NEWBIE with a project Bike

[jahames7]

Hey fellas im new on the site so if i ask any questions that are already on here please don't crush me, just post the link to the existing thread.

I grew up on 4-stroke trail bikes my whole life but i graduate college in less than 2 weeks and i just bought a 2000 RM 125 for a project bike. I'm an engineering major so this is right up my alley. The seller claims that the wrist pin clip came loose which messed up the piston causing the bike to lose compression. He claims the cylinder is fine. (i haven't had time to take it back apart yet, but i plan on boring it over anyways-we'll see) Anyway the rest of the bike is in excellent condition.

Since i am a newbie to the world of 2-stroke rebuilds im just posting this thread in hopes of gaining some much needed wisdom from all you experienced gearheads. I'm looking to build this into one sick trail bike beginning with low end reeds, larger rear sprocket, and maybe a flywheel weight - if i can weigh out the pros and cons. I know some ppl think 2-strokes don't make the best trail bikes but thats the challenge im wanting to face with this project. plus you can't beat the sound of a 2-stroke.

Please just post things i should look for and check on the bike before beginning my rebuild. Any parts combinations that yall have found to work for yall would be helpful too. Thanks for all yalls help in advance.

and p.s. i plan on documenting my build up here on dirtrider.net :laugh:

 

[julien_d]

IMO 2 strokes DO make the best trail bikes. Cheap to maintain, light, flickable, and the quick snap of power makes lofting the front wheel a breeze. A 125 might not be my 1st choice in a woods bike due to the lack of any real low end power, but you can overcome most of that with some mods.

It is highly unlikely that a circlip came loose and did not tear up the cylinder. Normally you'd find some gouging to the cylinder walls and ports. You need to tear it down and have a look. If you plan on a big bore kit for it, it may not matter too much anyway.

Sounds like a fun project. Gets some pics up of the bike as soon as you can!

 

[Porkchop]

None

Hey Jahames7, Good luck with your project bike, I hope that you don't weigh more than 140lbs or the 125 aint gonna be in your favor. Up grade parts such as a rad valve, larger bore kit, low/mid range porting, added flywheel weight & extremely low gearing
are key to a combo that will work for you on a trail. Any hardware that reduces weight is a added bonus, ( ti or aluminum bolt kits, pivot bolts, axles etc.) I desire a ti spoke & nipple kit to lighten up the wheels on my project bike, (have a look in gallery, Porkchop's Rotax project bike). That's a bike that is not light, 276lbs. dry weight, but it's a 560 4 stroke single- electric start. As with all bikes big & small,
THE LIGHTER THE BETTER. Remember I said lighter not cheaper, Good Luck.
Best Regards, Porkchop...
P.S. Learn from the sellers comment about wrist pin...BUYER BEWARE!
Don't believe a damn word that comes out of any used bike sellers mouth, either the bike runs, or it don't. Take it apart immediately & see what you've got.