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CR250R setup suggestions/help?

DieselTech

Always breakin' something
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#1
Hello all,

I have a 2004 CR250R that I started racing MX on this year. I'm somewhere between beginner & intermediate level in skill (this is my first year in MX, but I haven't ridden a dirtbike in over 15 years - mostly quads). I know that these bikes have jetting issues and no low end throttle response or power, but they are supposed to have great handling and suspension, a good midrange, and good reliability. It's probably a little too much bike for me right now because of my lack of ride time (I've put just over 10 hours on it so far, and raced in 5 races this year). I usually race Senior C here in WNY, and last weekend I tried 250-Open Beginner. I've done ok - my best finish has been 13th out of 18, but I'm certainly not the fasted guy.

I'm looking for some help in setting the bike up. So far all I've done to it is adjusted the forks and rear shock a little bit (I set sag at 3.8", turned the comp up 2 clicks). I recently added a set of FAAST Flexx Bars (I broke my wrist years ago, & I've been getting wicked arm pump - they seem to help). Other than WC radiator braces and a skidplate, that's it - bone stock.

I start in 2nd gear out the gate, and I still get a slight wheelie even with less than half throttle. I ride mostly in 2nd/3rd gear on our tracks. I'd like to get some more low end grunt, even if I sacrifice some top end, and better throttle response. I'd also like to change the gearing, but not sure which way to go with it - a tooth less so I can pull 2nd gear longer, or a tooth more and use 3rd more? I know I need to work the clutch more probably....

Finally, I want to get my suspension dialed in so that I'm confident in the handling of the bike - right now I'm not. I always seem to be getting poor traction - either the front or the rear - but it could be my riding style. I don't feel experienced/comfortable enough to ride with the throttle pinned all the time - I use mostly the low/mid. I ride probably a gear high in the corners, just so that it doesn't slide out on me (a combination of the poor low end/throttle response & good mid make cornering difficult for me - again, probably my riding style).

I'm just looking for suggestions on how to make this bike a little better suited to me, so that I can ride it easier. I'm not at a level where I can really ride this bike to it's potential the way it is now, so I just need to get it more in tune with me. Any suggestions are appreciated. Here's a run-down of my ideas:

1. ditch the stock Dunlops for something else! But what, ????
2. nice long testing session to tune/adjust the stock suspension
3. Boyesen RAD valve or V3 reeds to help the throttle response
4. nice long testing session with JD jetting kit
5. FMF Gnarly pipe to get some low-end
6. gear it up (down 1 tooth on rear sprocket) to mellow the hit & allow me to run 2nd longer


By the way, I'm about 170lbs, so not sure if I need to swap out springs (manual says it's sprung for 150-160lb riders). Thanks for any help!
 
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#2
Personally I would dial in the suspension first. Like you have already realized, unless you have the throttle pinned for like 90% of the lap, engine upgrades won't help a whole lot.


I realize we're right in the heart of the racing season, but it would still be worth it to send your suspension into someone who can set it up for you. The MX-TECH people who advertise here can help you a lot and have good prices. The stock suspension is good, but these people make it great. They will set it up for your weight, ability, riding type, etc.


I would actually run the rear sprocket up 1 or 2 teeth. You are already dissatisfied with low end power output, it will only get worse if you go down teeth.


I don't know how much $$ you have to spend on this, but if you want to do engine upgrades heres what I would do.

a. Pickup a FMF gnarly pipe and a shorty silencer.
b. Get boyseen or vforce reed setup.
c. Get jd jetting kit.
d. Pickup some VP racing gas (C12) (optional, see below)

Now install all of these addons and prepare to spend some time to tune the jetting. You will probably have to lean the bike out a bit. Assuming you get the jetting right, you will see improved lower end (the whole RPM range will be better as well).



Most serious racers run only racing gas for multiple reasons. One of them being consistency. They know the gas they buy next week will will respond the same as it did 3 weeks ago. With pump gas you do not get this consistency. It has also been shown that racing gas can improve throttle response a bit. Realize that once you tune / jet the engine with racing gas, you might have to rejet if you go back to pump gas. It won't hurt anything if you run 5 gallons through and then decide it's not worth it.



