the CB750 

[Stev-o]

Looks normal to me. Rear is supposed to be 3.75-18* though, front 3.25-19.
*3.75 is hard to find. Rear rim will accept 4.00. I always had a 4.00.

I think you are right.  On the front a 3.25 looks perfect but on the back a 3.25  looks ridiculously small.   I can see how a 3.75 would be the way to go but if it is a hard to find size tire I might have to go with the 4.00 which is the same as the CB750. The big beefy 4.00 back tire looks perfect on the CB750 

Optical illusion 'cause the tire is too small and the rear wheel is 18", 1" smaller than the front.
I also run a 18x4.00" on the rear of my 550F. 

[Don R]

 The 550 fork offset is shorter than the 750's it might turn is quicker. I have a set of 550 triples modified to fit a road race type 750 just for that reason. I'd read up on rake and trail and measure to see where it ends up.

[BenelliSEI]

The free length of the spring shock (wheel hanging down when on the centre stand) doesn’t really matter. It’s the loaded length, with you sitting on the bike,that will indicate the true difference. Sit on the bike and have someone else measure the distance from the ground to centre of the top shock mount with each shock set mounted to the bike. The shock with the lowest spring rates will “sag” the most. If the Konis have a lower spring rate than the originals (unlikely) you may in fact end up with a lower ride height. You won’t know the difference until you test them this way……

[carnivorous chicken]

Speaking of putting it up on the side or center stand, with a longer shock you'll notice that it sits much more angled on the side stand, and it's easier to tip over and more difficult to park on slopes.

[newday777]

That odd rear fender is the part that is wrong. Different shape and hangs down at the wrong angle.

[jonda500]

What carnivorous chicken said! The bike will likely lean over too far on the side stand if you use longer shocks and it could be hard to get it off the center stand if the rear tyre is touching the ground.
John

[kyle750]

That odd rear fender is the part that is wrong. Different shape and hangs down at the wrong angle.

An excellent observation and I agree that the rear fender is making the entire back end look cramped and small. I can't wait to remove that plastic monstrosity. 

Ordered yesterday but it will take a long time before they get here

[kyle750]

Undersized 3.25 tire and undersized and wrong angle plastic fender

[Deltarider]

Looks normal to me. Rear is supposed to be 3.75-18* though, front 3.25-19.
*3.75 is hard to find. Rear rim will accept 4.00. I always had a 4.00.

I think you are right.  On the front a 3.25 looks perfect but on the back a 3.25  looks ridiculously small.   I can see how a 3.75 would be the way to go but if it is a hard to find size tire I might have to go with the 4.00 which is the same as the CB750. The big beefy 4.00 back tire looks perfect on the CB750 

I always have had the 4.00 in the rear. When I acquired the bike secondhand in 1980, it had a 3.50 in front, but at the first renewal, I have replaced that one by a 3.25. All CB500/550s I have seen here, had the 4.00 in the rear. In those years most had Continentals. Now I have Bridgestone BTs.

[kyle750]

When I asked both the owners of the CB750 and CB550 why they never restored the bikes and they told me "They did not know where to find parts" and "no have money". I just bought this original CB550 rear grab rail in the US for $75. Looks to be in decent nick - mine is cracked and rusted.   

The rear rack for my Honda CRF250L costs $150 so IMO $75 for a 50 year old rear rail grab bar is very reasonable. It might take some time and money but I hope to get the back end of the CB550 looking good    It's a fantastic bike and deserves better!

[kyle750]

Could other SOHC Forum members please confirm the following.  Thanks in Advance 

The wheels on both the CB750 and CB550 are exactly the same size

Front 19 x 1.85 x 40 spokes
Rear 18 x 2.15 x 40 spokes

Both the front and rear hubs on both the CB750 and CB550 are the same size

so the spokes needed for lacing the wheels will be the same size

If this is correct then I will just go ahead and order the same set of D.I.D chrome wheels and spoke sets for the CB550 that I ordered for my CB750 from Yamiya

[bryanj]

Dont think hubs are same size as brake shoes and bearings are different

[BenelliSEI]

Dont think hubs are same size as brake shoes and bearings are different

Front hubs/ wheels are interchangeable but the brake rotor is smaller dia. on the 550.

[newday777]

Rear hub is definitely different