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Thread: Honda NC750 SD Suspension Upgrade

  1. #1
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    2nd February 2018 - 21:50
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    Honda NC750 SD Suspension Upgrade

    Because of age-related arthritic joints making conventional gear changing painful, in September 2017 I bought an ex-Japan 2014 model with just 4,500km on it. The SD has ABS and a dual-clutch transmission which can be used as an automatic and as a trigger-operated 6-speed manual.

    In mid Dec 2017 I rode the bike to New Plymouth for suspension specialists, Kiwi Suspension Solutions (KSS) to upgrade the suspension for my weight and to suit the often-ngarly-surfaced minor-roads where I prefer to ride. A dual-purpose bike would probably be better for this but they are too tall for me now because of arthritic joint-stiffness.

    KSS have transformed a few past bikes for me so going to them this time was the obvious move. Chief actor there, Robert Taylor, is a hard-working and no doubt demanding boss, and a real professional for suspension work. Heís also a man who doesnít suffer fools yet continues to accept me as a customer! Particularly as Iím probably a PITA with the very fussy way I want my bikes to ride like a magic carpet over even the worst surfaces.

    Before this upgrade Iíd rated the stock Honda suspension at only 4/10 because of itís harshness and generally poor compliance. The ride to NP was punishing for my arthritic back and hips and while the return ride with a Nitron shock and Cogent DDC valves installed was very much better, I still rated it at no more than 8/10. With-rider sags at both ends had been pathetically poor but now had become a perfect 40mm so maybe I shouldíve been satisfied with that, but since KSS had brought my other bike, a Buell XB12Ss, to what I rate as 11/10 I was hopeful that better than 8/10 could still be achieved on the SD. And so it has transpired.

    Because Wendy-wife and I were driving to NP anyway, this time I took just the fork legs and rear shock for further tuning.

    The first procedure by KSS had comprised of re-working the fork internals with appropriate single-rate springs, modified damper-rods etc. and Cogent DDC valves. The oil type and level were also set very differently from stock for better air-springing effect. At the rear, a Nitron R2 shock was fitted. This had been ordered from England a month or so before for my model NC, my weight and load-intentions, my mostly pretty-cruisy riding style, but on often imperfect road surfaces.

    Apparently Nitron supply the shocks set up for the specific bike model and then spring them to suit the payload. If that doesnít satisfy the customer, KSS as NZ agent has the right and ability to tune the unit further, which is what KSS did this time.

    Maybe because I showed more than average interest in what happens inside suspension components, or because I can be a PITA if ignored, Robert agreed to my being present to watch proceedings, and what a wonderfully instructive few hours that proved to be. Not only do KSS have an impressive setup and an amazing array of equipment, including an all-important suspension dyno, Robert and his off-sider, Dennis Shaw are true suspension gurus with a lot of experience with road and race-bike suspension development. I was surprised to learn that road riders make up about 75% of KSSís work. This is not just a race-bike specialist firm, but also there for the likes of road riders like me who realise that they need better suspension performance than manufacturers of road bikes can usually provide, and are prepared to pay for it.

    This time the goal was to achieve even more compliance by re-tuning the damping, especially the high-speed compression damping which is so critical for coping with harsh, abrupt bumps. The forks were dismantled completely, slightly-lighter springs fitted and the shim-stacks in the DDC valves altered.

    The Nitron shock and compression adjuster were de-oiled and de-gassed and then dismantled as far as necessary to alter the main-piston shim-stacks and for Robert to make another couple of adjustments which I didnít really understand. Spring and pre-load were not altered and a dyno run done prior to dis-assembly gave a reference force-curve graph. Once re-assembled, re-oiled and re-gassed using special equipment, further dyno runs showed nicely progressive response to different damping settings and then Robert re-zeroed the compression adjuster so that it will operate most effectively in the range where compliance is most critical, but consistent with proper ďpressure balanceĒ as Robert explained emphatically. Now I understand why truly-expert suspension work cannot be done without a suspension dyno if endless trial and re-adjustment work is to be avoided.

    To illustrate how far KSS will go when necessary to satisfy the more demanding (read infuriating!) customers, all this second stage work was done without further charge. All I had to fund was the oil used.

    And the outcome of all this? Once the bike was in one piece again I measured the with-rider, load and full fuel-tank sag readings again. The front sag was now 41mm while the rear was predictably still 40mm. Ideal. As Robert recommended, I backed off the rear rebound until getting almost a bounce under a static push-down test. That proved to be -13/24 so I set it at -12/24 for the test ride and the rear compression at -10/16 clicks. The first ride around my 100km Ďtest circuití showed that the latest work was not in vein and now deserves a solid 9/10 for the forks and 11/10 for the Nitron rear. Why only 9/10 for the forks? Because they must always remain inferior to the USD Showa 43mm ones on my other bike, a Buell XB12Ss. For the second 280km ride on different roads that same day I upped the Nitron compression to -12/16 and the rebound to -14/24 on the basis that if it felt good before, more of everything should be even better. Certainly it felt no worse.

