1993 vfr750f wont start

hi, i bought a 93 vfr750 recently. its my first bike. it is in excellent condition with only 17k mi. only problem was that it sat for a while. it would not idle, so i took apart the carbs and cleaned the jets which were clogged of course. also threw in new spark plugs and air filter. now that i put it all back together, it wont start, it started just fine before. tried jumping it and that didnt work. So my question is, what might i have done wrong when i put it back together that may cause it not to start?

 

petcock was the first thing i thought, but i cant find it on this bike! its not in the manual, and i couldnt find any pics online. where is it?

 

Looking at cleaning the carbs as a step to getting my 93 back running (it has been sitting for 7 years) I'm curious as to what this problem turned out to be.

2nd question: Doing a complete carb disassembly and cleaning looks a bit intimidating (back when I used to ride it I only did oil/filter changes, brake rotors and pads, and put on SS hydraulic lines but never did anything with the carb or engine. Looking at my shop manual, just taking the carb assembly off looks a whole lot simpler than taking it apart. It seems to me like one should be able to rinse it out with solvents such that all gunk would be dissolved once you have it off and thus not have to take it apart. Is there such a procedure?

 

:welcome: jrg and BamBam

The only time it's really necessary to separate the carbs is to replace the O-rings on the fuel crossover tubes, and about 90% of carb work only needs the idle jets, main jet holder tubes, and choke pickup tubes cleaned, along with inspection of the filter screens above the float needles.


Remember: don't remove the alloy airbox bottom from the set or you won't go to Heaven.

 

First check for a fat blue spark on any sample plug.

Next check that fuel is getting to the carbs by opening a float bowl drain screw and watching for drippages. Carbs that are dry after a cleaning need lotsa engine cranking to fill up again, which often depletes the battery voltage enuff so that the ignition system doesn't have enough juice to spark the plugs. Petcock on gen 3 is under the tank at left side.

 

Did you clean the fuel filter as well? Fuel pump?

Did you accidentlally leave the run/stop switch in the stop position? Don't ask.

Larry

 

Check your battery voltage before you try to start your "white-steed" and it its under 12.7 volts or so, replace your battery! You could also try using a trickle battery charger (optimia-or Deltran?)

I have a 91 with 92 body work that is a member of my family :smile:

 

Another thing to check (from personal experience) is the tank, look for rust. One thing that happened to me was I did a carb clean, then a couple of days afterward, the bike was running crappy again. Turns out there was rust in the tank. Double check everything else. Fuel filter, spark plugs, battery voltage.

 

AFP: the redish dust you cleaned out from carbs should have tipped you off to a rusty tank right away. What did you do with the tank in terms of cleaning or coating ??

 

I'm in the process of removing my carb assembly to send to Squirrelman for a full cleaning and have run into two problems (that I thought I'd just ask here even if Squirrleman is the one that answers for bennefit of others).

1) One of the little right angle inlets for the crankcase breather tubes on the front of the airbox poped out, and it looks like these are just glued in (with a little tab for alignment). Anyone know what sort of glue would be good here? Just some ordinary epoxy seems like it work work.

2) With the air box off (just the plastic) and the tank of course, now I'm trying to get the choke and throttle cables released. The choke was no problem as there is plenty of room, just move the lever on the carb (leaving the choke control alone) which makes plenty of slack and pop out the cable. But the throttles look to be much more difficult. Any pointers/technique on how to do this? I have taken the handlebar end out before, but recall it isn't easy either.

hmm can you take the assembly off (loosening the insulator clamps is all that remains I think) and leave the throttle cables on, then with a bit of slack pop them out after shifting the whole assembly to get a bit more room???

 

Take off the throttle cables down at the bracket on the left carb side by using a 10mm wrench on the lock nuts along the pull cable, screw the metal sleeve in until there's enough slack to lift it away, then move it forward and remove the end from the throttle wheel. After that the other cable just snaps off the bracket. Or sometimes it's easier to pull the carbs up and take the cables off then. Keep the cables close to where they were, cuz the routing needs to be exactly the same when reassembled, and cable freeplay will need resetting. While the cables are detached, check for smooth operation, and lube if necessary.

JB is good for anything but a toothache.

