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Suspension mods started
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ohiorider Offline
Running Like a Top

NE Ohio
Posts: 343
Joined: Jan 2017
Post: #51
RE: Suspension mods started
(09-29-2017 07:03 PM)spacetiger Wrote:  Bob,

I have a stock fork set, so I can get those measurements. Can you get the bike sag measurements?

Jerry
Jerry, I don't plan to return the bike to stock springs and spacers. At the moment it has the T Dynamics kit installed, and next step will be to install the lighter.90 springs. I may still have some readings I took with the factory suspension. If so, I'll post them.

Bob

1991 BMW R100GS
2008 Moto Guzzi 1200 Sport
2016 Triumph T120
09-30-2017 05:36 AM
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spacetiger Offline
1st Service Completed

N. VA USA
Posts: 59
Joined: Dec 2015
Post: #52
RE: Suspension mods started
Bob,

I meant for you to take bike sag readings on your current set up. Those will go with your bike sag readings from your earlier post.

I see your current springs are 0.9 kg/mm? That would convert to 50.4 lb/in. That is a bit high for your weight of 160 lbs. Your total steel spring capacity is preload plus spring capacity over 6.5" so, that would be (0.78" (20mm) x 50.4) + (6.5 x 50.4) = 39.7 + 327.6 = 367.3 lbs for a single fork. I am guessing they used a straight rate spring.

As a data point, I am 20 lbs heavier (180) and in my XL1200T (a little heavier than the CB1100) and I am running 0.85 lbs/in (47.6 lb/in) springs. I also have a shorter front suspension working range than your 6.5". I am also running lower oil levels so there is less air spring effect. In effect, your set up has about 20, possibly 30% (depending on oil fill) greater capacity than mine. And, your are lighter than me (by 20 lbs). You can see, even the "suspension guys" get it wrong. It seems like they set up the front suspension for a 200+ (aggressive) rider.

If I read your weight and spring rate correctly, you will have to go to lighter weight springs. A 0.8 kg/mm spring would lower your capacity to 35.3 + 291.2 = 326.5. That is getting you closer. A 0.75 kg/mm spring with only a 15mm spacer would have a capacity of 24.8 + 273 = 297.8 lb. That looks like a better starting point as you can adjust that capacity with your oil level. I know understand why your sag readings are too low (0.15). Also, the compression damping is adding to your over stiff suspension using the heavier weight oil.

Once I test the fork I have, I can tell you what the stock spring rating is.

Jerry

edit. The front suspension travel seems high at 6.5" The stock is 4.7". Are you at 4.7 or 6.5"?
(This post was last modified: 09-30-2017 07:33 AM by spacetiger.)
09-30-2017 07:08 AM
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ohiorider Offline
Running Like a Top

NE Ohio
Posts: 343
Joined: Jan 2017
Post: #53
RE: Suspension mods started
(09-30-2017 07:08 AM)spacetiger Wrote:  Bob,

I meant for you to take bike sag readings on your current set up. Those will go with your bike sag readings from your earlier post.

I see your current springs are 0.9 kg/mm? That would convert to 50.4 lb/in. That is a bit high for your weight of 160 lbs. Your total steel spring capacity is preload plus spring capacity over 6.5" so, that would be (0.78" (20mm) x 50.4) + (6.5 x 50.4) = 39.7 + 327.6 = 367.3 lbs for a single fork. I am guessing they used a straight rate spring.

As a data point, I am 20 lbs heavier (180) and in my XL1200T (a little heavier than the CB1100) and I am running 0.85 lbs/in (47.6 lb/in) springs. I also have a shorter front suspension working range than your 6.5". I am also running lower oil levels so there is less air spring effect. In effect, your set up has about 20, possibly 30% (depending on oil fill) greater capacity than mine. And, your are lighter than me (by 20 lbs). You can see, even the "suspension guys" get it wrong. It seems like they set up the front suspension for a 200+ (aggressive) rider.

If I read your weight and spring rate correctly, you will have to go to lighter weight springs. A 0.8 kg/mm spring would lower your capacity to 35.3 + 291.2 = 326.5. That is getting you closer. A 0.75 kg/mm spring with only a 15mm spacer would have a capacity of 24.8 + 273 = 297.8 lb. That looks like a better starting point as you can adjust that capacity with your oil level. I know understand why your sag readings are too low (0.15). Also, the compression damping is adding to your over stiff suspension using the heavier weight oil.

Once I test the fork I have, I can tell you what the stock spring rating is.

Jerry

edit. The front suspension travel seems high at 6.5" The stock is 4.7". Are you at 4.7 or 6.5"?
Jerry, I didn't mean to imply that the total suspension travel was 6.5", but that when I measured (with wheel off ground - unloaded,) the distance between bottom of lower triple clamp and top of wiper was 6.5". Here's cut and paste from my previous post:
Bottom of lower triple clamp to top of wiper with front wheel off ground/fork fully extended: 6 ½”
Bottom of lower triple clamp to top of wiper with front wheel on ground, 160# rider in saddle: 5 ½”

---------------------------------------------------------------------------------------------
Not related to our discussion, but thought you might like to know: It appears that the stock CB1100 fork springs are progressively wound. I took these rough measurements this morning.

Total spring length removed from fork: 13.25" approx
10 tightly wound coils: 3"
20 loosely wound coils: 10.25"

1991 BMW R100GS
2008 Moto Guzzi 1200 Sport
2016 Triumph T120
09-30-2017 09:01 AM
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spacetiger Offline
1st Service Completed

N. VA USA
Posts: 59
Joined: Dec 2015
Post: #54
RE: Suspension mods started
got you, I'll adjust the numbers for the stock damper rod length setting the suspension travel at 4.7".

