08 Dragon 700 bogging bad

[Stretch.]

Hello, Ive been having some issues with my 08 700 switchback lately. I was climbing some hills with some fresh powder and it was powering out at about half throttle. I thought i might have a bad plug so i pulled them out and they were both a nice brown. I put a new set in anyway and the sled ran great for about 5 minutes but started noticing the bogg again. Ive cleaned the surfaces on the clutches but havent had the primary apart, and put a new belt on. No change. The sled has lots of pull up to half throttle and then just gives up if i try to open it up. At first i could feather the throttle past halfway and it would have good top end power, but now it doesnt matter if im right out of the hole or pin it at 40 mph, it just boggs hard. any suggestions? the sled has 1500 miles and always use premium fuel. It almost feels like either the sled is getting way too much fuel for and cant burn it off, or is starving for it. plugs always look good though. I've also had the power valves out, there was a little carbon but nothin bad. i cleaned them up and reinstalled them but no difference. If it was a clogged fuel filter i would think it wouldnt run flat out at all because it would starve for fuel, it only seems to be a problem at around half throttle when the sled want to open up.

 

[Kraven]

Hello, Ive been having some issues with my 08 700 switchback lately. I was climbing some hills with some fresh powder and it was powering out at about half throttle. I thought i might have a bad plug so i pulled them out and they were both a nice brown. I put a new set in anyway and the sled ran great for about 5 minutes but started noticing the bogg again. Ive cleaned the surfaces on the clutches but havent had the primary apart, and put a new belt on. No change. The sled has lots of pull up to half throttle and then just gives up if i try to open it up. At first i could feather the throttle past halfway and it would have good top end power, but now it doesnt matter if im right out of the hole or pin it at 40 mph, it just boggs hard. any suggestions? the sled has 1500 miles and always use premium fuel. It almost feels like either the sled is getting way too much fuel for and cant burn it off, or is starving for it. plugs always look good though. I've also had the power valves out, there was a little carbon but nothin bad. i cleaned them up and reinstalled them but no difference. If it was a clogged fuel filter i would think it wouldnt run flat out at all because it would starve for fuel, it only seems to be a problem at around half throttle when the sled want to open up.

As a GENERAL rule, if it's bogging, it's LEAN

Check for ripped / torn rubber throttle body boots.

You may have to push/twist the throttle bodies and use a light close-up to see the actual exposed rips

 

[signdude]

I would start with checking the TPS. Also, if the VR is going out its like chasing a ghost. It can cause havoc on the sled's performance too. If it started suddenly, I would suspect the electrical, or like Kraven said , perhaps the throttle body boots.

 

[PaulAnd]

If it happens in the same spot on throttle suspect tps, check your tb boots, fuel filter, fuel pump sump hoses, fuel pressure

 

[sledneck_03]

May be ripped ves rubbers, mine bogged with one ripped

 

[SaskRMK]

Last time i rode i had a bog between 7000-7300 then it would clear right out and run %100. Turns out I had a torn bellow and it was spewing out of the top of the cap. I replaced the bellow and I still always have a bog during slow excel between 7000-7300. I had the MBRP can installed with the SLP Pipe and just switched it back to the SLP can so Im hoping that this was causing the issue but it never had bogged before with the mbrp can.

As kraven says most bogs are when your engine is running lean so I'm hoping the exhaust combo created a lean spot in the upper range. My plugs were also very dark and gunked up from my oiler being set above the alignment marks on the pump. I had installed a new oil pump and turned it up to ensure the assembly grease passed through it. Could chipped reeds cause a bog? what should the fuel pressure be at?

I also run only premium fuel, have new bellows, clean exhaust valves and a new fuel filter.

So I will have new plugs, Can swapped back to SLP and my oiler set correctly, We'll see what happens tomorrow.

keep us posted

Good luck man

 

[Kraven]

Last time i rode i had a bog between 7000-7300 then it would clear right out and run %100. Turns out I had a torn bellow and it was spewing out of the top of the cap. I replaced the bellow and I still always have a bog during slow excel between 7000-7300. I had the MBRP can installed with the SLP Pipe and just switched it back to the SLP can so Im hoping that this was causing the issue but it never had bogged before with the mbrp can.