    Is the upgrading finished yet? Not quite. Iíd like to see if the forks can be made better than 9/10 by improving further their high-speed compression response so I will remove the DDC valves and send them to Robert for more of his magic. Under front-only braking hard enough to activate the ABS the dive feels fine and 115mm of the 120mm stroke is being used. Currently 7.9N springs, Putoline 10W oil, oil level -140mm.

    So, unless you are lucky enough to be of whatever weight the designer specified the stock suspension for, then avoid riding a similar bike which has had an expertly upgraded suspension job or risk dissatisfaction. Remember that no amount of preload adjustment can alter the spring strength, only the ride height. The spring strength needs to be matched to your payload weight for ideal performance.

    The Nitron shock includes a small range of height adjustment which I would make use of to raise the rear and so reduce the overly generous fork rake and trail on this bike a little, but already the bikeís height is enough to make mounting and dismounting a bit difficult for my arthritic hips. The use of decent single-rate fork springs has reduced the excessive original sag of 54mm too, which hasnít helped with mounting but that is still a good trade-off.

    Given what I saw in the KSS workshop, itís clear that Robert and Dennis get to re-tune even the best suspension offerings, this for the same basic reason that nothing can match great components, expertly personalized.

    Forget more power, louder exhausts and bling until your bike gets good tyres and personalized suspension.

  2. #2
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    13th March 2003 - 11:47
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    Good to see you on here Graham and hear how the suspension upgrade is going. See you on the road sometime soon.

    p.s. Robert used to frequent KB a lot in the past then he did a runner and we don't hear his pearls of wisdom like we used to. I'm sure he would have a lot to say about the current Government as one example.
    Cheers

    Merv

  3. #3
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    15th October 2009 - 17:33
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    Wow thanks for the detailed review, Iíve got the same bike (not DCT) and have often wondered what Ďproperí suspension would feel like compared to the budget non adjustable OEM stuff.

    I donít really understand how it all works together as youíve described it but maybe one day...
    Moe: Well, I'm better than dirt. Well, most kinds of dirt. I mean not that fancy store bought dirt. That stuffs loaded with nutrients. I...I can't compete with that stuff.
    - The Simpsons

  4. #4
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    2nd February 2018 - 21:50
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    Quote Originally Posted by nerrrd View Post
    Wow thanks for the detailed review, Iíve got the same bike (not DCT) and have often wondered what Ďproperí suspension would feel like compared to the budget non adjustable OEM stuff.

    I donít really understand how it all works together as youíve described it but maybe one day...
    If feels a lot different, like OEM 4/10 versus now 9/10 front and 11/10 rear. If you're young and fit, weigh about 90kg when riding, and just ride commuting the OEM is probably OK. Just the same, after making sure you have good tyres fitted, the next thing to spend on is better suspension because it gives better comfort, road-holding, steering, braking stability and tyre wear.

  5. #5
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    Now go and order that loud pipe

  6. #6
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    Quote Originally Posted by merv View Post

    p.s. Robert used to frequent KB a lot in the past then he did a runner and we don't hear his pearls of wisdom like we used to. I'm sure he would have a lot to say about the current Government as one example.

    It may have been all the tight arse KBers who purchased fancy named shocks from the internet then bitched about having to spend $ in NZ making them work properly .........

  7. #7
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    2nd February 2018 - 21:50
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    Quote Originally Posted by AllanB View Post
    Now go and order that loud pipe
    I already have a Maccari silencer for the NC. Fitted it. Too noisy. Prefer original. I don't really like loud exhausts but do like to hear induction music, like the thunder in the airbox of my Buell. Sadly the Honda NC is a non-event aurally.

