1990 Honda VFR 750F resurrection

Would need to use micrometer and dial indicator to determine that. Pic isn't enough.

 

you see grooves, right ?

 

Re the rear brake rotor, yeah it looks worse in the pics than in person, consequence of sanding it for paint. The grooves are not palpable so gonna run it as is.

Well it's been a busy for me last few weeks with little time for the VFR. I took some time to reinstall the exhaust and fire it up and....

She doesn't want to run. After a few tries I got it to settle into an idle but stalls if given any throttle and stalls without full choke. I checked everything over to make sure no stupid mistakes were made on re-assembly, and no intake leaks I could find. I know it ran after I cleaned the carbs like six months ago so carbs back off the bike.
Yup, all the slow jets were clogged and there were black particles in the fuel I drained from the bowls.
I checked and no debris coming from the tank (and there's a filter anyway)
So it must be either the old fuel pump that shat itself sending debris up the line, or the new fuel pump or fuel line.
I'm going to flush some fuel thru the lines using the fuel pump and see what comes out.

 

the filters should handle a little debris, right ? and its always best to run the carbs out of fuel then drain them b4 storage, every time so u dont need to waste time cleaning them later.

 

With today's fuel... ALWAYS drain the carbs for any kind of storage, like SM said.

And not just run it til it dies. Actually drain the bowls.

 

I could use some guidance here from the VFR carb gurus.
After last week's problem (see previous) carbs are again cleaned and reinstalled. I ran about a pint of fuel thru the fuel pump into a container. I got three black specks of debris and then it looked clean. Reconnected fuel lines, cranked over until fuel made it to the bowls and she fired right up. Excellent!
Now...
I still can't get it to run unless choked, even after it's up to temp (verified on gauge and heard the cooling fan running).
It will run at a fast idle about 1800 rpm on choke but doesn't sound right
It stumbles and stalls if I back off choke
stumbles and stalls if I rev it and let the throttle snap back
It will rev, at first reluctantly but will hold 5000 rpm and sounds good there
When I was warming it up, the #4 header was not nearly as hot as the others

What I have done:
checked there's no intake leaks, no kinks in fuel lines, fuel pump is working, verified fuel getting to bowl on #4, verified spark on #4
valve clearances are good
carbs are bench balanced only at this point- carb tune instructions say it needs to be warmed up and off choke to balance (but I hooked up the carb tune anyway, and 1,2,4 are quite close to each other while #3 reads a little higher than the rest

Give it a listen. Bike is already at temp, but doesn't want to start. Got it to start with choke + throttle:
https://photos.app.goo.gl/46Yh1A6h1HqueT3B6

I am not touching any controls or making adjustments, idle is varying on its own
https://photos.app.goo.gl/9GddzmQto6dZGAip6

Ideas?
Clean carbs again? WTF?
Thanks in advance!

 

^^ typical on carbs needing accurate synch and dialing-in of the mixture screws

 

You may have a little carb balancing to do but the restore looks great, love seeing the optional clock, as a last note double check that you have no small air leaks like around the carb boots, mine was sucking air there after it warmed up and if reved the revs would hang up around 3000 for a few secs until it would settle down

 

Update:
This is what came out of the fuel line between pump and carb. Damn!




So I pulled the carbs again and found the slow jets mostly clogged again! Thinking I needed to flush the system, I removed the bowls and float valves and set up a bath of clean fuel. Jumped the fuel pump and pushed fuel thru the carbs.... repeatedly. Filter on the pump inlet side so any debris "should" have got caught in the filter.




After 5 mins or so I strained the fuel from the basin and got this:





I did this 3 times and kept getting debris, so went ahead and disassembled the carbs again. Full clean, split the carbs, all tubes and lines looked good, no debris found.
Now I need 2 new tiny cotter pins for carb reassembly. Little bastards snapped. Next weekend will be bench sync and reinstall carbs, new fuel filter and see if she'll run!

 

Got the carbs re-re-reinstalled (how many cleanings is this now? I've lost count!)
New fuel filter and new, better quality fuel hose. I'm throwing out the "Evil Energy" sh!t I bought on amazon.
Started her up and right away I have a fuel leak under the #4 carb. So removed them again and found that I pinched the o-ring on the fuel tube where it enters #4 during re-assembly last week. Good thing I have extras. New o-ring, leak checked and all was well.
Good news is I'm getting really good at cleaning and installing these carbs.

And.... Woohoo sounds good!

https://photos.app.goo.gl/QWMETNQDLLW8rZDP8

 

........and u didnt think to leak-test the carbs b4 installing ?

 

Here's a tip for jumping out the fuel pump relay to test fuel pump or force it to run. Instead of making a jumper with 2 connectors and wire, I bent a fork connector so that it would slip into the terminals for black and blue.

 

sure, that looks safe and can handle whatever amps might pass thru, right ?

 

Months ago when I pulled the centerstand bracket, some of the aluminum thread on the frame had fused to the steel bolts.



Threads on the bolts cleaned up nicely with a die



And threads in the frame



Of course some of the threads are now missing, so I'll have to use some loctite and keep an eye on it.

 

The little surprises you find with an old bike....
As I was reinstalling the gas tank I noticed some electrical tape. I've not known Honda to use electrical tape
what's this? peel it off and found this



No attempt at a proper fix, the PO just hooked one wire around the other and taped it up!!!
That tape was old. I bought the bike in '97, so I know it's older than that.

 

Now that the carbs are balanced and pilot screws adjusted she's running great! Almost roadworthy.
It was so much better using a carb adjustment tool to reach those balancing screws. Tight space in there!
Does anyone know where this belongs on the bike? It looks like a shroud for the space forward of the battery box, around the starter relay?

 

Correct. I actually left mine out on my 92. It just never looked like it was configured properly to fit right, I couldn't find any good reference diagrams or pics and I got tired of messing with it. But I also switched to a 94- battery box heat shield that extends out over the rear manifold, and the 94- doesn't have that extra rubber shield, so it's sitting in the "92 VFR" box.

When you get it installed, please snap a pic.