Krannie McKranface

2008 WR450F WITH YZ SUSPENSION AND CAMS / PART DEUX

133 posts in this topic

........fixed it.........

OK, let's all learn together:

This is a stock FCR CR Needle jet (emulsion tube) (main jet shown attached): No part number, no 'jet' number. No holes.

141_0707_17_zkeihin_fcr_carb_techneedle_jet.jpg

The one inside that was originally inside my carb, is on the left. Corroded, and ovaled, and needed to be replaced.

The one on the right is a 'Factory 150" 8 hole perforated Needle jet: supposedly the exact same as stock, but with emulsion holes.

That is what I replaced the stock one with. The picture makes them look different in size. They are the same.....don't know why they look so different in the pic.

IMG_25881_zpsd3e014c0.jpg

Results? Chasing a gremlin for a month+, trying to figure out why at 1/16 -1/8 throttle, there was a massive flat spot.

Turns out, the Factory 150 Needle jet was wrong. Don't know why it was wrong, but when i changed to a 16 hole genuine Keihin Needle jet, everything went back to normal.

WR250ET.jpg

This is the Needle Jet I have used before, and thought the the Factory 150 was the same. WRONG.

This comes out of the 2002 WR250F as a stock carb part. It has 16 emulsion holes.

I came across this part when trying to tune a friends FCR carb on a DRZ400. This fixed his flat spot problem.

Essentially, what it does is atomize the fuel sooner, and better, for better partial throttle control.

Using a stock WR450 carb part probably would have worked too....but not quite as well.

Well, that only took two months.................

Share this post


Link to post
Share on other sites

I just found a post about someone else trying the same Factory Pro needle jet and having the same flat spot problem I had.............

Apparently they just were all made wrong, and actually don't even work very well.

Oh well..........

Share this post


Link to post
Share on other sites

So, now the power is back to normal, with more over rev and power on top (yz spec hot cams for wr).

Power off-idle is just like stock. You are able to grunt down low, keep it there or run it up to more power, with no hiccups, shelves, or issues.

OK, so NOW would I do it all over again, with the hot cams???

...maybe....

Share this post


Link to post
Share on other sites

"I just took mine out for a 25 mile dual sport ride, after spending a month chasing issues. My issues was not the decomp pin, mine was fine. It was a bad Needle jet.

I have a very quiet slip on mounted now, so the top end power is down a little bit, but the power overall is very good. Very smooth, easy normal power at small throttle openings, and some serious pull from the mid rpm's up with a tug on the throttle."

-from another post

1 person likes this

Share this post


Link to post
Share on other sites

........fixed it.........

OK, let's all learn together:

This is a stock FCR CR Needle jet (emulsion tube) (main jet shown attached): No part number, no 'jet' number. No holes.

141_0707_17_zkeihin_fcr_carb_techneedle_jet.jpg

The one inside that was originally inside my carb, is on the left. Corroded, and ovaled, and needed to be replaced.

The one on the right is a 'Factory 150" 8 hole perforated Needle jet: supposedly the exact same as stock, but with emulsion holes.

That is what I replaced the stock one with. The picture makes them look different in size. They are the same.....don't know why they look so different in the pic.

IMG_25881_zpsd3e014c0.jpg

Results? Chasing a gremlin for a month+, trying to figure out why at 1/16 -1/8 throttle, there was a massive flat spot.

Turns out, the Factory 150 Needle jet was wrong. Don't know why it was wrong, but when i changed to a 16 hole genuine Keihin Needle jet, everything went back to normal.

WR250ET.jpg

This is the Needle Jet I have used before, and thought the the Factory 150 was the same. WRONG.

This comes out of the 2002 WR250F as a stock carb part. It has 16 emulsion holes.

I came across this part when trying to tune a friends FCR carb on a DRZ400. This fixed his flat spot problem.

Essentially, what it does is atomize the fuel sooner, and better, for better partial throttle control.

Using a stock WR450 carb part probably would have worked too....but not quite as well.

Well, that only took two months.................

Surprised a wr250 part would work. Different needle jets are even listed between a 08' yz450 and a wr450.

Share this post


Link to post
Share on other sites

So what ended up being your final configuration? Still running the YZ header or R&D bowl?

Are you going to try and add some of the stuff back to the bike now that you found the original gremlin?

Share this post


Link to post
Share on other sites

So what does the stock 08wr450 needle jet supposed to look like? The one with 16 holes or the one with no holes? I'd have to remove one to see what they look like.

Share this post


Link to post
Share on other sites

So what does the stock 08wr450 needle jet supposed to look like? The one with 16 holes or the one with no holes? I'd have to remove one to see what they look like.

It's supposed to be a 16 hole version, but many many were shipped with the "no holes" version.

My 2003, 2006 both had 16 holes. My 2007 did not, and my 2008, who knows....

Share this post


Link to post
Share on other sites

It's supposed to be a 16 hole version, but many many were shipped with the "no holes" version.

My 2003, 2006 both had 16 holes. My 2007 did not, and my 2008, who knows....

Great, now I am going to have to pull it out and check just to make sure. :banghead: even though it seems to run good.

Share this post


Link to post
Share on other sites

Great, now I am going to have to pull it out and check just to make sure. :banghead: even though it seems to run good.

