What different front end swaps have you done to your CB125S ?

G

grcamna5

Over 1,000 Posts
I'm restoring my 81' CB125S and I think the front forks are a little light for me(the stockers are 27mm)plus the front brake's a drum..a tiny drum.I'm about 210lbs. and I'll be carrying stuff most of the time and running along at a good speed so i'm considering thicker fork tubes.Have any of you considered installing an 85-87' CMX250C Rebel front end ? it's 33mm tubes w/ an 18" front 3.00 x 18" tire and front dual piston hydraulic disc brake.
The triples/steering stem are the same size head bearings but the trail is a lot less which could make the little bike kind of 'twitchy'... I imagine the 250 Rebel fork tubes are longer than my stock CB125 tubes.. also the trees are a lot wider than the 125 which would change things a little too.
your thoughts.. :)
 
I swapped a CM200T front end on mine, 31mm tubes and bigger drum. Definitely longer than the stock forks. But, it was a direct swap, just bought some new all balls bearings. Haven't ridden it yet so I can't really say how the handling was changed, but even with the forks slid up 3/4" in the trees the front is still taller than it was. Hope this helps!
 
CALfeRacer said:
I swapped a CM200T front end on mine, 31mm tubes and bigger drum. Definitely longer than the stock forks. But, it was a direct swap, just bought some new all balls bearings. Haven't ridden it yet so I can't really say how the handling was changed, but even with the forks slid up 3/4" in the trees the front is still taller than it was. Hope this helps!
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Yeah Cal,
That sounds like a good swap,I'd like to hear how it handles w/ the longer forks.I think it's just about certain that I'll install a front end from an 86' Rebel 250,the bearings are a direct swap(checked'em online)and the fork tubes..I'm not too sure how long they are compared to my CB125 stock tubes but I'm willing to 'go for it',I don't see any other small bike front end that'll give me a good hydraulic front disc w/ an 18" wheel and large fork tubes.I know the triples are a Lot wider and I'm hoping that won't affect the nimble handling of the bike much.. The other thing I'll need to do is create 2 steering stops(I can't see how the Rebel 250 'stops' their's)on the top of the bottom triple clamp.
 
Check out Inari, by Deus' Bali shop. It's a CB100, but the major components are the same between the 100/125. They used the front end off of a (I believe) Yamaha XT225. I'm sure you've seen it, but the All Balls conversion table is a very handy little piece of information, at least for bearing swaps. The rest just depends on steering stem, stops, and fork length, as you mentioned.
 
I'll let you know when I get to ride it. But, I'm also putting on longer rear shocks to raise the whole bike a little and even out the rake angle.
 
coyote13 said:
Check out Inari, by Deus' Bali shop. It's a CB100, but the major components are the same between the 100/125. They used the front end off of a (I believe) Yamaha XT225. I'm sure you've seen it, but the All Balls conversion table is a very handy little piece of information, at least for bearing swaps. The rest just depends on steering stem, stops, and fork length, as you mentioned.
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coyote,
I saw that a few times;he did use the Yam XT225 Serow parts.The engine w/ an 88mm piston Wow,that's huge :o 8) . He chopped down the length of the forks though
 
Yeah I would think 180cc is really maxing out the capacity of that little bike. You can get up to 145cc using a stock CB750 piston though, I hear it was a pretty common "back in the day" upgrade
 
I'm under the impression you can swap in XR engines up to the 200 without any major work. I think the rear mount holes are 2mm wider is all. And the CB750 swap came up a lot when I was looking at engine mods. I ended up finding an oversize piston and getting it bored out to 135cc.
 
CALfeRacer said:
I'm under the impression you can swap in XR engines up to the 200 without any major work. I think the rear mount holes are 2mm wider is all. And the CB750 swap came up a lot when I was looking at engine mods. I ended up finding an oversize piston and getting it bored out to 135cc.
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Cal,I'm looking for an 86'-02' XR200 engine myself,w/ that I should be able to get up on an Interstate if necessary.I like small bikes.
 
Take a look at the Lifan engines if you're planning to do a swap anyways. Cheap and plentiful, and I've actually heard pretty decent things about longevity and performance.
 
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