TTXS 125

Discussion in 'Some Assembly Required' started by molochnik, Oct 9, 2019.

  1. molochnik

    molochnik Anhedonic Enthusiast

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    I thought perhaps I’d chronicle a project that I claim is for my wife...but it might turn out to be for me too.
    After my TAT adventure I realized the only place I could really take advantage of the DR650’s power was on pavement, interstates in particular. It’s nice to be able to just hop on a major highway and have the bike just loaf along at 80mph.
    The biggest lesson learned was that light weight and a light balanced load is crucial for keeping exhaustion at bay, whether it’s wrestling the bike on a difficult trail or having to pick it up.

    What to do?

    We have a 2004 TTR 125 and an 81 XS650 that have both been languishing.
    So the plan is for the 650 lump out, 125 squirrels in, and hopefully it will become a light, robust desert sled.

    Just thought I’d get a thread started; have to be somewhere. I’m not great at documenting so this may just fizzle out.
    I will provide some shots of the project currently in track day trim since we all like pictures

    Attached Files:

    #1
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  2. molochnik

    molochnik Anhedonic Enthusiast

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    As the XS sits right now, it only weighs 285 with a battery and lights - a constant loss system that made it acceptable for street testing. A stock TTR-LE is just shy of 200lbs.
    Considering my surprise at how heavy the XS engine is, the last time I had to heft it from bench to frame was when I was in my early 30s and much stronger, I would guess that the XS lump has *got* to be at least 85lbs heavier than the little TTR engine.
    I certainly don't expect the bike to do 80mph, but if it can get to something around 65 and still climb like it used to I will be happy.
    It's a shame there aren't any trail bikes out there with adult-sized ergos and a tame engine. When the TTR began to feel too small - ergo wise -I got Mrs. M a YZ125 because the 230s of the time were not quite full-sized and still sorts heavy. The YZ chassis was better but, as most folks might agree, the engine required an aggressive riding style that wasn't how she wanted to ride. I loved it, as did most kids who had only ever ridden their 4 stroke 250s.
    Anyway, the 125 is what we happen to have and while its horsepower is not impressive, the torque has been even after I geared it a little higher to give it longer legs. I think it also only ever needs to be fueled once.
    So these are my early morning musings as to why I would do a seemingly ridiculous thing like this.
    I couldn't really find the unicorn bike with a blown engine and figured that it won't cost me any more to get this bike re-registered, no DMV gymnastics since I already own it, and I'm just not interested in the bike for track duty or street duty for that matter. There are some awfully clever treatments of XS dual sports out there but this one won't need to be as serious. Just neutral feeling, light, and trail-worthy,
    #2
  3. cedric

    cedric Been here awhile

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    WTF? Why would you take two good bikes and make one POS...
    #3
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  4. molochnik

    molochnik Anhedonic Enthusiast

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    Hah, I was waiting for this question!
    At the risk of venturing into subject matter that may belong somewhere else, and I'll refrain from injecting my contempt into the dialogue, the administrative laws regarding vehicles in CA essentially turn a bike into parts, at best, or junk at the very worst. I haven't registered the TTR in over a decade. In fact it has been out of state yet remains titled here. PA doesn't care where your OHV is titled as long as it isn't stolen.
    That said, I could not sell the TTR as its penalties will likely be the same as the value of the bike. I'm philosophically opposed to paying the state to *not* ride my own bike.

    I thought I explained the reasoning on the merging of parts in my last post with reasonable detail...but was trying to avoid the "whys" of why the TTR is essentially a rolling parts box at this point.

    The XS, on the other hand, has also been out of state and titled in CA, but it only has value to me as a robust street-legal frame. The engines are old and hard to find part for, and I could likely sell it and pay for a good portion of this project. Almost 20 years ago one could only order one half of the transmission gears from Yamaha anymore and I'd be surprised if the rest of them haven't dried up by this point. The engine is of no use to me for the purposes I want to explore; I'm sure I can find someone who will want it. It's a solid runner.
    The old twin shock enduros are what I'm trying to replicate but those bikes have spindly forks, drum brakes, and engine parts are becoming boutique items.

