450er Jetting Advice?

[Rohr397]

My posts are hit or miss over there on the 450r forum sooo I'm taking my business back over here to you guys!

I've got my 06 450r, all stock right now but using a 162 main or whatever it is that comes in the HRC kits, and the 55 leak jet as well. I just bought a White Bros Aluminum Pro full exhaust for a good price and will probably remove the airbox lid as well. What should I do jetting wise to compensate? I'm close to sea level and air temp is useless to attempt to jet for, it'll literally be 40 and raining, then 70 and sunny in the same day here. There's no hope, but I refuse EFI.

Anyways, what should I try, if anything at all? I'm hope I don't need much for jetting but I'm not great with this stuff. I just figured I'd try what I got now and then go from there, which I'll probably do anyways, but if it doesn't work I wanna know which direction to go. Thanks!

[CJM]

450r.org or 450rhq man.

[atvrider13]

That hrc jet kit is for a stock muffler with the hrc end cap kit. With a aftermarket silencer you will more than likely need a larger main jet, like a 180?

[JOHNDOE83]

Also go to www.jetsrus.com and read the entire FAQ section.

Read it several times over.

180 main sounds about right.

Youll have to buy multiple jets and jet it using the main jet tunning method at www.jetsrus.com in the FAQ section.

[Rohr397]

Originally posted by CJM
450r.org or 450rhq man.

I've tried posting stuff on there several times and haven't gotten replies, then I copy and paste the same thing to this forum and have waaay better luck.

Alright I'll pick up a few jets right around 180 and see how it goes.

[CJM]

Sorry the org hasnt worked out for ya.

180 is awfully high for an 06+ quad with FCR. Id say a 162 is probably damn close as its designed for the HRC kit with the exhaust setup which is similar to a fullexhaust.

At most Id say approx 170 or lower.

[Rohr397]

See that's what I was thinking originally, it's designed for a lot more than just an exhaust tip so I'd think it's either gonna work with those jets or need a slight bump.

[atvrider13]

This is what Curtis Sparks recomends for their exhaust on a 06 and up. Better to be safe than sorry, being too lean. http://www.sparksracing.com/page.asp/csasp/DepartmentID.173/cs/SectionID.1400/cs/PageID.5719/csasp.html

[Rohr397]

Okay I got the exhaust on today and I definitely need to rejet. It starts fine, idles fine, but when I hit the throttle it bogs and wants to die. I can get it to rev up slowly but when I punch it too fast it bogs. It also backfires and shoots a flame out occasionally when I give it gas. Too lean, too rich, where should I go from here?

[Blodg]

Sounds lean, like Johndoe recommends start big and work your way down.

[JOHNDOE83]

Originally posted by Rohr397
Okay I got the exhaust on today and I definitely need to rejet. It starts fine, idles fine, but when I hit the throttle it bogs and wants to die. I can get it to rev up slowly but when I punch it too fast it bogs. It also backfires and shoots a flame out occasionally when I give it gas. Too lean, too rich, where should I go from here?

Deffinetly to lean.

Read the FAQ on the jetting procedure at www.jetsrus.com

youll need some 200 size jets down to 180 depending on what you have already.

Rich on gas will "WILL" sound like a rev limiter or wont let you rev up without stuttering.

Lean can also sound like a rev limiter only with flames and popping added to it. Backfiring/poping on decel, spiting back through the carb, heat, hesitation, random backfires, slow reving are all lean signs.

You probally need 220-175 in incriments of 5, you might already have a 170 or 180 in the carb, in that case get from 220-190.

Thats 8 jets at 2.99 or 3.99 a piece, not bad.

youll also need a bigger pilot jet, try to turn your A/f screw out to 3 turns and see if it backfires on decel still? if it doesnt backfire just use your same pilot jet for now.

[Rohr397]

Okay so I started with a 162 main, 42 pilot, 55 leak and whatever the rest is when it's stock. Went up to a 48 pilot and 170 main and now it backfires on decel with a huge flame out the back. It shouldn't need any more since it's all stock minus the pipe, the dealer thought I was crazy for even going above 165.

The other backfire was on acceleration, it would bog then backfire on accel.

[JOHNDOE83]

the dealer doesnt know ANYTHING!!!!! Trust me!

When I bought my 450r carb it had a 180main and a 50 pilot. my 400ex with the same carb uses a 220 and a 50 pilot.

try turning the af screw out more, you can go 3.5 turns safely, if you go over 3 your supposed to go up on the pilot jet.

I was once asked by the lead tech at a honda dealership "why do you need to rejet it" talking about my 400ex.

I once saw a honda dealer jet a bike by revving it up in neutral.

In cheater13's case, a certified mechanic told him he was to rich on his main and to lean on his pilot. "he was the exact opposite"

The dealer is nothing more then a salesman, even the service tech, even a certified trust worthy mechanic is just a salesman.

keep in mind if you go somewhere for work or parts, they will want to sell or charge you as much as possible. "Its a buisness"

[Rohr397]

Okay here's what I've got.

170 main, 48 pilot, 55 leak

Backfires with flames on deceleration right before it comes back to idling. Little bit of a hesitation and flat feeling when I rev it.

If I put the airbox lid on the bogging and hesitation goes away and the backfiring is a lot less severe.

