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2007 Stock CR125, looking for some advice

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Hey guys,

Well, I ended up picking up a 2007 CR125 with very low hours on it.  It basically sat in a barn for most of its MX life.  The Bike is 100% stock and I am looking to add a few upgrades to it and I would like your input on what should make the top of the list.  

I have an complete top end (full OEM) waiting to be installed, that is the first thing I need to do, then add an hour meter.  The top end is needed as the previous owner mentioned that the engine has never been opened up and my compression test at home measured 55PSI, which is SUPER low, maybe thinking my compression tester is not reading it right?  None the less, its getting a new top end!

So, after the top end is complete, what should I consider?  Was thinking of the following, not in any particular order:

  1. New reed valve system (Boyesen or vForce3)
  2. Maybe a new silencer
  3. new rear sprocket, increasing rear tooth count to 53

Anything I might be overlooking?  Just want to get a bit more out of the bike.  

Thanks!

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Go thru the bearings and such, regrease, torque, etc.

 

Repack the stock silencer, OEM reeds will be just fine as a replacement . Flush the rads and put new coolant in. Rear shock should be re-charged at a minimum, but suspension is due for service.

Edited by DEMI
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Yea, I took it out on the track for the first time this weekend...ran GREAT considering the piston is about to go with 55psi compression.  LOL.  Cant wait to get it rebuilt, then jet/tune it.  I put a 420 MJ in and raised the clip up one to make the bike run a little bit leaner.  Being down here in Florida with high humidity, the bike was a little boggy.  Was thinking about getting a smaller pilot jet as well, then taking the needle clip back to the 3rd slot (stock).

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Yea, I took it out on the track for the first time this weekend...ran GREAT considering the piston is about to go with 55psi compression.  LOL.  Cant wait to get it rebuilt, then jet/tune it.  I put a 420 MJ in and raised the clip up one to make the bike run a little bit leaner.  Being down here in Florida with high humidity, the bike was a little boggy.  Was thinking about getting a smaller pilot jet as well, then taking the needle clip back to the 3rd slot (stock).

Where do you ride at in FL? I'm in the north east part near Pensacola.
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As suggested, refurb the suspension: new oil, seals, bushings, nitrogen charge.

 

Flush all fluids, despite low usage

coolant gets acidic and brake fluid absorbs moisture over time

 

Skip the VForce reed cage as they are often problematic, rather go for Boyesen stock replacements.

Inspect the fuel system from A to Z for crud, from tank, petcock, line, carb inlet, bowl, jets etc.

 

Check the connecting rod's side to side and up / down play while the top end is removed,

wiggle the flywheel and check for play in the crank shaft. Spin it slowly and feel for rough bearings.

 

Prolonged storage without fogging the engine with oil may have pitted the bearings over time.

 

You may want to preventatively replace the crank seals,

it would be unfortunate to seize your newly replaced top end due to an air leak.

 

Ideally perform a crankcase leakdown test before tearing into the engine.

 

Edited by mlatour
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PWK Airstriker

Pull the bladders out of the forks

Make sure the rear shock linkages have no slop or you can get head shake.

Castrol TTS @ 32:1 and you'll get lots of miles out of it.

Change the transmission oil often, I recommend Rotella T T-6.  These only hold 650cc and if the level gets low the clutch shaft bearing can go and cause mucho damage.

We've had one for about 11 years.  Neither one of my kids, both grown up now, will let me even consider parting with it.

 

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I have recently done a ton of work on my 07 CR125. For jetting in at a 45 pilot and 410 main with the stock needle and the clip  right in the middle slot. The reeds that come on the 07 CRs are carbon fiber and unless they are chipping and look bad, I wouldn't replace em. They're good. Stock pipe is also good if yours isn't super dented. I'm running a PC works with PC shorty silencer. First things first though, I wouldn't ride that bike again until you put a new top end if I was you. Check out my build thread for more info on the CRs.

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14 hours ago, gscx said:


Where do you ride at in FL? I'm in the north east part near Pensacola.

I am in the Tampa Area.  The farthest north we have gone is to Ocala Hard Rock MX Track.  Where do you typically ride?

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Yea, I took it out on the track for the first time this weekend...ran GREAT considering the piston is about to go with 55psi compression.  LOL.  Cant wait to get it rebuilt, then jet/tune it.  I put a 420 MJ in and raised the clip up one to make the bike run a little bit leaner.  Being down here in Florida with high humidity, the bike was a little boggy.  Was thinking about getting a smaller pilot jet as well, then taking the needle clip back to the 3rd slot (stock).

Were you at tampa Mx this weekend?

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No, we went to Ocala. Still have not been to Tampa MX. Were you there?

I put in two motos saturday at Tampa before they called practice for rain, Headed to Florida tracks and trails on sunday and got all day to ride without any rain.
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