M8 Lean bog?

[Cascade Crud]

I have a 09 m8 sp 153 with bdx intake, slp exhaust and last year a bd box. I never rode the sled stock, but I have always had a bog in the bottom end that sounds like the engine is starving for fuel. It only happens when I first start the sled, slowly ride about 15' then wether I'm on the throttle or not it acts like it's starving for fuel, goes BWRAAAAAAAPPPPP!!!!!!!! and hesitates for a second then takes off just fine. I can also get it to do this if I feather the throttle alot at speed. I havnt been able to get it to go away with bd box ajustments and now am trying it with the box off, allways the same. Help! any imput apreciated

 

[donaldej]

My experience, i put a bdx intake and full slp exhaust on three weeks ago ( i already had rtk head). My house is at 800 ft so when i took it for a grass ride ( i have 5 acres) i found it would do the same thing. Hit the gas and the sled would go brraaaaaaa and put me over the handle bars. I had also put on a power commander, I figured i was lean since the modes let more air through but for fun i leaned out the power commander and made it about 20ft before proving that theory true. So i richened it out all the way across the board and the bog was gone and it about ripped my arms off. I ride at 4000 ft and up so i think close to stock setting will be fine for me but i won't know until next week. If it's happening after you have taken off it could be clutching but i'm guessing you have a lean spot. Does it do better when the engine is cold? Mine ran somewhat ok at the very first but as soon as the engine made temp it did the braaaaaa.

 

[aktreekiller]

hey

My 09 hcr had a low end bog stock, and still has it with slp kit and bdx intake. It flat rips hard when it gets past it though. the dealer said nothing is wrong with it at all.

 

[0neoldfart]

Re: Lean bog...

My wifey's 08 M8 has the RKT head, SLP pipe set and intake. Had a lean bog at lower rpm, added fuel with a BD box, the sled runs great. You will find that although SLP doesn't recommend adding a BD box, the M8 runs better with a touch more fuel - even on top.

 

[wiley75]

I have a 09 m8 sp 153 with bdx intake, slp exhaust and last year a bd box. I never rode the sled stock, but I have always had a bog in the bottom end that sounds like the engine is starving for fuel. It only happens when I first start the sled, slowly ride about 15' then wether I'm on the throttle or not it acts like it's starving for fuel, goes BWRAAAAAAAPPPPP!!!!!!!! and hesitates for a second then takes off just fine. I can also get it to do this if I feather the throttle alot at speed. I havnt been able to get it to go away with bd box ajustments and now am trying it with the box off, allways the same. Help! any imput apreciated

I've owned two M8s and my girlfriend owns one as well. All three of them have done that. I believe the sled's ECU is cycling the powervalves, perhaps as part of a system check or calibration procedure. It does it when you first start out, just like you describe. Don't worry about it. It's normal.

 

[Cascade Crud]

Thanks for the imput. I just lived with it last year but then this year I rode a buddys 09 m8 with full bikeman exhaust and slight intake mods and it was waaaaay pipier and crisper thru the midrange and bottom end with no lean bog in the bottom end. Made me wonder what the heck?

 

[slyrydr]

the ecu has an enrichening circuit that stays activated until the sled starts to warm up, that could be what you're feeling.....so let the sled get nice and warm, feel the rear heat exchanger.....to tell the difference between rich and lean.....add throttle so the sled starts to go, add the throttle slowly until the condition starts to appear, rich will act like it's gurgleing, but will clean out if you blip the throttle or just keep adding throttle until it's gone.....then let off the throttle and go back to where the problem is, this time smack the throttle full on, if it feels like it wants to throw you over the bars and then goes, it's likely lean....if it gurgles and goes, it's likely rich....when you add/take fuel changes, just go one step at a time...repeat test proceedure until it works for you.....methodical, one step at time will get you where you want to go...

 

[mountain mafia]

I have the same pipe and intake set up and mine is way rich on the bottom, My plugs are black. I ride above 6k ft. Once I am past 1/4 throttle it runs great.

 

[wiley75]

Thanks for the imput. I just lived with it last year but then this year I rode a buddys 09 m8 with full bikeman exhaust and slight intake mods and it was waaaaay pipier and crisper thru the midrange and bottom end with no lean bog in the bottom end. Made me wonder what the heck?

When you originally described the condition you said it only does it the first time you start the sled and about 15' after you first take off. That is definately not a "lean bog" because it is not consistantly there... only on initial start-up.

That being said, I have noticed a lean bog when previously running a Speedwerx pipe with a BD box. I was able to add a small amount of fuel on the bottom end to fix it. But be careful because the condition you originally described is definately not a lean bog in my opinion.

 

[skimike]

my 10 m8 sp does the same thing, I wouldnt call it a bog, its more like maybe loading up or starving , I feather/bilp the throttle ad it goes away, it didnt do it as bad when the belt was out of adjustment but it banged when it took off. I have only had my sled 10 days, I am taking it to the shop tomorrow to get a handwarmer working and a check up. my biggest complaint is its very darty and sketchy on trail, I noticed that one ski looked towed in some so I readjusted it by eye today and that might have helped, I think the telescopic steering has too much slack. I may look into changing that out for a regluar coloum and a riser because I only ride with them in the up position