hey guys i m new to this site.. i just got a superhawk last errk and i love it.. how ever i am having a problem with it. at idle it missis up too 4 grand then it runs good to 7 where it will miss again. i have a k&n air filter and kurker ext. i cleaned the carbs with no improvement. i also checked my valves and it was all in spec. im thinking it may not be jetted right or carbs may need to be syncronised. it would help alot if i could get some tips
thanks guys

 

Welcome.

There have been a few people with this problem, and there are several possibilities:

The easiest one to check for is what we call PVLIR, that is petcock vacuum line inadvertent relocation. The small hose to the petcock goes on the rear of the petcock that points to the right, and not on the one on the bottom that looks like where it goes.

The next possibility is if this only happens in the rain, it is likely to be the tank vent hose because that needs to be rerouted from the stock location otherwise it gets plugged with water.

Also often when you get this symptom it is a bad coil.. They may even test fine and still act up this way, the only real way to tell is to swap them out and ride it.

If I have forgotten any (and I am sure I have) someone will chime in. This is not a common problem, but it has happened enough that these are the fixes I recall.

 

The petcock itself ma also be damaged.

 

Also did you have the bike jetted for the K&N? If not, go back to a stock filter to see if that helps. Our bikes are picky about filter changes, not so much about exhaust.

 

As Lazn suggested, This is a rather common occurance on this bike, I have read of several instances as well as my own experience.
#1
The easiest one to check for is what we call PVLIR, that is petcock vacuum line inadvertent relocation. The small hose to the petcock goes on the rear of the petcock that points to the right, and not on the one on the bottom that looks like where it goes.

Additionally to this, you should disconnect the PVLIR line from the intake port fitting and apply vacuum(or suck on it using a CLEAR hose and see if fuel is leaking past the diaphram directly into your intake port. Which will foul your plug in a major way.

#2
Also often when you get this symptom it is a bad coil.. They may even test fine and still act up this way, the only real way to tell is to swap them out and ride it.

The sure fire way to check this, since it will ride virtually the same whether the front or rear cyl is not firing, (without buying an extra coil) swap coils from front to rear, rear to front... Having checked which cyl was cold prior to the swap, you can now determine if the "cold" cyl has swapped positions, following the bad coil.

I do this using a cheap screwdriver handle and touching the exhaust header about an inch from the port, you will notice a significant difference in which the handle will melt between the hot and "cold" not firing cyl, checking at diff RPMs will be necesary, depending on when your "missing"

Visually checking for a blue spark is no good! I had a consistant blue spark on the cold cyl, yet it failed to spark when under the cylinder pressure it experiences when installed in the eng.

These are the first, most important, and only steps you should address, until you are 100% satisfied they are ok.

 

im at my buddys shop now i tested the petcok it tested good and i had the vacume line in the correct place im now going to check the coils. however the air filter it came with a k&n and i have no idea whats up with the jets if they were changed or not. nor do i have the stock filter. should i get a regular filter. and check the jet size. also im still waiting for the choke cable it broke off in the carb so i really need that untill i can really sync or anything like that.. i also saw that the airfilter has a gap im going to silicone after i change the choke cable.. one more question whats the stock jet size.. and what size should i use for the k&n and ext...

thanks guys helped out alot

 

I would fix your air leaks before you go any further, as these could be the problem.

 

well the shop said they would take it back and fix it for me so i took it there and it was 3 weeks till i just worked on it my self. had it running so good in 9 hours fixed my coolent leak, my fan not coming on, oil leak, choke cable, swaped my coil. synked carbs.. and fixed air gaps.. now this is the bike i thought i bought.. the ony thing now is when its cold the carbs will sneeze on me.. any idea...

and thanks so much guys helped alot

 

welcome aboard. ask the shop if they adjusted the TPS. It made a significant diff on mine in terms of smoothness. if not search this forum for the "how to".

 

If it sneeze pull the needles up, is there a jet kit on this bike now ??
It will need a bit more fuel, check the plugs, may be white from lean mix.

 

"sneezing," I think this term describes it better than a "lean backfire" or a "carb fart"... I motion to replace said terminology from here on out.