CM400 Re-Re-rebuild.

Thought I might share my build here as well as Hondatwins. In the continuing saga of my 1980 CM400 (original re-rebuild here:http://www.hondatwins.net/forum/viewtopic.php?f=5&t=17879&hilit=guinea+pig) and in response to a conversation about suspension upgrades with LDR(http://www.hondatwins.net/forum/viewtopic.php?f=61&t=23600), I've started working on my bike. Again. Take 3, or something like that. Here's one last look at where I am now.



Note the large dent in the tank from a recent spill. That's part of what has me thinking I need some work. The bike doesn't fit me as well as it should, and I've never really tackled any suspension work. The plan is to rebuild the suspension with some upgraded parts and then work on the ergonomics a little with some clipons and rearsets. In order to get a full Progressive suspension, as they don't make front springs for ours, I decided to slide 1979 CX500 tubes in my trees. Same diameter, and even the same fork sliders, down to the part number. I THOUGHT they were an inch longer. Didn't turn out to be the case, however.



I don't think this is going to be a huge issue, but I guess we'll see when I go to figure out my ride height. I'm also using a Nighthawk 450 swing arm to give me a slight stretch, and maybe a 130 rear tire, along with an 18" hawk rear wheel. Looks to be around an inch longer. Not a huge difference, but I didn't really want a whole lot.



So now I've got the bike torn down, waiting on the rest of my parts.



There's a lot of stuff on the way. I'm going to change the seat at some point, as well, just waiting for dime city to get it back in stock, and may wait until after the next VJMC rally that I'm trying to get it ready for. Oh,and if anyone has a decent CB360 tank laying around, lemme know. The wife has me talked into a killer new paint scheme.....

So here's a mockup of about where I had the forks before.



It's pretty darn close to bottoming out on the lower triple. About 3/4 of an inch. I've got a fork brace on the way, too, so that's not gonna work. I was planning on putting my clip ons above the upper triple, but I don't think I'm going to do that now. Better safe than sorry on the roads I ride.

Wasn't thrilled with the black painted sliders, either, so I stripped them down and did a quick polish. Actually a little shinier than I wanted, but they'll dull down soon I'm sure.



Did a quick look at the rear, too. Just eyeballing things, but it looks like I need to add 4.5 mm to each side to line things up. Sounds pretty close to the 4.6mm extra length on the nighthawk engine output shaft, too.



A good friend of mine (KZsAll) is going to help make the spacers once I get the rest of the parts.

Just out of curiosity I wanted to see about what it would look like at ride height. I've always felt like it needed more tire and wheel versus the fender. This is the old wheel, but I think the 18 will look even better.



It follows the lines of the fender so much better. I'm liking how things are looking so far!

I recognize this bike. LOL. Your shop looks like mine when I get "involved" in a project. Cant wait to see what she has you talked into and help where I can. Looking forward to the VJMC event and hoping to have mine going by then. Following along as you work out the details.

Got a second shipment of fun stuff today!





My wheel and Swingarm bushings are here! I don't plan on using this tire, by the way. It's an original looking tire, and kinda dry-rotted. But it'll work for fitting purposes. About 30 minutes later....



Hit it with a wire brush and some carb spray to clean it up. The swingarm's drying in the sun as we speak, then I'll get some things put together. Wish my stuff would get here!

Got my lowering spacers made. They're not real pretty, but they shoulld do the job. Should keep me from bottoming out on the triple clamp, too. (I hope.)




Got the swing arm painted and put back together with new bushings and zerk fittings.



And I couldn't resist trying everything out.



With my temporary axle spacers, the chain seems to run fairly true, although it's really too tight to tell for sure. I have it slid all the way up and it's still too tight at ride height. And my new chain won't be here for two days! But it looks so bad a$$! I'll probably have to chop the fender a bit, as the wheel's about 3/4 to a full inch ahead of where it should be at the moment due to the chain. But that tall wheel makes such a big difference, I think. I'm getting excited about this thing for sure, now.

Looking great! I know your getting excited. I'll get up with you on bringing that tire I have to you or something. Actually the chain being tight can help with the alignment check. See how the sprockets teeth line up in between the links. With it so tight the chain doesn't have in side to side "play". So if the teeth are centered in between both sprockets as it sits now you will be good. Can't wait to see this on the road again and at the VJMC event at the end of the month.

Right now I may be just a little off to the right side, but my spacers aren't exactly precision. Hard to cut something that close with a band saw and a grinder and get it straight. Lol. I'm real damn close, though. Stuck waiting on UPS and USPS right now. :'(

So work has gotten in the way a bit, but I've gotten some parts in. Shocks and springs are here, the new front tire, chain, axle, and the Tarozzi fork brace. I wasn't going to do any work tonight, but it happened anyway. Threw the new chain on and played around trying to center the wheel and make sure the chain ran right. My initial measurements were way the hell off. The chain ran ok I thought, but the wheel wasn't centered in the bike, even though it really looked like it was from the rear. The good news is, now I don't need to make spacers. The long spacer from my bike and the long spacer from the nighthawk axle centered the wheel perfectly. I've measured it in two different spots, between the arms of the swingarm, and between the passenger footpeg mounts, and it's dead on. I would like to know if there's a better way to measure this thing for sure, though. I was just talking to my friend earlier about them, and how I bought an axle with spacers to see what I could make work. Didn't think they actually would, though. Lol. So here's where it sits now, with new everything in the rear.



And here's my fork brace. This thing is BEEFY.



