Author Topic: '80 Cm400 Scrambler  (Read 3281 times)

Offline Zweihammer

  • Posts: 18
'80 Cm400 Scrambler
« on: Mar 21, 2016, 01:37:05 »
Here's my current project, one of a pair of sad, neglected 80 Honda 400s I was given a couple years ago. Between the two bikes and a bunch of left over parts from earlier projects, I started screwing around with the idea of a minimalist urban scrambler style. The only "off road" this will probably ever see is the occasional fire road around here.

The problem I am puzzling through now is I am extending and bracing the swingarm while I convert to monoshock. I already have a 2005 GSXR shock to use, but without utilizing the linkage I am finding it very soft, stupid soft. Like an '80s dirt bike soft. I'm a big guy at 230, and prefer my set up on the stiff side. Does anyone have a suggestion for a different, direct acting shock I could look into?

Here's how it sits now, the swingarm will be braced and the lower shock mount was a quick SWAG from a clevis I had just to see if I was in the ballpark.
And, yes, I know the forks are in backwards. Just wanted to throw it together to see how it would look.

« Last Edit: May 07, 2016, 02:13:39 by Zweihammer »

Offline JustinLonghorn

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Re: '80 Cm400 Mongrel Scrambler
« Reply #2 on: Mar 21, 2016, 07:45:25 »
Yep. I'm in.
I'm going to eat your brains and gain your knowledge.

Into The Sunset, CB750 build

TT500 the Animal

Offline 2.3efi

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    • Wrench Tech Racing
Re: '80 Cm400 Mongrel Scrambler
« Reply #3 on: Mar 21, 2016, 09:16:00 »
Looks awesome. It looks like you have a slight extension in your rear arm. If you cut out the stock bracing and replace it with tubular bracing, you could probably fit the linkage in.

I'm on my phone now, or else I'd link to my pix, but check out my cm450 build. You can see how we braced the arm for the monoshock.

Offline Hurco550

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Re: '80 Cm400 Mongrel Scrambler
« Reply #4 on: Mar 21, 2016, 10:39:23 »
"If you just picked up a drug habbit instead of a kawasaki triple at least you could get high while you waste money"
~ bradj

2006 Suzuki DR650 Adventure monowheel trailer build:
1976 BMW R90/6 farkilitious:
1975 RD350 Road Racer:
1973 Ironhead Hardtail:
1976 GT250 Rebuild:
Full Custom Pit Bike:
1971 Yamaha 90cc twin HS1:
"much ingenuity with a little money is more profitable and amusing than much money without ingenuity" - Arnold Bennett

Offline wahvtec

  • Posts: 290
Re: '80 Cm400 Mongrel Scrambler
« Reply #5 on: Mar 21, 2016, 10:44:47 »
Yup I'm in looks like a cool start for sure.
1969 CB350 (barn bike) (sold)

1998 Yamaha Riva XC125.  Gotta scoot.

1982 xl185.  "In progress"

Offline Kanticoy

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Re: '80 Cm400 Mongrel Scrambler
« Reply #6 on: Mar 21, 2016, 11:23:53 »
Yep this is rad.

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I get not knowing, but I can't for the life of me understand not trying. It's only metal it can be fixed. Man up and risk a mistake in exchange for a lesson.

Offline Zweihammer

  • Posts: 18
Re: '80 Cm400 Mongrel Scrambler
« Reply #7 on: Mar 23, 2016, 00:56:19 »
Thanks, everyone!
  2.3efi, your guys' Cm450 is certainly one of the best, an inspiration. I see you sell extensions for the 360 swingarm, are those swingarms made of two thinwall tubes sleeved within each other like the '80 400s are?
   I was more than a bit annoyed to find that was the case when I added the extensions to mine. I realize these were originally designed to a price point, but I can't think what the benefit Honda realized by sleeving two as opposed to a single heavy wall. I will be using .120 wall DOM tube for the additional brace and shock mount.

Offline NoRiders

  • Posts: 624
Re: '80 Cm400 Mongrel Scrambler
« Reply #8 on: Mar 23, 2016, 05:42:45 »
Liking the look of you bike fella, hope your tech mods work out.

Could you change the coil spring rate/poundage and notch up the damping adjuster (if it has one?).

I have a made to measure, direct acting, 13 stage damping adjustable Protech Shock with a 6" 650lb coil-over set up which I can wind the coil up and set damping so plenty of tuning in it. Might suit your requirement?

Offline svkustoms

  • Posts: 2
Re: '80 Cm400 Mongrel Scrambler
« Reply #9 on: Mar 23, 2016, 17:37:48 »
I did a cx500 with an r1 shock. Changed the spring. Had to jump up to over 1000 lb spring

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