RB carb/head vs Fredette port/head/carb for KDX220

dsmitty · Post by **dsmitty** » 04:04 pm Jun 24 2015

I have only read a couple remarks directly comparing the two, (RB carb/head mod. vs. Fredette port/head/carb mods.). A lot of guys say not to mix the two. So, for, more, smooth, better, etc. power, throughout the powerband, Which is the better set up for the KDX 220. The Fredette porting, head, carb. package..... Or the RB carb./head mod. (with the stock porting)?

LOTS of great stuff about the RB carb/head mod. Rave after rave. Does it improve the TOP end of the 220?
I've read mixed opinions of Fredette's work.

All respect to the KING, It seems that the GOOD reviews of his head/port/carb package. RAVE about it and it's "more power EVERYWHERE" result.

My 220 has boyesens, twin air w lid removed and a PC2 pipe. It was a friends bike that I rode around last week and I bought it. LOVE THE GRUNT!!!

Totally fits our riding. I just wish it would wind out some more up top for when we open it up. (I already have a modded 200).

Took it apart to check it out and it still has the STOCK PISTON!!!

KIPS need cleaned. etc. So i want to do the mods while I have it apart.

So. Original question. Fredette port/head/carb package.....Or, RB carb/head mod. with stock porting for my KDX 220.

dsmitty · Post by **dsmitty** » 12:43 am Jun 25 2015

I just bought a KDX 220. It's got a boyesen 607's, twin air filter with airbox lid removed and a PC2 pipe. We took it apart and saw it still has the stock piston

(I think). The KIPS need fixed also. So I'm going to do the RB or Fredette thing while it's down.

For this 220, which is the better mod.? RB carb and head work with stock porting or Fredette's porting, with his head and carb work?

Sounds like the vast majority have done the RB work with Great results. How does it compare to FRP port/head/carb work for my 220

cornishwrecker220 · Post by **cornishwrecker220** » 02:40 am Jun 25 2015

Speed is just a question of money......

How fast do you want to go !
Yep RB head & carb mod will make your kdx run well...... But nowhere near as well as a full port job with added head & carb mods.
My 220 has had a full port job done with the head squished, jetting dialed in on a dyno & running a 36mm carb off a kx 125, boyesen rad valve with modded air box, timing adjusted & all breathing through a full FMF 'woods' pipe...... My bike just puts out shy of 40 bhp at the rear wheel, now you may think that with all these mods my bike runs like a mx bike but you'd be wrong, for the power delivery is very smooth with lots more bottom end pull , a healthy mid range plus a few extra rpm over run ....that's what I asked for when I spoke to the tuner & that's what I got....
So to answer your question .... Go to fredette & get the full works .

dsmitty · Post by **dsmitty** » 05:13 am Jun 25 2015

Thanks for the info.

I wonder why the Fredette port/head/carb mod package doesn't get NEAR the raves as the RB carb/head mod.

I've read that the Fredette port/head/carb package delivers "more power everywhere". Low, mid and high

KarlP · Post by **KarlP** » 07:20 am Jun 25 2015

I ran an RB modded 220. It worked very well.
My buddy built a hybrid with Fredette porting and I put an RB head and carb on it. That worked REAL well.

How's that for a not very usefull answer?

Slick_Nick · Post by **Slick_Nick** » 10:10 am Jun 25 2015

My bike is fredette ported, with RB carb and head. It SCREAMS and can outmatch many a 250. Bottom end is great, the thing just will not stall out on you. It's also jetted perfectly though.

jjavaman · Post by **jjavaman** » 10:41 am Jun 25 2015

My bike is very similar to your bike,PC pipe,boyesen reeds,airbox modded. I got the rb head/carb mod......omg the thing flys, I don't think you can go wrong with that set up. Great bottom end and lots on top.

dsmitty · Post by **dsmitty** » 12:36 pm Jun 25 2015

Kinda sounds like you can't go wrong with either one.

Anybody rode both for a direct comparison? I'm curious what the difference is and if one is better than the other. Overall, low, mid, high, snap, smooth etc. Mixing the Fredette porting with the RB carb/head work sounds killer. A lot of guys have said not to mix them though. Advice is to have same co. do the head and porting. I guess they haven't rode Slick_Nick's bike!

Is RB head work better than FRP? I wonder why a lot of other guys don't do the Fredette porting with RB carb/head mod. Or the RB carb with Fredette port/carb,?

I'd still love to know opinions on which is the BETTER one. RB car/head or the FRP port/head/carb. Anyone rode or had both?

Thanks for the input guys! Greatly appreciated!!

