Sign in to follow this  
Followers 0
wr450_bob

'05 WR450 Tuning - Uncorking, Jetting

24 posts in this topic

I have finished my first break-in ride on my '05 wr450 (CA) and am ready to open it up. I have already removed the smaller inner tube inside the baffle and the noise and power is about the same. I will remove the whole baffle assembly leaving only the spark arrestor. I will also pull the gray wire, unplug the airbox and will install an adjustable fuel mixture screw. The throttle stop has already been replaced.

My question is with regards to jetting: With the above changes, will adjusting the fuel mixture screw be enough to insure the engine doesn't run lean? I will check the plug but wanted to get a baseline to start. The dealer says I don't need to rejet but am not 100% convinced he is correct. Please help if you have gone thru this on a '05. Thanks.

Per Yamaha manual:

main jet 165, pilot jet 45

Share this post


Link to post
Share on other sites

It's going to be lean and the best upgrade for your carb is the JD jetting kit (TT shop). He has all the parts and instructions you need to make it run very well. Mine went much improved.

Share this post


Link to post
Share on other sites

Thanks for the info. The '05 stock needle (per manual) is not adjustable - only one groove. Will the stadard 5 groove JD needle work? If so, I'll get the JD kit, but if it doesn't ship right away, will the wr450 be too lean to run uncorked with stock jetting or will to just not be tuned ideally? I'm planning on a 2 day trip next week and may not have the time in rejet unless it arrives before this weekend. Also, can I just rotate the carb to access the needle or did you have to remove the carb? My xr400 was not so easy. Thanks

Share this post


Link to post
Share on other sites

I've got an 04 and I ran mine without the buttplug several rides without issue, in fact the bike ran great. At least I thought it did until I picked up a pipe and JD kit. No it runs about 4.5 times better than great. I made both chnages at the same time but I would put my money on the JD kit before the pipe.

BTW you can just rotate the carb to get to the needle on the 04, very easy and forward install :cry:

Share this post


Link to post
Share on other sites
Thanks for the info. The '05 stock needle (per manual) is not adjustable - only one groove. Will the stadard 5 groove JD needle work? If so, I'll get the JD kit, but if it doesn't ship right away, will the wr450 be too lean to run uncorked with stock jetting or will to just not be tuned ideally? I'm planning on a 2 day trip next week and may not have the time in rejet unless it arrives before this weekend. Also, can I just rotate the carb to access the needle or did you have to remove the carb? My xr400 was not so easy. Thanks

You can shim the needle with washers... I have the 04 WR needle in my 03, it works quite nicely and has 7 grooves. I had the carb out anyways, but I don't think you can rotate it enough to get to the needle.

Share this post


Link to post
Share on other sites

I ordered the JD kit last night. The stock restriction is so great I think it would have to be lean when uncorking with the stock jetting. Thanks for everybody's help.

Share this post


Link to post
Share on other sites

don't know what all the talk is about re-jetting. never had to touch mine on my 04 WR450 runs strong and tons of power with the stock jetting

Share this post


Link to post
Share on other sites

i havent had mine jetted it runs fine

no backfireing unless its ran out of fuel

[thank god for the reserve].but i havent

taken out the baffel as the back of my

exaust is welded on

Share this post


Link to post
Share on other sites

i think it depends on how yamaha jetted the bike and of course where you live. my friend with an '03 had to lean his quite a bit, but the jetting he ended up with is the same as my '04 came stock. so, his theory is that yamaha jetted the '04 to run unplugged and the '03 run plugged.

Share this post


Link to post
Share on other sites

I was able to get away with all of the other mods with stock jetting UNTIL.... I opened the airbox up. That one will likely give you the bog from hell. Leave it alone until you're ready to rejet would be my suggestion. JD advised me to raise the stock needle 1 position, and jet 2 sizes higher for the airbox mod. I did this and the bike runs great. I'm not sure what you do on the 2005 if the needle is not adjustable, but it will likely take 2 sizes up on the main jet.

Share this post


Link to post
Share on other sites

I ordered the JD kit and plan on bumping up the pilot and main by at least a point or two or will see what JD recommends. I don't see how the bike could properly run when the stock baffle is restricted to about 5/8" in diameter. I'll post my results on Sunday if I receive my jetting kit on Friday. If you don't hear from me it probably means one of my neighbors turned me in for zipping up and down the street. Thanks for everyones help.

Share this post


Link to post
Share on other sites

Thanks James. I'll install the JD kit tomorrow. Ordered it Wed night and it arrived today. Great service. I mainly ride in the so cal desert and Gorman so will use the 70 main and the needle in the third position (full baffle removed) I guess if I were to get a FMF Q the 3rd position would still be ok? or if I get the FMF power core 4 the 4th position? Thanks, Bob

Share this post


Link to post
Share on other sites

Yes, the settings you suggested should be good with #170 main jet and fuel screw out approx. 1 3/4 - 2 1/4 turns.

Thanks,

James

Share this post


Link to post
Share on other sites

Looks like Yamaha took care of the air box mod on the '05. At least on top. Mine was already open and breathing from the factory. Course, this does make sense if you're objective is green sticker (factory speaking). Lean out the fuel - shove in the air......see how clean it is !!!

Share this post


Link to post
Share on other sites

James,

I put the 170 main with the blue needle in the 4th position. Full baffle removed, airbox plug yanked, yz stop and gray wire pulled. The bike runs great and the plug was nice and tan but the "Scotts" mixture screw doesn't change idle much. There is a slight drop when the screw is closed but the bike still runs. Between 1/4 and 2 turns the idle remains the same. Idle is good and the bike runs great. Good low, mid and high acceleration and no backfire or stumble. Is my setup ok? Thanks, Bob

Share this post


Link to post
Share on other sites
Looks like Yamaha took care of the air box mod on the '05. At least on top. Mine was already open and breathing from the factory. Course, this does make sense if you're objective is green sticker (factory speaking). Lean out the fuel - shove in the air......see how clean it is !!!

really? i think thats y me and my dad couldnt find the air box boot thing. we were trying to find it so we could take it out but we couldnt find it. did they not put it in the 05 models?

Share this post


Link to post
Share on other sites

The california 05 has a restrictive insert right behind the battery. It had two square windows with the center section closed. Maybe this in only on CA models? To remove, note the bracket to hold the battery strap holds the insert in place. To remove, put a screwdriver behind the battery bracket and carefully pry in out. It pops right out if you pry from the front side. If you pry from the back it won't come out.

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
Sign in to follow this  
Followers 0