m7 bogging

Burton · Dec 1, 2007

2005 m7 runs terrific out of the trailor then develops a BOG! seems as if the machine only starts bogging after it is up to full heat? we have checked power valves,plugs,and still confused. sled has twin pipes, reeds, and TFI box. Heck we even tried to disconnect EFI box today and bog is still there. What is weird is that when you stop and let machine totally cool down then it runs great once restarted then starts bogging once hot again??? Curious if maybe the pipes, when hot create a vapor lock of some sort on the fuel injectors (being as the pipes are pretty close to the top of injectors) Any suggestions would be appreciated. Thanks....

24footjet · Dec 1, 2007

I had the same problem. I just had a can on, took it off and now no bog. I'll just run it normal. I'm assuming the bog is on the low end?

Burton · Dec 1, 2007

actually it is on the high end mostly??

Burton · Dec 2, 2007

please help if you can this ruined 4 rides so far..pretty bummed

SoDakCat · Dec 2, 2007

Are your pipes coated or have some type of heat shield or heat tape betweent the pipes and the injectors. I know with my jaws twins they make things pretty hot and if its happening only when the pipes get hot i would check how hot your injectors are or if you are getting too much hot air drawn into the intake.

Burton · Dec 2, 2007

my pipes are SLP and they are coated. What happens inside the injectors if they are indeed getting too hot? Also I rode this machine with no problems for 2 seasons without this problem.maybe I should put stock pipe back on? I did put some heat tape on the top of injector closest to the pipe. However I did this at the end of the day yesterday on our way back to the truck and wasn"t able to notice much of a difference?

Burton · Dec 2, 2007

Oh yaa one more thing....my sled is using alot of fuel??

TheOnlyBFC · Dec 2, 2007

You did the same thing i did, i bought twin pipes first before i really did any other mods. I have heard from a few reputable sources that pipes don't really help this sled until you get some porting done. I got tired of dealing with finiky pipes and went back to my stock pipe and silencer. No more hassle and the sled runs great.

diggerdown · Dec 2, 2007

I'm not a big fan of twins on that sled either. Insulate the injectors and tube. Stock air box. The air temp sensor in the air box is quite touchy and you could be getting too much heat and messing that up. Logically it would lean it out too much and you're starving it out at high rev. High fuel usage goes along with twins and poor tuning. We tried some slp twins on one last year, we sold them at haydays!

picks · Dec 3, 2007

I would keep the twin pipes, they really wake the m7 engine up when tuned right. You should not have to add very much fuel at top rpm especially with it being an 05. Heat tape any areas the pipes are really close to but you don't have to get too carried away with it having pipes coated. ( I run coated jaws pipes) Check your air temp sensor plug for moisture and put a bit of dielectric grease on connection and it doesn't hurt to put it on other connections. Found stock air intake to work the best as the twins create too much under hood heat for filter type air intakes ( if you have stock hood).

BigRed118 · Dec 3, 2007

I have a lot of tape around the injectors. I would look at the 08' heatshield there. If you have had no problems w/ this set-up for two seasons, check the rollers. It would create a bog type symptom. I would think it would be at all temps but something to check.

graveler · Dec 3, 2007

if you have an 05 then check your coolent bottle top to see if its warped and the cap is not sealing which would make it not make presure and boil the water enough to make the over heat sensor bog the motor, the bottle and caps on the 07 and newer have been changed to a twist on because the old style caps pull on the bottle when there hot and make them out of round.. you could pull the cap off without untwisting it, you did say this is happens when its hot?

not sure if you can see that its warped on the pic, the second one is the new style that comes with a heat shield, and a twist on cap!

graveler · Dec 3, 2007

with the new bottle you need the lower hose from an 07

Seeyacop · Dec 3, 2007

yep the twins are a pain to tune however they rip when working properly. I had a similar problem with my sled last year. I have heard from several people that coating twins is a bad idea because on long pulls the pipes get too hot inside and result in bogging/loss of power. I doubt this is your problem though.

What TFI box are you running? If you have not had it updated and got it this year you should call the maker and get it updated. Many of them have updated the software over last year. Also make sure your air density hose coming out of the ECU did not melt shut. Sounds like you are in need of better tuning since it it could be too lean.

bluebear · Dec 3, 2007

Almost sounds like a stator? Sometimes if they are going bad they will work fine when cold but when warm they'll start going bad.

Chris.

Burton · Dec 3, 2007

Thank you so far and yes I did replace the stator to no avail...I will try everything suggested thus far. never thought of coolant bottle and will check that tomorrow.

madcat · Dec 3, 2007

check your fuel lines for leaks. I had a little hole rubbed in my fuel line where it sits on the motor. It was running like yours and used a ton of gas. If it worked before it's probably not your pipes

insane_sled_posse · Dec 4, 2007

m7 bog

I had a similar problem with mine and i thought for a long time that it was the jaws twins. I randomly decided to run through my secondary as well as replace the spring. The next ride I nearly threw my back out, there was no more bog.

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m7 bogging

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