    The XS has adequate forks for the limits of the engine and my wife's level of riding. They are not up to snuff for a road race track, not to mention that I found myself dragging the lower frame rails at Buttonwillow.

    The TTR engine has some aftermarket support and OEM parts are still available. It's got a charging system and electric start. It also is a light and unintimidating. The entire family loved the way it would tractor up hills but it's just too damn small for adults to ride. If I happened to have a 230 engine I'd happily use that, but it is not the case and I can certainly stand to have one less bike around here.

    In my research on the TTR125 engine, I found that they were used in Betas and Shercos...I think on dual sports. Even if they were trials models, it gives me confidence that they are mechanically sound.

    So I guess I rebut your assertion that I have two good bikes and prospectively one POS. I have two collections of parts - some I want to use and some that are of no use...and intend to make something useful out of both of them. Height and weight are two big factors that scare off or frustrate casual and/or beginner riders. Wicked acceleration is another. I think you can see what I'm aiming for here.

    @cedric I will be sure to not ask you to buy it if it doesn't work out.:lol3
    #4
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  5. dirt hokie

    dirt hokie Long timer

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    I would find a TTR 250 engine, or a TTR 230 at least. The TTR 125 looks good, I would sell it and use that money to find a bigger donor engine.
    I don't see how a ttr 125 in a big heavy street frame is going to improve anything, other then be "intersting"

    but carry on, I build weird stuff too.
    #5
  6. cedric

    cedric Been here awhile

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    Well that makes a bit more sense now. I'm all for these projects but was having a hard time understanding why. Not that my opinion should matter to you. Good luck.
    #6
  7. molochnik

    molochnik Anhedonic Enthusiast

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    I think one of the biggest mistakes Yamaha made was to not offer the TTR250 as a dual sport. It's a nice engine but didn't really have a point as a trail bike in the time of the YZ-Fs and easy credit. Of course, few people were very happy when those YZ-Fs/RM-Zs/CRFs all came due for valves...if they hadn't already fallen into the cylinder.
    I would have really preferred an air cooled two valve head like the 230 but We can see that Honda gave up after there weren't enough luddites (like me) to make the line viable. It's a shame...but I also agree that something larger would be "nice".
    I'm not convinced that the XS frame with the TTR engine will be a bad mismatch when all is said and done. Like I said, the TTR is surprisingly heavy and nearly 200lbs. The XS only weighs 85 lbs more and I'm sure that engine is close 160lbs.

    Thanks! I realize the reason for one to say WTF!? But considering what else is out there I don't think I can do any worse than a T-dub/Van Van or a Chinese bike in terms of power to weight and seat height. The TUs and the SRs are attractive but I've read some disappointing things about using them as serious scramblers.
    Opinions mattering? Meh, I started the thread and ostensibly offered the project up for judgment. I concede I'm at the very lowest threshold of obtaining a possible machine of utility.
    In the vein of dirt hokie's subtext, I could possibly sell off enough superfluous parts to purchase a TTR/CRF 230...but all of these parts are devils I know which has some value to me.
    I like frankenbikes but I'm not as patient or motivated to deal with mission creep as I used to be.
    #7
  8. dirt hokie

    dirt hokie Long timer

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    well on the bright side, and I hope I don't jinx the project, but the engine should fit real easy in that frame, with lots of room to adjust location to make everything work. Most people try to fit a bigger engine in a small frame.....
    #8
  9. molochnik

    molochnik Anhedonic Enthusiast

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    I'm sure it will fit easy too. Back in the 90s WERA had a specific prohibition on smaller engines put in frames meant for larger engines. My guess is that it had to do with frame rigidity; a cheap way to have a stiffer frame and race against bikes of similar displacement.
    I was running any real fancy tires on the XS at Buttonwillow but it would get real squirmy in the corners. The forks felt like they were just going to crumple up with the big supermoto disc and going into a turn.
    #9
  10. Pezz_gs

    Pezz_gs Cant ride for crap

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    Im looking forward to this . . . . building bikes doesn't always have to make sense :thumb

    Like you are working with what you have :1drink

    Imagine you will be running the TTR front end and wheels?

