# back firing???



## 07 BRUTE (Jan 27, 2010)

i just put hmf utility on 07 brute 750 the bike is snorked and i figured i would have to rejet but the bike runs great without rejetting. my question is when i hit ab 30 and go to decel it starts to back fire do i need to rejet or what??


----------



## fstang24 (Jan 9, 2010)

Good question as i have been dealing with this issue. I have 2010 Brute 750 and installed the hmf slip on my bike and notice the backfire on deacceleration. So i installed the hmf optimizer and still does it, but have not modify any of the settings yet, but i also discovered i had an exhaust leak at the rear cylinder pipe. Some people say a small pop on deaccel its a sound of perfectly tuned bike, but who knows im confused


----------



## Bootlegger (Dec 18, 2008)

07 BRUTE said:


> i just put hmf utility on 07 brute 750 the bike is snorked and i figured i would have to rejet but the bike runs great without rejetting. my question is when i hit ab 30 and go to decel it starts to back fire do i need to rejet or what??


at what Throttle position is it doing it at most? You may be able to shim your needles and get rid of it...just depends on what your plugs look like. Check you plugs and let me know.



fstang24 said:


> Good question as i have been dealing with this issue. I have 2010 Brute 750 and installed the hmf slip on my bike and notice the backfire on deacceleration. So i installed the hmf optimizer and still does it, but have not modify any of the settings yet, but i also discovered i had an exhaust leak at the rear cylinder pipe. Some people say a small pop on deaccel its a sound of perfectly tuned bike, but who knows im confused


No...thats not a perfectly tuned bike. If I were you I would sale the Optimizer and get a Power Commander 3 "PC3" You can have it tuned on a Wideband and then you will have a perfectly tuned bike. The Optimizer you cannot take away fuel....but you can with the PC3. With the PC3 you can tune it at every 20% throttle position. Trust me...once its tuned on a wideband you can tell the difference. The Optimizer is only good if you just have a Pipe.


----------



## fstang24 (Jan 9, 2010)

no reason to take away fuel if my bike is running lean, popping is a condition of a bike running lean, the optimizer only ads fuel and cannot take away fuel past the factory setting. i only plan to run a slip on nothing else, dont need snorkels or any other stuff, dont water ride or submerge in mud, my bike is a trail bike, most people dont know the meaning of that


----------



## zacksbf (Sep 11, 2009)

ohh a trail bike. I remember someone else had one of those one time and they told me about it. I have just never actually seen one. 

Your right the popping is generally a lean condition BUT... What bootlegger is telling you is the "tuneability" of a PC3 is far greater than the optimizer so if you want to make sure it is tuned properly then put on a PC3 and get it tuned on a wideband so your A/F curve is the same throughout the RPMs.
Or you can just add fuel with the opti until the popping goes away but your tune will possibly be a lil rich after that, which robs power.


----------



## Bootlegger (Dec 18, 2008)

fstang24 said:


> no reason to take away fuel if my bike is running lean, popping is a condition of a bike running lean, the optimizer only ads fuel and cannot take away fuel past the factory setting. i only plan to run a slip on nothing else, dont need snorkels or any other stuff, dont water ride or submerge in mud, my bike is a trail bike, most people dont know the meaning of that


I know the meaning of that.  ALL I was doing was trying the help explain something. The Optimizer will only add fuel a certain throttle positions... where the PC3 will add fuel at a LOT more and you can tune your bike better with it. You can actually tune it at every 20% throttle....and every 250 RPM's if you want. The throttle positions you can tune at with the PC3 is 2%,5%,10%,20%,30%,40%,50% all the way up to WOT. You can add as much fuel as you like to get your bike tuned how it needs to be to where you can only add a certain amount with the Optimizer....but you can get by with the optimizer, but sometimes you can't. A lot of folks use them. You can actually feel more difference with the PC3 with it tuned correctly and get more power outta your bike. I know that popping is a condition of running lean.  Your bike may be lean at one position like where its popping and rich at others. With the Optimizer you can't adjust it like that if you need too and a lot of bike you will need too. I am not saying the Optimizer is junk...the do what they are designed to do. With the PC3 you can add fuel at some positions and take away at others when you need too at the same time. Again...I was just trying to help you out man. Good Luck!


----------



## Polaris425 (Dec 16, 2004)

If I were you, I'd listen to bootlegger. Unless your an expert (and he is) I doubt you have any hidden information that he doesn't. And as always, taking a smart *** tone like that won't get you anything but a vacation. We have plenty trail riders here. I do a good bit myself.


----------



## sweeper (Apr 10, 2009)

My bike is a trail bike .I don't mud on a regular basis, and I don't want to submerge it,but I have the MIMB snorkels and the MIMB exhaust mod just in case I have to.


