The Yamaha Road Star Warrior Forum

Hi,

Brand new to this forum. Got a problem. Own a 2004 Warrior with less than 7000 miles on it. Stock, except for cosmetic upgrades (chrome). It backfires. Started after they did the Throttle position sensor and pick-up coil recall (may or may not be related). Local dealer can't fix. Worse - they say it's normal for Warriors to backfire when decelerating and that I should engage the clutch and brakes everytime I want to decelerate - no engine braking. Think I'm being fed a line. Anybody had this problem?

Manny 

You are being fed a line about not using engine braking.  That's just BS. They are correct about back firing.  It is the nature of this beast.  On the left side, under the fake air scoop, is, among other things, the Air Injection System, AIS. This system injects air into the exhaust to cut down on emissions.  If you remove the system it will reduce the back firing a bit.  Putting on a Power Commander III to handle the fuel mapping will also cut down on the back fire.  I don't think anyone has managed to completely eliminate it but you can greatly reduce it.

Now then, back to that left side scoop. Also under there you will find the Fuel Pressure Regulator, FPR, and a gas line dry break.  The FPR can easily be relocated under the tank.  The dry break can be replaced with a smaller unit and the fuel line run behind the motor mount.  That cleans up the left side of the engine so you can leave the scoop off and show off those big jugs.  Look in the gallery to see what it looks like.

One of the members, Churchkey, makes a kit that replaces the complete stock air filter system.  This lets the engine breath better.  You get a noticeable increase in power.  It also allows you to remove the huge shield looking box on the right side.  Once again, look in the gallery to see the custom pieces guys have put on the rig side to hide the FI wiring after removing the shield.  Really makes the bike look better.  

Manny, I almost forgot, welcome to the forum!  Lots of great members, lots and lots of knowledge.  The Warrior is a great bike to leave as is or modify the hell out of.  Browse through the gallery and you'll see some beautiful bikes. 

Thanks OldMan,

Appreciate the advice. I'll look Churchkey up. You used to have a Governor hotter than mine!

Manny V.

Check it again, it says my ex-governor.  That was changed the day she officially stepped down.  I had to do it that day or these Sweet Old Boys on here would have been all over me.

+1 to everything Oldman said.  To which I'll add....

The described 'deceleration backfire' affects most V-Twins and is generally caused by a lean (more air than fuel in the cylinder) condition. Basically the fuel mixture fails to ignite consistently. This un-burnt fuel works it's way into the exhaust pipes where it's ignited causing a backfire. Just a note, aftermarket pipes often increase the frequency of backfiring as the freer flowing pipes make the bike run even leaner . Removing the AIS (Air Induction System) may alleviate the issue (I never noticed a difference) but I think you would see better results by bumping up your fuel via the ECU or getting a PCIII.

Welcome to the Forum!

You're right. All that backfiring has rattled my brain. Sure could use her at the WH now.

 Welcome to the board Manny.  I can't really add anything to what the others have sai.

1st I will say, welcome to the forum

Manny V.:

You're right. All that backfiring has rattled my brain. Sure could use her at the WH now.

2nd I will say WHAT?!?!?!?!?!?!

 Welcome to the 4M.

The backfiring can be almost completely eliminated with a PClll, and a knowledgeable MAP! By that I mean that if your dyno guy knows the Warrior, you'll probably get a good map. I just happened to stop by the the shop where the guy that mapped my bike works, & he sees me & asks how is my bike running? I tell him good 'cept for some backfiring on decel. He told me that he's learned a lot about the Warrior since I had my MAP done, & he had me wheel my bike in & hooked it up and added about 25% more fuel at the closed throttle position at several RPM settings. He said it won't do anything to the fuel economy, or make it run more rich. It just adds some more fuel at the closed position to help cut down on the backfiring. It really minimized the backfiring. I still have it on occasion but nothing like before. That little tweak made a huge difference. I will always get it if I decel in the morning, with the engine cold, so I do what another member said, I pull the clutch at the same time I brake for that first stop in the morning, after that the backfire is very rare. I have 75K+ miles on my '02, still get 39+MPG commuting, and 40+ while on rides. I've never had to repair anything on my bike, outside of the recalls, and with over 75K miles on it, I feel like it's the best ride on the planet.

