CB550 Project Scruffy Racer

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
so what exactly did you need to do to the speedo to make the dual disk fit?
It‘s pretty simple :

machine / dremel the speedometer drive smaller so it will fit inside the second brake disk
fix newly machined drive to the wheel hub
longer bolts for securing the twin disks
mount second caliper to existing bolt holes, may need ’shims’ / washers to centralise / align pads to disk
replace master cylinder with bigger bore, GL1000 is perfect and looks right
new brake lines

detailed instructions, which i followed, here :

http://www.huelligan.com/cb550/dual-disc-brake-conversion

the twin disk setup, with all new lines and mc, is significantly better and i think worthwhile

steve
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
Stripped the forks down this afternoon ready for the Emulators which should arrive in the week :)

059716E8-9C4D-45A7-B8A1-AD4E6E508A83.jpeg
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
Yss emulators arrived on a cold wet day, so heating on in the workshop and fitted them

ECFC5596-EC33-42FA-81FC-C624AFDAF06C.jpeg


the only ‘difficult’ part is drilling additional holes in the damper rods.

instructions called for a total of four 8mm holes

original configuration was four 5mm holes, but these were quute close together so i wasnt happy opening them up to 8mm

i calculated that 6 6,5mm holes had almost exactly the same area as four 8mm ones, so thats what i went for.

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reassembled easily, just need some dryish roads for testing :)

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doc_rot

Oh the usual... I bowl, I drive around...
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did you get new springs as well? Not sure how YSS does it but Racetech requires their springs be used with the emulators.
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
I decided to try the emulators on their own first, yss do not require use of their springs

really easy to replace springs if i decide to

hoping to test in the morning if its dry
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
tested the bike today and a bit underwhelmed.

initially there was very little change, but i realised that two of my new holes would be covered by the ‘foot’ so i added two addition 6.5mm holes higher up.

this did seem to improve the harshness somewhat, but not as much as i had hoped.

i’m using 12.5w oil so might try 7.5 or 10, but didnt have enough in the garage.

any thoughts from anyone who has used these emulators before ?

steve
 

teazer

Over 1,000 Posts
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I haven't used YSS emulators but have some from race-Tech and from MikesXS and they work best with much thinner oil than I used to use in old Honda forks from the era. I use 10Wt as a rule but down as low as 5 if needed.

If your issue is high speed damping as the wheel hits potholes, that's harder to tune out, but try thin fork oil and you can also adjust the spring so that the valve stack blows off at lower force, but that may allow it to dive more under hard braking.
 
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Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
Thanks teazer

i’m on 12.5 at the moment so will try maybe 7.5, and also adjust the preload on the emulator.

my goal is to remove harshness from minor bumps\potholes\road imperfections which at the moment mar riding pleasure as my wrists are taking a beating

steve
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
Teazer, any thoughts on springs?
ie is it worth replacing the standard old spings and if so with what ?
 

teazer

Over 1,000 Posts
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It's reasonable to expect that the springs may have lost their springiness by now, but before you do anything about springs, check the sag and how much they dive under hard braking. If there's too much static sag, they will probably need to be replaced and if so measure them and see what's available from say Race Tech. Don't worry of the replacements seem much shorter than stock. You will probably have to make new spacers out of PVC tube anyway.

You will probably have to compromise on a softer than "ful race" damping set up to take the edge off of high speed bumps (ie high rate of change not high road speed).
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
Thanks

i think the springs are still springy as dive on braking is acceptable, and i’m looking for comfortable and fun road handling not any kind of racing

next step is lighter fork oil, i may go for 5w and then mix to increase if necessary.

it’ll be a week or so before i get back to the 550.... so watch this space for updates !
 

teazer

Over 1,000 Posts
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Thinner oil will lighten up rebound damping as well as compression. Have someone hold the bike and then press down hard on the front end and let it spring back on its own. If it comes up too fast, you need more rebound damping and if it takes more than about a second to rise, it needs less rebound damping. Likewise for compression damping. You can feel the resistance as you press down. If you can push the forks down with little resistance, they probably need more compression damping and if it feels like the forks are full of sticky goop, there's too much compression damping.

That will give you some idea as to how the damping is balanced. You may need to drill another pair of holes in the damping rod further up to eliminate any restriction there and to allow the emulator to take care of all the compression damping needs.

With emulators, the spring preload controls high speed damping (hitting a pothole etc) so get the low speed damping right with oil viscosity and then soften the preload to take the edge off high speed damping by allowing the valve to blow off earlier. If you can't get them right within the range of adjustment, you may have to try softer preload springs on the emulators.

When the front end is right, repeat the push down but this time closer to the rear of the tank and both ends of the bike should rise and fall together - not one end all stiff and the other end diving. It should be reasonably balanced back to front.
 

Luugo86

'73 CB350, '78 XS650 Cafe Killer
Thinner oil will lighten up rebound damping as well as compression. Have someone hold the bike and then press down hard on the front end and let it spring back on its own. If it comes up too fast, you need more rebound damping and if it takes more than about a second to rise, it needs less rebound damping. Likewise for compression damping. You can feel the resistance as you press down. If you can push the forks down with little resistance, they probably need more compression damping and if it feels like the forks are full of sticky goop, there's too much compression damping.

That will give you some idea as to how the damping is balanced. You may need to drill another pair of holes in the damping rod further up to eliminate any restriction there and to allow the emulator to take care of all the compression damping needs.

With emulators, the spring preload controls high speed damping (hitting a pothole etc) so get the low speed damping right with oil viscosity and then soften the preload to take the edge off high speed damping by allowing the valve to blow off earlier. If you can't get them right within the range of adjustment, you may have to try softer preload springs on the emulators.

When the front end is right, repeat the push down but this time closer to the rear of the tank and both ends of the bike should rise and fall together - not one end all stiff and the other end diving. It should be reasonably balanced back to front.

Just from reading this I have learned more about motorcycle suspension in 3 minutes than I had in the past 5 years. Teazer your a Jedi Master dude
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
Thanks again Teazer, very helpful

as i didnt have any lighter weight oil in stock i tried backing the emulator preload back to 1 turn, from 2, on either side.

this helped, there is definitely less shock getting through to the handlebars, and the handling is still ok as far as i could tell on a short blast.

i’ll get back to this project in a couple of weeks

steve
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
I’m back from a trip and today the secondhand Delkevic can arrived, so i fitted it!

was able to use an, enlarged, original mounting hole and the bike sounds good :)

BA9BCA4A-FDC4-4241-AFFB-9185D8054486.jpeg


short video here :

https://1drv.ms/v/s!AhDJKiWSrX7_u0BgN85lYrYGGfAb

next i’ll change the fork oil to 7.5w but a testride might have to wait for the end of lockdown, unless i can think of an ‘essential’ journey that Scruffy can make.....
 

Jimbonaut

Over 1,000 Posts
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Good score on the Delkevic, sounds pretty good too - is the baffle removed? Sounds louder than mine
 

Jimbonaut

Over 1,000 Posts
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You've removed the stock airbox I think - idle sounds like it's bogging when you crack the throttle?
 

Sderbyshire

Into Sailing, classic Triumph cars and motorbikes.
You've removed the stock airbox I think - idle sounds like it's bogging when you crack the throttle?
Well spotted!
i’m rebuilding the motor to 600cc this winter so havent bothered syncing the carbs properly yet!
 

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