Kawasaki VN750 Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter #1
My bike runs well, but on occasion it after a ride when I go to start it again it will seem to flood out and then a major backfire. It will start after that, but it is pretty embarassing.

I also apparently need to look into how my carbs are vented because at highway speed the bike tends to sputter, but only when the wind is blowing a certain direction. I have read a few posts on this, but haven't tried anything yet. I do want to get all the bugs worked out because I am going on my first long trip in a few months.

Thanks,
Scott
86 750, 6,200 miles
 

·
Registered
Joined
·
1,253 Posts
I also apparently need to look into how my carbs are vented because at highway speed the bike tends to sputter, but only when the wind is blowing a certain direction.
Make sure the vent hose behind the right ear (air filter) is plugged into one of the slotted holes. What you described here sounds like the issue that a dangling hose will cause. Also, if the hose did come out, you should go ahead and cut the end at a 45 degree angle so it won't bottom out.

Also as far as the backfire, I had my bike do that once when the hose fell out of the ear too. Never had it happen again after that was fixed.
 

·
Old Truck Junkie
Joined
·
4,133 Posts
Back fires like that also come from weak or low battery. Since we get spark at both power stroke and exhaust stroke some times a low voltage will not ignite at compression but it will on the exhaust stroke.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #5
Thanks for the tips. Last night it "went off" and sounded like a shotgun being fired in the neighborhood. I'll check it out over the next few days. I had a friend of mine rebuild the carbs about a year ago, and he removed all of the smog stuff, put in plates to cover the emissions outlet and installed K&N air filters. I have no idea what he did with the vent tubes...The battery is only a year old, but I'll check on that too.
 

·
Registered
Joined
·
3,353 Posts
if the battery is a wet cell type...get rid of it and replace it with a AGM maintenance free battery. The VN750 needs a good voltage source to start and run well.

A weak battery can...and does cause backfire on starts.

thanks niterider for the reminder!
 

·
Registered
Joined
·
319 Posts
My bike did the same thing and when I finally changed the plugs (I replaced mine with the iridium plugs) and it stopped doing this. Plus it started much easier too.
 

·
Registered
Joined
·
384 Posts
Another possibility is after you shut it off, and start it again, and you get a backfire, that sometimes will indicate raw fuel in the cylinder and or exhaust pipe igniting and causing the backfiring.
If at all possible after running it, pull a plug and see if it's wet or dry. A wet plug indicates fuel in the cylinder. A dry plug indicates no raw fuel.
 

·
Registered
Joined
·
46 Posts
Back fires like that also come from weak or low battery. Since we get spark at both power stroke and exhaust stroke some times a low voltage will not ignite at compression but it will on the exhaust stroke.
I agree with Niterider on this one.... I was having having backfire issues at startup and all of the classic symptoms of "POOGS". I ran Seafoam through a couple of tanks of gas but saw no improvement.... (except that my fuel guage started working again) Checked the plug gaps and they were fine. So I decided to check some electrical connections under the seat for possible corrosion. What I found almost made me soil myself:wow:. There was enough corrosion on the positive battery post to cover it. After cleaning the whole mess up, I bought a new Deka AGM battery (American Made) at Advanced Auto for around $73.00. Before installing, it got a charge on the Battery Tender... Old "Trigger" never started better since I bought her back in 1989. And I haven't had any "POOGS" symptoms since. It's true!! A weak battery can cause all kinds of headaches that can make you think that it's fuel related. "Now if I can just use some of that Seafoam to get my tach working again".... Hmm. Lol!!:)
 

·
Old Truck Junkie
Joined
·
4,133 Posts
Check your tachs ground and the connection to the front coil. Thanx for the vote of confidence. lol
 
1 - 11 of 11 Posts
Top