My teenage daughter on motorcycle maintenance and repair

[seavoyage]

School's out for summer and my teenage daughter was looking for a project to keep her occupied:

1. find a bike on Craigslist for under $1K;
2. disassemble and inspect all the major components; and
3. rebuild the bike from the ground up.

Here's the Craiglist find she chose for her project: KTM200MXC

Inspection: absolutely filthy, probably last washed 3-years ago. Engine runs first kick hot or cold, smooth shifting through all gears. Magura clutch OK, no clutch drag/slip. Brembo Brakes OK. Radiators, and plumbing are fine but need coolant replaced. No cracks in frame. DID rims straight and true. Tires need replacement. Missing kick stand spring and exhaust/silencer rubber. Throttle rubber cover ripped, Seat cover rip and covered with duct tape.

Aftermarket items: Acerbis hand guards, Acerbis large capacity gas tank, E-line CF pipe guard and rear disc protector, Works Connection frame guards, Devol radiator guard, Pro-Taper fat bar (CR Hi-bend) and Scotts bar risers, Galfer Wave brake rotors, Renthal sprockets, Guts racing seat.

Identified replacement items after dis-assembly and inspection: kick start spring, countersprocket oil seal, fork seals, wheel bearings, a front spoke. Seized rear axle needs to be polished and greased. Brakes need to be bled. Faded and cracked plastic. Exhaust pipe dented and rusty. Seat cover. Miscellaneous rusted, mismatched or missing fasteners. Promptly put in a parts order to RockyMountain ATV MC and trolled eBay Motors for deals.

1-week later... She's now up to speed with every component and system of 2-stroke dirt bikes.

Engine: Replaced piston-rings (Vertex). Used a wire brush and Naval Jelly to restore FMF Gnarly pipe w/ Turbine Core 2 SA. Replaced waterpump O-ring seals. Replaced counter shaft seal. Clutch friction plates were at 10%-50% wear; con-rod/crankshaft/clutch basket and hub/transmission inspection = OK. Cleaned and rebuild carburetor. Reed block was fine. Chain, sprockets, and brake rotors were OK.

Set Powervalve to Langston modification: http://motocross.transworld.net/100...-shares-some-speed-secrets-for-the-ktm-125sx/

Chassis: Quite a lot of corrosion control: After a thorough degrease and wash; Replaced all chassis bearing w/ All Balls (shock pivot, swing arm pivot, steering stem, F/R wheels); Replaced rusty fasteners. Note: the wheel spacers where seized to the wheel bearing - had to be cut out! Copious amounts of waterproof grease, anti-seize, WD-40, silicone grease, chain lube to lubricate every moving part and metal fastener. Replaced footpegs with IMS SuperStock footpegs.

Consumables: She learned how to manually mount the Dunlop MX51 Front and Rear tires using the ISDE technique. Replaced front and rear brake pads. Degreased and lube O-ring chain. Replaced air-filter (No-Toil). Replaced brake fluid and Magura clutch mineral oil. Running Shell Rotella T 15W40, Putoline Coolant, NGK Spark Plug.

Suspension: Revalved and changed springs on WP forks and rear shock. Thanks to Joel @ 707 Racing Suspension. The cartridges and valve stack shims were an absolute mess, and the fork seals were due for replacement. To achieve correct suspension sag for my daughter: changed fork springs, and changed rear shock progressive springs to linear rate.

Cosmetics: FX seat cover, shaved 2.5" off seat. Cleaned the plastic (razor blades and heat gun); taught my daughter to plastic weld to repair the cracks. I let her customize the bike graphics with decals left over from previous projects.

Thanks to neduro for the KTM setup tips: http://www.advrider.com/forums/showthread.php?t=66607

Lessons Learned:

1. Chassis and wheel bearings are consumables: Most owners don't maintain and replace bearings. If the bearings have not been replaced in more than 2-years, odds are your wheel and rear suspension bearing need replacement.
2. The piston, piston rings, and the clutch plates are consumables: Perform a compression and leak down test. Disassemble the top-end and clutch on every purchase of a used bike and inspect and replace all items beyond maximum tolerance limits.
3. Suspension fluids need to be replaced frequently: Most owners don't adhere to the suspension maintenance schedule.

Break-in and function check: Saturday. Riding Sunday!