    Can you convert the alloy swingarm to twin shocks for simplicity?

    [​IMG]
    #10
  11. molochnik

    molochnik Anhedonic Enthusiast

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    I'm actually using the entire XS chassis. The TTR forks are just too flimsy. I can remember having them twist under normal riding, but I'm not the size rider it was meant for either.
    I've looked at a bunch of XS-based dual purpose bikes and they often find a way to use a single shock. This model TTR actually has a decent shock with compression and rebound adjustability. I'm still contemplating whether I'm going to try a single shock set-up or just use the Works Performance shocks currently on the XS.
    When I set about altering the XS to see if it would make a decent track-day bike, I used the Talon hubs I've had sitting around from my YZ when I raced supermoto. I laced the front hub to the stock rear rim from my DR650 and used the big Braking rotor and 4 pot caliper. For the rear I just laced the former front supermoto rim (3.5X17 Behr) to the rear hub and used a YZ250 sprocket disc and fabbed up a hanger for an RZ350 caliper I removed the inboard housing and piston from; there was a clearance issue with the spokes so I just made a backing plate for the inboard pads. I learned road racing in the late 80s so rear brakes weren't so important; I figured a single pot on the rear would be fine.
    Yesterday I got a set of spokes and a DID 21" rim to lace onto the front hub. I figure the long footprint of the 21" tire will help make up for the limited travel of the stock XS forks. I'm gonna leave the rear wheel as is - a 606 will fit on there fine. I'm running a 3.5X17 on the rear of my DR too.
    I've never learned to weld beyond extracting broken studs and bolts so I'll have to find a welder to add a brace to the XS swingarm if I intend to use it. Something like the first monoshock bikes would be a cool set-up and the TTR shock *appears* to be small enough to fit where the battery used to be in the XS.
    I have entertained the idea of possibly using the TTR swingarm. Once I get the most massive items in place I'll do some experiments on configurations and spring rates. The springs on my Works shocks are super stiff. When I ordered them I told the dude it was an 81 XS650. I didn't think about how it was going to be almost 100lbs lighter in street tracker trim, and it's 100 lbs lighter now without any electronics and the laced wheels instead of the RZ350 wheels I was using.
    I believe I have Progressive springs in the forks so those ought to be fine.
    This is how it looked when it was a street tracker

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    #11
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  12. Pezz_gs

    Pezz_gs Cant ride for crap

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    This one was clicked at Phillip Island in Victoria a few years ago now

    Grafted WR/YZ suspension front and rear into the XS frame

    ISLANDCLASSIC236.jpg
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  13. molochnik

    molochnik Anhedonic Enthusiast

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    I've seen a few pics of that bike around the web. It's a nice job!. Now that I'm home, I had a chance to measure a few things. The TTR forks are an even 30mm while the XS forks are 35mm. It's not much but it's heavier duty. I measured the swingers and while they are of equal length in terms of pivot to axle, the TTR swingers is about an inch too narrow to fit the hub and wheel.
    #13
  14. molochnik

    molochnik Anhedonic Enthusiast

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    As an existential nihilist I question the utility of everything I do and typically act/plan due to compulsion. The all-to-human expectation of the delayed reward has shown itself illusory.
    Your statement has stuck with me and I felt compelled to address it...and I do agree!
    #14
  15. Pezz_gs

    Pezz_gs Cant ride for crap

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    Here’s one of mine...... It didn’t make sense but was a hoot to ride

    Reg the RV125 running PE175 motor among a lot of other mods
    [​IMG]

    [​IMG]
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  16. tinwelp

    tinwelp Professional Idiot

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    I like your style molochnik, but I too need to question your motives... unless you're a big guy, in which case maybe what you're proposing is absolutely sensible when taken against the backdrop of your earlier musings.