Thanks Jim,

I'll look into the PCIII. Do you recommend it for a stock warrior, or just for one that is modified? 

I may have found a fix. As I was researching the forum, I came across a site that has the Warrior's service manual. Looked it over a bit and came across the suggested idle speed - 850 to 950 rpm. Mine was running between 5 and 6 hundred. I changed it to just shy of 1000. Minor detonations remained but the big bangs were gone. I increased it to around 1100 rpm, and all's quiet! 1100 is higher than the suggested, but easier to deal with then the backfires. Do you think running it at this higher than suggested idle could cause problems? 

I still think the problem originated with the TPS recall. The service manual says the idle speed must be properly set before the TPS is adjusted - maybe they missed that. There were no deceleration detonations before they did the recall, and the idle speed was below 1000. 

Manny V.  

 I wouldn't think a higher idle speed will do anything bad, it would just bug me at stops. Even 850 - 950 is a little hi for my taste, but I run it there anyway. A PClll may help even without Mods. My brother owns an '04 & he went to the Yammi dealer to get his ECU adjusted for his air kit & exhaust changes, but he was informed that they have no way of adjusting it, that it is a factory adjustment. I asked him what about the guys who do the engine mod "stage 1 - 2 etc" which increases the rev-limit? I wonder if part of the kit is a new ECU unit? IMO if you went ahead & installed a PClll, and do the "perfect PClll install", instructions are found on the 4m, search for the "perfect pclll install". You at least could take it to a Dynojet tuner & adjust the FI for your needs. Then when you do install a BAK & replace your exhaust you are already set with the PClll, and a dyno run later you'll be dialed in. What the "perfect install" does is it corrects a problem that the pclll has with the throttle position stability. There is a long explaination, which I would just paraphrase here, so I'd suggest to search out the thread.

 Manny,

Have you read anything on the 4m which has instructions that will enable you to tweak your fuel/air mixture? That may prove to be useful until you acquire a PClll. I'm not 100% sure how to search for that, I'd guess just type in ecu adjustment. One thread just explains which wires you need to jumper & how to go about getting into the "brains" of the ECU & perform the adjustments. The other thread I'm thinking of is the one which has instructions on how to install a switch near the ECU, so that you can tweak it on the road. That is the mod I performed, & I had to use it a couple of times on the road. This little mod allows you to richen or lean out either or both cylinders. There is a whole explaination, if I recall, on how to read your plugs, etc...However, the PClll really is a useful mod, and you can get various maps off their site & through this 4m.

Good luck on which ever direction you procede.

Jim

Manny, you said your bike has no engine, performance, exhaust, or intake mods.  Its essentially 100% stock except a few chrome bits.  So a PC3 or a dyno-tune or a Bump will have zero affect and are not a cure.  

Some downshifting is fine, but this isn't a 1970 V2 machine.  Big cube V-Twins backfire on hard decel, it goes with the territory.  Ride it like what it is.  Use the front/rear brakes to a greater extent, and after a few weeks you can decide if the backfiring has diminished.  Heck, lots of us have had this bike so long we sorta forget we ride it a little differently.  Its a hot rod.  Its make noise.

Some things that will add to pop-on-decel are dirty air filters (changes air:fuel ratio), dirty oil/filter (heat build-up), fouled plugs (reduce available spark), and crud on the pistons from using the wrong fuel (use a good brand of regular unleaded gasoline).  Like everything else, keep it tuned and it'll be fine.  

Manny V.:

Hi,

Brand new to this forum. Got a problem. Own a 2004 Warrior with less than 7000 miles on it. Stock, except for cosmetic upgrades (chrome). It backfires. Started after they did the Throttle position sensor and pick-up coil recall (may or may not be related). Local dealer can't fix. Worse - they say it's normal for Warriors to backfire when decelerating and that I should engage the clutch and brakes everytime I want to decelerate - no engine braking. Think I'm being fed a line. Anybody had this problem?

Manny