Boyesen Rad Valve

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#1
Just saw the 04 YZ250 rad valve review in MXA and it sounds like something I want but is it for 04 only? It was my understanding that the engine stayed the same this year. So wouldn't the 04 Rad Valve work on an 03?
 

Rcannon

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#2
The bolt pattern is identical all the way back to 97.

I would love to know how they installed it without screwing up jetting. Figure 150 for the valve and another 150 in jets to get it correct.
 

elf

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#3
Go ahead and try it. boysen gaurantees it will work or return it for refund. I had one in my 00 yz250 and it worked good just had to move the clip on my needle and drop the main a couple of sizes.
 
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#4
ONly reason I ask is that Rockymountainmc.com has a listing for 02-03 YZ and then a seperate listing for 04. They don't give part no.'s so I'm not sure if they are the same. I think it is different in the sense that it includes everything and not just the valve part? Added the tubing?
 

elf

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#5
I looked up the rad valve part numbers at another dealer and the 03 and 04 were the same. If your worried about it get the 04 part it should work the same on the 03.
 

Studboy

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#6
Originally posted by Rcannon
The bolt pattern is identical all the way back to 97.

I would love to know how they installed it without screwing up jetting. Figure 150 for the valve and another 150 in jets to get it correct.
As you can tell Rcannon has had less than stellar tuning results with the aftermarket reed valves...... :p

 
 

Studboy

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#8
It wouldn't be so expensive and time consuming if you would just buy the right ones the first time!!! :silly:

Did the leaner needle help at all?
 

Rcannon

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#9
I made a dumb mistake on the needle. I did no thave time to look it up myself. I asked Plaza Cycle for ..One needle leaner"

I ended up two steps more rich. Live and learn, right???
 

Rcannon

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#11
I hate answering stuff like that....In my opinion, NO!

The stock reed setup in the later YZ's is very good. I have tried the v force as well as the rad valve. Both are very similar in my bike. If I use my imagination, it might pull slightly better down low with either one.

I think a port job or afresh top end (if needed) would be a much better use of the 150.00 these both cost.

Neither one will drop into my bike and run well without major jetting changes. I believe I can get performance as good fine tuning the stock jetting with the stock reed cage.

I have tried a lot of hop-up parts on this bike. Nothing has really given it more power. Most pipes move the power around, but create nothing extra.

I also believe this stuff we read in magazines about how wonderful these valves are...NOT!!! The articles are printed to suck up to the makers of these products. Feel free to experiment. This is what it is all about. I do not regret spending money on the parts because I have fun playing with them. Just do not be dissappointed when they dont do much!
 
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#12
Thx for you opinion! I checked and the 04 has a different part no. than the 03 rad valve. 02 -03 ends in 34h while the 04 ends with 34I. So they must be different.

As far as magazine reviews go I haven't had a bad expereince yet. Everything I bought did exactly as they said it would. The Vforce was siad to have a minimal increase if any which you also mentioned too. This is the first review that actually said it was a BIG difference for a YZ.
 

James

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#13
I can see where Boyesen would have different rad valves for dimensionally same engines if they actually do what they claim. They claim that they flow test each model year and change the shape of the intake for maximum gain. That may be why there is a different part number for 04 from 03.

My own personal experience with this is that the 00 CR uses a different Rad Valve than the 01 and I think the 99-92 uses a different one yet, but the dimensions of the intake on all of these bikes is exactly the same, the cylinders are interchangeable, BUT the porting is different. I can see a minor physical difference between the two rad valves but haven't switched them to see if it matters.

I CAN tell a difference with the Rad valve compared to stock without using my imagination. Much stronger pull off the bottom with it BUT I hear you can get the same result by simply using the Boyesen pro series reeds for $100 less (the rad valve comes with pro series reeds). I am going to try the reeds only in the 02 and see if I find this to be true.

I agree with Rcannon that it is best to experiment if you really want to know because you will get opinions from all over the place and they often contradict each other. Unfortunately, this experimenting costs money...lots of it.

I hear that the 04 YZ motor is awesome as it is....looking forward to riding one to find out.
 

Rcannon

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#14
The experimentation is fun. Ebay makes it very easy. I have been able to try a lot of different things on my bike without losing a ton of money!
 

muddy226

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#15
FWIW I found on my RM that using the Boyesen reeds on the standard reed cage the best value, I have got the rad valve but but can't notice a difference between them if using the dual stage reeds.