As the proud owner of a 2002 CR250 with the above mods I mentioned I must say that my bike has no lack of low end torque. I can consistently pull the front end off the ground from a dead stop while sitting my ass (165 lbs) on top of the gas cap, with little clutch work.
 

mx547

Ortho doc's wet dream
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#3
get rid of the crappy mikuni and replace it with a keihin - jetting problems are solved. i run a 51 tooth rear. i run an exhaust spacer on a dep pipe with an fmf shorty. i also installed the cometic high compression head gasket and run race gas 50/50 with pump 91. mine is an '02. i like it.
 

cnielse5

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#4
I have an 03 cr250. Here is what I have done to mine. I use the low end more and am not that fast. I Have set the sag, and messed with the clickers until it felt comfortable on the bike. I am not far from the stock clicker settings maybe 2 clicks at the most. I did put dunlop 773 tires on it and that helped here in the michigan sand. then I change my tire pressures from 10 to 15psi depending on conditions.

As for engine mods I have vforce3 reeds, procircuit works pipe, and pc r304 silencer. I think I am going to go to a platuim 2 pipe (pc version of the gnarly). I went up 2 teeth on the rear to a 50 tooth.

as for the jetting I left bike with a 400 main and stock pilot. moved the needle to the 1st position. and My fuel screw is at 1.75 turns. I ride mostly at 600-1200 feet elevation. I also just run Honda HP2 mixed with sunoco 94 octane fuel. I only get detonation at low speeds and when the temperature is below 65 degrees.
 
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#5
eric gorrs "mo betta" porting is the best fix for the jetting issues. many people have swap carbs or jd kitted ther stock carb but its only a band aid fix. i had eric do mine and will tell anyone who is have case reed honda blues this is the first step. he has un beatable price and service. plus it actually works. his set up allows me to run higher gears when i forget to shift, no biggie it still pulls. i can cut inside lines up to the face of jumps with no fear of dead spot. it pulls cleanly from bottom to top. plus my jetting is near stock and i have no problems fouling, sputtering, or pinging. i also running v-force but cant comment on performace cause i bolted it on same time i had port work done.

for ur starts u just need to scoot farther forward on seat, squeeze tight with ur thighs, and let clutch out evenly (dont dump it)

one more tooth on the rear also helps on tight tracks, makes third much more usable.

tires r gonna depend on type of dirt u ride. ask around at track and see what is common tire.

these bikes like 110mm sag. if ur not very agressive suspension is gonna seem a little stiff. just back clickers out a few and turn turn them back in as u progress. suspension always feels ruff when u dont clear obsticles like they are meant to be cleared.

hope that helps
 

DieselTech

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#6
mox69 said:
I would actually run the rear sprocket up 1 or 2 teeth. You are already dissatisfied with low end power output, it will only get worse if you go down teeth.
- Yes, I see your point about how it will affect low end, but if I do that, then the bike will have more tendency to wheelie than it does already, and 2nd gear won't hold out as long - meaning I'll do more riding in 3rd, correct? I'm not sure which is better, so I guess the only true way is to try it out and see. However, this doesn't really address the low end power/response issue - it just help cover it up by shifting the revs upwards.

mox69 said:
I don't know how much $$ you have to spend on this, but if you want to do engine upgrades heres what I would do.

a. Pickup a FMF gnarly pipe and a shorty silencer.
b. Get boyseen or vforce reed setup.
c. Get jd jetting kit.
d. Pickup some VP racing gas
- Pretty much mirrors my thoughts on mods - well, except for the racing gas, didn't think of that. Right now I run premium unleaded with 104 octane boost + Golden Spectro Synthetic Premix Oil @ 32:1. How much of an improvement does the first 3 mods make - is it very noticable compared to stock as far as low end/throttle response? Thanks.
 
