Sikk Trail 125 rebuild

Discussion in 'Some Assembly Required' started by mr.jadkowski, Apr 24, 2019.

  1. mr.jadkowski

    mr.jadkowski Been here awhile

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    What the hell is a Sikk Trail 125? Great question. It’s basically a pit bike, with an extended swingarm and fork so you can stuff 21”/19” wheels underneath. Why? Because it gives you a 140 lb motorcycle that handles like a mountain bike. Is it an awesome motor? No. It’s a piece of junk from China. Is the suspension excellent? No. It is adjustable, in that it adjusts up and down when you ride over stuff. How did I come to own such an amazing machine? That is a bit of a story…

    I saw this thing on craigslist back in 2015. It was only a couple hundred bucks, and I could swing by on my drive from Maine to Vermont to pick it up. The only problem? I was driving a Volkswagen GTI, which is not known for it’s moto-carrying capabilities. You can fit anything into a car if you take off enough parts, so running with that theory I started removing bits until the bike fit. Was I 100% high from gasoline fumes by the time I got home? Yes, but it was worth it.

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    The Sikk had a few issues… like not really running if the choke was off, a badly slipping clutch, a non-functional rear brake, leaking fork seals, ect. This is where I discovered the magic of these bikes: cheap parts. Because the Sikk Trail 125 is essentially a pit bike, most of the generic pit bike parts on eBay will fit. You need a new rear master cylinder, brake line, and caliper? That’ll be $28 please…

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    With a little bit of love the bike was running well, and turned out to be a real hoot to ride up in the mountains. Unfortunately I still didn’t have a way to transport it, so my riding area was limited to what I could reach from my house. There was one logical solution: exploit Vermont’s extremely lax rules about what is street legal and put a plate on it! It’s not unusual to see motos running around here with a squeeze-bulb horn on the bars, because that’s pretty much what it takes to plate a dirt bike in Vermont. I like a good project though, so I went all out. LED headlight, LED brake/tail light, LED turn signals, electric horn, folding mirror. This baby was ready to OWN the streets… at up to 45 mph. I think the project cost me $100 in total, thanks to more cheap Chinese parts from eBay.

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    This is where the story gets weird. My former-moto-riding neighbor (we’ll call him Gentleman #1) wants to take it for a rip. I’m a nice guy, so I say sure… The bike comes back missing the rear brake line. He says he’ll get one fabbed up and have it replaced in no time. He asks to borrow it again… comes back with no front brake lever, and no front fender. He tells me, again, that he’ll fix all that stuff, plus the rear brake line that he never replaced. I wait a month or two… still no parts, and now I’m moving. I didn’t really have space for this thing before, and my new apartment definitely won’t have space for it, so what to do? I end up selling it to my other neighbor (Gentleman #2) for the princely sum of $300. Bye-bye Sikk Trail 125… or so I thought.

    Fast forward to Fall 2018. I’m living back in the same building where I lived when I owned the Sikk. My current (and former) neighbor (Gentleman #3) asks me, “Hey, remember that little dirt bike you had? Do you want it back?” Apparently Gentleman #2 broke the clutch lever off in the first day of riding it, dumped it at the house of a mutual friend (Gentleman #4), and then went on the run from The Law. Gentleman #4 was moving, and was going to take the bike to the scrap yard. I said “sure, I’ll take back that motorcycle that I sold for $300”. Three days later, it shows up on my porch. Yikes. No front or rear brakes, no clutch lever, the chain is totally rusted out, there is corrosion on the fork tubes, the exhaust can is broken off, all those sweet parts I installed to make it street legal are gone… it’s a mess. I put some fresh gas in it and kicked it over a dozen times to see if it would run. Nope. Not exactly a surprise, but still disappointing. With winter approaching, I stuffed it back under the porch. There it sat, under a snow bank, all winter, until this morning. Behold its wretchedness…

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    No matter; like a phoenix this piece of shit is going to rise from its own ashes!

    Plans for the near future:
    • Go through the ignition system to make sure it’s sparking
    • Clean out the carb
    • Get it running again!
    • Reattach or replace the exhaust
    • Fix front brakes
    • Fix rear brakes
    • Replace clutch lever/cable
    • Replace front fender
    • Replace chain
    • Make roost!
    This will all be happening as cheaply as possible. If you're looking for some high-end custom build, look elsewhere. If you want to see what happens when an inexperienced home mechanic tries to polish a turd on a pauper's budget, this thread is for you!
    #1
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  2. Navin

    Navin Long timer

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    @Pitster is Mr. Pitster Pro/GPX and has new parts along with a pit bike bone yard.

