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Jack8745

Yamaha WR450F questions

28 posts in this topic

Hi, I'm looking at a 2006 alloy frame wr450f has around 3500 miles on the clock it's been used for light green laning and the odd enduro race.

What are the main issue to look for with this year and bike?

I currently have a drz with 440 kit, stage 1 cams and a fcr would I notice the difference in bikes or roughly the same?

How would the bike hold up being used everyday for a 30 mile ride?

One last question the bike has enduro wheels I'd be looking at putting it into supermoto trim. Would I need a cush drive or would I be fine with a standard hub?

Thanks in advance and sorry if the questions have already been asked.

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The WR/YZ engines have great durability compared to a CRF Honda

You would also be selecting a vastly more advanced bike and lighter

If you plan on logging gobs of hiway miles maybe not though

 

As you may know, one major issue is valve wear and valve shimming

As the valve wears the gap between valve stem and rocker arm gets SMALLER not bigger

So long as you stay on top of that adjustment these engines last a fairly long time

 

If it has FI (or carb) perhaps jet if an RCH on the rich or 'fat' side so the engine will last longer too

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Not over here. I know of 3 long running thousands of km WRs who never needed any shim change:

My WR400F never changed valve clearance, sold it at 20.000 miles. 

My '03 was sold with ~10.000 miles on the clock w/o any valve shimming maintenance needs.

Same goes for my buddy's WR426F(!), still running with the same set of shims and clearances well within spec!

Mind you, we are talking about well over a decade of offroad and freeway usage here!

 

BUT you should check the FCR.  At high milage (concealed by fresh chain, tires and graphics)

the slide's rollers might have dug into the carb's body, over time squeezing the slide's aluminum plate on engine side.

I'm taking about part #11 here

http://www.boats.net/parts/search/Yamaha/Motorcycle/2006/WR450F%20-%20WR450FV/CARBURETOR/parts.html

 

If that plate start to be subjected to the forces of intake air hammering at the slide it will break.

If you are lucky like me and my WR400F, the part that breaks off gets stuck in the intake duct on a valve's stem.

If you are less lucky, like some ohter high milage guy a decade ago, the broken off part will find its way into

the combustion chamber.

 

I my book that is the only true reason for picking an EFI version over the FCR one, when buying second hand WRs..

Edited by WRF-Rowdy

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I would be doing a mix of highway and country roads depending on my mood and weather I guess. I'm fine with getting hands on with the bike that's not a problem.

Would you recommend a cush drive or isn't that really necessary?

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You don't need a Cush drive.

The 07 was the first year of the aluminuim frame.

Not sure what's going on with FCR carbs but they are pretty free of issues I know of. I am not a fan of the fuel injected versions. But that's just me.

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You don't need a Cush drive.

The 07 was the first year of the aluminuim frame.

Not sure what's going on with FCR carbs but they are pretty free of issues I know of. I am not a fan of the fuel injected versions. But that's just me.

Ok that's bonus then. What's the problem with FCR carbs? Got one on my drz and seems fine? The wr I'm looking at is 56 plate with the alloy frame.

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I think someone above said to watch the rollers in the FCR carb. I have never heard of any issues with the rollers or the carb body where they ride into. That's why they used rollers. They last as long as you use a air filter.

What is a 56 plate ?

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I think someone above said to watch the rollers in the FCR carb. I have never heard of any issues with the rollers or the carb body where they ride into. That's why they used rollers. They last as long as you use a air filter.

What is a 56 plate ?

Ok I'm not to familiar with carbs so I'll need to do some reading up on them. 56 plate is a 2006 model

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If you re-route all your vent hoses to under the tank, and filter them, the carb lasts much longer.

Ok thanks for the info appreciate it

How much abuse can these wr's take?

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Ok I'm not to familiar with carbs so I'll need to do some reading up on them. 56 plate is a 2006 model

So if it's a 2006 model it would be a steel frame with a aluminuim rear sub frame. Only the 2006 YZ450 had a aluminuim frame.

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I think someone above said to watch the rollers in the FCR carb. I have never heard of any issues with the rollers or the carb body where they ride into. That's why they used rollers. They last as long as you use a air filter.

What is a 56 plate ?

Well, we had quite some early FCRs (WR400F time) where the rollers did dig into the aluminum body in the slide's predominant position, idle.

This only happens with dual purpose usage where the bikes get to see a whole lot of milage.

My WR400F developed the crack in said plate complete with a huge part breaking off and getting stuck at a valve stem in the middle of a club race in a gravel pit.

 

While idling, the intake "vaccum" is the greatest. That is at every intake cycle the cylinder removes the air on the engine side of the carb

and to the carb's slide the now overwhelming ambient air pressure feels like a hammer comming from the air filter side.