----------



## fstang24 (Jan 9, 2010)

simmer down guys didnt mean to step on anyones toes, i race mustangs so i know all bout air fuel mixtures and modding engines. For my purpose of riding and the mods i have done i think i will be happy with the optimizer, and dont want to take into extreme when my modding my brute. I know the PC3 is a better programmer, and has far more user end adjustability which is great if my bike was really modified other than a slip on exhaust. Im aware also the richer you run the more power you loose, and the leaner you are the more of chance of damaging the engine, anyways guys I appreciate you guys suggestions, and my opinion of trail riding, is a tract of land with nice trails, off camber trail, hills etc, not a track of land with a bunch of mudholes. I respect and i know we all have different taste in what we do with our quads, i just perfer to have a good ole relaxing trail ride...whats again guys thanks for your suggestions very much appreciated.


----------



## zacksbf (Sep 11, 2009)

I got cha! I was joking about the trail riding thing because I think most of us bought our bikes to trail ride but depending on location realized that most of the good places to ride are rutted up and muddy (around here) so my setup quickly changed to a mud bike.
My neighbor ordered the opti and pipe for his brute and the tune installed was suppose to support the pipe and it runs better on the factory settings because the place that setup the tune obviously did something wrong. We are working at getting his lined out because it pops some at idle and a lot when he lets off the throttle and will sputter under constant throttle position. I we figure it out without just tossing the opti I will let you know what settings we used.


----------



## fstang24 (Jan 9, 2010)

thanks zack apreciate you understanding, my bike runs great with the setup of the optimizer and hmf slip on, idles and runs smooth, only issue i have and dont like is the popping on deaccleration other than that bike runs great. Have not had time to adjust much on it yet but will this weekend. The optimizer settings from hmf for the brute force efi are 2.5/3.5/4, hope this helps


----------



## 07 BRUTE (Jan 27, 2010)

BOOTLEGGER.. when i rev the bike it pops very little and at half to three quarters when i decel it back fires 2 or three times thats it.. also another question i started to hear a tick in the motor after i put the pipe on think it may be timing chain idk.. any help???


----------



## bayou_boy_22 (Mar 13, 2009)

Could be an exhaust leak. that could make it run bad as well.


----------



## wood butcher (May 11, 2009)

07 BRUTE said:


> BOOTLEGGER.. when i rev the bike it pops very little and at half to three quarters when i decel it back fires 2 or three times thats it.. also another question i started to hear a tick in the motor after i put the pipe on think it may be timing chain idk.. any help???


 ur tick might be the rear header gasket leakin


----------



## 650Brute (Dec 18, 2008)

The tick, as posted above is more than likely a small exhaust leak, I battled that for a while.


----------



## 07 BRUTE (Jan 27, 2010)

ok so say the tick is an exhaust leak. that still leaves me with the backfiring prob think it just needs a jet kit??????? by the way woodbutcher thanks for the pipe again great doing bussiness with you


----------



## Bootlegger (Dec 18, 2008)

The exhaust leak could cause the back fire...but try shimming your factory needles about 0.040 I am almost outta shims....I only have 3 left and you would need 4...two on each side of the ones I have. I could send you the 3 I have and you could go to any hardware store and find a matching size...or if you like and your not in a big hurry I can do it for you this week....just let me know. To be honest...if its only doing that I would shim the needles and buy two Keihen jets that are one size bigger and smaller since there only $2.49 each...that would be the cheapest way....but if its running like crap all over I would get a jet kit. I just find it easier to get a Dynojet kit if its running bad all over...but since yours is not I would try that. if you like I can send you a link to the ones you need at Jets R Us.com If you at factory jetting with a HMF Utility and snorkels.....that is amazing to me that its running that good. I have only seen one other bike do that. Let me know and I will be happy to help you all I can.

Also get a new gasket for your pipe to stop the leak that should help it. Fix teh exhaust leak before you do anything....you make not have to do anything but shim the needles.


----------



## 07 BRUTE (Jan 27, 2010)

yea i found the leak i sprayed the hell out of the rear seal with soapy water and she barely bubbles so im thinking thats the tick and to be honest i dont mess with carbs alot so i wouldnt feel sure ab myself working on them


----------



## 07 BRUTE (Jan 27, 2010)

where do i get the new gasket to fix my leak???


----------



## Bootlegger (Dec 18, 2008)

07 BRUTE said:


> where do i get the new gasket to fix my leak???


local dealer or order it online...I would suggest DGY...

http://www.dgy.com/default.asp

This is the part number you need. GASKET,EXHAUST HOLDER 
11009-1894 


It is the rear cylinder...correct?


----------



## 07 BRUTE (Jan 27, 2010)

yes its the rear thanks for the help so far


----------



## Bootlegger (Dec 18, 2008)

Yeah...order that new gasket and we can go from there.


----------

