1992 Honda VFR 750

http://vfrworld.com/forums/introductions/9893-1993-honda-vfr-750-a.html

 

Nate:

There are so many things so make a list and be ready to check them off as people give you suggestions and you eliminate them.

First, have you checked your vaccum hoses that come off the bottom of you gas tank?

Second, I know you can't fully check your charging system, but check what you can!

BZ

 

Nate:

Have you adjusted your idle cable?

BZ

 

Hi,
yes I did adjust the throttle cable at the carbs and I made sure that all the slides are in sync, so none are higher or lower than the others, as far as the vacuum hoses off the bottom of the tank? no I have not.
I see your point considering this bike sat for 8 years they might be dry rotted.
Where is a good starting point for checking the charging sys other than at the batt with it running? Do you know what thr voltage should be at idle at the batt? thanks Nate

 

Nate:

Not your throttle cable, your idle cable. It is located, If sitting on your 93, behind the left fairing. You can see it almost sticking out of the fairing. It has a little black plastic knob on the end with a philips head screw in the middle. You can use a screwdriver or your hand.

Charging at idle? Unsure, let me go grab my manual and I'll respond later tonight!

Do you have a manual nate?

BZ

 

Okay,
yes I have adjusted the idle cable, as soon as I start to turn it up or down it will stall. It's set right now where it will just idle and thats all it does. It will not even attemp to rev, it will just stall. No I don't have a manual yet, yeah I know I need to get one soon. Thanks for helping me out im really at a loss here.
Nate

 

How many miles does the bike have?

The things I would check is

1. what waldrum said about the additional clogged jets
2. the fuel tank vents, when you drain the gas from the tank and reove it from the bike not all the gas is out, so when you flip the tank over you hear a little whistling sound and gas often spurts out of the small vent hole on the bottom of the tank.
3. what did the previous owner say regarding the bike before the asshole just let it sit for 8 years?

At idle you really won't get a reading, but even a little engine rev should show some charge on your mutimeter.

In addition, check for a plugged fuel tank cap vent hole. also, did you clean out the fuel supply valve and how did you sync the carbs?

You really need a manual too.

www.amazon.com

BZ

 

BZ,
The bike has a little over 30,000 miles on it,
As far as the previous owner go's, he said it ran great when he parked it.
He bought it with 2,000 on it and always kept up with the maintenance untill he parked it. Hes my neighbor and I remember when this bike ran good years ago! I really don't know what the hell he was thinking leaving it like that for so long. I will go out and pick up a manual, in the mean time I would like to get more info on the jets, I must have missed something. Well thanks again for all your help.
Nate

 

Nate:

I am actually using my manual to help you LOL!

There are many things this could be, so try and eliminate them one at a time. It could be something as a mouse nest in your muffler(collection box). I have a feeling its still the carbs like clogged slow jets or incorrect pilot air screw setting.

Keep us posted!

BZ

 

BZ,
Well im going to work on this thing tonight, I'm going to start with the charging system, then remove the tank and check those vacuum lines.
Then those carbs are coming off one more time lol.
I will keep you posted, thanks
Nate

 

How did you clean the carbs?

Best way is to dip them in Berryman's carb cleaner for 24 hours, rinse, and then take an air compressor to blow out the passages. Also clean any corrosion with 0000 steel wool. Make sure your float valve settings are correct. If your jets are green, replace them.

Maybe you have a vacuum leak? Spray the carb boots with WD-40 while the bike is idling. If the rpm's change, you have an leak.

 

Nate:
Start with the carbs and tank vents and try masons suggestion too before you move to the charging system. Remember, eliminate the carb and vent stuff first. And you have not answered us on how you cleaned the carbs and how you sync'd them. Start with that stuff first, trust us!

BZ

 

BZ, Masonv45,
When I cleaned the carbs I used spray carb cleaner through every jet and passage then used compressed air through the passages. As far as the floats I used an old float measurement gauge I had to check float travel then the opening and closing points. Then I checked all the diaphrams for holes or cracking, they looked ok.
What I meant by getting the carbs in sync is that I adjusted each carb so the slides were opening and closing at the same time, and made sure the throttle plates were not partially open with a closed throttle. I'm still not sure what you mean about the tank vents? I seen a line coming off of the tank that looked like a vacuum line but I thought that was for a drain?
Nate

 

Masonv45,
I did try spraying around the boots with it idling, nothing changed.
Thanks,
Nate

 

You still need to soak them to be 100% sure they are clean. Berryman's Carb cleaner with mesh basket is available at Autozone for about $20.

