79 Honda CM400T - Nerdsports Racer - SHE'S DONE!!

nerdsports

Active Member
UPDATE: Here's the completed bike.


I have no idea what to call this thing. I had lots of inspiration but the stock frame pretty much ruined it for me. After one text message, the direction changed and the label/style was lost.

Night I picked it up.


Fresh gas, new plugs, and mildly clean carbs got her running this night.


After some disassembling, I finally had it the ugly factory stamped metal.


This is when things changed. Got this 2006 CBR600RR front end.


As if the stamped metal wasn't ugly enough, the frame loops just never sat right with me.


Front end was tough so the rear had to match. [in progress shot of the mono shock brace]


That's it for now!
 

Frankenfe

Coast to Coast
Re: 79 Honda CM400T - Sporty on a budget

Wow one of if not the most aggressive transformations I have seen to the 2nd Gen Twins (CB/CM's) frames/suspension.

Interested to see your sub frame/shock design, as well as seat and tank choices.

What Rear Wheel Brake set up do you plan? What do you have planned for the engine/exhaust?
 

nerdsports

Active Member
Re: 79 Honda CM400T - Sporty on a budget

Rough cut on the top edge of the top shock mount.


Tacked on.


Rear angle shot.


Best part is that it worked. I have an R6 shock coming that has the reservoir mounted behind the spring rather than off to the side like this CBR shock.
 

longhorn717

Active Member
Re: 79 Honda CM400T - Sporty on a budget

I like the design but looks like travel is much shorter and I think I'd be worried about it binding. Most of the mono shock set-ups I've seen are laid down more or have a link to redirect the movement/energy. Just my .02

I really want to do a monoshock setup but I think a pipe bent into a u shape same as the swingarm and braced like a trellis with the shock mounted on top of the pipe or off to the side would work good.

Look forward to seeing your progress. Looking very street-fighter-ish is that what you're going for?
 

nerdsports

Active Member
Re: 79 Honda CM400T - Sporty on a budget

longhorn717 said:
I like the design but looks like travel is much shorter and I think I'd be worried about it binding. Most of the mono shock set-ups I've seen are laid down more or have a link to redirect the movement/energy. Just my .02

I really want to do a monoshock setup but I think a pipe bent into a u shape same as the swingarm and braced like a trellis with the shock mounted on top of the pipe or off to the side would work good.

Look forward to seeing your progress. Looking very street-fighter-ish is that what you're going for?

I wanted to do exactly what you said but this bike is small and I didn't think I had enough room to place the shock higher or more laid down. Once I tacked the top mounts I put the bike down and jumped on it. It seemed fine other than the suspension being set way too soft. I'm going to ride it before I disassemble it for paint & final assembly so if I have to change it, I will. Thanks for your input!

I have no idea what I'm going for. It's a mutt between cafe/brat/streetfighter. I can't seem to label it.
 

longhorn717

Active Member
Re: 79 Honda CM400T - Sporty on a budget

Yea I've got an '80 cb400t and it keeps changing. as soon as I get some money and time maybe in a month or two. I've going to jump into working on it again. My thought on the shock is one of two designs both I've seen used on custom and production bikes.

1. double up the swingarm and fab a upper shock mount between the frame rails as close and high behind the carbs as possible.

2. same swingarm but push the lower shock mount back and move the upper mount as forward and high as possible on only one side. Ideal if you were so inclined to find or make a single-sided swingarm.

I know these bikes are low on most peoples lists. but a lot of the fun and enjoyment comes from making a faster and unique bike. Not from the most popular bike but with a bike we already have.

Looking forward to see what other mods you have in store.
 

longhorn717

Active Member
Re: 79 Honda CM400T - Sporty on a budget

Oh and as far as the rear section goes. I'm considering doing a upswept tail section. come from the top of the frame hoop up and back about 14" narrowing them about an inch front to rear. then bend them up about 60 degrees for 5" or whatever floats your boat. on my reckoning you should still have about 7-10" between your new rails. bring them back enough for a second seat and a small hump if you want. I'm thinking about 3-5" at the rear where you'll make the u-turn. of course you'll need to come down a bit from where you started your new tail section and add some supports. and this is little area is where I would put my electrical and battery.

