2002 cr 125 mods

[marcusgunby]

Whoa there xtreme -if you are cutting the base of the cylinder leave the exhaust side as it is(std) what we are doing is making the various part of the engine work in tune with each other,Std cylinder has big exhaust port and needs a large inlet/exhaust to match up.If you cut the cylinder it will match up well with the std exhaust manifold(in terms of tuning).It depends on what type of power you want.If you cut the cylinder it will peak at about 11000rpm and be nice and torquey but will not have much overrev.With the opened up exhaust/inlet it will with a std cylinder peak nearer 12000rpm and have good overrev.Time to choose you powerband.

 

[xtreme73]

Oops I pasted in the wrong thing. Powerband for overrev. The only thing I'm confused is with the head, not cylinder, mod. What head mod are you suggesting. You said the simple and cheaper route to keep on using pump gas is two head gaskets to reduce compression. What mod by Eric were you talking about? But for now I'll probably just want to add a gasket to get by.

 

[marcusgunby]

I would just run 2 head gaskets for now and the best pump fuel you can get.If you can get the head modded use the figures quoted by eric on without cutting the cylinder base.

 

[xtreme73]

Ideally you'd do everything at once but that ignition is expensive. If I did the V-Force reeds and intake/exhaust mod at first then put in a vertex within a month at the rebuild. Probably in May then get the ignition. Would having the vertex with 2 gaskets and not the AOF ignition cause problems or should I put them in together?

 

[marcusgunby]

Its good to do things in stages to see how each one works.Do what your budget allows.The CDi isnt necessary to get good power, the mods you listed will give you one fast Cr. :)

 

[YZ326]

Buy a Boyesen Exhaust Flange

The boyesen exhaust flange will help the bottom response and mid range.
Plus, it is more durable than the stocker.

 

[Rich Rohrich]

Originally posted by TFR
I know we're not supposed to do business or sell things in this forum, so I would prefer that you e-mail me (twofastracing@yahoo.com). THANKS

Thanks Jim :D

 

[JTCR]

Hey guys wud up? I ride a 01Cr125r and I just cut the fins off the back side of the side panels for more air flow, and I shortened my stock silencer by 50mm. What else could I do for more low-mid without spending money (ex. cut 50mm of silencer)? Should I take m yreed spacer out marcus? Thanks guys.... Peace

 

[marcusgunby]

JT your bike doesnt have the reed spacer but a cheap mod would be the cometic thin base gasket.You will need to run 2 head gaskets to stop the compression going to high.

 

[marcusgunby]

YZ326 have you tried the boyesen exhaust manifold?

 

[JTCR]

Marcus>> So buy another head gasket, combine them, and screw it back on with two instead of one?

 

[marcusgunby]

Yep

 

[JTCR]

Marcus -wold it be okay to ride it this weekend without two head gaskets?

 

[marcusgunby]

If you have really high octane fuel you may get away with it.

 

[JTCR]

and if I dont?

 

[marcusgunby]

Detonation causes damage to the piston crown/head and plating.An expensive problem.

 

[xtreme73]

so marcus your now having some troubles. I think for now I'll just put V-force reeds and try a shorty exhaust to play it safe. I don't wanna get to tearing the engine apart 20 times :-) Hope you can get all the wrinkles worked out soon. Are there really any differences between aftermarket 01-02 pipes?

 

[marcusgunby]

The thing is i have this SST pipe thats good for power but makes my previously good set up detonate.The std Cr pipe is good enough for it not to be worth paying for anything else.

 

[xtreme73]

a friend is selling his 01 pro circuit pipe because it has a little road rash, just a few inch long scrapes. I think I'll test that out

 

[<HONDA>]

Hey I bought that pro circuit pipe off ebay for dirt cheap ($93.00) So I will let you know how that works. I had to get a new one because my stocker got mashed from a little bumping and grinding while racing. It's kind of crazy because it seems that the new technique to getting better places is to knock the person over or out of the way.

 

[marcusgunby]

I really dont like that type of racing but them im getting old at 29.

 

[vetrider]

we put v-force reeds and a intake manifold from a 99 cr. the bike had to be jetted up consideralby. it still seems to cutout at high rev's. do we need to hog out the exshaust manifold to make it rev more. he says(my boy) that the bike wants him to shift when he could be just over revving. other than that he loves the bike.

 

[marcusgunby]

vet rider i too noticed the 02 want to be ridden up the gears compared to my 01.I would try a 01 exhaust manifold and match the barrel to its larger bore.A 38mm carb does help in this area but the 36mm as im finding isnt far off.The FMF SST helps but is overpriced for the gain.I picked up a 01 SST for £50 which makes it worthwhile.I fitted up with tiny adjustments(dent to clear the hose)

 

[xtreme73]

On Sunday I put on a borrowed Pro Circuit expansion chamber. I really didn't notice much difference, except for a crappy overrev associated with popping. I was jetted at a 410. Would richer jetting get rid of this? The guy wants to sell it to me dirt cheap and I figure if I can get the engine to run just as good or a little better I'll buy it.

 

[marcusgunby]

I would try a 420.