WR450F ´07 running hot


8 replies to this topic
  • ASEMA

Posted February 05, 2011 - 04:27 PM

#1

I just install the powerbomb4 by FMF and the GYTR exhaust by FMF too, and i feel the bike is running at a higher temperature than with the stock pipe system, i would like to know if it´s normal with the new powerbomb or if i should keep working on the jetting, i think the jetting its ok now but the overheating makes me think i´m doing something wrong or if its normal.

maybe its important to mention that i usually ride in tight trails and that i did all mods for the WR450f (grey wire, AIS and snorkel removal, YZ throttle stop etc...). We ride long enduro trips and we have big changes in altitude during the same trip.

One of my enduro friends told me that i should go back to the stock because this new system just give me some extra torque in top end and in tracks where you keep riding at the same altitude and you don´t need to work the jetting every time. He should be wrong as someone told me in one of the forums here in thumpertalk.

  • RichGuy

Posted February 06, 2011 - 07:23 PM

#2

My 07 has always run hot as well. They come jetted very lean if you are in lower altitude. It sounds like you did some jetting already, but I invested in a JD kit recently and am looking forward to trying it out soon. I did all the uncork mods too with Q4 slip on and JD gave me some setup direction for my carb to adjust to the changes for 0-3000 elevation.
Needle - Red #5 slot from top (stock needle not adjustable)
Main - 170 (162 stock)
AP o-ring for more snap
Pilot - stock is usually okay

  • William1

Posted February 07, 2011 - 05:03 AM

#3

How do you know it is hotter? Did you use a temp probe or contactless temp sensor? Did you check the jetting after you installed the pipe?

Most aftermarket systems run a thinner wall pipe that radiates heat faster than stock and it can appear hotter. Just like a lot of after market pipes seem faster because they are louder. The point being you cannot assume something exists without quantively testing it (temp sensor hor heat or a stop watch for performance)

The bike does not 'come jetted lean' from Yamaha. It comes jetted for 68 degrees, 30 inches of mercury and 50% humidity. If you live in the mountains, t will be too rich. If you live in Death Valley, it will be too lean. Other than that, you cannot assume the jeting is good or bad, you must compare the number and do testing.

  • ASEMA

Posted February 07, 2011 - 08:37 AM

#4

thank´s for your help, fortunately yesterday i did some jetting again and after that the bike was perfect!!!!!!!

all this process left me two more questions that i hope you can give some advice, i live in the montains and in the tropic, so you can imagine that sometimes in one trip i can ride from 3.000ft to 9.000ft just in one day, (you don´t have enough time to stop and rejet) so the question and please correct me if i´m wrong : you should be more precisely with the jetting if you have install the powerbomb than with the stock system? because i guess the powerbomb gives you less tolerance to changes in altitude, humidity, air pressure? ............that was my personal impression.

If that´s correct and the stock system is less sensitive to changes in altitude, humidity, pressure etc...than the powerbomb i should use the stock system during those trips and keep the powerbomb for tracks and trails where conditions are the same or similar during the ride?

or again i´m wrong and the tolerance to changes in alt, hum etc... are the same for both systems and i should keep the powerbomb and enjoy the performance.

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  • dgcars

Posted February 07, 2011 - 09:00 AM

#5

thank´s for your help, fortunately yesterday i did some jetting again and after that the bike was perfect!!!!!!!

You say you are riding tight trails, so what jetting changes are you making and how do you determine which is better?

all this process left me two more questions that i hope you can give some advice, i live in the montains and in the tropic, so you can imagine that sometimes in one trip i can ride from 3.000ft to 9.000ft just in one day, (you don´t have enough time to stop and rejet) so the question and please correct me if i´m wrong : you should be more precisely with the jetting if you have install the powerbomb than with the stock system? because i guess the powerbomb gives you less tolerance to changes in altitude, humidity, air pressure? ............

You are on the brink of 'Information overload syndrome'.

Decide what exhaust you prefer, jet for that (if you need to change anything at all) and the conditions you ride in. Then leave it alone and enjoy....:thumbsup:


Hope this helps.

  • ASEMA

Posted February 07, 2011 - 10:32 AM

#6

Hope this helps.

with the new powerbomb and exhaust i felt that the bike was overheating in the tight trails and at lower speed, i think was too rich for the new system so i changed and it looks it works great yesterday.

Maybe your right about the "syndrome " and as you can imagine i received a lot of opinions from my bike partners and don´t want to think that i made a bad investment on the powerbomb. Meybe the right question besides what i feel with the new powerbomb, i would like to know if you recommned (off course is your personal opinion) the powerbomb for enduro rides in as i told you tight trails at low speed.

  • dgcars

Posted February 07, 2011 - 11:06 AM

#7

with the new powerbomb and exhaust i felt that the bike was overheating in the tight trails and at lower speed, i think was too rich for the new system so i changed and it looks it works great yesterday.

A rich motor will generally run at a lower temperature than a lean one

Maybe your right about the "syndrome " and as you can imagine i received a lot of opinions from my bike partners and don´t want to think that i made a bad investment on the powerbomb. Meybe the right question besides what i feel with the new powerbomb, i would like to know if you recommned (off course is your personal opinion) the powerbomb for enduro rides in as i told you tight trails at low speed.


For tight technical trails, the stock system will work fine. The FMF with a PB header is a good system. Put in some ear-plugs and you might not notice the difference......:thumbsup:

  • William1

Posted February 07, 2011 - 12:13 PM

#8

thank´s for your help, fortunately yesterday i did some jetting again and after that the bike was perfect!!!!!!!

all this process left me two more questions that i hope you can give some advice, i live in the montains and in the tropic, so you can imagine that sometimes in one trip i can ride from 3.000ft to 9.000ft just in one day, (you don´t have enough time to stop and rejet) so the question and please correct me if i´m wrong : you should be more precisely with the jetting if you have install the powerbomb than with the stock system? because i guess the powerbomb gives you less tolerance to changes in altitude, humidity, air pressure? ............that was my personal impression.

If that´s correct and the stock system is less sensitive to changes in altitude, humidity, pressure etc...than the powerbomb i should use the stock system during those trips and keep the powerbomb for tracks and trails where conditions are the same or similar during the ride?

or again i´m wrong and the tolerance to changes in alt, hum etc... are the same for both systems and i should keep the powerbomb and enjoy the performance.

No, jetting accuracy is the same no matter the exhaust however, a good system will probably make jetting miscues more apparent.

Jetting for 6,000 elevation change really forces you to accept poor running at some point. Fortunately, running lean with a 4S is not bad for the engine. Normally, I'd rec. jet for the mid point (6,000) and then experiment. Chances are, jetting perfection at 5,000 will be the least intrusive over your wide range.

  • TLRam1

Posted February 07, 2011 - 02:54 PM

#9

with the new powerbomb and exhaust i felt that the bike was overheating in the tight trails and at lower speed, i think was too rich for the new system so i changed and it looks it works great yesterday.


If you were rich in jetting you were not overheating, rich jetting and you will run cooler, this is what William was talking about you have to know by some measurement.




 
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