What jet should I change and which direction do I go?

I'm reading all these threads and articles and some say backfiring is too lean, too rich, an exhaust leak, etc. I checked for exhaust leaks, that's for sure not the case. I don't think it would still be lean since a full pipe is my only mod. Idk I'm pretty stumped at this point on where to go.

[Rohr397]

I just tried running it with the choke on and the airbox lid on and it ran beautifully, so I'm thinking it's too lean for sure?

Assuming that's the case should I pick up like a 172 and a 175 and see where that gets me?

I wouldn't mind running it with the airbox lid on since I live in the rainiest place on earth....

[atvrider13]

Originally posted by Rohr397
Okay here's what I've got.

170 main, 48 pilot, 55 leak

Backfires with flames on deceleration right before it comes back to idling. Little bit of a hesitation and flat feeling when I rev it.

If I put the airbox lid on the bogging and hesitation goes away and the backfiring is a lot less severe.

What jet should I change and which direction do I go?

I'm reading all these threads and articles and some say backfiring is too lean, too rich, an exhaust leak, etc. I checked for exhaust leaks, that's for sure not the case. I don't think it would still be lean since a full pipe is my only mod. Idk I'm pretty stumped at this point on where to go. When you put the lid back on it richens it up, so thats why it ran better. You need to richen that thing up. And up the pilot jet to a 52 and your decel backfiring will go away .

[Rohr397]

I upped it to a 50 pilot and 175 main, shimmed up the needle and had the AF screw 2.5 turns out and it runs almost perfect but wants to rev out early and still shoots flames and backfires a tad. If I up the main to 180 the backfiring gets worse

[Rohr397]

Okay with a 50 pilot, 180 main, AF screw 2.5, needle shimmed up and the airbox lid on I managed to get it to stop backfiring but it now just pops really bad on decel. I could try a 52, but honestly doesn't this seem really rich for a completely stock bike? I can't believe it needs to go higher than this!

[atvrider13]

Well your exhaust pipe to cylinder gasket could be leaking. Causing it to pop on decel

[JOHNDOE83]

your gonna need possibly a 190+ main jet.

Try 3 to 3.5 turns out on the a/f screw.

[Rohr397]

Originally posted by atvrider13
Well your exhaust pipe to cylinder gasket could be leaking. Causing it to pop on decel

Went to 1.5 turns out on the AF and it's just doing a pop or two on decel which isn't nearly as bad... I'm trying to figure out whether it's jetting or exhaust leak that's causing this last bit of popping cause it seems to be running really well with all these changes minus those little pops.

[Blodg]

Rohr, if it is just a very minor popping on decel I wouldn't worry about it. I guess it may be possible to get rid of it completely but all of my 4-stroke performance motors over the years have had some minor popping on decel and I felt they were jetted perfectly and that slight popping never hurt anything.

[Rohr397]

I'm gonna throw a brand new header gasket in there and see where that gets me, also gonna re-seal the connection from the header to the pipe. I don't think it's the jetting at this point... I mean this is a stock motor, air box lid is even on it right now, I can't see a 180 main and 50 pilot being too lean. It's just one or two loud pops on decel and that's it. It's not doing the pop pop pop pop thing where it's a bunch of little ones in a row, I let off and about midway down it'll pop sometimes, not backfire, but a loud pop will go off. I didn't think it'd be an exhaust leak cause it seemed pretty tightly sealed, but it's all I got right now for guesses. Also I've got this thing packed super tight, so it doesn't have all the back pressure of a loosely packed pipe.

[atvrider13]

Mine always used to pop on decel. I recently put a 52 pilot in it and its gone now. Not much done to mine either. Just a cam and exhaust.

[Rohr397]

Brand new header gasket fixed it, also had one of the two bolts on the header a bit too lose for some odd reason, could see the carbon on that side of the header.

Lesson learned, just cause the gasket looks okay doesn't mean it is, and for $4 why not.

That being said the 180, 50, shimmed needle and 1.5 AF is jetted perfectly, maybe a tad rich even but I have yet to test without the airbox lid so I'll see what that does for it.

[JOHNDOE83]

Originally posted by Rohr397


That being said the 180, 50, shimmed needle and 1.5 AF is jetted perfectly, maybe a tad rich even but I have yet to test without the airbox lid so I'll see what that does for it.

And the dealer thought you were crazy for being in the 160 range. :rolleyes:

The rules for jetting are if you keep going up and it keeps running better, keep going up!

The main jet will only be to rich when the topend stutters instead of fully reving out.

If the airbox lid removal makes it to lean again, try to go 190 or higher.

[Rohr397]

Yeah haha the dealer is usually right but not this time. Only reason I trust them is cause the lady at the parts counter has been doing the job for almost 40 years and since I'm in there so much I wouldn't say we're friends but she knows my name, what I ride, all the problems I've had in the last six years on my quads, and it's not just some random dude without a clue behind the counter. Plus she's got an 06 crf450r so she can usually make a pretty accurate guess on my jetting, last time was dead on, but obviously this time the jetting didnt match up between the two.

As for it being too rich, it just revs out really fast like when I hit full throttle it does the whole sounds like the rev limiter thing, but I bet with the lid off it'll even it out