I have been searching and reading threads for hours now and I can't see anymore and there is so much to take in I am not sure where to start. Please forgive me for the redundancy.

Ok so my 02 CRF450r seems to be running pretty good but I am wondering if I can get a little better bottom end response/more power through doing more carb mods if there are any I can do. It does still bog if I whip it WOT from idle in nuetral when at heat but seems decent out of corners the last time out to the MX track.

It is an 05 carb that is stock except for the TM bilet mixture screw, bowl drain, and hot start nut. The diaphram is the much smaller rivet type and the AP link lever does follow the Ap set screw so I don't think the Redbeard mod applies.

The induction is stock 02 boot, box, and screen with a uni filter. I have put the 04 flywheel in with entire 05 electrics except for the kill switch which is a new 02. I have a FMF powerbomb header and FMF titanium muffler. Everything else is stock.

Should I go with the Merge APS spring and adjust the timing of the squirt? Modify the induction to a newer boot/subframe/airbox with cut-out and no screen with a No-Toil (sounds expensive)? Jettng kit? Power bowl 2?

I am open to any and all suggestions. I just don't won't to get into engine mods. Don't need the power THAT bad lol.

02 CRF450r
05 Carb w/TM billet mixture screw, bowl drain, and hot start nut
Pilot #45
Main #172
Leak #55
Needle 4th
Elevation sea to 1300' temp 50-75 current. 75-100 summer
FMF Powerbomb w/FMF Titanium Muffler
04 Flywheel w/05 electrics CDI/Stator/Coil/Harness etc

Thank you all!!

Also, if this should be in the Intake - Jetting / Fuel Injection forum could a mod please move it? Thanks again!

almost any bike will bog if you "whip" the throttle wfo from idle.. search "ap mod" or accelerator pump mod

Sounds like the AP timing and squirt could be fine tuned. You can either get some new leak jets and start there. But you have to remove the bowl each time.

I have the factory R&D adjustable leak jet cover. Comes with the AP spring, cover and all other parts needed. Very nice unit, easy to tune externally. I would suggest one.

MELK-MAN, on 03 February 2012 - 07:25 AM, said:

I tried the Redbeard mod when I pulled the carb to clean and jet it but it already has the smaller riveted diaphram and the AP link lever does follow the Ap set screw.

Is there another ap mod I missed?

Here is what I tried but does not seem to apply to my carb
http://www.gldsmc.or..._450_AP_Mod.pdf

JJRace, on 03 February 2012 - 07:38 AM, said:

Yes I have been looking at the R&D Power Bowl 2 and I have read many good things about it both here and elsewhere. I have also read peeps saying that a correctly tuned carb shouldn't need this so I am torn. I am obviously no expert so a easier solution that cost more $$ is something I definatley consider. Doesn't mean I won't try the other way's first.

try a 42 PJ and 168 MJ I'd bet that your plug is black take a picture of it for us

oakhillbiker, on 03 February 2012 - 08:34 AM, said:

Should I go to a #50 leak as well? Pretty sure I have the 42/168 but not the leak. I also don't see the #50 in the Honda parts catalog so I may have to order it online. I will pull the plug later today after work and post the pic. Thanks!

I have an 03r with an 03 carb. I done the apmod, jd jets with the blue needle. 45 pilot. Not sure on the main but it's the one recommended in the kit. I've got a 90 leak jet in. The bike has zero bog when cracked wot from idle. Absolute beast.

nickdawg18, on 03 February 2012 - 12:41 PM, said:

From all the reading I have done it looks like a lot of people use the JD kits. How many jets/needles are in those kits? Where do you ride? Just wandering what the conditions are there.

Travis at Thumper racing does a carb mod that makes the bike feel like it has EFI. Something about modifying and adding in a tube that atomizes the fuel better, along with a few other things. His mod really does make the bike more responsive than a carb. I rode an YZF 315 kit he built for one of the magazines and after the ride I mentioned how well the EFI ran and felt compared to the carb version. He then showed me the carb…

Jon-D, on 03 February 2012 - 02:16 PM, said:

Thank you! I sent them an email asking for more info. I will report back on this when I have the info.

Here is the plug. I am no expert but I think it looks ok

Plug looks fine, my '02 will bog if you whack it from idle to WOT as well. If you tune the accelerator pump to the point where it doesn't bog at all from an idle-wot throttle snap, you'll be dumping insane amounts of fuel into your motor with any throttle movement. You'll blow through fuel. The stock air induction is not a restriction - especially at low RPM/throttles.

What the '02 Cam likes is compression. They had 11-11.5:1 stock compression, which is really not enough for the cam. The '02 Stock Cam is comparable to a Stage 2 Hotcam. The 13.5:1 compression piston seems to be the preferred choice for the '02 Bikes. Really increases the bottom end. If you have a lot of hours on your crank - you can go to 12.5:1 like I did if you're worried about durability, and it will still make a very large difference in terms of bottom end power. My bike will start to loft the front wheel in 5th now.

Lead Head, on 03 February 2012 - 08:32 PM, said:

What gas do you run? Here in California the best you can do at the pump is 91 octane. Also, what brand of piston are you running in your 02? I was hoping to not dig into the engine yet as it is really strong but if going to a new piston is fairly painless $$ wise I would certianly look at doing it.

read the info on the factory R&D parts. I dont have the bowl, but the adjustable leak just cover. It works.

JJRace, on 03 February 2012 - 08:59 PM, said:

Read up on it. Looks good. Also, TT store has a good price and my new member discount would help!

mrmoto35, on 03 February 2012 - 08:58 PM, said:

93 Octane here on the east coast, but 91 can support 13.5:1. I believe Shawn_MC uses 91 with a 13.5:1 Compression.

I'm using a Wiseco 12.5:1. It came with rings, new pin, and new clips for ~$140. The 13.5:1 piston costs nearly the same. The new head and base gasket set was only like $30 as well. Not a big deal. I left the head and valves alone. The thing with these 450s, is that they make so much power, even with a "spent" piston and ring set, they're still fast. With a new piston and new ring set, you'll realize just how much power you had lost - especially the low end torque. I can pretty much tractor my 450 around now.

looks rich to me. can you drop the needle down any more if not you need to go down a size. I'm not looking at the electroid like how a 2 stroker fouls a plug its more about the color of the burned carbon around the ID of the threaded area if you had a bore scope you could see carbon build up on the head too the spark plug is just a easy way to see into the head

oakhillbiker, on 04 February 2012 - 06:53 AM, said:

Yes I was kinda wondering about that too. I was concentrating most on the elctroid like I would with my RM250. It could be that before I did the recent carb work (cleaning and jetting) it got that way.
I am going to go to the track today and ride it as last week it was muddy and hard to judge how it ran exactly. The week before it ran pretty good on the track. Will work on the mixture screw again. I will probably go tomorrow as well and I will throw a new plug in first as I don't have time to do it today.