86' VFR 700 spits & sputters low rpm

My 86' has devoloped a problem I noticed yesterday, when requesting full or near full throttle from a low rpm ( under 4K ) it spits & sputtetrs. The best way to describe it is the firing of a full auto rifle. It will pull itself though it & cruise normally @ speeds up & over 100 mph. This is what I have done so far, there was a small pin hole in a vacuum line going to the ACV valve on the right hand side of the engine, I was able to repair by shorting the line a bit. I pulled the air cleaner & found quite a bit of pink insulation inside( $#@*^ mice) my bad though for not checking earlier in the year. K & N filter so I cleaned, dried, reoiled & reinstalled, I also removed the intake snorkel from the air cleaner cover & upon reinstalling the tank lifted the nose of the tank with a couple washers to allow more air; something I picked up by reading past posts. Any way I reassm the bike & test drove, the problem is still there; what else should I be checking ? I did pull one plug & it appears to burning fine. I do have a new set to put in but my gaping tool is MIA so I am reluctant to put them in. I have also noticed w/i the last week that it has'nt been starting or idling as well as it has in the past. I would really like to ride this weekend so any help would be appreciated. But if you are all out riding trust me I understand:biggrin:

 

That almost, to me, sounds like it is starving for fuel somewhat. did you replace the fuel filter? maybe a piece of dirt is floating around and blocking it. I have a radian that when the fuel level gets low enough it sounds like its missing and has no power. Also, just from my own point of view, I would clean the carbs, check the floats, and sync them up. I admit to not having much experience with mutli carbs, so I am inda shooting in the dark, but it sounds like you started with attempting to eliminate the easy items first.

Check the fuel line and filter
check for good connections between the plugs and plug wires
check for loose wires at the coil and grounds. If you haven't done these already.

Hope this helps.

 

I haven't replaced the fuel filter yet but I do know fuel is flowing thru it, if the fuel line is the same size I can try the one off my dirt bike as it only has about a 1/2 hour of run time on it. Does any one know what kind of fuel pressure the pump is supposed to be putting out? Being a carb set up I would assume it to a pretty low pressure, but a spec would be helpful. This is the only one of my bikes/cars/sleds I don't have a manual for. I do now that think about recall more of a gas smell than usual but no visable leaks. I've treated the bike fairly well since I've owned it not really doing more than 90. But the day before it was supposed to be sold I had to find out just how fast it went I had it somewhere around 160 when I backed out of it( I was paying more attn to what was in front of me then the speedo, as I was in notorious deer country @ night). Any way I had some much fun I've run it up to over 120 quite a few times over the last two weeks. That said could that have something to do w/ my current problem. I do plan on getting the vlv clearance set & carbs cleaned & sync'd but it wasn't in the budget until july the may/june budget just got spent on a new rear tire/brakes/chain & sprockets & new lower fairing panels.

 

sputter

Its gotta be either fuel or spark related.
Change your fuel in case you got a bad batch and
check your fuel filter, then drain the residual out of all 4 carbs with the drain screws, , If that doesnt help change your plugs ( i used the NGK iridium ) if the problem is still there it is either fuel pump or electrical in nature
( rectifier?) IMHO

 

Hopefully you didnt suck a spec of dirt into your carb float bowel causing it to be sucked into one of your jets, I had a grain of sand partially block a main jet once causing similiar symptoms, but be forwarned removing cargs from a v Four motor is a freaking nightmare.
If you can get to the float bowel base and remove it without pulling the carbs you are truly blessed.
you can also check for varnish goo after long storage.
Being in florida I dont have to srore my bikes in winter anymore, but I remember the value of pulling and emptying the tank then draining the float bowel.
That was before the days of gas stabilizer

 

Well heres what I found, I'm pretty sure it is the fuel filter because the only thing I did different today as opposed to yesterday was back flush the fuel filter w/ a low pressure gas supply & reinstalled. Test drove & it runs like a scalded dog; actually the strongest it has since I've owned it. I will be purchasing a fuel filter on tuesday being a holiday weekend & all. The good that has come from having the tore apart several times, I found that the fan fuse was blown, I adjusted the rear suspension more to my liking & performed a minor air box mod. The bad Is I think I have a weak radiator cap as after my spirited test ride I was leaking coolant from the cap( I was just screwing w/ maybe it didn't seal ) spring seems very weak; does Honda still sell these? Might as well do a tstat right away too.

 

Update - I didn't have the rad. cap on right, 500 trouble free miles yesterday. The air box mod has definetly altered my torque curve a bit though, not in a bad way I'm just not used to it yet.:biggrin:

 

Glad you gto ti worked out tbones. Now be sure to enjoy all that v4 power. ;-)

 

Added bonus I figured out my milage today, 44.5 MPG normal cruising w/ a purportional amount of tame horse play. In my year of ownership I have never gotten over 35 mpg, I just assumed it was due to being piped & jetted. I can now go 200 miles on a tank w/ only the the last 10-15 miles on reserve. The low fuel light would alway come on between 135-150 depending on how I was riding; it did not come on today until 180+.

 

My fuel light comes on about 160 or so. According to the owners manual, at that point I woul dhave a little over 1 gallon left so I can get close to 200 miles on a tank, though I probably would not push it that far.

 

Preregrin, The S.O. doesn't let me out much to play with the boys so I make it count( I get to play baby sitter alot for her four kids but she makes good $$, I do too but the ex gets most of it). I have been checking into the Iron Butt site but I will definetly be buying BWM K1200LT before attempting a 1000 miles in a day. I'm not exactly a small guy (6'/300#) built like your average NFL line backer. I was quite amazed myself that I was able to ride that far & was still able to move @ the end of the day. Long straights kill me on the VFR my knees can't take it for more than an 1.5 hrs but most of those miles where in the twisties through the bluffs in southwest WI; so I got to move around alot. I have decided that my idea of lowering the pegs was a bad idea after monday though when I realized just how close my pegs where to asphalt. It may have been my riding partners too, one who went to Calgary BC & back taking the scenic routes in 7 days spending 2 entire days in Calgary on a 95' 800 Intruder & my other buddy who has so may pins screws & rods holding his leg together do to a bought w/ bone cancer that he cant bend his leg any more. He has some goofy looking brackets mounted on the side of his Mutant Buell xb( the bike is so insane, I swear it forged in the fires of hell) so he can ride with his rh leg straight out. He runs track day with it all the time too!! So there wasn't anyroom for me to complain about a little discomfort.

 

The BC trip mentioned above was 9 days not 7, but still a respectable distance for only 7 actual days of riding. 2 days out, 2 days there, 5 days back meandering across the west from Idaho to Wisconson 5000 mile trip.

 

Just update on the origanal complaint, I replaced the fuel filter the bike seemed to run good for a week or so. Now I can feel surging & some what of a flat spot in the mid range. I plan on setting the valve clearances, not that I think that will cure the problem I will also be putting NGK Iridium plugs when they show up. Then the real issue I am fairly certain the carbs are out of sync & I also have come to the conclusion I am running to lean. Being that I have no idea if the bike was ever jetted for the exhaust that is on it ( Basically an open header w/ a Kerker slip on to make things look good ) & then after my air box mod I have inadvertently made the lean condition worse. It is running a little hotter than usual but not much. So I need to find myself a carb guy I trust the one person I would trust has went from being a wrench to the dealership owner, so it may be a challenge to get him to dust off the tool box. Wish me luck