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#7
I have an 03 cr. I don't race on the track but i'll tell you what gained me great throttle response. I just added a vforce3 and a jd jet kit. The bike doesn't sound the same, it's very crisp now. I run a 51 in the rear, but i would recommend a 50 or even a 49 for track. Starts in second will be fine with either of the gear combos, you just need to get more practice controlling things with the clutch. Make sure your tires are new and not rounded and as mentioned, make sure to get tires that match your track conditions. I ran the stock dunlop 755 and i liked them until they were worn. Play with your suspension and then practice practice practice. It will come around.
 
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#8
When I bought my '02 it already had all of the mods on them so I can't really comment about improvements over stock. I will say that I had a '90 CR250 right before this that ran awesome. When I hopped on the '02 it basically pulled harder and and better throttle response throughout. When my dad hopped on my '02 (he had rode the '90 as well) he said the exact same thing; more power, improved throttle response.


These bikes get a bad rap in stock form, but most people also agree they respond to these bolt on upgrades as well as, if not better than most bikes.


At the very least, I have not ever heard a single person say they were disappointed with these things :)
 

DieselTech

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#9
Thanks guys. I was pretty sure that I was on the right track with the mods I am considering. The gearing thing is what I'm not sure about - I know that it seems like I'd want to go up on the rear sprocket to get more low end, but I think I'm better off going with taller gearing - it will mellow out the power in the midrange - I mean, this bike lifts the tire with ease in 2nd/3rd as soon as it hits the mid. If I can get the throttle response and a bit more low end, I think taller gearing would work best. I think 50 is stock, so 49 seems like the place to start.
 

tony91

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#10
I posted this a while back.

tony91 said:
Initial Mods
MX Bonz Airbox fix
13/49 gearing
Rad Valve
Extensive carb tuning
PC pipe and PC Shorty
Straight C-12

Recent Mods
Eric Gorr Overbore (265) and "Mo betta" Porting
RC valve tuning
All steel clutch plates
Flywheel weight
Stock Pipe and PC Full length silencer
13/48 gearing

Future Mods
PWK
FMF Fatty
V-Force

I started with the gearing, pipe and silencer, Rad valve, and straight C-12. With those "bolt-on's" and lots carb tuning, I had a really fun, capable bike to ride.

I got a little bored and was leaning towards a 4T. As a last ditch effort to stay away from the darkside :p , I sent my jug off for the overbore and porting mods. It came back an absolute beast! I couldn't be happier with Eric's work. It's stronger off the bottom with plenty of over rev. I started fooling with the RC valve, got it to where I liked it (11mm). I liked the mid-range better with the stock pipe and felt no bottom or top-end loss versus the PC pipe. I tried the shorty too which seemed to kill the mid-range and over rev. To help with traction and to tame it just a tad, I went with all steal clutch plates and a 9oz FW weight. You will lose some "feel" with all steal plates, but it did help smooth things out a bit. And along with the FW weight, traction is improved.

I need to work on my jetting more. I think I can improve there. I'm looking for a deal on Fatty as Eric recommends it on his overbore jobs. Also, do a search on the PWK carb swap, lots of folks here swear by it. I’m looking for a deal there too.

I had it to do all over again, I would go with Eric's work and the race gas first...then play with the bolt-on's. And I really can't say enough about Eric's mods....no 4T for at least another season... ;)
Do the porting first. Eric's work IS the best bang for the buck. Highly recommend the race gas too. The RC valve mod was a nice freebie. I haven't got the PWK yet... but an s-8 nozzle was the best jetting mod I made along with trail and lots of error. I've tried every gearing combo possible and I'm back to stock (13/48). Before the overbore 13/49 seemed best. Also, the stock pipe is really good on the 03-04's. I've got a PC and had a gnarly. The PC gave a tad more over rev but the loss in bottom was very noticeable. The gnarly seemed to crush the top. I only ran the gnarly a few times...so please don't take that as gospel. Eric Gorr recommends the fatty. As soon as I find a deal, I'm gonna try one. Hope all this helps. BTW, how much do you weigh and at what altitude do you ride?
 