Let me know what you think. pretty lightweight but you still look tough and have a room for a girl.
 

nerdsports

Active Member
Re: 79 Honda CM400T - Sporty on a budget

Frankenfe said:
Wow one of if not the most aggressive transformations I have seen to the 2nd Gen Twins (CB/CM's) frames/suspension.

Interested to see your sub frame/shock design, as well as seat and tank choices.

What Rear Wheel Brake set up do you plan? What do you have planned for the engine/exhaust?

Hey, bud. Sorry I missed replying to you. For now I'm keeping the stock rear wheel/brake setup. I'm going to look into a) 4" wide sport bike wheel & disc brake or b) converting to laced wheels front & rear and then deciding between disc or keeping the drum. The engine is staying stock internally for now. Going to clean the crap out of it and throw some foam pods and fabricate a 2 to 1 exhaust. I'm still not sure on the specifics of how I'm going to run it but definitely 2 to 1. I do want to pep the engine up with some higher CR pistons (maybe more displacement if possible).
 

nerdsports

Active Member
Re: 79 Honda CM400T - Sporty on a budget

Here are some updates - got the stem bearings in (tapered rollers), the tube bender is setup for making the seat tail/bracing, tank is mounted, ordered CB400 rear passenger peg mount brackets for rearsets.

Changed the shock from the all black CBR unit to an R6 because the reservoir/accumulator is mounted differently.


Profile shot


My buddy SOKFAB turned these for me. Counterbored bungs for the headlight bracket.


Made these fork clamps for the headlight bracket setup.


XL500 tank came in.


I like this profile of the tank most.


Stock coil tucks nicely under the raised tunnel of the XL tank.


My bikes.


More coming very soon!
 

oldskool

Joon-yah
DTT SUPPORTER
DTT BOTM WINNER
Re: 79 Honda CM400T - Nerdsports Racer

FYI an 82 cb450 with 6speed will drop in and hookup with no prob. Thats what I'm running in my 81cm400.
 

Rich Ard

doin' the backstroke in an estrogen ocean
DTT BOTM WINNER
Re: 79 Honda CM400T - Nerdsports Racer

I dig the giant sissybar on the sportster. If a thing's worth doing, it's worth doing right. :)
 

nerdsports

Active Member
Re: 79 Honda CM400T - Nerdsports Racer

oldskool said:
FYI an 82 cb450 with 6speed will drop in and hookup with no prob. Thats what I'm running in my 81cm400.

Thanks for the heads up!! Once it's up and running I'll see how I feel about it's performance (I'm not expecting much). I'm already tinkering with the idea of throwing together a small turbo setup.


Rich Ard said:
I dig the giant sissybar on the sportster. If a thing's worth doing, it's worth doing right. :)

Glad you like it. Might be redoing it at some point as it wiggles a bunch when I hit road bumps.
 

nerdsports

Active Member
Re: 79 Honda CM400T - Nerdsports Racer

While I wait on access to my friend's tube bender to fabricate the seat frame/tail, I figured I'd replace the CM400 peg brace/swingarm mount/i dont know with one from a CB400 which integrates the rear passenger peg into a nice one piece mount. Unfortunately, they're not as plug & play as I had expected.

I only got a picture of the right side which had 2 bolt holes line up.


To make the left side fit I will have to drill a new hole into bracing that's underneath the peg braces. It'll only have 2 mounting locations which makes me extremely uneasy since the swingarm pivot is secured to them. They're going to require much more work than I anticipated. Should've made them one-off. :-\
 

longhorn717

Active Member
Re: 79 Honda CM400T - Nerdsports Racer

looking great. Yea those are a PITA for rearsets or anything other than stock. I'm thinking its definitely a one-off situation. Looking forward to what you come up with.
 

mohabie

Been Around the Block
Re: 79 Honda CM400T - Nerdsports Racer

I haven't quite decided on rearsets on my CM400 build and will be monitoring your progress :)
 

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