CB125s My First 2-Wheeler - stretched and mono-shock

Fifty1

New Member
5/6/14

14+-+1





as of 4/22/14

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Building/modifying my first bike!!

I have really liked the idea of having a bike for a while but in my area its harleys and sportbikes, neither of which I care for much.. you just dont see cafe style bikes around here, so for the longest time I was oblivious to the whole cafe racer scene. So a year ago I really started to take notice of all the cool cafe bikes on the net, and last summer I picked out my first.. an 82 honda cb125s got it for 600 in Michigan with only 900 miles on it!

Ill let the pictures do most of the talking...

here it is just as I bought it
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Some shots of it with all the crap stripped off and the handlebars flipped just to get the feel of lower bars
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Here are some more recent shots, just trying to mock up a stace for it.. I think it looks good with the rear sitting up high
so far the only real mod is the tarozzi clip-ons

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Now the part where I could use some advice and some help.. how to get the bike to sit that high in the back? because the swingarm (for mock up purpose only) is mounted in a lower hole in the frame and not in the actual pivot hole.

The swing arm in its stock form will not angle down far enough without hitting the frame so my first thought is maybe a swing arm swap?

second problem, dual side mounted shocks to lift it that high might look dumb, so maybe a monoshock conversion would work?

the swingarm pivot mount is almost exactly 6.5 inches wide. Does anyone know of a monoshock swingarm that measures 6.5 inches wide at the pivot?

thanks for looking, feedback and advice is is very much appreciated, this is my first attempt at a bike and maybe there are some things to avoid??
 
Re: CB125s My First 2-Wheeler

working on the seat pan and tail fairing

started by making a wire frame

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wrapped the wire frame with steel using a hammer.. this piece is more of the 'fighter' style

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Re: CB125s My First 2-Wheeler

I dig the tail piece man. Good job. Also, listen to Alpha. Raising the ass up as high as you had it woukd make that bike a bastard to ride. You'd also need some of those super rare 22" shocks. Ha...
 
Re: CB125s My First 2-Wheeler

some more progress.. looks like im going to need about a 16" or 400mm shock
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Re: CB125s My First 2-Wheeler

what about the chain?the rear sprocket is also goimg down with the end of the swingarm.the countershaft stays in the same position and the cahin would ride on the swing arm,it seems it would wear out a rub block in no time with that much angle
 
Re: CB125s My First 2-Wheeler

ole rob said:
what about the chain?the rear sprocket is also goimg down with the end of the swingarm.the countershaft stays in the same position and the cahin would ride on the swing arm,it seems it would wear out a rub block in no time with that much angle

yea, I have that concern as well. My first thought like you said, would be a rub block. I have also seen some people use roller tensioners with a small sprocket mounted on a spring loaded lever.

I will have to check the extent of this when I get the bike mocked up further.
 
Re: CB125s My First 2-Wheeler

Or you could consider a less fucked up, death trap design. Taking away that much rake and trail from the front end will make a bike that isn't all that stable to begin will give you a twitchy, tank slapper prone death trap. You'll hit a little dip in a curve, go into a tank slapper, and they'll be scraping your sorry ass off of the guardrail with rubber spatulas.

Oh, not to mention all the chain issues with the chain going tight on suspension compression, and loose on suspension extension. Don't even consider idlers sprockets to route the chain and tension it. Nothing but trouble.

Use a little common sense, and maybe, MAYbe, you will build a bike that is actually rideable. But hey, if that isn't even your goal to begin with, go ahead and make driveway jewelry that you can ride as far as the nearest bar and crash on the way home.
 
Re: CB125s My First 2-Wheeler

On the other hand, nevermind. I already told you this and you've chosen to ignore it.
Make sure you have a good life insurance policy. Your family will appreciate it.
 
Re: CB125s My First 2-Wheeler

AlphaDogChoppers said:
Or you could consider a less fucked up, death trap design. Taking away that much rake and trail from the front end will make a bike that isn't all that stable to begin will give you a twitchy, tank slapper prone death trap. You'll hit a little dip in a curve, go into a tank slapper, and they'll be scraping your sorry ass off of the guardrail with rubber spatulas.

Oh, not to mention all the chain issues with the chain going tight on suspension compression, and loose on suspension extension. Don't even consider idlers sprockets to route the chain and tension it. Nothing but trouble.

Use a little common sense, and maybe, MAYbe, you will build a bike that is actually rideable. But hey, if that isn't even your goal to begin with, go ahead and make driveway jewelry that you can ride as far as the nearest bar and crash on the way home.

