What fits a sl125 frame

S

Steaksauce

New Member
So I'm going to a swap meet this weekend and figured I might keep an eye out for a motor bigger than my 125 if one would just bolt right in, I'm not looking to do any modifying if possible bc I'm fine with the 125 but wouldn't mind the extra power if its easily aquired. My current 125 needs torn down and completely rebuilt so thats why I'm kicking this idea around.

Anyone know of a list or have experience? I've seen that maybe a xl200 would be the same but wanting to get some more feedback since I'm newer to small bikes and you guys have some serious knowledge.
 
You'll want to look for XR200 engines, specifically the 1980-82 models. These *should* be a direct bolt in. Other XR200 engines might fit, but may need some modifications to the frame to make mounts (bottom mounts seem to be OK, but the top mounts no so much).

Attached is a PDF document with more information than you could possibly ever want about the CB/CG/SL/XL/XR engines.

tl;dr for the PDF: Any of the 125cc singles are going to make around 10hp but the transmission gearing will be slightly different.
 

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This is geared towards the 100's, but there should be some information for you in here.


http://www.thumpertalk.com/topic/404455-hotrodding-an-sl100/
 
Forgot to mention, a fairly common mod is to put an XR200 top end on the CB/XL/SL/125 bottom end. There's more to it than just swapping but a couple people here have done it.
 
Shit the XR200R fits with about 2 mins of grinding on the frame. Its a good fit but the kick start will hit the rear sets. I have done it
 

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Thanks for the input guys! I'm curious on the 200 what did you have to grind on and did you have to change any of the mounts? Also did you use the 200 gearbox as well?
 
You have to cut a "C" out of the rear stamped frame to get the engine to go in, if I remember it's the kick starter that needs clearance.
We did it with a plasma cutter and it was literally a 10 second job.
 
Yes,the whole XR200 engine is a easy bolt-in job and the sprockets from your CB125 will fit right on to it and it'll work fine;you'll have to change final gearing(rear sprocket)for it because the XR200 has a bit taller primary gearing... go w/ a bit taller rear sprocket than the 125 has;you'll have to play around w/ the size of the rear sprocket until you arrive at the 'sweet spot' for your riding/loading style and road conditions and desired rpm's while cruising;it'll depend a lot on the power of the XR200 engine you install.
I'm doing this same swap in my 81' CB125S and it already has the factory frame cutout where the decompressor 'hump' on the back of the(125) eng. cases are larger, so for me it's a drop-in set up.I'm going w/ an 83' XL200R bottom end(and XR200R piston) w/ it's 12 vt. strong alternator,neutral switch and 5 spd. trans. but I'll swap in a 6 spd. trans. from an XR later on.I'll be changing all the electrics to 12 vts... I bought a complete 83' XL200R parts bike for this swap.
I'm hoping that she'll be pushing 85 flat out when I'm done and cruising at around 70;that'll be enough to let me run on the Interstate for a short 'hop'.
I highly prefer two-lane roads over Interstate Any day and having a 'little' bike is fun for me,I need to slow down and save gas anyway..
 
The twin shock XR 200 had basically a XL125 six speed transmission so second gear is a little weak.
The five speed is a little stronger but not by much
 
crazypj said:
The twin shock XR 200 had basically a XL125 six speed transmission so second gear is a little weak.
The five speed is a little stronger but not by much
Click to expand...

PJ,
I just found a bottom end from an 01' XR200R on CL,just had it sent to me:it was in Oak Ridge,TN. from a salvage yard there before the guy got it,it had the top end off of it for a bit and has a little dust inside it.He checked if it shifted before he sent it.I've checked it out and looks to be a good one :);I got it for the parts/trans. The oem Honda i.d. code is the newer 'KTO' rather than the orig. '446' on the cases but I believe it's the same 'animal' and should fit my 83' XL200R cases which are the same as the XR200 '446' code.
 
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