    I've ridden (but not owned) both a TTR250 and an XS650; the former extensively, the latter just for an afternoon. My dirt bike at the time was an EXC400 and my road bike a DR650, so relevant to the thread, but quite different beasts respectively. The TTR was slow, a bit heavy and poorly suspended to ride fast off road, to the point where I feared I'd pogo into the trees many times, so eventually I just rode it like the trail bike that it is. The XS was fun, but felt like a refined British twin carrying an anchor around all the time. Describing it as "heavy" is being kind; I'd go for the more accurate "lard arse". And that was on the road. A goodly proportion of this is undoubtedly the engine which I suspect houses a crank with flywheels made from purest osmium.

    I gather the TTR125 is smaller than the just about adequately sized TTR250? I'm very not big, so if you are and the TTR125 is, yup, got it: too small. I suspect pushing the XS frame around may mask the doubtlessly stellar output of a softly tuned 125cc single, mind...

    Hell, what do I know? I say tuck away your inner nihilism, suspend all judgement of sense or utility and build the bugger!! It'll be a wheeze to tag along and frankenbikes are very cool whether they work or not. Build it and they will stare.

    I'm in, 100% and I wish you the bestest of luck.

    Cheers... Paul
    #16
  17. Navin

    Navin Long timer

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    There is a manufacturer who builds ONLY trail bikes with friendly engines, and in kid, small adult and full adult sizes.

    Read up on GPX, there are threads in thumpers about every model, and the Pitster Pro XTR 250 is from the same Mfg. They are also inexpensive, and I think you would be better served by one of them than where this project will end up.

    The XTR250 is even available with 21/18” or 19/16” wheels and is under $3000 brandy new. Electric start, adjustable suspension, and every part available direct from the manufacturer.

    https://gpxmoto.com/index.php?route=product/category&path=5

    Good luck if you go forward but I can’t see this being a better mousetrap. $0.02
    #17
  18. molochnik

    molochnik Anhedonic Enthusiast

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    You had me at "PE". A piston port two stroke in a billy goat frame? Seems sensible to me! Is that a rear wheel from an RZ on the front?

    This is all very good...I am a frequent user of the Socratic Method (for working out problems - not for dating) as long as it all stays civil; the engineers I deal with often bristle when I begin asking questions.

    Too bad the TTR250's chassis was a mess. I've never ridden one but maintenance manuals are like p0rn for me...except the collection doesn't need to be hidden and I don't care if anyone finds them when I die.
    Looking through the manual for the 250 (probably over a decade ago) I fell in love with that engine. Yamaha didn't use their Genesis nonsense in the head and it otherwise seemed like a solid bike. I thought it had the open cartridge forks on it but I could be wrong about that.
    My XS was not loved much before I bought it and I managed to in early 2000 for $500, before they went up to $3000 and were rare as hen's teeth. It was complete and, I agree, *HEAVY*. I think it was all but 500lbs with gas. I opened up the engine and measured, replaced, and upgraded wherever I needed too, or could. Then I broke out the sawzall and whittled the frame. Long story short, it's a 752cc with a "Shell" cam and a freshened up valve train. I tossed the electric start monkey-motion and had a custom exhaust welded up. When finished, it was down to 390lbs and it moved (moves) with authority. I was still stuck in the 80s so I opted for a set of RZ350 wheels and brakes. I had no idea what boat anchors those wheels are until I set it up with my old supermoto gear for road courses.
    I wanted to see if I could find another one of my bikes to do track days to reduce risk to my beloved 87 GSXR750. It was not to be though; I wadded the 87 at Willow Springs the day before I left to get my XS and a 2000 Buell Cyclone from PA.
    Long story short, neither one turned out to be suitable for the track. Riding up Angeles Forest, Big T, and 10 miles on the Crest to Newcomb's was fine. Buttonwillow, not so much.
    I don't *think* I'm a big guy; only 5'10" and typically around 210lbs. However, this project is an attempt to get my wife to do some riding with me again.
    She rode a 78 DT125 but two strokes demand an aggressive style that is not intuitive for her. When I lowered my 02 YZ250 smoker for flat track, she decided she wanted to try it out. I told her she could ride if she could start it. She couldn't kick it so she coasted down the driveway, grinning back at me and bump started it and took off. I ended up going to look for her on the DT and couldn't find her. She and the bike were laying in the shrubs.
    The TTR125LE was on sale at a local dealer so I got her that. She loved it even if the narrow 19" front wheel was troublesome in sand. It eventually became too small/slow for the tribe of families we rode with. I tried to get her to ride my YZ (now in supermoto trim) and it was ok other than the front slick pushing/tucking in sand. Same deal with a KTM 525SMR I had even though she liked the 4 stroke better, and electric start...but supermoto bikes in the desert just wasn't the right thing. I found an 02 YZ125 since it appeared she needed something light, not as powerful as my full-sized bikes, a low seat height, and full sized ergos.
    I lowered the YZ125 and put a flywheel weight on it. I also retarded the timing for easier starts. She loved the chassis but the characteristics of the 125 smoker was intimidating...as many people claim them to be. I loved that bike but understood how it was to be ridden, or perhaps didn't mind riding it how it needed to be ridden.