 

[OaklandF4i]

Thats frickin awesome! Its the way I learned to wrench on my own machines. In my early teens during the winter I would wrestle my CR125 down the stairs and into my mother's basement. Then I would begin a complete tear down and rebuild of the machine. Talk about a life skill and building confidence in a young kid. Kuddo's to you for teaching your daughter a great skill and having a great time sharing with her! :thumbup

BTW, what did you think of your 125 MX bike turned trail machine project? I've been half heartedly looking for an 02 YZ125 on craigslist. Thinking of a 144 kit and then setting up the suspension for offroad. But, as I remember it was a ton of clutch work to keep that bike singing when I was much lighter... let alone my 220lb adult frame.

But first I need to figure out what the heck I'm going to do with this plated XR400R I just bought yesterday. :rofl

 

[undertheoaks]

Awesome job you guys, really impressed with her work. How much was her and how much did you do mister Drew ? When are you guys going out to practice trials ? Have you been to club property yet ? Maybe next weekend ?

 

[seavoyage]

Thats frickin awesome! Its the way I learned to wrench on my own machines. In my early teens during the winter I would wrestle my CR125 down the stairs and into my mother's basement. Then I would begin a complete tear down and rebuild of the machine. Talk about a life skill and building confidence in a young kid. Kuddo's to you for teaching your daughter a great skill and having a great time sharing with her! :thumbup

I did a similar project with my eldest son when he was a Junior in HS. We restored a 1973 Honda SL125 we found for $200 on CL. Nothing like 6V electrical systems and points ignition on a SOHC air-cooled 4-stroke with damper rod front forks and cable drum brakes and clutch. Jeez!

BTW, what did you think of your 125 MX bike turned trail machine project? I've been half heartedly looking for an 02 YZ125 on craigslist. Thinking of a 144 kit and then setting up the suspension for offroad. But, as I remember it was a ton of clutch work to keep that bike singing when I was much lighter... let alone my 220lb adult frame.

But first I need to figure out what the heck I'm going to do with this plated XR400R I just bought yesterday. :rofl

My current opinion: a 125cc MX bike with single ring pistons means much more frequent top-end rebuilds. I performed compression checks after every 3 rides; and changed piston rings when the compression would drop 25-30% from baseline = every 25 hrs.

I think the YZ125 is the best of the bunch (Big 4) for a conversion but an Athena 144 kit has to be balanced out with the right pipe and jetting. I don't agree with adding flywheel weight to a 125cc and as I recall FMF doesn't even make a Gnarly pipe (torquey) for a 125cc... it's just too anemic. Another issue if you are into trials tires is the 19" rear wheel.

As far as riding; it's so much fun wringing out that 1/8 liter motor. A 125cc MX bike will teach you how to ride fast since you have to ride it 'on the pipe'. Get used to WFO and fanning the clutch. If I weighed 220 lbs. I would pass on the 125/144/150/200 class.

The current KTM200 was chosen since my daughter had a KDX200 (CA plated) prior to the CR125; and the KTM200 has 2 ring pistons = less frequent top-end rebuilds. The KTM200MXC feels so much heavier than the CR125; but everything feels like a pig when you ride trials bikes. KTM PDS suspension with progressive rate springs have always been a bitch to tune.

Awesome job you guys, really impressed with her work. How much was her and how much did you do mister Drew ? When are you guys going out to practice trials ? Have you been to club property yet ? Maybe next weekend ?

Found the KTM on CL and negotiated down to $900. As strong willed as my daughter is, I pretty much had to step back and let her do the work. I'd limit my involvement to describing the nuances of each system and provide guidance: How to measure a clutch stack; Piston ring end gap; inspect a conrod lower end bearing; burp the cooling system; measure for static and race sag; reverse bleed a clutch; clean and oil an air filter; do the oil change; adjust the powervalve; set carburetor idle; align front forks; etc.

Been putting around the house on her GasGas Pro. Didn't get out to Donner last week.

 

[Lunch Box]

Drew, I just saw this thread. You and your daughter are awesome. I still need to do some additional tear-down and build-up work on my 250, but just haven't found the time. I need to do a new piston/ring (single ring piston on this one, too), as well as new bearings all over the place. I would also like to have the suspension sorted out for my fat arse. I've replaced a few seals and done some other basic stuff on it, so it's coming along. This thing is a blast, and will be even better once I get it fully sorted.

Looking forward to riding with you and Anna soon. :thumbup