To bench sync the carbs, cut a slip of 3/32" copy paper and use it to sync the carbs. You use it like a feeler gauge between the throttle plate and bore of the carb. This will get them really close - but a standard carb sync is usually still necessary.

What are your pilot screw settings?

Here is a page with some good info:
http://www.vsource.org/VFR-RVF_files/Bvfr750fl-p-mi.htm

 

Masonv45,
Now with that berrymans, does everything that is rubber or neoprene have to be reomved first? I seen the pilot screw settings are very limited on how far you can go with them, they will only go a half of a turn either way so I set them in the middle at first, then I tried adjusting them with the bike running and really got no change so there back in the middle again.
Thanks for the tip with the copy paper.
Nate

 

Yes, all rubber has to be removed. Carb cleaner will either swell it up or destroy it.

I've not dealt with the '92's - only the 1st gen's, but on the 1st gen's there is a felt washer on the throttle plate shaft that you have to remove the throttle plates to get to. So you don't have to remove the throttle plates (staked screws), you can just leave the felt washer installed.

Here is a link that shows a write up on carb cleaning. Yours should be similar: http://users.rcn.com/kochc/moto/carb/carb.html

You may have a different type of pilot screw - check your manual...
>>>>
The sticking point you may run into is getting the pilot screw washer and o-ring out - usually they are stuck in the pilot screw recess. A dental pick will help get it out.

In a pinch I have used a wide thread deck screw. Remove the pilot screw and insert the deck screw. GENTLY turn clockwise until the screw stops. Now GENTLY turn counter-clockwise 1/8 of a turn until you can gently pull the screw out. The washer and o-ring should be on the threads of the screw.
>>>>

Put the slow/main jets - plus the emulsion tube in the mesh basket. Now put the disassembled carb in the basket along with the parts. Drop basket into the can, be careful none of the cleaner overflows. Move the carb around as much as you can to remove any air pockets.

Allow to sit for 24 hours. Remove and pour water over the parts to clean them and to remove all the carb cleaner.

Use compressed air to blow out the carb passages. I stick the red straw of WD-40 and spray to verify the slow/main/emulsion tube jets are clear (don't spray yourself in the eyes - BTDT)

If you need to manually remove gunk from the jets, use a strand of copper wire from stranded electrical wire. Copper is softer than brass so it won't enlarge the jet holes.

The dipping can is small so you can only do one carb at a time. This is fine because you do not want to mix parts.

While the carb is being dipped, I inspect the other carb's parts.
- Does the float valve needle rubber tip have a permanent ring around it? If it does, it may leak.
- Is the little float valve seat/filter clean?
- Does the float valve leak? Dip it in a cup of water and find out.
- Does the brass choke valve move smoothly? If not, clean with WD-40 and 0000 steel wool.
- Is the slide needle smooth with no marks. If not, clean with WD-40 and 0000 steel wool.
- Do the pistons slide in their bore smoothly? If not, clean with WD-40 and 0000 steel wool.
- Do any of the cotter pin edges catch on anything else when moving?
- Add 3-1 oil to the threads of all screws.
- After assembly verify all the springs are in their correct places and the slides do not "snap" shut. Do the throttle/choke linkages work correctly without rubbing on anything?
- Now sync in order per the manual using the slip of paper. (make sure the slip of paper is on the section of plate furthest from the shaft - the sides put more pressure on the paper than the middle. Snap the throttle mechanism to "set" the plate after each adjustment and re-measure.

Note: When installing the throttle screw, screw it back in so it just barely lifts the throttle plates. You will more than likely have to adjust after getting the bike started and warmed up.

Test the choke cable tension by pushing down on the choke valves. If you can compress them at all, the choke cable is too tight.

 

Masonv45,
Sounds good, I will be heading for the garage in a few.
Thanks for all of the advice, I will keep you updated on my VFR crisis!
Nate

 

By the way it's a 93, I hit 2 on accident.
Nate

 

In one of the posts you say you can only adjust the pilot screws 1/2 a turn either way, I'd say that points straight to your problem, sorry if that sounds too obvious and smartass, maybe i,ve missed something.