Fuel spray back into air filter
Advanced
Joined: Jul 2006
Posts: 87
Likes: 0
From: Western New York
Fuel spray back
Cheap fix first, Mikuni has a nasty habit of sending their carbs with their accelerator pump turned all the way to wide open!Also the timing always seems to be just a little out of whack, along with that! Had a very similar problem years ago.
Don't play with the jets till you've tried this. Turn the pump all the way off,then road test. Might stumble along the way,at that point add a quarter (At the most) turn to the pump adjustment. Should not take or need all that much in adjustment to weed that stumble out of there.
That fuel should not becoming out of the pump like a garden hose! Should be just a short spurt in duration, and just enough for a smooth transition. Also,that stream should not be hitting the slide or the pin! Both are easy to fix.
Don't play with the jets till you've tried this. Turn the pump all the way off,then road test. Might stumble along the way,at that point add a quarter (At the most) turn to the pump adjustment. Should not take or need all that much in adjustment to weed that stumble out of there.
That fuel should not becoming out of the pump like a garden hose! Should be just a short spurt in duration, and just enough for a smooth transition. Also,that stream should not be hitting the slide or the pin! Both are easy to fix.
Stage II
Joined: Sep 2009
Posts: 2
Likes: 1
From: gettysburg
you have reversion or stand off like the other guy said. theres many things that account to it. im guess you have open pipes. an easy fix to try is to get a set of torque cones. they are what the name suggests, theyre cones that make more torque. they go in your pipes at the head and should greatly help with your reversion and keep your bike from carb farting when you pull out. ive seen this happen bad on a sportster with an 800 dollar 2-1 rhinehart exhaust so its not just open pipes that do it but having open pipes greatly accounts to it cause there isnt back pressure. a way you can check that this is what it is is to take off your air cleaner and start your bike up. when you crack the throttle, you will have a mist of gas and air flying out until your main jet takes over the work from your accelerator pump. that is the reversion. now have someone ball up some rags and hold them against your exhaust openings, to close off the tail pipes basically. now start your bike with the rags over the pipes and see what happens when you crack the throttle. the reversion will most likely be gone. reversion is the exhaust going in and out of the exhaust and it goes through your valves and everythings pulsing back and forth, not a constant vacuum going in the carb and out the pipes. the rags create backpressure and keeps the fuel mixture going in and not blowing back out. those torque cones should get rid of this. i hope this helps. i may have said something incorrect somewhere but this is the general idea of whats going on in your intake. the cones are pretty cheap and worth it if it keeps your filter and bike dry and smoothes out the carb by getting rid of lean pops or carb farts
Road Captain
Joined: May 2008
Posts: 539
Likes: 0
From: Elkhorn Mnts Oregon
The oil is coming from the crank case breathers...there is always a fine mist going on there but if you ride the bike hard the oil will be more evident....if the oil is getting all over your bike, from the breathers, it's called 'oil carry over' and it needs to be addressed.
OIL CARRY OVER:
Oil pump alignment is aligning the oil pump with the ports in the cam plate. Its done with installing two tapered threaded pins in hole #1 and #2 in the cam plate while rotating the engine. If the pump isn't aligned it damages the pump body and the oil pump is no longer efficent. Now when you ride hard (80 mph) for40 min or so the cam chest fills up with oil because the pump can't pump it out fast enough so the oil is forced up the push rod tubes by the crank case pressure (from the pistons on the down stroke) filling the rocker boxes with oil and out the breather it comes as 'oil carry over'
A new way oil pumps are getting damaged causing Oil Carry Over is from flywheel shifting on the 07 and up bikes.
OIL CARRY OVER:
Oil pump alignment is aligning the oil pump with the ports in the cam plate. Its done with installing two tapered threaded pins in hole #1 and #2 in the cam plate while rotating the engine. If the pump isn't aligned it damages the pump body and the oil pump is no longer efficent. Now when you ride hard (80 mph) for40 min or so the cam chest fills up with oil because the pump can't pump it out fast enough so the oil is forced up the push rod tubes by the crank case pressure (from the pistons on the down stroke) filling the rocker boxes with oil and out the breather it comes as 'oil carry over'
A new way oil pumps are getting damaged causing Oil Carry Over is from flywheel shifting on the 07 and up bikes.
Can anyone else elaborate on his statement of :
"Oil Carry Over is from flywheel shifting on the 07 and up bikes"
Is flywheel shifting, shifting without use of the clutch?
thanks for the help.
Road Warrior
Joined: Aug 2008
Posts: 1,306
Likes: 865
From: Sheboygan, WI
Nope. What he is talking about is the flywheel moving slightly out of it's intended spot in the engine.
Banned
Joined: Sep 2009
Posts: 3,569
Likes: 624
From: deland,florida
what he means is that the f/wheel are becoming untrue.the twin cam f/wheels are 3 peices,pinion side f/ wheel,crank pin & spkt side f/wheel,when they move on the crank pin,this is called "shifting".from the factory,f/wheels should have 0 runout(their usually about .001 per side.when they shift they can be as far as .010-.015(we got a FLHR in about a month ago that the f/wheels where out .039 at the pinion shaft!!)on any twin cam thats going to see high revs or holeshots,we weld the c. pin.pretty much a must,or they`ll move.not real sure if this is your prob.you can remove your cam plate & put an indicator on your pinion shaft,if its within spec,S&S makes a breather that goes behind your oil pump to stop the motor from oil sumping(i think thats more likley your problem)
kirby
vee twin racing
kirby
vee twin racing
Last edited by prodrag1320; Oct 6, 2009 at 07:20 PM.
Road Captain
Joined: May 2008
Posts: 539
Likes: 0
From: Elkhorn Mnts Oregon
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Stage II
Joined: Nov 2009
Posts: 2
Likes: 1
Hi geads! have you swaped your camshaft? If you have done that the chances are that there is a bit to much of overlap, meaning that intake are open longer with the exaust. And that will cause a spray back on lover rpm and when you crack the trottel wide open it will unfortunately spray back.
I use Bob Wood,s exelent camshaft, short duration but high lift. ( TW-6HG)
Sinserely Peder.
I use Bob Wood,s exelent camshaft, short duration but high lift. ( TW-6HG)
Sinserely Peder.
Cruiser
Joined: Oct 2006
Posts: 143
Likes: 0
From: Lockport, NY
I just swapped out the pipes on my bike and rode it today for the first time. THey are extremely short and I didnt add baffles. I rejeted the carb to a size higher on the main than it recommeded because Ithink it was running too lean with the recommended jets. THe bike rode OK but did backfire and pop some. When I came to a stop the bike started spitting fuel out the carb. Not a little oily residue but actually spitting gas out the side until I shut the fuel off. It was like it was puking it out. This thread explains alot. I will try to add baffles and see if it helps.
Should I rejet it? I just went to a larger main because I thought it was running lean. THe old pipes were very discolored and looked like the exhaust temp was high.
Where do I start? add baffles or cones? Back the jet back down to run a little leaner?
Should I rejet it? I just went to a larger main because I thought it was running lean. THe old pipes were very discolored and looked like the exhaust temp was high.
Where do I start? add baffles or cones? Back the jet back down to run a little leaner?