Maybe not the nicest way to put it, but it's all true.
Suspension adjustments should be made millimeters at a time, not inches.

I think stock length is 10.5" on the CB125 and you're talking about going to 16"? I went +1.5" on my CB360 and immediately went back to stock before I covered more than 20 miles. Too much instability. You ride this bike with 16", it won't be on the road for long.
 
Re: CB125s My First 2-Wheeler

AlphaDogChoppers said:
You had better do some calculations with a rake and trail calculator. Raising the rear reduces steering stem rake. You could end up with a twitchy, unstable bike that wants to do tank slappers.

http://www.rbracing-rsr.com/rakeandtrail.html
http://www.rbracing-rsr.com/advchoppercalc.html

What AD said. I lowered my front 1.5 and raised the rear by adding an 18' rim and 1/4" longer shocks. Handles good up to 90 (as fast as I've had it yet), But I also have a steering damper added.
I would think if you were to have the swingarm in the pivot location correctly and tried to achieve that height you would have the chain grinding the swingarm as well.
When changing front or rear heighth be careful with how drastic your changes are. Better to have a little lower angle and a ridable bike than a nice show piece you can't control.

Gary
 
Re: CB125s My First 2-Wheeler

Sonreir said:
Maybe not the nicest way to put it, but it's all true.

I only had 2 1/2 hours sleep last night, so I might be just a tad crankier than my usual crankiness.

GET OFF MY LAWN!
 
Re: CB125s My First 2-Wheeler

I only had 2 1/2 hours sleep last night, so I might be just a tad crankier than my usual crankiness.

who could tell the difference ?

~kop



:p
 
Re: CB125s My First 2-Wheeler

The rake and trail calculator are good tools within limits .
From experience the amount of stem to tube offset will not allow a good sense amount of trail with your intended modifications .
As for the swingarm interference all you can do is relocate the swingarm pivot . Not an operation for the faint of heart or the weekend welder . Better a roller with bearings than a rub strip . Still any device over the top of the swingarm will place stresses on the chain , countershaft bearing , swingarm pivot and transmit those stresses to the rear axle as irregular drive pulses .
At the top of the 1-800~ section is a sticky including several front end swaps that you may want to look over . Although available easy possibilities are limited a little outside the box thinking is in order .

Only after all that will i say what the hell are you thinking ? I don't get the object of the exercise in engineering futility .

~kop
 
Re: CB125s My First 2-Wheeler

Well sounds like all good advice.. And I'm not too sensitive so no worries on the harshness if that's how strongly you feel about it.

Bike is not on the road yet and I have not made any modifications other than letting the swingarm droop in a way that gives me 4" of lift at the rear shock. To put it back to stock all I have to do is take it off of the jackstands..

That being said, is there any pitfalls to setting the arm at stock level and angling the angling the seat section of the frame upward to give me a higher riding position??
 
Re: CB125s My First 2-Wheeler

Yes. Itll look funny and make the center of gravity way too high. Plus the riding position will be terrible. Is the bike too small for you?
 
Re: CB125s My First 2-Wheeler

kopcicle said:
who could tell the difference ?

STFU!

Just got up from catching 5 hours sleep, so THIS is me regular crankiness, motherfucker. :D

Some say I am "blunt." I say, "Sometimes it takes a few whacks with something blunt to get through a thick skull.
 
Re: CB125s My First 2-Wheeler

VonYinzer said:
Yes. Itll look funny and make the center of gravity way too high. Plus the riding position will be terrible. Is the bike too small for you?

yea it might be on the small side for me.. Im 6"1' 185 I can ride it at stock height, but where I would like to put the rear sets comfortably, seems very low to the ground and may be close to scraping the ground if the bike is leaned over too far.

I think there is some room to sit up higher, the stock seat has at least 4" of padding, and now Ill basically be sitting on the frame with a very small padded seat, the overall riding position wouldnt be far from stock.
 
Re: CB125s My First 2-Wheeler

okay, made some adjustments.. to make the chain clear the pivot and the rest of the swing arm, I pulled up the droop to set the rear shock at 2" over stock. does that make for a better MAXIMUM amount of lift and adjust down to stock from there as needed?

It doesn't look too bad at this height and I seem to fit comfortably..

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This height is just over 2" over stock now in the back
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Chain clearance at 2" over stock height in the back.. is there a recommended minimum?
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Stock shock is about 12.25" eye to eye
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new shocks would need to be about 14.25"
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