As kraven says most bogs are when your engine is running lean so I'm hoping the exhaust combo created a lean spot in the upper range. My plugs were also very dark and gunked up from my oiler being set above the alignment marks on the pump. I had installed a new oil pump and turned it up to ensure the assembly grease passed through it. Could chipped reeds cause a bog? what should the fuel pressure be at?

I also run only premium fuel, have new bellows, clean exhaust valves and a new fuel filter.

So I will have new plugs, Can swapped back to SLP and my oiler set correctly, We'll see what happens tomorrow.

keep us posted

Good luck man

REEDS: Doubtful on the chipped reeds causing a problem. When the reeds break off, usually it makes the engine hard to start

FUEL PRESSURE: If you want to check fuel pressure, take an old automotive style oil pressure gauge,(needs to read up to 60 psi) connect it to the stock fuel line (schraeder valve fitting) near the top rear of the air-box. Duct tape the gauge (temporary for diagnosis) to the handle bars to where you can monitor it while riding.

59 P.S.I. is where you want to be at, whether it's idling or full throttle off a 100' cliff.

 

[SaskRMK]

Not trying to thread jack but i hope my trouble shooting can help the thread starter! I pulled my pump and there is no sediment or damaged feed lines that could cause a clogged line or fuel filter(just replaced 5 rides ago). Tomorrow I will be buying the fuel gauge to test the system and ensure I always have 59 PSI.


Thanks Kraven!

 

[SaskRMK]

Borrowed a fuel pressure tester from a friend this AM, I also picked up a new belt to ensure mine wasn't worne and the bog was actually in the clutching

 

[SaskRMK]

new plugs, oiler tuned, new belt, back to slp can from mbrp
lost the 7300 rpm bog and now its up at 8700...

Opened the hood and noticed my air box had jumped off the throttle bodies mid ride. Tonight when i got it back in the shop I reinstalled the tb clamps and tested the fuel pressure, it was right at 60 PSI. I am hoping the unregistered air passing by the air box was causing the high RPM bog.

Riding again tomorrow so I can only hope i have lost the bog because I am REALLY running out of ideas here besides having the dealer hook it up to the shop tool and test my tps

I was running 68's and reving to 7650 so i tossed the 64's in because i didn't have 66's and my rpm's are up at 8400. Could this be a problem? My primary has been completely rebuilt but i have yet to touch my secondary, could this have anything to do with it?

thanks!

 

[PaulAnd]

Mountainhorse, if you see this... Could you edit your tps setting and checking sticky for back probing tps output and ground @ the computer for a quick sweep test, I looked for a wiring diagram to post here could only find a partial on hcs. Thanks again for all the help!!
Paul

Sask, that is what I would do before pulling air box and TB's again.. The tps checking and setting tool is a must have to replace it.

 

[SaskRMK]

Pretty sure I found my issue. A broken engine strap! I also found a bolt that backed out of the clutch side strap. I have never removed these before so im pretty surprised the bolt had managed to back out. A friend had a spare so i reinstalled it and all bolts with blue loctite

My "bog" must of been my belt dropping down from the clutch because it was completely unaligned. The bolt must of been backing out for some time because it was not until yesterdays ride I noticed the engine was vibrating violently as soon as i unloaded it from the deck. Hoping to ride this weekend and let everyone know if this has fixed the issue

 

[SaskRMK]

Engine strap was the culprit! Back to running awesome with no issues

 

[TheBCSledder]

Engine strap was the culprit! Back to running awesome with no issues

glad you got it fixed. What is the engine strap?

 

[SaskRMK]

the engine strap bolts to the bottom of the engines block and the strap slides over the motor mount studs on the bulk head.
#19 broke on my sled