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R&B designs Boring my 200 bigger ???

Posted: 09:30 pm Dec 05 2006
by beeds3000
All my buddies I ride with have KX 250's or CR 250's I like my bike alot and would rather bore it out, being cheaper and easier than selling than getting a new bike, because I am wanting more power. My question is basically is it a bad idea, I have heard before people saying they don't run is good, run hot, etc. R&B seems like he knows what he is doing and I have heard of people boring out their motors before, It is winter time so now would be the time to do it so let me know what your guys feelings are towards this ???

Posted: 09:35 pm Dec 05 2006
by Indawoods
You still won't run with KX's and CR's... just a fact. Different porting and the KDX was not designed with motocross in mind or else they would have called it a KX. :wink:

You can get more out of it but is it worth the cost? :hmm:

Posted: 09:47 pm Dec 05 2006
by bradf
If your buddies and you ride wide open tracks like fire roads then you will never keep up with those full blown 250 MX motors. BUT, if you ride tighter trails and single track you can be very competitive and keep up if not ahead with some of the basic mods like suspension and RB goodies, VF Reeds and pipe. The only time the MX bikes have a decisive edge or are way faster is when you are on their turf which is the very fast stuff. You don't need to bore it. I have had some very experienced riders take a spin on mine and they are simply amazed that the KDX has the broad B-R-O-A-D power and rideability that they said they felt. Most had ridden KDX's in the past and "thought they knew" they were anemic. At least the last ones they rode were. But they never rode an RB’d KDX with other goodies. The difference the mods make is totally amazing. So unless you are going to ride the MX tracks or the very fast single tracks you can have as much bike as you can handle with a tweaked KDX.

Posted: 09:47 pm Dec 05 2006
by beeds3000
I know I wouldn't run with them still, I just wanted more power and I have some money to play with this winter, just wondering if it would make a big difference ???

Posted: 12:20 am Dec 06 2006
by AZRickD
...amazed that the KDX has the broad B-R-O-A-D power and rideability that they said they felt. Most had ridden KDX's in the past and "thought they knew" they were anemic...
My buddy that got me back into riding was peeved that I bought a 2T rather than matching his Yammi WR450F. I let him ride it for a few laps around the staging area and he came back with a googie eyes. Kind of like he was a bit sceered. "Wow. That thing's touchy." It had plenty of power for him, just a different delivery than he was used to (and not enough top end for him... I told him to up-shift). Then I got on his bike -- while it was easy to lift the wheel on the WR, I felt that his stock gearing was a little tall for my liking -- as if the engine was hampered in getting things spooled up from a slow walk up to mid-revs).

Different "strokes" for different folks.

His bike will do 90+MPH while mine will do 70MPH on the street (low gearing at 13/50). I haven't seen a trail (even jeep trail) that I'd want sustained speed much above 50MPH (but I'm a sissy).

Lots of fairly cheap things you can do to your stock KDX to make it run much, much better before even coming close to considering getting into the engine.

Rick

Posted: 03:07 am Dec 06 2006
by beeds3000
It's not stock, I have FMF Pipe, FMF slipe on woods silencer, Reeds, 13/50 gearing, & removed air box lid, looking for bigger more noticable modifications

Posted: 10:07 am Dec 06 2006
by AZRickD
Easy... RB-Designs head and carb mods.

Rick

Posted: 06:02 pm Dec 06 2006
by canyncarvr
I guess I might find out if I went looking. But I don't care to take the time.

You have a 220?

IF you have a 220 and are running a -35 pipe (you don't say that, either..and sorry, I don't remember) with the OEM 33mm carby, there is a LOT of room for improvement.

And you don't need that 13/50, either.

Maybe you have a 200.

In which case, there is a LOT of room for improvement.

Probably still don't need that 13/50.

Posted: 06:31 pm Dec 06 2006
by Mr. Wibbens
>|<>QBB<
canyncarvr wrote:I guess I might find out if I went looking. But I don't care to take the time.
Check out the title of the thread dummy! :roll:


I don't really see what boring it out is gonna give you
My KDX has plenty on the topside, more than is ever needed around here, up to around 70mph
When on the pipe I can go from 1st gear to 6th in about 5 seconds and the back end is spinning every gear if I'm on gravel (about the only time I ever go that fast). Boring it gonna make it faster?

Seems like your fuel mileage is going to suffer

Posted: 07:20 pm Dec 06 2006
by canyncarvr
Oh...yeah.

I thought I'd seen it somewhere :neutral:

I didn't want to take THAT much time, either!


Fine. There are still lots of rooms for improvement. :wink:

Something about the 'tone' of the question gets my vote for:

Get a different bike!

Posted: 03:46 pm Dec 07 2006
by dave04kdx
I put the LA Sleeve 240 kit in my 86 KDX. Before the kit my brother and I were neck and neck top end. (He had an 88 KDX.) After the big bore kit we were still dead even top end. I did however gain a whole lot of low end grunt. Down side to the big bore, lower life on the top end because of cast iron sleeve and hotter running temps in summer.