Topic: Modding/restoring a 1975 xl125

[Vintage SM]

I have acquired a 1975 xl125 from my Mom, who is the original owner, and what I used to learn how to ride back when I was 12 years old. the bike was in excellent shape when I had the opportunity to learn how to ride and work on "real" mechanical things. As time went on, I slightly abused it by tearing all the street legal parts off, (lucky me I kept all of the parts in a box in storage) adding real knobby tires to it, jumping it as far as I could off some bigger than the bike could handle jumps at a friends property, leaving it out in the weather, and forgetting about it completely for years... needles to say, It was pretty trashed/weathered when I went and picked it up from my parents place.
    So far I've got just about everything apart, some things painted and ready, some things are blasted and ready for me to powdercoat, the frame and swingarm are going to be professionally blasted and powdercoated due to size, and i've got about halfish of the new things needed for the project.
    My plan for this is to restore the bikes color scheme, and modify some style appearances to be Supermoto like, Use 18" alu. wheels and full street tires, as if the bike could have come from the dealer that way, with a slightly modern accent to it, like slimline mirrors and lighting, but keeping the vintage look.
    I have a few ideas about the engine. First thing that came to mind was fitting a later model XR200 engine, then I figured i'd rather keep the original engine to keep it looking more original and just freshen it up, but it needs more power, I came across a very small turbo, probably off of an old audi or diesel vw, so I'll be doing some fun fab work and tuning... probably going to blow a thing or two up, but meh... I expect that. Btw, I have lots of automotive turbo knowledge under my belt and wanted to attempt some small engine boosting.
   So I've got a couple questions, hopefully some of you have answers.
cams, did any of the other 125, 175, or 185 engines of that era have hotter cams that could drop in? how about the 175 or 185 cyl. jug, piston, and/or head fit the 125 bottom? any experience that anyone has and pics of like bikes would be appreciated.
   On to some pictures
   

Mom in 1975 with her first motorcycle


Brand new in all of it's glory


the day I got it to my house




buffed and waxed the tank first thing, I'm not refinishing the tank because I think it being nice and original will give it character, and tell a story.







day two, had the bike stripped down a bit and a few things cleaned and painted.







found that I had bent the stanchions so I found a good set on ebay and rebuilt the forks with new seals, oil, lowered about an inch and polished the lowers. also had to buy another swingarm cause that was bent to hell too.
I'll keep this updated as I get more done.

[scunny]

I seem to remember back when I had a cb100 that the 100's and 125's could be bored to 145cc, using a stock honda piston and rings from some model ? good luck on the boost

[Vintage SM]

I seem to remember back when I had a cb100 that the 100's and 125's could be bored to 145cc, using a stock honda piston and rings from some model ? good luck on the boost

Was the 145cc a big bore kit or something for that era? or just a piston and rings from something else with more cyls that measured the same in piston height and same size wrist pin?

[kirkn]

Go here, search in the SL100/SL125 sub-forum for this topic.  I posted extensively there describing how I did it with the 150cc kit, and others chimed in on the thread with all the details on the other ways.  I can be done with the other Honda parts, but it isn't a trivial deal...

http://xlboard.aimoo.com/

But, as mentioned on Thumpertalk, where you also asked, the whole "keep it stock / put on a turbo" philosophies don't jibe...

Kirk

[Vintage SM]

Go here, search in the SL100/SL125 sub-forum for this topic.  I posted extensively there describing how I did it with the 150cc kit, and others chimed in on the thread with all the details on the other ways.  I can be done with the other Honda parts, but it isn't a trivial deal...

http://xlboard.aimoo.com/

But, as mentioned on Thumpertalk, where you also asked, the whole "keep it stock / put on a turbo" philosophies don't jibe...

Kirk

Thanks for the link, last year I found that site, and when I came back to my project this year, I forgot what that forms name was.
I don't want to keep it completely stock, just trying to keep as much of it period correct as I can with a twist.

[Vintage SM]

Quick update for you guys, lots has happened in the last couple years... since this has been an on and off again project it's taken that long, I've kept up a little bit better with the updates on Thumpertalk, so for those of you who don't get on there, here is the bikes current state.


I decided to go with a 150cc kit from ebay and 2mm bigger carb, ported the intake and exhaust ports, and made a muffler of my own.



plowed right through the upper oiling galley like I expected so I had it welded up and re-ground to make the cyl fit.

re-shaped the seat foam a little, sewed up and re-covered the seat myself. this was a practice cover that came out better than expected so I'm going to run it till I can make a better one with more stitching details.



the wheels are 19" front and 18" rear Excels with Buchannan stainless spokes


Hope you guys enjoy.

[albertaboy]

Great bike and resto-mods.  Nice job on the muffler too. I wish I had your skills.  My first bike back in 1979 was a 1975 XL350.  Sold it about 1983. I'd luv to get it back and I know where it is too.  Gotta finish my cb750 first.