    So I said all of that to say that this is primarily for my wife who stands 5'4". She doesn't ride enough to build a base of skills from which to draw...which drives my requirements of
    a weight of 250lbs or less
    a seat height of around 30-32"
    low C/G
    a tame but torquey engine
    full sized adult ergos
    air cooled
    street legal

    The XS frame seems to be a natural choice since I'm out of dirt bikes to modify. ALTHOUGH, I've PMing with a dude who has a "plated" WR400 (with a blown motor) for a reasonable price. If we can get schedules to align I'd be very interested in the bike as long as the DMV will transfer the title with the plate. I've got enough stuff hanging around for that era Yamaha and I like the open cartridge forks. Lowering it won't be a big deal; I did it to my 250 and my wife's 125.
    Stock the bike was (claimed) 258lbs which already makes it lighter than the TTR and it comes with proper suspension. The TTR125 engine should be just fine in there.
    If the WR doesn't happen, again, the XS ought to be fine. The lazy steering angle with a 21" front wheel (@Boxerbreath should be proud to have convinced me of the value of the chopper wheels) and the other wise neutral frame geometry ought to make a fine bike for her to tractor around on.
    I've been kicking around a few different ideas for the XS but I don't think it'll be happy putting around.
    I'd rather not go buy a slightly larger engine since I have the 125 and no purpose for it. I can't sell it because the DMV penalties are probably equal to its value...unless someone buys it to ride as an outlaw.
    The XS was not a show piece when I bought it, and aside from the magneto, all the money and time I've put into it are long gone and probably would have been spent elsewhere. It was always an experimental bike so I have no unction to treat it as some kind of virginal sample of an XS.
    That was probably too long but I appreciate the opportunity to continue working out my motives and the utility of the project.

    One last thing though - considering I end up with a 125 that weighs between 200 and 250lbs, how much worse off would I be than any of the current offerings that weigh more, have smaller wheels, equal or negligibly more power, and a higher seat?
    I keep wondering how much power the old 125 enduros had and how much they weighed.
    #18
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  19. molochnik

    molochnik Anhedonic Enthusiast

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    I looked at that link; I've checked them out before and you're right, lots of current tech for a cheap price. Unfortunately, I'm a luddite and prefer air cooling and carburetors - my current bike is a DR650 and I put up with its weight because of its lack of technology:D
    #19
  20. molochnik

    molochnik Anhedonic Enthusiast

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    No air cooled carbureted dual purpose bikes.
    The 190cc crate motor looks interesting but they either don't provide exhaust for it or the site is counter intuitive.
    Everything else looks like power I could achieve with a few mods to the TTR engine; could be wrong about that, but there is plenty of support
    #20
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