  8. #8
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    Quote Originally Posted by GrahamA View Post
    I already have a Maccari silencer for the NC. Fitted it. Too noisy. Prefer original. I don't really like loud exhausts but do like to hear induction music, like the thunder in the airbox of my Buell. Sadly the Honda NC is a non-event aurally.
    Mine came with a nice Mugen exhaust (itís also a used import) which looks better and has grown on me - just adds a little bit of character.

    https://m.youtube.com/watch?v=GUAPUJyh10A

    Just as a matter of interest, roughly speaking what sort of cost was involved in sorting your suspension? No problem if itís commercially sensitive
    Moe: Well, I'm better than dirt. Well, most kinds of dirt. I mean not that fancy store bought dirt. That stuffs loaded with nutrients. I...I can't compete with that stuff.
    - The Simpsons

  9. #9
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    2nd February 2018 - 21:50
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    Quote Originally Posted by nerrrd View Post
    Mine came with a nice Mugen exhaust (itís also a used import) which looks better and has grown on me - just adds a little bit of character.

    https://m.youtube.com/watch?v=GUAPUJyh10A

    Just as a matter of interest, roughly speaking what sort of cost was involved in sorting your suspension? No problem if itís commercially sensitive
    $2,500 and worth it. Despite my bike having under 4,500km when I got, so hardly worn out, the suspension was awful, especially when compared with the upgraded suspension on my other bike.

  10. #10
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    19th October 2014 - 17:49
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    I've got a 2014 CTX700 with DCT, and that shares the fork tube/slider with the NC700X and NC700S, and also some of the 750 twins. I bought a Matris cartridge conversion to upgrade the forks. I haven't had a chance to try it out as the bike is out of operation (it was bought as a long-term FF conversion project) but I expect it to be a good improvement over stock (which shouldn't be difficult to do). That does rebound in one leg and compression in the other, with external damping and preload adjustment in the top caps. The parts are very nicely made.

    I considered the Cogent/RT "emulators" but I didn't want to have to take things apart in order to try different settings.

    I went with the Matris on the advice of someone who does a lot of fork work as a side business. He's used the Matris, Ohlins and Andreani, and in his opinion the Matris works better and is made to a higher standard than the others. However, he does think they all need some help on the compression damping so he fitted his own design of compression piston and shim stack on that side before sending the kit to me.

    The Matris travel didn't match any of the three 700 models so I set it at 120 mm since that is common for GSXR etc. I wanted more than the CTX but not as much as an NC. The Matris doesn't require any modification to the fork tube or slider -- it has a "damper rod" section at the bottom below the cartridge that controls the travel just like the stock damper rods do, so I made a spacer to go there to set the travel. I added a couple more circlip grooves to the existing 3 just in case I needed to have more range of adjustment for the bottom spring perch.

    I also turned a shallower taper onto the stock bottoming cone to make that a little more gradual. But really the only thing likely to need to be done for most people would be to make the spacers for setting the travel. I used an Ohlins spring to get the required rate with a good fit inside the tube.

    Here's a photo of the modified Matris and the OEM components:

    http://www.eurospares.com/graphics/F...a_CTX_1146.jpg

    FWIW, I like the DCT and see no reason to have a bike with manual clutch. It works fine.

    cheers,
    Michael

  11. #11
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    2nd February 2018 - 21:50
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    Hi, Michael

    Interesting post, thanks. I'd never heard of the CTX700 before so I checked it out and it looks like an interesting bike. Forward rests don't suit me though.

    The bottoming cones in my forks were also machined for a softer landing. The cartridge system you've gone to sure looks more sophisticated than using Cogent DDC units. The cost of those parts?

    Are you happy that the rather slender axle system will cope OK with each leg doing a different damping task? High-speed compression impacts can be pretty harsh.

    Tomorrow morning my DDCs are off to KSS for another look at the high-speed damping shim stack and to soften the low-speed damping a bit. Your right about it being a pain having to remove DDCs. It could be done without removing the forks but I can't eat a meal without making a mess so removed them. Only a 20 minute job for me to have fork legs out and no mess.

    What are you intending to do at the rear?

  12. #12
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    19th October 2014 - 17:49
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    Graham, the CTX is going to end up with much higher and even more forward pegs and the rider about 6-8" lower and 8-12" farther forward when I'm done with it, like a Gurney Alligator but with the feet high enough to not drag if at 45 degrees of lean at full bump. The DCT makes relocating the feet a lot easier, as there's no shifter to worry about and the rear master cylinder is moving to the left handlebar.

    The NC700s and CTX700s (and I think some of the 750s) share probably 80+% of the main components. Wheels, brakes, fork tube/slider, swing arm and links are the same part numbers, the frames are nearly identical except for the subframes and brackets, the powertrain is shared, etc. I could have just as easily started with an NC for my project but a CTX with DCT came along at a good price first, so that is what I got. All the bodywork except fenders will be replaced.

    I got a lightly used NC-700 spec Ohlins, rebound adjustment only, for the back. The price was good and I suspect it will be more than adequate, and the prior owner was about my size/weight and he said that he never changed spring or settings from how they were when Cogent sold it to him.