And damn my garage is a mess. I'll get it cleaned up. After this bike. Maybe. :lol:

Hell yeah, my Dime City order came in! I'll post pics later, but I wanted to pose a quick question before I went to bed. When I do the linkage for my rear brake, I obviously have to change the ratio due to pedal travel. Is there kind of an optimal ratio to look for here? Should I make the brake arm itself the same length to the pivot point as the lever on my control (1:1) or should I change it up or down from there?

Had a big visual progress day!

Got some advice from hondatwins, and it turn out the stock lever ratio is pretty much 1:1, too. They're just both longer than hell. Lol. So, here's what I came up with for the brakes. I really need to get some longer linkage, though. I think it looks a little funny. I used what came with the Dime City kit.



It should work, I just need a little more tweaking,and to adjust my exhaust a little inward. I have to room now that there's not all that other brake stuff in the way.

Gear shift side, I need to shorten this one some more, for comfort and for looks, but it does work.



And, since my for seals and stuff came in, I went ahead and put the front end together. Haven't filled it with oil yet, though. Just had to put it down on the ground to check out the stance and peg posistion.



I did go ahead and use the lowering spacers for the front, even though I've kinda been debating on not. I'm glad I did, though. It feels right now. I'm leaning forward with the clip ons and rear sets now, too. I'm really looking forward to getting this thing going. All I need now are some tweaks to the rear sets, mount the new tires, fill the forks with oil, and mount the headlight and controls. Won't probably have the tires done until next week, but maybe I can take a quick spin around the neighborhood by the end of the weekend!

Really digging the stance and look. Cant wait to see her with the tires on and riding around. VJMC event should be a blast. So looking forward to that ride and don't worry I go slow. LMAO

Bike is looking great. Couple questions on the fork brace I'm looking for something similar for a cb400 front end. What size tire are you running? Would you be able to get me a measurement from the fender bolts to the bottom of the brace and maybe a few more pictures of the brace? Thanks in advance.

I really like these tanks... Very cool bike. Question on the forks too.

What made you go for the CX forks other than they fit what you have? Are they any better than others of that size? I'm not sure what you mean by full progressive suspension, I don't know much about the cx forks if they are superior than others in their class or not.
Thanks

Mike

Honestly, the CX500 forks aren't really an upgrade if you already have straight forks. At least the 79 model forks I got have the exact same part numbers as my 80 CM, but stiffer springs. I had one that had a slight curve to it, and I got them because Progressive (brand name) makes a spring for them, and not for the CM400. But they're the same length and diameter, so there's no reason I know they won't fit. They're made for a little heavier bike, but the front could use a little stiffening anyway. That and I'm 6' 1" and 200 lbs, so I'm sure it won't hurt. Lol.

Just saw the question about the fork brace. It's listed on the fast from the past site as a cx500 part, but I'm only using the actual forks and sliders in my triple trees, and it works just fine. I looked at some part numbers and the lower forks sliders are identical part numbers. Depending on your year CB400 it may bolt right up. I did find another site somewhere that listed all of the fork braces as the same part number anyway. I'll check the measurements tomorrow when I go out tomorrow to work on it.
Oh, and it's a stock 100/90 18 tire.

Ok, got bored and decided to take you a couple of pictures. Lol.







There's plenty of room for a taller tire if I were to ditch the fender, and probably plenty for the CB front wheel. I hope this helps. I bet it would probably fit if it's an 80 model or prior. The CM forks seem to change in either 81 or 82. There's an actual part number listed for those years, though.

Been a slow couple of days, waiting to get my tires mounted, and my favorite local shop is apparently closed on Mondays now. Lol. It's race season, he's pretty busy. Did come up with a stop adjustment for the rear brakes. Pretty simple little bracket. And attempted to make some linkage, but it's too flexible for my liking,so now I'm waiting on an order from McMaster Carr, as no one around town carries M6 all thread.



And here's a closer view of the stop.



It gives me some of the adjustment back at least. Before I would have had to move my foot A LOT to stop. Now I can set a little kind of pre-load on the brakes. Put the controls and headlight on, too. It dropped everything on my front end quite a bit, so I lowered my gauge mount and bent it upwards to even things out. Also moved the choke cable to the old hole from the handlebar mounts like I've seen on several other bikes now.



Hopefully I can get my tires mounted tomorrow, and maybe mid-week I'll have it back down on the ground for some adjutments for the controls.

One question. I haven't filled my forks yet, as the Progressive instructions talk about measuring the level of oil in the forks. Last time I did it, I just poured in the specified amount. They say the way the springs are made now, that may be too much. What's a good estimate of how much to use,or how to measure it?

Sorry for late reply,

Gotchya on the forks, makes sense. They really haven't changed much in those few years. Pretty cool how a lot of these parts are interchangeable to an extent.

I've seen that fork brace on a few other bikes on other forums, they seem to work well. Yours looks great. Nice rear sets as well. Nicely lathe work on the knurled*not sure how to spelled it*

Can't take credit for the machining. Came from the good folks at Dime City! They're really nice, though. I finally got the stuff in today to make my rear linkage. It's been so long in coming I've been through about fifty more possible designs in my head. Settled on a hybrid setup once I learned that the stock adjuster nut was the same thread that I had just ordered to match the heim joints they sent with the kit. It's got all the adjust ability of a stock setup. I have no idea how to get a brake light switch on it yet, but I'm looking. Sorry for the crappy pics.





Yeah, I still need to cut a bit off the rear, but it's late. Feels comfortable, too. We'll see after the test ride. Still have some cleaning up to do, making sure that big rear tire clears by shortening some bolts and my turn signal stalks inside the rear fender, and lubing everything up. Haven't had much time to work on it lately, maybe tomorrow night I'll have a little time.

Very nice. I am going with big wheels and tires on my 125. Big issue with a front fender.