If it ain't broke......tear it down to the last bolt anyway and modify everything, and get it running really really good, then do it again a few more times, until you reach Nirvana......or don't fix it.

1 person likes this

Share this post


Link to post
Share on other sites

If it ain't broke......tear it down to the last bolt anyway and modify everything, and get it running really really good, then do it again a few more times, until you reach Nirvana......or don't fix it.

My winter jet is coming up next. Will check then, if I can wait that long. Now I am curious.

Yep, gonna pull it tomorrow.

1 person likes this

Share this post


Link to post
Share on other sites

I think the 2007-2011 do not have any holes.

So far I have had a 07, 09, and 11 WR450 carb apart in the last couple of months and none of the needle jet tubes had any holes in them.

Picture is from a brand new 2011 WR450 carb.

IMG_10201.JPG

Edited by gcally

Share this post


Link to post
Share on other sites

I think the 2007-2011 do not have any holes.

So far I have had a 07, 09, and 11 WR450 carb apart in the last couple of months and none of the needle jet tubes had any holes in them.

Picture is from a brand new 2011 WR450 carb.

Correct, I have a 07,08,and 09 no holes. The holes wouldn't make any difference anyways. The carb main air jet area is not drilled through, so it wouldn't do anything to have the holes.

Share this post


Link to post
Share on other sites

I think the 2007-2011 do not have any holes.

So far I have had a 07, 09, and 11 WR450 carb apart in the last couple of months and none of the needle jet tubes had any holes in them.

Picture is from a brand new 2011 WR450 carb.

I just went through the parts fiche : 2000-2003 WR's all have the 5JG 14264 Needle Jet, and the later years have the 5TJ14947 Jet.

I assuming that's the 16 hole vs the no-hole versions.

Share this post


Link to post
Share on other sites

I think the 2007-2011 do not have any holes.

So far I have had a 07, 09, and 11 WR450 carb apart in the last couple of months and none of the needle jet tubes had any holes in them.

Picture is from a brand new 2011 WR450 carb.

Correct, I have a 07,08,and 09 no holes. The holes wouldn't make any difference anyways. The carb main air jet area is not drilled through, so it wouldn't do anything to have the holes.

I just went through the parts fiche : 2000-2003 WR's all have the 5JG 14264 Needle Jet, and the later years have the 5TJ14947 Jet.

I assuming that's the 16 hole vs the no-hole versions.

Good. Now I can just go ride and not worry that my bike could run just a tiny bit better. :ride:

1 person likes this

Share this post


Link to post
Share on other sites

Did you change the needle jet and the RD Powerbowl at the same time?

Share this post


Link to post
Share on other sites

Good. Now I can just go ride and not worry that my bike could run just a tiny bit better. :ride:

Oh no you don't get out of this that easy. You could always drill the hole or have it drilled through. :rolleyes:

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

  • Similar Content

    • By BMar
      Hey everyone!
       
      I went out to the desert last weekend and decided to record it. We rode mostly tight sand washes. Check it out!
       
      PS Turn up the resolution and  the cameras were faced too far down but I tried to make it work
       
       
    • By C-P
      Looking for the 2009-specific head pipe for 09 YZ250F.  Let me know what you have, thanks!
    • By Lachie carwo
      does anyone know if a 1997 Yamaha WR250z is legal on your L's/LAMS?
    • By owainyz03
      Hey folks,
      I'm delighted to be back in the YZ 2 stroke forum after a bit of an absence. I used to own a 03 YZ 125 which always regret selling. I currently own a 2011 yz 250f and owned a 03 rm 125 until recently when I sold it to a friend. Only a few weeks later I got the 2 stroke itch and began looking for a 06+ YZ 125, after being blown away by the SSS suspension on the 250f. A few came and went that I missed out on but finally one popped up. Advertised as a 2007 yz 125 (vin checks as a 06) priced at  2500 Euro. The usual BS advertised was on the ad "good tires only one ride, chain and sprockets good etc " Arrived down and found the chain and sprockets absolutely shot, tires were worn, Leaky fork seals(looked like new oil?) rear fender broken few bits and pieces. Talked him down to 2200 euro and was happy enough with that. Picked it up on friday on my way home from college and started ripping it apart. And that's where things go down hill 
      Found the air filter in a shocking state (see pics) which caused a major groan.... still at least its a 2 stroke. From looking in the exhaust and intake ports I could still see crosshatching very clearly, unfortunately I didn't have time to rip the cylinder off yet. Counter shaft seal appears to be weeping so that will get replaced, also isn't there an issue with 06 shift stopper or something? It does have unbreakable levers which is one of the few plus's
      All of the bearings will be inspected and replaced if necessary, new top end most likely, new bars, grips, tires, fork seals, chain and sprockets, air filter, restyle plastics more than likely and whatever else I uncover 
      Keep in mind this will be a slow build as I'm in college 5 days a week.
      Now some pics
       
       




    • By Joseph18roberts
      My dirt bike was driven daily no issues besides petcock leaking a little gas and one day It quit running while I was riding it and started acting up the next day I tried and it would start but it wouldn't idle I would have to rev it high to stay running and it would backfire real bad this was a couple months ago anyone know what could be the issue if so let me know please gonna look at it tomorrow thank you in advance