[grcamna2]

How many options did you consider on the Big Bore choice ?? I'd like to do a similar Big Bore on my 82' CB125S.

[bj]

Very cool. Love the old XLs.

[grcamna2]

How many options did you consider on the Big Bore choice ?? I'd like to do a similar Big Bore on my 82' CB125S.

Nice Job VintageSM !

[Vintage SM]

Thanks guys.
  grcamna2, I chose the Ebay kit because of the price for the time being, I'll be looking for a 76'-on lower-end and the 76'-78' head and do a 199cc kit when I can afford to throw a bigger chunk of cash at it again, I was informed on Thumpertalk recently by a guy who worked with Powroll that can set me up with the parts and machining to do a legit big bore/stroke change to get what I want out of it.
The muffler is mounted now, and I just need to make the mid-pipe that connects it to the header, then have it powdercoated.



And here's a pic of 3/4 of my current fleet.

[grcamna2]

Vintage SM,
     What type of machine work is required to bump an 82' CB125S up to 199cc ? or is it even possible ?

[Vintage SM]

I'm not super familiar with all the in's and outs of what needs to be done on all years of engine, but what I am to understand, on pre 76' lower ends, the opening in the case is too small to just put a bigger sleeve in, but the 76' and on do have a bigger opening, so depending on what year case/engine you start with and how big you go, case boring, and bigger sleeve/boring of the cylinder is the required machine work, now changing the length of the rod length and/or piston height are also required to increase displacement beyond the limit of boring. the 125cc engine is basically what the xr200 engines were derived from.

muffler and pipe are done and the exhaust note is great, sounds like a big bike now, I'll get a sound clip for you guys when I can.

[2strokeTrush]

I have acquired a 1975 xl125 from my Mom, who is the original owner, and what I used to learn how to ride back when I was 12 years old. the bike was in excellent shape when I had the opportunity to learn how to ride and work on "real" mechanical things. As time went on, I slightly abused it by tearing all the street legal parts off, (lucky me I kept all of the parts in a box in storage) adding real knobby tires to it, jumping it as far as I could off some bigger than the bike could handle jumps at a friends property, leaving it out in the weather, and forgetting about it completely for years... needles to say, It was pretty trashed/weathered when I went and picked it up from my parents place.
    So far I've got just about everything apart, some things painted and ready, some things are blasted and ready for me to powdercoat, the frame and swingarm are going to be professionally blasted and powdercoated due to size, and i've got about halfish of the new things needed for the project.
    My plan for this is to restore the bikes color scheme, and modify some style appearances to be Supermoto like, Use 18" alu. wheels and full street tires, as if the bike could have come from the dealer that way, with a slightly modern accent to it, like slimline mirrors and lighting, but keeping the vintage look.
    I have a few ideas about the engine. First thing that came to mind was fitting a later model XR200 engine, then I figured i'd rather keep the original engine to keep it looking more original and just freshen it up, but it needs more power, I came across a very small turbo, probably off of an old audi or diesel vw, so I'll be doing some fun fab work and tuning... probably going to blow a thing or two up, but meh... I expect that. Btw, I have lots of automotive turbo knowledge under my belt and wanted to attempt some small engine boosting.
   So I've got a couple questions, hopefully some of you have answers.
cams, did any of the other 125, 175, or 185 engines of that era have hotter cams that could drop in? how about the 175 or 185 cyl. jug, piston, and/or head fit the 125 bottom? any experience that anyone has and pics of like bikes would be appreciated.
   On to some pictures
   

Mom in 1975 with her first motorcycle


Brand new in all of it's glory


the day I got it to my house




buffed and waxed the tank first thing, I'm not refinishing the tank because I think it being nice and original will give it character, and tell a story.







day two, had the bike stripped down a bit and a few things cleaned and painted.







found that I had bent the stanchions so I found a good set on ebay and rebuilt the forks with new seals, oil, lowered about an inch and polished the lowers. also had to buy another swingarm cause that was bent to hell too.
I'll keep this updated as I get more done.

What method did you use for painting that rear brake cover?? and what type of primer and paint? i really want to do that to my Cb

[Vintage SM]

for both front and rear brake covers I bead blasted them with aluminum-oxide, then sprayed them Dupli-color self etching primer and satin black Krylon for the top coat. This is more or less an experiment, if/when the paint get pitted or damaged too much I'll re do them with powdercoat.

[2strokeTrush]

for both front and rear brake covers I bead blasted them with aluminum-oxide, then sprayed them Dupli-color self etching primer and satin black Krylon for the top coat. This is more or less an experiment, if/when the paint get pitted or damaged too much I'll re do them with powdercoat.

Thanks!

[Vintage SM]

Here's a sound clip of the muffler, filmed from my cell, hope it sounds good