Another Jetting question ... (I know, I know)

8 replies to this topic
  • odonnks

Posted March 04, 2006 - 04:38 PM


I relyed on this site to help decide which to but and BOY am I glad. I am very satyisfied with my new WR450F!
You folks are great !

Heres the scoop...
New bike with free mods done. Once off idle it runs awsome. Better than expected for so little done.

If the throttle is 'blipped' off of idle under load or not the bike will fall on its face. Roll it just past idle and wack it and its like a rocket. I read pretty much all jetting threads and are pretty sure of what to do for PA at 1000 ft.

It sounds like the leak jet needs to be reduced in size but does anyone know what size is installed from the factory?
(if it matters the bike was sold new in PA).
For that matter, how about all the stock sizes?

Main ?
Pilot ?
Starter ?
Leak ?

Also, Can someone list the effects a rider might notice if each or any of these is incorrectly sized?

Thanks !

  • 25year2stroker

Posted March 04, 2006 - 05:18 PM


Pg. 2-8 05 manual

Main #165
Pilot #45
Starter #65
Leak #50

  • OneToGo

Posted March 04, 2006 - 07:08 PM


You dont say what jetting you have installed.
If you have done all the "free" mods and fitted a freer flowing exhaust/end cap then the you need to richen the jets.
If you are at 1000 ft then go with Clark4131 guide, you probably have this - roughly:
MJ: 168/170
PJ: 48
JD? - as per instructions, Red#5/Blue#3
LEAK: 40 or less if cold (#35/#0)
The pilot sets fuel delivery for up to around 1/3 throttle (see manual) and the LEAK sets initial throttle response. See other jetting posts on this and tech articles.
In your case (slight hesitation/bog), I suggest #40 Leak and make sure the AP timing is correct. Also put in PJ 48 if not already done so.
:thumbsup: Hope this helps.

  • odonnks

Posted March 04, 2006 - 07:42 PM


I did find the as shipped jetting in teh manual like 25year... said. I was looking in the carb section and not the maint. section.

With off idle bog at temps below 30 deg F. and a #50 stock leak jet, is it likely that the bog rill reduce once temps get to 50 deg F or so?

I don't consider the riding I'm doing now normal, just break-in.

Thanks again !

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • clark4131

Posted March 04, 2006 - 07:59 PM


To cure the off idle bog, if you want to do it properly, follow these steps...

1. Properly set the AP linkage per the manual
2. Time your AP squirt accurately (Video method works best)
3. Adjust the squirt into the .75 second range with the proper combo of leak jets and/or AP diaphragms
4. Properly jet/adjust the Pilot circuit and Needle position for temp and elevation.

It took me a LONG time to get mine right, but with a little perserverance and patience, I achieved jetting Nirvana...SC

  • odonnks

Posted March 05, 2006 - 04:20 AM


aaaaahhhhhhhhh.... jetting Nirvana....

I want that too... I'll see you there !

Thanks !!

  • odonnks

Posted March 05, 2006 - 04:56 AM


Ok, I just received word that my TT store order is sitting in my office, (can't ship to home no winter maint on roads and UPS or FEDx won't come in..)

Anyhow, I ordered:
JD Jet Kit Yamaha
ThumperTalk AIS Smog Removal Kit

Question : With the bog off idle and likely replacement of leak jet required, is there any benefit to installing the JD kit and ZT screw without installing the leak jet? That may be another week till I get it. :thumbsup:

Thanks :thumbsup:

  • clark4131

Posted March 05, 2006 - 07:20 AM


Question : With the bog off idle and likely replacement of leak jet required, is there any benefit to installing the JD kit and ZT screw without installing the leak jet? That may be another week till I get it. :thumbsup:

Thanks :thumbsup:

Yes! You can get your Main and Pilot dialed in and then go on to the AP circuit when the leak jet comes in. The AP works somewhat independent of the other two, as the other circuits rely on vacuum to suck gas through the carb, and the AP is mechanically activated. BTW, Zanotti's is a great way to go for discount OEM parts, if you don't know about it already...SC

  • odonnks

Posted March 05, 2006 - 03:07 PM


Sounds good, thanks !


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.