    Wacky lil bike there, I bet it would rip with the new high power Daytona engine in it!
    #2
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  3. mr.jadkowski

    mr.jadkowski Been here awhile

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    Ooh... Pit bike boneyard sounds right up my alley. I'm not really interested in re-engining it. I have a DR650 if I feel the need for power. This is really just a play bike for low speed, rough riding. Hence my desire to get it running for a little as possible. If I can't get the motor running I'll pull it and use the chassis for an electric motor conversion.
    #3
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  4. mr.jadkowski

    mr.jadkowski Been here awhile

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    I finally got around to making some progress on this. I pulled off the tank and seat to take a look at the carb and ignition.

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    The slide was stuck in the carb, so I pulled the carb off the bike. Even if it ran, that carb was going to get a good cleaning, so that didn't really change the game plan. I pulled the spark plug, held it to the head, and kicked it over to check for spark... nothing. That doesn't necessarily mean anything, because the plug and the head are so corroded that I don't know if I even had a good ground connection. Oh well, I guess i'll just have to replace the whole ignition system... for $16. Yes, that's right, a new CDI, coil, and plug wire cost me $13.99 on eBay, and a new plug was $2 at the auto parts store. That's the beauty of the pit bike... the parts might be crap, but they are cheap to replace!

    The carb got disassembled and received a good pine-sol soak to clean out all the passages. It was surprisingly clean after sitting for a couple years with untreated E10 gas inside. Everything came apart just fine, except for the idle mixture screw, which I stripped :doh. Normally that would send me down a parts rabbit hole, but since the theme of this rebuild is "cheap" I decided to just leave it and see if the bike would run with it stuck in whatever position it was stuck in. Zero o-rings or gaskets were replaced, since a brand new knockoff Mikuni VM22 (the "OEM" carb is also a knockoff VM22) costs the same as a rebuild kit. I wanted to at least hear the bike run before I invested $30 in a new carburetor.

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    This is pre-cleaning... not bad, right?

    All that happened about a week ago, and yesterday I got around to reinstalling the carb on the bike, along with the new ignition system. I put some fresh gas in the tank, hooked up the fuel line, primed the carb, and started kicking. It took a loooong time, long enough that I was starting to doubt it would run, but eventually it started to sputter a little on each kick. Between playing with the choke and throttle position, I was eventually able to get it running continuously. It revved nicely, but it wouldn't idle. I then remembered that I took the idle speed adjustment screw out, so I gave that sucker a half turn and she ticks along nicely! Looks like whatever position the idle mixture screw is stuck in will work!

    Click here to see the mighty Sikk Trail 125 clearing its throat for the first time in two years

    Now the real work can begin; since I'm satisfied the heart of this bike is intact I can spend the money to fix all the other stuff that's wrong with it. Here is the list of what it needs to become whole again:
    • Front brake lever
    • Clutch lever and perch
    • New muffler (although the straight exhaust is about as loud as the old muffler....)
    • New chain
    • New rear brake master cylinder, hose, caliper, and pads
    • New shift lever
    • New front fender
    • New grips
    • Lube the throttle and clutch cables, and maybe replace them if they are still sticky
    • Clean up the corrosion on the fork lowers
    • Clean up the corrosion on the shock shaft
    The only thing that I'm not so sure about is my broken spoke. I've never laced or replaced spokes on motorcycle wheels before, but I know that figuring out the right spoke length on a bicycle wheel is huge pain in the ass. I may just zip-tie it to it's neighbor and say screw it... This thing is just going to be puttering around in the woods, not casing doubles at the MX track. I saw that @EvergreenE ran the Helles Rally with a broken spoke, and I know I won't be riding it that hard.

    It's good to see this bike running again!
    #4
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  5. YamaGeek

    YamaGeek Skeletor sparklemuffin.

