# BF 750 misfiring/lugging BAD



## tony1j (Mar 11, 2011)

Hey guys. First off let me assure you that I have combed this forum looking for the answer to my question already and cant find it but I believe it is mainly because I am going backwards here. So here is the deal;
I just got an 05 BF 750 in a trade. It is snorkeled (sides, 3" intake 2's on C.C.) and I was told that it was jetted, the guy I traded with had just had the carbs rebuilt at a reputable shop (he took them off and brought them to them) and they told him they were jetted. He said that the guy that had it before him had an HMF exhaust (dont know which one) but it has the stock exhaust now. And I dont know if it is running a tuner or not.
Well it backfires and misses a little on idle and when you give it a little gas to try and go or even just revving it up it backfires and misses a lot. If you pump the throttle a lil bit it clears out and runs like a spotted ape. So mainly it is on the low end of the throttle that it is bad.
The guy I traded said that he was told that either the carbs would have to be set back to factory or another after market exhaust would have to be put on to fix this issue. 
Does this sound right? I am new to the BF family have always been on suzukis before so the V twin is new to me. 
Thanks for any help.


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## tony1j (Mar 11, 2011)

oh and I forgot to tell you that the plugs coloring is good, not quite black but close to it and they are a little wet so I am sure that it is running a little rich? But also the other night after running it up to wot the exhaust pipe on the front of the engine was glowing for about 2 inches from the engine. is this normal?


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## countryboy61283 (Mar 20, 2010)

Your jetting is way off, if I read it correctly, you said it has 3inch intake, stock exhaust but used to have a hmf? More than likely it was a slip on hmf utility cause that's the common hmf people get. Cover up your intake snorkel half way and see if it runs different. It will give you a idea of what to do. But to me it sounds like your jetting is way off and still setup for After market Exhaust


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## wmredneck (Dec 6, 2011)

Same thing I'm thinking here. 


Pull the seat off and look at the CDI. Money is he had an aftermarket comp too. 




Wishing I was home instead of on the road using TapTalk


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## countryboy61283 (Mar 20, 2010)

Its Carb so it wont have a tuner, but could have a after market dynatek cdi box like he said above


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## tony1j (Mar 11, 2011)

ok, I brought it to work with me so I just went outside and experimented with my hand over the intake snorkel like you said, half covered it still spit and sputtered a lil bit, cupped my hand over it to where it was probably 75% restricted and it purred like a kitten in heat!! So what does this mean? order a slip on exhaust and problem should be fixed minus a lil tweak tuning on adjustment screw?
Checked under the seat, had 2 black boxes, 1 smaller with 2 harnesses and the other having three harnesses plugged in, little one did not have an emblem and is black with some numbers on it, the bigger one had what I am thinking is a kawasaki emblem, best I could describe it would be three triangles stacked in a triangle pattern and a bunch of numbers stamped into the box. Oh and it is flat black also.
Thanks for the help here guys


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## countryboy61283 (Mar 20, 2010)

More than likely you could just buy a slip on exhaust and should fix it with some tweaking, u have to much air coming in and not enough coming out with stock exhaust in return causing it run rich (wet plugs u were talking about)


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## tony1j (Mar 11, 2011)

Ok. Looks like I am about to be scouring the internet for an exhaust then!! Any suggestions? I know, there are a million threads on here about exhaust, read thru about half of them last night lol. 
Guess since he had an HMF on it I will be searching for one of those noisey things. Have to get all my buddys some ear plugs!!:aargh4:


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## jrpro130 (May 10, 2009)

HMF swamp is the only way to go if you ride water AT ALL. The regular HMF gets way too loud! As for jetting, just jet it right so you know exactly what you have in there, it's not too bad to re-jet.

Where are you located btw? Bike looks familiar...


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## tony1j (Mar 11, 2011)

Where are you located btw? Bike looks familiar...[/quote]

Gulf Coast of MS. the bike came out of Gulfport. Wish I could find someone that knew it lol that away I could find out exactly what exhaust was on it and what size jets they went with.


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## jrpro130 (May 10, 2009)

Well I've had hmf, hmf swamp xl, muzzy, big gun, stock, and stock mimb mod...and out of all of them, I like the swamp the best. I ride deep water and mud so I like the fact that it has no packing to go out in it! 

As for jets, just take the carb apart and find out, it will be engraved on the side of the jet. Get a dynojet jet kit and start over, if you do some searching people on here will tell you exactly what jets to run...just play with it. It's part of buying a used bike


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## countryboy61283 (Mar 20, 2010)

U can find good deals on eBay


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## JLOWERY (Jan 30, 2010)

I've got almost a whole dynojet kit left over all I used was the 144 and 150

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## tony1j (Mar 11, 2011)

Against my better judgment, I ordered a slip on hmf performance because that is supposedly what was on it before. Its coming with the jets they recommend and they agree as well that is the culprit. I do plan to go with the swamp series with in the next two months but want to get the bike back running 100% first so the one I just ordered will either end up on here for sale cheap or in a spare parts pile at the house lol.
Thanks for y'all s help and I'll let you know if that fixes it. 
Fingers crossed!!


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