I think the stock spring will be a 2 rate spring, that is what most honda's come with. Your description matches what you would see for a 2 rate spring.
09-30-2017 11:11 AM
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Houtman Offline
Been There

NC USA
Posts: 4,481
Joined: May 2013
Post: #55
RE: Suspension mods started
THIS IS ALL VERY INTERESTING BUT THE ONLY THING I HAVE LEARNED SO FAR THAT I HAVE TO LOOSE WEIGHT !
ALL KIDDING ASIDE , THANK YOU ALL FOR EXPLAINING THIS.
09-30-2017 06:26 PM
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ohiorider Offline
Running Like a Top

NE Ohio
Posts: 343
Joined: Jan 2017
Post: #56
RE: Suspension mods started
Some of the post below may not compute, since I was responding to Jerry's PM. Point is, the CB is much more compliant over semi bad roads now that lighter springs and different fork oil level have been done. I may still contact Ikon to determine if they can supply rear shock springs that are a notch or two lighter weight. I think a lot of my problem may be that I spent so much time on older BMWs over the past 30 years, that anything other than a lounge chair ride feels harsh to me. Anyway, the following is the latest update on my suspension issues.
-------------------------------------------------------------------------------------------
You're getting old?! WTH, Jerry, I'll hit 75 this coming January. I know the feeling. Although I still ride my 2008 Moto Guzzi 1200 Sport (love that bike!) she's a bit too top heavy and overall heavy for me, so it isn't my jump on for a 5 minute ride to the grocery store.

Well, the CB front end is much better after following your directions.
- we pulled the 1.00 spring, spacer, and RaceTech valve.
- I very carefully set the RaceTech valve preload to 3 turns in from zero preload.
- replaced the 20w fork oil with 10w Honda fork oil.
- after inserting RTV, set fork oil level 175mm below top of fork tubes.
- installed the .90 springs and spacers from Traxxion Dynamics.

Even with the Ikons on the rear, and the improvements to the forks, the CB isn't an R100R, but she is finally rideable (for me.) Before making any more changes, I think I'll try to get in some riding as we rapidly drift toward cold weather. The poor little Honda has only had 2200 miles put on the odometer since April of this year. Not fair to such a nice bike! I will admit, I'm having a somewhat difficult time adapting to the smoothness of the 4 cylinder DOHC engine, after so much saddle time on twins, whether Kaw W650, Triumph T100, or my long time ride, the BMW R100GS. I do like twins!

Jerry, once again, thanks for all your advice.

Bob

1991 BMW R100GS
2008 Moto Guzzi 1200 Sport
2016 Triumph T120
(This post was last modified: 10-06-2017 05:36 PM by ohiorider.)
10-06-2017 05:29 PM
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ohiorider Offline
Running Like a Top

NE Ohio
Posts: 343
Joined: Jan 2017
Post: #57
RE: Suspension mods started
(10-06-2017 05:29 PM)ohiorider Wrote:  Some of the post below may not compute, since I was responding to Jerry's PM. Point is, the CB is much more compliant over semi bad roads now that lighter springs and different fork oil level have been done. I may still contact Ikon to determine if they can supply rear shock springs that are a notch or two lighter weight. I think a lot of my problem may be that I spent so much time on older BMWs over the past 30 years, that anything other than a lounge chair ride feels harsh to me. Anyway, the following is the latest update on my suspension issues.
-------------------------------------------------------------------------------------------
You're getting old?! WTH, Jerry, I'll hit 75 this coming January. I know the feeling. Although I still ride my 2008 Moto Guzzi 1200 Sport (love that bike!) she's a bit too top heavy and overall heavy for me, so it isn't my jump on for a 5 minute ride to the grocery store.

Well, the CB front end is much better after following your directions.
- we pulled the 1.00 spring, spacer, and RaceTech valve.
- I very carefully set the RaceTech valve preload to 3 turns in from zero preload.
- replaced the 20w fork oil with 10w Honda fork oil.
- after inserting RTV, set fork oil level 175mm below top of fork tubes.
- installed the .90 springs and spacers from Traxxion Dynamics.

Even with the Ikons on the rear, and the improvements to the forks, the CB isn't an R100R, but she is finally rideable (for me.) Before making any more changes, I think I'll try to get in some riding as we rapidly drift toward cold weather. The poor little Honda has only had 2200 miles put on the odometer since April of this year. Not fair to such a nice bike! I will admit, I'm having a somewhat difficult time adapting to the smoothness of the 4 cylinder DOHC engine, after so much saddle time on twins, whether Kaw W650, Triumph T100, or my long time ride, the BMW R100GS. I do like twins!

Jerry, once again, thanks for all your advice.

Bob
Does the CB ride like an older BMW R100R or R100GS yet? Nope! But for my weight, she's a lot better now than stock. I may still contact Ikon and Traxxion Dynamics and go for slightly lighter springs. Some good days left this season, The remainder of this week in NE Ohio will be in the 70s during the afternoon. For some reason I haven't yet determined, the old R100GS has developed a case of vibes not related to carburetor balance. Hope it's nothing as serious as big end bearings or tranny bearings or driveshaft failure. Actually, what I hope is that I can determine the problem without a lot of false and expensive starts. Could be anything at 155,000 miles.

In the meantime, I can finish out the 2017 season on the Moto Guzzi Sport and Honda CB1100.

Bob

1991 BMW R100GS
2008 Moto Guzzi 1200 Sport
2016 Triumph T120
10-18-2017 04:54 PM
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