    Having only one type of damping in each leg seems to be more and more common, even with OEM teleforks. The Honda has a 20 mm diameter axle which is about 3X stiffer than a 15 mm and not quite 2X stiffer than 17 mm, so I doubt that street use is going to see a problem with the axle bending from the damping forces. The improved compression damping should be more supple than the OEM damper rod harshness.

    IIRC by the time Matt's modest charge for installing his compression-side modifications prior to sending the kit to me and all the postage was included I was still under US$600 for the Matris conversion. That seemed pretty reasonable to me for the external adjusters and not having rebound damping changes done by changing the oil instead of the cartridge adjustment. The stock fork internals can all be reinstalled if needed as they were removed/replaced, not modified. I can make the spacers etc here at home and did not have any labor charges other than Matt's quick install of the comp piston.

    Matris lists 7075-T6 as the aluminum alloy used. I have zero issues with the quality of the machining.

    cheers,
    Michael

  13. #13
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    2nd February 2018 - 21:50
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    Hi, Michael

    Another great post, thanks. Why would a Frisco rider want to belong to this forum?

    Being something of a bike builder and modifier myself I'm fascinated by what you're doing with that CTX and wish I could visit your workshop easily. Have you any sketches or drawings you could share with us?

    The front axle. It's not fear that the axle will bend that makes me question the wisdom of putting any differential loads through them but that the anchorage into the legs isn't up to much compared with higher spec forks. The bridge over the wheel too is pretty low rent. If you ride on harsh surfaces I'd watch for any distress on those anchorages. The price of your mod compares very well with what has been done to my forks.

    Not everyone likes the stranger bikes from Honda but they fascinate me. Your creation should be a jaw dropper too.

    The latest Goldwing with DCT sounds like a bike I'd love to own if I was a lot younger and stronger than I am now. I have to reverse my bikes out of the garage then turn them around in a two point maneuver before riding down a sloping driveway to the road. I used to do it on an ST1100 but that was 1990-94.

  14. #14
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    Graham, it is difficult to find people interested in building/modifying things (other than chopper stuff) and I follow the foundry, race chassis, oddball engine and ESE works tuner threads here because they are full of like-minded people doing interesting things. I wish we'd had something like bucket racing over here, that looks like a lot of fun with DIY bikes vs the usual "ho hum, there goes another lightly modified street bike just like all the others" club racing we have had for decades since the GP bikes died.

    The damper rod Showas on our Hondas are low tech but they seem sturdy enough, and the Matris/Ohlins/Andreanis in similar forks on various Yamahas and Kawasakis don't seem to cause any problems so I'm not going to worry about it. Besides, my CTXFF will be a mild street bike, not a racer. I have a trackday/clubman project but that will get a Hossack or other FFE on it, not teleforks.

    I do a lot of my conceptual thinking by grabbing a good side view image and modifying it in a graphics program. This continues until I finally have something that seems to make sense (or more sense than not). I don't have anything very good to show you but I took a screen capture that shows the front end with the wheel at full bump and full lock, the base of the footboxes, the CRF450 heat exchangers and the 45 degree lean angle at full bump planes.

    http://www.eurospares.com/graphics/F...yscreencap.jpg

    The footboxes that will be hung off the mounts I made at the beginning of the year are still vague as I'm also juggling relocating the radiator to above the front wheel or replacing it with a pair of CRF450 radiators if they work better to allow a decent inlet/exhaust duct to them. I've also been sidetracked with a major garage clean-up/reorganization to make some space for a new welding table as well as making it easier to move around without tripping and impaling myself on something.

    But to not hijack your thread further I've seen reports from people with both Race Tech and Cogent emulators in these forks that are very happy with them and I'm not expecting the cartidge conversion to provide a significant improvement over a well-sorted RT/Cogent fork. Buying it was primarily a convenience decision.

    ETA: a lot of people knock the idea of FFs for other than touring or chops. I know several people with FF trackday bikes, and Tony Foale spent a day with Dan Gurney riding an assortment of his FFs in the SoCal canyons and said he enjoyed them. I see some possible pluses from FFs for those of us who don't qualify as fast riders on the track and I want to investigate that. They may not be what Rossi or other aces need in the very specialized world of MotoGP, but then I'm neither Rossi nor racing MotoGP.

    cheers,
    Michael

  15. #15
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    I too deal a lot with Robert Taylor, very worthwhile having bikes that do what they should do.

    Not cheap but worth it.
    Quote Originally Posted by Katman View Post
    but once again you proved me wrong.
    Quote Originally Posted by cassina View Post
    I was hit by one such driver while remaining in the view of their mirror.

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