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    I've got nearly the same engine in my Honda Cub, and I've got over 17k on it, these engines. just because they're Chinese doesn't necessarily mean they're junk. Change the oil often, like every 700~1000 miles intervals, especially if you like running them WOF most of the time.
    #5
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  6. mr.jadkowski

    mr.jadkowski Been here awhile

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    For the price, I definitely don't think it's junk. I would say a lot of these Chinese bikes are 3/4 of the bike of their Japanese counterparts, for 1/2 the price. Are you going to do more work to it? Sure, but for someone who likes tinkering that's not so bad. At least the parts are cheap and readily available.

    I bought everything that I needed, except for the parts to fix the front and rear brakes and the clutch lever, and I still haven't broken $100 on the entire project. It'll come in under $200 for sure, and I'll have a nice little play bike and loaner for my friends to try. It's hard to argue with that, and I would be paying a hell of lot more to fix all that on a Japanese bike.
    #6
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  7. YamaGeek

    YamaGeek Skeletor sparklemuffin.

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    The other thng about these engines is that. at least in my bike's case. they have a really wide spread of gears, First gear IIRC is like 3.25:1 and fourth is 0.98:1. Mines a stroker meaning it's 52mm bore and 56mm roughly stroke so they're little tractors.

    I kind of wish there was a 5 speed 'kit' for them, as I percieve that this engine could probably pull 5th gear in level road, no wind conditions if it was about 0.8-ish:1. But otherwise there's a lot of old school, old world thumper in these 125cc Honda clone engines.
    #7
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  8. Navin

    Navin Long timer

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    $800 at Pitster Pro gets you fifth gear in a 19 HP 190 crate motor.

    $1300 gets you the +22 hp Daytona four valve with this gear box.

    Primary Reduction Ratio : 67 / 18 (3.72)
    Transmission Type: 5-Speed
    Gear Ratio :

    1st : 14 // 34 th = Ratio 2.43

    2nd : 15 // 26 th = 1.73

    3rd : 18 // 24 th = 1.33

    4th : 22 // 24 th = 1.09

    5th : 24 // 22 th = 0.91

    Gear Shift Pattern : 1-N-2-3-4-5
    #8
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  9. YamaGeek

    YamaGeek Skeletor sparklemuffin.

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    Yeah I think I paid $288 for mine back in 2010, and the gearing on those is too close ratio. good for MX, not for trail plonking.
    #9
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  10. mr.jadkowski

    mr.jadkowski Been here awhile

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    More update:

    I went on a parts buying spree, taking care of all the little things that needed to be replaced. The grips (my most favorite Pro Grip 710s), chain, and shift lever were the first things to arrive, so I had a nice little work day.

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    The world's cheapest chainbreaker, which is included for free with the world's cheapest chain. The chain and the breaker cost me $21.50. Don't see any o-rings? That's because there aren't any. An o-ring chain is far too bourgeoisie for this beast.

    This is the current state of affairs:

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    It still needs the clutch and brake levers and a rear brake setup, which are sitting in front of me now. Figuring out the rear brake was a real pain; I ordered the closest thing I could find to the original but I didn't actually expect it to fit 100%. The rear wheel has a minuscule 160 mm brake rotor, so none of the off-the-shelf brake caliper mounts will fit, and I couldn't find a caliper that appeared to fit the original mount. However, my hail-mary parts ordering technique worked and the caliper that showed up should fit, despite being sold with a different style mount! I'll likely have to fabricate a new brake hose for the rear, as the Sikk Trail has a pretty massive swingarm for a "pitbike" so none of the off-the-shelf hoses will fit.

    It also needs a front fender, which is on the way, and a muffler, which is somewhere in the pacific on the slow boat from China. I need to clean up the surface corrosion off the fork stanchions before I actually ride it, so the seals don't get wrecked. It took me forever to find fork seals the first time I changed them, and I don't want to do it again. Still, I'm not that far off from making this thing go, stop, and turn, which is enough functionality for me!

    Total costs for the project are now at $133.47, which theoretically includes all the major parts I need to get the bike back to 100%. The only things I have yet to buy are a few small pieces of hardware, and that brake hose. There is a good chance thing bike could be riding around by the end of the day!
    #10
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  11. fast1075

    fast1075 Not a Lemming Supporter

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    I know a guy that had one of these. He would go ride it at the city skateboard park. At first he got nice warnings. He sold it after being told if he brought it to the park one more time, he was going to jail. Pure hooligan machine!
    #11
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  12. mr.jadkowski

    mr.jadkowski Been here awhile

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    Ok boys and girls, big news: SHE GOES!