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#11
DieselTech said:
- Yes, I see your point about how it will affect low end, but if I do that, then the bike will have more tendency to wheelie than it does already, and 2nd gear won't hold out as long - meaning I'll do more riding in 3rd, correct? I'm not sure which is better, so I guess the only true way is to try it out and see. However, this doesn't really address the low end power/response issue - it just help cover it up by shifting the revs upwards.



changing sprockets will not help ur "wheelie" problem. its caused by poor riding technique. on starts get as close as u can to tank, head over bars. when riding keep head foward even with bars. stand up as much as possible. i can ride wheelies on a 50 if i sit on the back of the seat and wick throttle with out care. work on throttle control and riding style first.
 

DieselTech

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#12
flattie said:
changing sprockets will not help ur "wheelie" problem. its caused by poor riding technique. on starts get as close as u can to tank, head over bars. when riding keep head foward even with bars. stand up as much as possible. i can ride wheelies on a 50 if i sit on the back of the seat and wick throttle with out care. work on throttle control and riding style first.
Yes, I know I need to work on my riding style - I have only 10 hrs on this bike so far. However, I DO get way up on the seat towards the tank on my starts, and when cornering. What I'm saying is that when this bike hits the midrange, the front wheel will come up. Not a big deal, but when coupled with the poor throttle response and lack of low end, it's not a smooth transition - it's abrupt, and for me that makes the bike harder to ride. How do I know? Because my son has a KXF250, and I don't have this problem on his bike - it's got more low end and not as much power, which makes it easier to ride. Now, if I was an advanced rider, keeping it pinned most of the time, it wouldn't be near as much an issue. Unfortunately, such is not the case. I got this bike mainly for 2 reasons: 1) I'd be able to "grow" into it, thereby not needing to invest in a new bike in a year or two, and 2) I don't care for the expense of a 4T - I already have enough 4T's to take care of (I have like 8 machines total). 2T's are so easy to maintain, and inexpensive when compared to a 4T. With the number of machines I have, less maintenance=more time to ride.

So, I appreciate your input, but I have to disagree - changing the gearing WILL affect wheelies - if it's geared taller, there's less torque at the rear wheel. Less torque=less tendency to lift the front end. That's why it's easier to do wheelies in 2nd gear as opposed to 5th. 5th is much taller, so less torque at the rear wheel.

tony91 - I weigh about 170lbs or so, and my elevation is maybe a few hundred feet above sea level? Keep in mind that I'm not looking for more power - I just want to shift the power down some - I'll give up top end for low end right now - I don't need the top end, as I can't use it at my skill level right now.
 

_JOE_

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#13
Your best, easiest, most reliable, and most cost effective mod is a GOOD port job. Send it to Eric, as everyone says, he IS the best.
 
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#14
DieselTech said:
So, I appreciate your input, but I have to disagree - changing the gearing WILL affect wheelies - if it's geared taller, there's less torque at the rear wheel. Less torque=less tendency to lift the front end. That's why it's easier to do wheelies in 2nd gear as opposed to 5th. 5th is much taller, so less torque at the rear wheel. QUOTE

i undersatnd the mechanical aspect of it. but u will be only making the transition from blah blah blah bottom to hard hit midrange worse. gearing down will help smooth the transition.


also again the ERIC GORR porting is absolutly the best. it will pull harder on bottom and smooth out the "hit".
 

tony91

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#15
DieselTech said:
tony91 - I weigh about 170lbs or so, and my elevation is maybe a few hundred feet above sea level? Keep in mind that I'm not looking for more power - I just want to shift the power down some - I'll give up top end for low end right now - I don't need the top end, as I can't use it at my skill level right now.
Gotcha. Not to be redundant but... the proper port job should do that for you. If you don't want to send the cylinder off, go with the Rad valve, a shorty silencer, and get your jetting dialed in. Race gas will make the jetting work easier and you'll be surprised how much throttle response will improve with good gas. The flywheel weight really helped smooth things out too. I got a PWK on the way. I have a ton of TMX jets lying around. I'm gonna get them listed in the For Sale forum at some point. Good luck with it and let us know where you end up.