 

Thanks squirrelman, that sounds like it will work.... if I can get the rest of if off. Boy this does not appear as easy as the service manual shows! The clamps around the insulators just need to be loosened it says. I've got 3 pairs of those done no problem, but the right rear, man I can barely even glimpse those screws. Can you really do this without taking off other stuff?

some sort of tiny flexible flashlight would be good as its very hard to see, but still there just doesn't seem to be a way... but will keep working on it. Why it wasn't designed to have the screw heads pointing backwards where they are easily accessible is beyond me.

and once all 4 pairs of band clamps are loose, does it just lift off? with 3 sets loose it seems very solidly attached still.

 

In the ideal world of brand new parts in the FSM things come apart easily, not so after years and miles.

Bit of a problem for sure. I'm certain all the clamp screws were positioned for best access when the bike was new, so some clueless dolt worked on it in a dark garden shed..............but how did he tighten the screws?? (if he did), so you need to figgher it out. there must be screwdriver access from some angle.

If you can get a LONG screwdriver in back of the clamp from the other side, try pushing it around where you need it.

If your mounting boots are seriously hardened or cracked after exposure for 20+ years to heat, age, hydrocarbons, and atmospheric pollutants, plan on replacing them, and note that there is a specific angle and direction for proppa boot installation.


It's usually tough to dislodge the carbs after years and years in place with original, rock-hard mounts. You can't usually just jerk it off ....LOL ! Heat and WD-40* help. Try jerking up forcefully on each corner of the airbox a few times rather than trying to lift the whole assembly. You gotta get 'em rockin' bit by bit slowly, watching for increases in movement, then it's sittin in your hands, and you can sit down and open another beer !! There are approved pry points, between the carb tops and the rear cam cover, but best to avoid if possible. In most cases some cautious prying applied to the rear carbs WILL be necessary, and after that, the fronts pop out easy.


* Not a compensated endorser.

 

Thanks. I'll get it eventually. I found a good technique for trying to find the path to some remote fastener. Without too bright external light snake in a tiny led gooseneck ($10 at the local hw store) as to shin just on the screw your want to get to, its only 4 lumens but with a dim environment that lights it up enough that the issue of the brighter exterior and the dark interior is not so much of a problem. Then its much easier just to scan around until you can see the head from some position. With a longer screwdriver I think it might be possible. As you say, someone had to put this thing on... though at the factory, its hard to say at what point it is put on and I'm less sure about it being oriented ideally then either, and I don't know that the carb assembly has ever been off.

The service manual does show (and comment on) them all with the heads pointing out to the sides, as I found them.

 

There are indentions on the mounting sleeve to locate aNd hold the clamps from being moved while being tightened, and that exact position best corresponds to exactly centering of the carb mount cutout at the top.

Possible problem is having those clamps rotate back while tightening. Solution is to hold a long screwdriver in back of clamp when screw tightening starts on the other side, 2-handed style.

Photo'ed is impropopa mount positions i found on a friend's bike brought to me for work, where the paint spots should be centered vertically. This is the only sign i've seen that Canada may still be a primitive country.

 

Unfortunately when I said that "I did a carb cleaning" what I meant to say was I paid someone to do it (first time). I learned really quick to do this myself. As far as the tank, I used BB's and hot water to flush out all the "gunk". I did that procedure about 10 times. After that, I put in Alcohol, drained and then let the rest evaporate. As far as a coating, I went to a local John Deere dealership and they had a coating for gas tanks, specifically for one's that used all the additives for up here in the NE. I keep checking the tank every season, and so far (knock on wood) no issues.

 

It's a simple practical fact --yet unacknowledged by some-- that most carb problems begin in the fuel tank, as me ole Grampy useta say. Rust, water, unidentifiable flakes, more. Don't believe any filter stops it all.

Ideally, to help prevent carb problems, someone would completely drain the tank about twice a year. It's also a good easy precaution to crack open bowl drain screws occasionally to flush out water that may collect at the bottom along with any reddish flakes which you know is rust and could migrate into a jet orifiice at any time, with consequent sub-optimal combustion.

 

Imagine if you would-ah gotten a ticket from that slack jawwed mouth breather up there (no name-randy?) sSHHHHEeeeshhhhh...I would still have a Canadian Club with that bastard :canada: F u Le0 :flip:

 

Anybody who had his Mounty uniform could get girls ANYTIME !!!!!