    A few days ago I took the new rear brake setup and new levers to the shop. The rear brake sort of fits... the rotor is contacting about half of the pads, and I had to grind quite a bit of metal off the master cylinder to make it fit. Surprisingly the hose is just long enough. It's not the snappiest rear brake setup in the world, but it's good enough to lock up the back tire so I figure that's good enough! I was wrong about the caliper; it would not fit on the stock mount so I had to use the mount that was included. I can fix the spacing issue by replacing the rear rotor with a 190 mm version, but right now it is functional and that's all I'm looking to get out of this project.

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    I also put the new levers on. Lucky for me the front brake lever actually fit the master cylinder. I wish I could find levers of this length for my DR650; they are perfect for a two-finger brake and clutch grip. Now that I'm thinking about it, I may just try them in my DR650 to see what happens!

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    The last piece of the puzzle before this beast could move under its own power was the clutch cable. After I put the clutch lever on, I discovered that the clutch cable that was "installed" was in no way ever meant to fit this bike. The attachment at the clutch end was all wrong. No wonder I was told that the clutch was shot... I can't imagine how it ever worked in the first place. I know that wasn't the cable that was on it when it left my ownership! I ordered a new cable, but when it arrived I was dismayed to find that the quality control on my $6.98 cable wasn't very good, and it had 5.5" of free play in the cable instead of the specified 4". There was absolutely no way that cable would work with so much extra travel.

    I wasn't confident that I would get a workable cable if I ordered another one, as all the "48 inch cable, 44 inch housing" clutch cables I could find had the same part number as the unusable one I received. Advance Auto Parts came to the rescue, with a Dorman cable stop that was definitely never intended to be used this way. I drilled out the cable stop to fit the cable, cut the cable to length, put it all together, and then soldered it all up for some extra reinforcement. Voila, my clutch was functional!

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    Somewhere along the way I also installed the $30 slip-on muffler that I ordered from China. It ended up being so small that when USPS delivered it, they stuffed it in my PO box! I'm not so sure that it is doing any "muffling" whatsoever. It may actually be louder with the muffler on! It does sound a lot nicer than the straight pipe, so I guess I'll leave it. With all of that in place, it was time to give 'er a go. It started cold on the first kick, and after a little clutch cable adjustment I was running up and down the road shifting through the gears. Nothing about the bike feels great, and it never did, but it goes, stops, and steers! I thought maybe the clutch was slipping a bit, but it's hard to tell because first gear is geared so low. I was trying to do some burnouts in the gravel for "testing", but I didn't realize I had zero PSI in my rear tire. I'm now pretty sure that my "slipping" clutch was just the rear wheel spinning in the tire, and the tube is basically shredded rubber at this point. Oh well; a new tube is on the way. After getting the engine warmed up I changed the oil, and the oil that came out smelled so bad that I decided to change it again just to get the nasties out.

    I still need to receive and install the front fender, which was "out for delivery" yesterday and then was inexplicably in New Hampshire this morning. I also need to do a proper bleed job on the front and rear brakes. You'd never guess, but the $30 complete rear brake setup feels a little soft. I did a half-ass bleed on the front just to get some functionality so I could ride it around, but it really needs a true flush and some fresh fluid. I'm still not sure what to do about the broken spoke. I'll probably just pull it out when I change the tube and forget about it.

    I'm up to $157.01 for the whole thing. Not bad for a junk bike that I sold for $300 and then got back for free!

    [​IMG]
    #12
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  13. mr.jadkowski

    mr.jadkowski Been here awhile

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    Another quick update: The bike is basically done and riding as well as it ever has. I still need to bleed the front and rear brakes, but they aren't that bad. The carb is dripping gas out of the vent hose if the bike is anything other than vertical, so I may replace the carb. The price of a whole new carb is the same price as a rebuild kit. I gotta say... this thing compliments my DR650 very well. The DR is a little heavy to practice with (stuff like wheelies, riding over logs, ect) but the Sikk is perfect; it's light and easy to bail from if things go wrong. It is also exceptionally fun for just bashing through the woods. They should have called it the Sikk "Doesn't need a trail" 125. I think I'm gonna keep it around!

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    #13