2007 and 2009 silencer

[Modmotoman]

Will a 2009 YZ450F OEM shorty silencer fit on a 2007 YZ450f.

I will be using my stock 07 header too.

If so what would perform better?

[todds924]

Yeah it will bolt up but you need to use the 07 mid joint gasket.

You probably wont be happy with the results.

I ditched the shorty off my 08 and ran the 08 headpipe and a stock 06 silencer and it worked great.

[KJ790]

You can make it work, but the 08 and 09 stock silencer is the worst performing silencer you could possibly get. It will hack a pretty good amount of power off by putting that on.

[grayracer513]

(The '08/'09 silencer) will hack a pretty good amount of power off ...

Oddly, it seems to do the most "damage" to the mid range, but you could lose as much as 6 hp or more at 5000 rpm, which will definitely make the bike seem rather more sluggish.

[Modmotoman]

Really? The 07 already feels sluggish vs the 06 CRF450r i had and they are both stock. it just does not have the bottom to mid rip that the crf had but the forks on the YZF are hand down better, so are the brakes.

[clutchless]

Really? The 07 already feels sluggish vs the 06 CRF450r i had and they are both stock. it just does not have the bottom to mid rip that the crf had but the forks on the YZF are hand down better, so are the brakes.

comparing bikes like that doesn't really mean much. different tranny set up combined with gearing will get you different results.

the 07 with 13 / 48 gearing stock header, slip on exhaust (freshly packed), properly jetted should give you plenty of low end and mid end on a moto track.

[Modmotoman]

I think the stock gearing has a 49 rear sprocket?

Anyways not a big deal i just have to use the clutch coming out of corners harder or more often. Kinda reminds me of my two stroke days.

[grayracer513]

... i just have to use the clutch coming out of corners harder or more often. Kinda reminds me of my two stroke days.

You should give some thought to downshifting.

[clutchless]

I think the stock gearing has a 49 rear sprocket?

Anyways not a big deal i just have to use the clutch coming out of corners harder or more often. Kinda reminds me of my two stroke days.

yes, but i am suggesting adding a 48 instead.

and as Gray says. downshift. you shouldn't have to clutch at all riding a 4 stroke. they have enough torque.

i can enter sweeper turns just engine braking and get on the gas hard half way through, by the time i am coming out i have plenty of speed.

if the turn is really tight i click down to 2nd in the air if it's a jump or right before if its not a jump and engine brake into the turn gassing out.

only time i clutch is if i am locking up the rear wheel so i don't stall. but i try to use my front brake combined with engine braking as much as possible.

[Modmotoman]

Down shift just to up shift 15 feet out of the corner before a triple? no thanks.

I have tried using 2nd and 3rd out of most corners at my local track,1st gear is for pit use only.

Its no secret that the 07 YZ450F is a bit soft down low I have even tried using a 51 rear sprocket but I found myself shifting way too much.

I like to focus on the track and not the bike. I am sure that once I have more time on this bike I will make it work but for now that silencer sticking 10 inches out the rear is driving me nuts (shorty looks cooler).

So far this bike has only 12 hours of use and im starting to blow some packing out not a big deal though.

[Modmotoman]

One more thing

Here in florida we dont have the hard pack soil that you may find other places. If the corner is deep enough i have been known to get on the gas as the bike is laying over.

[clutchless]

Down shift just to up shift 15 feet out of the corner before a triple? no thanks.

I have tried using 2nd and 3rd out of most corners at my local track,1st gear is for pit use only.

Its no secret that the 07 YZ450F is a bit soft down low I have even tried using a 51 rear sprocket but I found myself shifting way too much.

I like to focus on the track and not the bike. I am sure that once I have more time on this bike I will make it work but for now that silencer sticking 10 inches out the rear is driving me nuts (shorty looks cooler).

So far this bike has only 12 hours of use and im starting to blow some packing out not a big deal though.

you are hitting triples with stock suspension? get that done ASAP!!!!

[Modmotoman]

Raise fork oil hight, adjust sag and turn your clickers.

Unless your out of your range there is no need for a revalve/springs.

[UpAllNight]

I have cleared the 115 foot table at Bostwick every lap on my bone stock (aside from tuning) YZ250 2 stroke. I'm still alive.

I have cased a triple on a RM125 that was used by anthony pocoraba in the 1996 Atlanta and Daytona supercross, that bike had everything done to it available at the time. I broke a IMS foot peg and got kicked over the bars. I dont know if any suspension could have saved me.

[Family Man]

Actually, to get more bottom end go up a tooth, not down. Going down in size will give you more top end and make it more sluggish off the bottom. But as Grey said try down shifting, or just shifting more in general. Takes some practice at first but will improve your speed/fun.

[grayracer513]

Actually, to get more bottom end go up a tooth, not down. Going down in size will give you more top end and make it more sluggish off the bottom.

If you recall, he said he tried dropping the gearing by two teeth and ended up shifting too often as a result. This is one of the effects of lowering the overall ratio; the gears all get closer. Conversely, raising the overall widens the gear spacing, and you shift less.

When you have a situation where one gear is too short, causing you to shift soon after a corner, but the next gear is too high, you can rectify the problem by going in either direction with the gearing. By going higher, you extend the range of the lower gear so it no longer needs to be shifted so soon, and widen out the gear spacing so you don't have to shift so often. A bike like the YZ450 can almost be set up to run many tracks in one gear.

You can beef up the low end of the '07 or '08 by installing an '06 exhaust cam, if that's where you'd like to go with it.

[Family Man]

Wait he dropped two teeth and ended up shifting too often? Dont you mean he added two teeth, or am I confused. Most people add a tooth or too to the rear to close the gaps in the tranny. Does mean a tad more shifting as the gears wind out slightly faster. But more bottom end snap. Even with a 50tooth Im rarely in 5th gear on a mx track.

[grayracer513]

Wait he dropped two teeth and ended up shifting too often? Dont you mean he added two teeth, or am I confused.

Yes, adding teeth, dropping the gearing by two is what I should have said. Yesterday was a long day.

IMO, there are no gaps to close on the YZ450, and the bike covers a such huge range of speed in any one gear that lowering the gearing from stock results in a gear box that's just too close ratio for my taste. Like Clutchless, I went higher and I like it better.

[Modmotoman]

I tried a 48 and 51 So far i think the stock 49 works for me the best.

The low end is not too bad its just not as rugged as the CRF and i hate to lose any more bottom to a new silencer.

The track I go to is more of a fast track and i do see 5th twice but as soon as i see 5th im going over the last jump down that section and braking for the next turn.

I think Yamaha did a good job with the gear ratios they used.

[Mfinazzo]

I have an 07 as well and hated the OEM exhaust. Do yourself a favor and buy an aftermarket exchaust....doesnt matter what brand. All will wake up the low to mid range.