2002 cr 125 mods

[marcusgunby]

The p/v mods are to raise the roof of the p/v so it doesnt interfer with the exhaust gasses.Its mainly for top end power.Im a bit confused as to your question as you mention manifolds and then the power valves-please rephrase so i can help more.

 

[Einstein]

with that D-shaped port I believe you just only take material away inbetween the p/v and the manifold making a nice round port. Is this correct??? Where do you reference for the amount of grinding on the p/v?? I'm sorry I got you confused...I just want to be 100% sure before I start grinding. Probably being a bit over cautious.

What is a good compression reading...mine was 130 (ouwa!) Lastly are the Wiseco and Vertex comparable in performance?? Thank you

 

[Einstein]

About the left crank seal...is it pretty obvious if it was installed wrong. I've got a few drops of oil below the crank on the seal (but only the seal and not the aluminum around it), but then again that clutch actuating arm seal was leaking and letting trans oil in.

 

[marcusgunby]

I would leave the d shape as is but raise the roof of the d shape 3-4mm as the d shape has IMO advantages to bottom end pick up.
The powervalves i just blew up the picture in the gallery and tried to grind the same away-if you then install the p/v you can see if you have removed enough as the idea is to have a uniform roof of the port.

On the crank seal you always have a bit of oil underneath as when they install it with a bit of grease and it gets hot and runs.If your bike is suddenly runs lean i would look into it.

 

[marcusgunby]

I get around 145psi on comp reading but others get up to 200 so im not sure whos right/wrong.The main difference in pistons only comes from the window in the back-no window is for more bottom, window gives more mid less bottom.

 

[Moto Squid]

Help...Anyone with an 02 cr 125

I'm not a Honda guy, but am learning, and really got myself into something I should not have with my friends bike :scream: . Under the powervalve cover is there suppose to be another pin in the hole above the pin that arm rests on? Best I can tell it's only for setting the spring tension. But that brings me to why is there that spring?? Is this some dual stage gizmo? Best I can see that spring would never move...

And lastly do you guys have a noticable rattle when the bike is on idle but with some RPM's goes away or the other noises drone it out?? It seems to get a little less after warm up...he didn't think it did this before the new top end (or it was there but not as bad to be noticed, I dunno :think: ) The piston/cylinder tolerance was measured on the loose side of the tolerances, would this be a possible cause? Any thoughts are GREATLY appreciated.

Where's my full time factory mechanic when I need him...oh yeah missing in action :D :(

 

[marcusgunby]

I think the spring is there only to help the govenor if the pv is jammed with carbon or maybe its designed to take the abruptness of the system when the pv opens and reaches the end of the travel.That hole doesnt have a pin.

The rattle is generally from one of 2 places-the clutch basket on the 02 has a lot of movement and sounds horrible at low revs-the othe ris the piston-the std one slaps alot even when new.

 

[Moto Squid]

Thanks Marcus...that calmed a few nerves :)

 

[dave wright]

I have been following this thread since the start, thanks for all the great tips. Now its my turn to hassel you all, I bought an sst pipe/shorty2 silencer combo(before I heard it was crap) and the bike runs terrible. It really drops off between shifts and doesn't seem to fit on properly, like the headpipe/exh. manifold is too long. Any help would be appreciated.I am running stock jetting, openend up intake w/ v-force reeds,race fuel 60/40 w/pump fuel,cleaned up ports, and opened up the exh. +2mm

 

[MikeeeP]

Anyone tried one of these yet? The Rad Valve from Boyesen obviously comes with it's own intake manifold - the 02 prompted Boyesen to come up with a new reed design and for the 02 (and 03) they are now three stage. They look just like a regular rad valve with two small reeds on top of that - interesting looking.

Anyone tried one yet?

MP

 

[marcusgunby]

dave did it run like this before the fmf??on the +2mm is this the exhaust manifold at the top?

 

[dave wright]

The bike works great with the stock pipe and shorty silencer(fmf) and the 2mm is off of the top like was mentioned way earlier in the thread but you suggested taking off 3mm. I thought that i would start off with 2mm and see how that worked. Would I be better to just forget about the SST?

 

[marcusgunby]

for me the sst was a good pipe only when used with a wulf ignition.Also it tends to cause detonation where others dont.I would sell it and ask steve 125 to chime in on the best pipe for the 02.The one thing you could try is to get a 01 manifold and it may work alot better with the sst.

 

[dave wright]

I have tried to rejet to make the pipe work better but it was no good. I was happy with the stock pipes' performance but it is starting to get pretty rough looking( I have popped a few dents out) and just thought I would try that pipe one last time. I get my parts at cost so I may just get another stock pipe - thanks for your input, much appreciated.

 

[steve125]

Dave here's my 2 cents on the 02 cr125. First on pipes while i never tested an FMF sst i did test a 00PC,02PC and DEP pipes. I felt the DEP pipe was excellent and much better than the stocker as it made power from the mid up. I feel the std pipe for the 02 cr125 is one of the worst pipes Honda has put out in a long time. As the norm the std Cr pipes are hard to beat like in the case of my 03CR. Of course a pipe alone is not enough for this bike, but good results are easy with a few simple mods done to it.