That very effect was the reason why early non-roller flat slide carbs (a certain local Mikuni tuned XR Honda comes to my mind)

would act as if they were stuck in closed position when engine braking.

 

The beauty in the FCR's desing lies in the idea to separate air pressure resistance from sealing the intake port.

They added a small aluminum plate (sometimes called "Vacuum Releave Plate") to the slide, held in place and preloaded only by a rubber spring (looks like an oring).

Hence all the pressure from the intake side is handled by slide + rollers + carb housing, so the alumlinum plate

doesn't "feel" any big forces, it's "releaved from the vacuum". Even during excessive engine braking one can easily and gently open the slide.

 

However, over years of commuter usage the hammering took its toll and the rollers did dig into the aluminum housing.

That way the slide would creep towards the plate. Until it has taken up all the rubber ring's clearance and starts to

press the plate against the intake. That plate is a coated, rather brittle piece of aluminum (magnesium?) which cannot bear the mechanical force

and starts to develop a crack, typically starting at the hole at it bottom. This is your last chance to save the engine.

From now on you can only start buying plates by the dozen, the carb is terminally shot. (or you do the VB mod, see later)

To see what I'm talking about google   fcr cracked slide

It looks like this http://i38.photobucket.com/albums/e142/motoxer667/IMG_5183.jpg

The end is near : http://www.thumpertalk.com/topic/127978-broken-throttle-slide-plates-aka-direct-metal-injection/?p=1969675

 

The solution is to fix that only real flaw of the FCRs before it'll bite you by

1) selling your bike in time and pass on the hot potatoe (that is why I be very vary of "low milage" used FCR-WRs) :devil:

2) add rails to the carb :thumbsup:

I started out by inserting L shaped profiles made of brass between rollers and engine side of the slide's cavity.

They must be very thin or the rollers will bind on places where they did not dig into the aluminum of the carb's body.

They must be full length of the slide's cavity so they stay put.

It is a critical component, you do not want to end up on a WR with the slide stuck at WFO.

Brass was no got idea, too brittle, started breaking, too.  Buddy Volker Bartheld picked up and made these "rails"

from stainless steel, send me a set and that is the only reason my WR400F's FCR survived 20.000 miles!

You might find info on the VB mod somwhere.

 

The nice thing about the rails mod is that their added 0.1 mm thickness will save a carb that already squeezes it's plate.

The poblem is that such carb doesn't have a level roller riding surface anymore. Your rails will not sit snug on the

carb's housing in exactly these places where the rollers did dig in. The rollers will eventually break the metal

in their preferred digging location.  But a set of rails per, say 1000 miles is a very economic fix, in my book.

Edited by WRF-Rowdy

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what I forgot whil being carried away by old memories im my previous post is

how to tell if a used carb is worn:

 

That it out, or at least twist it out of both rubber connections (engine, airfilter).

With the side in idle position press with one finger at the slide from the airfilter side.

When you now tap gently at the engine side of the slide, while still pressing onto the air box side,

and you hear some rattling the carb is still ok.

If tapping the engine side of the slide is slient, no rattling, the carb is shot.

Edited by WRF-Rowdy

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Ok thanks for the info appreciate it

How much abuse can these wr's take?

If you keep the oil tank filled and occassionally check coolant they are indestructible.

Sustained freeway riding (Vienna to Florance is ~500miles) at 80mph,

to be followed by a week of off road torture, rounded of by another 500 miles freeway back home

is what I call normal enduro bike usage pattern.

During such events we had LC4s ruin their big end bearings, or my KLX650R burn through the head gasket.

 

I am the exact opposite of the attentive, caring US offroad aficinado, who throws bling at his bike,

changes oil mid week only runs conoco race gas, and uses a fresh air filter every second day.

 

Checking valves every second year (has been unnecessary in recent 17 years of various WRs)

greasing rear linkage (all bearings, including the swingarm ones)

Changing oil and filter once a year, maybe washing and regreasing the air filter, while at it,

that is all these bikes need.

 

Of couse your throttle or clutch cable will tear after a 10000 miles,

and it's a good idea to change brake fluid every two years, but that's all.

 

When I bought my first WR in '98 an XR400 buddy of mine was partial to my anticipated joy

because of yamaha 's requirement  to adjust(!) valve clearances every 500 miles.

Today we laugh at that statement.

WRs are the only bikes I know of, that have zero adjustment requirements.

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Ok thanks for the info appreciate it

How much abuse can these wr's take?

 

More than you can give it. Seriously, it's the most reliable off road bike made.

Not the highest performance (especially the susension), so you have to 'prep' several areas for better, more 'linear' performance.......

 

....but if you don't do something as re-grease the linkage with real grease, just like any other bike, it will eventually sieze up....and several other things.

Edited by KRANNIE
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