BlackMist · Post by **BlackMist** » 08:28 pm Jul 13 2015

RB is the better of the head and carb modifiers, but doesn't do porting. (From what I've gathered) and
Fredette does a superb job of porting. SOOOO

Why not run both?! It's already been done in Nicks bike, and in our altitude/conditions I couldn't imagine it in lower altitudes...would need straps or Popeye's forearms to hang on. Rest assured I will be opting this route over the winter as its in need of a resto/refresh.

Post by **bufftester** » 10:35 pm Jul 14 2015

RB has really dialed in the carb/head work on the KDX, but as mentioned above doesn't do porting. The 220 really benefits from a good port job. If I were spending my money I'd have RB do the carb and head, and then send it out to Fredette for the porting work, they all address different areas of the issue and don't preclude each other.

Friedom · Post by **Friedom** » 02:38 am Jan 08 2016

I'm weighing these options also, although I sent my cylinder to millennium technologies on recommendation to replate and went ahead with having them do a port and polish while they have it.
Now I think I'll run the carb as is or tune it a little and see if I'm getting what I am looking for out of the engine. Next consideration will be either carb mod or a new rb carb.
Anyways, I intend to contribute to this thread, so here's a consideration: do you need to run high octane with porting? How about with head work? Fuel availability could be part of the considerations.

Thread resurrected - it lives!

Joy to the world!

Post by **SS109** » 03:24 am Jan 08 2016

Porting doesn't change fuel requirements. Now, the head is a different story. RB gives you two options, pump or race gas. I went with pump on my '90 and I could run 91 octane with no problems. BTW, I still have an E-series RB modified head around that could use a new home.

6 Riders · Post by **6 Riders** » 03:45 am Jan 08 2016

SS109 wrote:. BTW, I still have an E-series RB modified head around that could use a new home.

What are you asking for the head?

Post by **SS109** » 05:13 am Jan 08 2016

$60 shipped.

6 Riders · Post by **6 Riders** » 05:21 am Jan 08 2016

SS109 wrote:$60 shipped.

K, I'm right in the middle of moving this week. Give me a few days and we'll make arrangements [OK HAND SIGN]

Friedom · Post by **Friedom** » 09:35 am Jan 08 2016

That's a deal for you man! What's the stock fuel octane requirement for these, anyways?
I'm hoping to take mine out to a socal rally weekend in March, but have to do some serious testing to see what kind of fuel range it has. SS do you recall the range you had on the E?

Post by **SS109** » 01:03 pm Jan 08 2016

You should be able to run 89 with no problem but I always run 91 regardless. Bike just seems to run better on it. Fuel range on a stock tank, providing not doing a lot of sand riding or climbing, was easily over 100 miles. Jetting, gearing, terrain, and how you ride all affect your mileage.

Friedom · Post by **Friedom** » 11:58 am Jan 12 2016

SS109 wrote:You should be able to run 89 with no problem but I always run 91 regardless. Bike just seems to run better on it. Fuel range on a stock tank, providing not doing a lot of sand riding or climbing, was easily over 100 miles. Jetting, gearing, terrain, and how you ride all affect your mileage.

I just saw this reply now.
Are you serious?? There must be some serious jetting issues out there. I've been reading of people hitting reserve at 40 miles.
The rally trip requires up to 120 miles between stops on one of the days. I can bring spare fuel, but I'm not into carrying 3 gallons.

Hey SS, I lost track of the thread that we talked about kick starter parts on. I didn't clarify - I'm just looking for the kick lever and boss. Still have them around?
Joy to the world!

6 Riders · Post by **6 Riders** » 12:28 pm Jan 12 2016

SS109 wrote:$60 shipped.

I can't tell if PMs are working.....I'm, sort of, moved in.....So send me your info at 6Riders@c0mcast DOT net and I'll get you some money

Tim

Post by **SS109** » 02:48 am Jan 13 2016

Friedom wrote:I just saw this reply now.
Are you serious?? There must be some serious jetting issues out there. I've been reading of people hitting reserve at 40 miles.
The rally trip requires up to 120 miles between stops on one of the days. I can bring spare fuel, but I'm not into carrying 3 gallons.

Hey SS, I lost track of the thread that we talked about kick starter parts on. I didn't clarify - I'm just looking for the kick lever and boss. Still have them around?
Joy to the world!

40 miles on a KDX tank? Holy crap! That is some seriously bad mileage! I think I posted a video up of the Taco Ride in the vids section. That was 80 miles round trip with some sand riding. I burned just a touch over a gallon at the half way point.

Yes, I still have the kick start parts.

KDXRIDER.NET

KDXRIDER.NET