This bike dynoed at 36hp! and was very easy to ride and flat out ripped :thumb:

1. fuel 50/50(I know Rich must frown when I post 50/50! yikes! but it works for me, sorry Rich)  VP mr2 and pump premium
2. jetting 340/350main, 25pilot, 2.0AS, std 2000 YZ125 jet needle, mid clip
3. Delta valve set on low tension and a 00Cr125 intake manifold that both it and the Delta valve mounting plate were both opened up for a full reedcage flow.
4. cylinder ports were matched but not changed, the cylinder was lowered .012, squish measured at .8mm and the head was stock.
5. PV's were moded per Wes Gilbert specs...search for that in Rich's pics!
6. SRS piston no intake window(nice and quiet!!!)
7. Ign. JD from Pro Circuit and mapped to Team Plano specs.( adds 1 hp at peak power) Std ign. base timing with the DEP pipe and a 1mm retard with the 00PC pipe,for the std ign use std timing or a 1mm advance
8. PC shorty silencer both pipes, 2000PC pipe (it fits with a little work) and the STD exhaust manifold shortened 4mm(only with the 00PCpipe) or the DEP pipe with the std manifold.
9. STD gearing 13-52
10. If you skip a step then your on your own :eek:

 

[MikeeeP]

We've got an SST pipe on the bike and the new 02/03 CR125 three stage Boyesen Rad Valve...

Back to back with the stocker is no comparison I don't have a YZ125 to match it up against in drag races, but so far this is a big gain over stock CR125 which is just terrible in my opinion. We haven't rejetted yet, and the bike probably needs to go down 2 sizes in mainjet so can't wait to see the top end when it's leaned out.

The bike PULLS much harder than the stocker - it's not even close. I'd suggest that whomever said the intake was a huge problem was correct because with the Rad Valve installed it started accelerating much harder. I’m a big guy well over 200lbs, and I would cruise along slowly click into 2nd, then third and then roll it on to see if the engine had enough torque to pull me up onto the pipe (just slang for into the powerband) with the SST it didn’t want to do it so well, with the addition of the Boyesen Rad Valve it did it much better and when it started pulling it was very linear and got stronger and stronger no sudden burst or yank, just stronger and stronger. Nice smooth feeling power, hope it translates onto the track as well as it does in just straight line testing by the seat of the pants.

We have a "Phat Head" high compression head on the way as well. It's coming with three domes, stock/higher comp and even higher yet. So we'll see how that works. If the compression is too high and the bike loses some top end, we'll adjust the engines timing to see if we can give it back some over-rev.

Sir Eric Gorr of the Wisconsin “Gorrs” (no relation to Al Gorr) will be doing the third stage which happens to be cylinder mods. At that point we’ll be taking the Phat Head back off, because Eric does extensive work to the CR125 head… so we’ll let you know how the two other stages work (phat head and then Eric Gorr cylinder). www.eric-gorr.com

MP

 

[Moto Squid]

I've gotten my 02 where it pulls a heck of a lot more than stock. I did most of the mods all at once....had my fingers crossed that everything would work together. Last year I started with a 99 intake manifold and VForce reeds, and 13/52 gearing. My new list is: 01 exhaust manifold and ground out cylinder to match, 01 stock header pipe, 01 stock silencer with 3" cut off the end, Cometic thin base gasket, 2 head gaskets, and a head done by Pro Tech that I got off ebay (I have no clue as to the specs) Without race gas and a 390 main jet and 3rd position needle clip the thing rips. It loves 2nd gear and pulls it better and noticeablely longer than before. :yeehaw:

 

[soquel]

HEy guys I'm trying to set up my 02 cr125 for mid and up. I have a PC pipe with the standard length sliencer, an "A" piston in my "B" cylinder, and a v-force reed valve set on low tension. With these few mods alone the bike is night and day faster than the stocker, although I am wondering if the low tension on the v-force is canceling out the over rev I'm goin for? what do you guys think? I heard somewhere that the low setting helps the top end too, is that true?

 

[steve125]

Yes! in my dyno testing, the low tension had the best over rev when using the V Force reed valve. I have found it's best to set up the CR125 for mid to top power. The motor is just not designed to have a YZ like low end and trying to match that you will end up with a motor with a low peak HP. The CR when tuned correctly will run with, if not beat any bike in it's class from mid to top. The riders looking for low end are just tuning for a slower and not easier to ride motor.

 

[jmekeel]

Steve,

Tell me if this sounds right?
V-Force or Boyesen Reeds with Spacer.
DEP Pipe & Silencer
13/52 Gearing
Race Fuel (VP112)
Should this increase power throughout power band?

Thanks

 

[soquel]

Hey guys, well my spring series ended today. So time to overhaul my 02cr125. One thing I thought I would remind you guys to do is to rebuild your throttle assembly! I took apart the whole thing from tube to carb and lubed the cable. And now it rotates to wide open effortlessly with a flick of a wrist. I feel my lap times dropping already! And it didn't cost a cent. I got my shock valved to compliment my forks today by BR1 in Soquel Ca. Huge differnce! now I know why people like tracks with ruts, the stocker was way to stiff for my 130 pound frame, I was maxed out on high and low speed compression. Now the bike is balanced and the rear settles into ruts and railsssss. Oh one question, is it acceptable to just replace my piston ring without changing the piston? I'm tryin to save some of my lunch money for food!