New Life for an Old 86 VFR700

Morning,
To make a long story short , (33k miles on the speedo) I have had the bike for about a month. It did crank when I got it. No it hasn't fired up yet. The PO did a hack job on the carbs and now that is another beer I'm figuring out. Currently trying to do a compression test to see if the bikes worth putting money into. Can't do a compression test if I cannot get it to crank.

Now the bike won't crank with the START button. If I cross terminals on the solenoid by the battery it will crank. Battery with a multimeter reads 11.6. Reading to the solenoid is same. No change on reading to the solenoid when I push the button but the lights dim as though it's trying. We may have nocked something in transportation.

Where do I start?

 

Am hopeful for you that it could be something as simple as the connectors in the START / STOP switch. Seperate the halves of the switch at the bars and try some electrical contact cleaner and a general "go through" . Hope that does the trick.

Rick

 

"Am hopeful" that concerns me.

 

Worry NOT. If it's more serious than that there are MANY helpful enthusiasts here more than willing to help. You have to have a place to start and the switch is an easy step to work through.
Best of luck.

 

Check out the starter button

 

pull out the headlight fuse while you're working on the bike (far right). a healthy battery is around 12.6 volts, so your seems low. if you can get it tuning over by jumping the starter relay, that's OK for compression testing.

check the manual to see what factors can inhibit cranking: in gear, not in neutral, clutch switch, lockout diode, etc. don't take switches apart until you check continuity (or not) at the plugs first.

 

I know, I can do compression test by crossing the solenoid... but I could not leave it alone...tested these in this order
1. start button~Good
2. clutch switch~Good
3. Neutral Switch~Good
4. Solenoid switch~ Good
5. Clutch Diode~ Good

All good. No where else to go but start examining the wiring harness. Figure i'd start by the tree, first wire harness I grabbed and what do I see..smashed wires. So I spliced them together and with fingers crossed what cranks....YUP....she turning over again. Now I can do the compression test.

Bike Wire by Dr.Инженер posted May 20, 2019 at 8:25 PM

 

that could be rodent damage. i am an expert.

 

Now this bugs me...one of the PO's was a Walmart rattle can weekend hero and painted over the beautiful white paint this bike use to be. At first I thought the bike was black with the OG paint job going bad. But nope, bad rattle can job. I get it, if the paint is bad from gas pours or negligence, repaint it correctly. But there's nothing like a/any vintage bike with original style fairings and original style paint.

 

Compression numbers in piston order cold engine :

Dry: 20,30,20,30

With oil

90,140,40,90

Number 3 needs to see a doctor

 

First, I would pop the valve covers off, do a visual inspection of the cam lobes and the visible valve train components, and if everything looked OK, I'd check the valve clearances and make sure the cams are set right. After that, I would pop the plugs out and use a syringe to inject a little marvel mystery oil into the cylinders and let it sit for a spell. After it sat for a couple days, I would give it a good spinning on the starter motor. Then I'd put the plugs back in and see what kind of numbers it has. Could just be gummed up ring grooves or the valves aren't sealing properly if it's been sitting for a long time. There are a myriad of reasons as to why the compression numbers are skewed and I've seen that it isn't always a terminal engine issue.

 

Thanks for the advice, I really don’t want to abandon this bike. I’ve sourced another 700 motor with 9k mike and 2 year warranty for $700 delivered. But that eats up most of my budget.

Back on topic, I just put mystery oil in and will check again Monday.

 

Morning, new compression number after sitting in mystery oil for 3days.

50,60,30,50

 

I'm assuming those are "dry" numbers. Have you checked the valve clearances, especially for the #3 cylinder. Without knowing if the valves are in spec, the information you are gathering might prove to be erroneous.

 

Sorry, yes they are dry number.

I'll start on checking the valve clearance tonight. I need the upper and lower tolerances for both intake and exhaust. Who on here would have a manual for the 1986 VFR700 and provide the specs? The manuals provided on here aren't working.

 

Hmm, I don't have one, but they have to be somewhere on the google. There are a couple guys here that might have it in their head, Captain 80's and Squirrelman1. Once you get the settings confirmed, and you are still seeing number 3 as a little off, you can then proceed to a leak down test to try to narrow down where the pressure loss is occurring. A leak down test is a little more informative than a basic compression check. It was a positive thing to see the numbers bump up just a bit after the marvel soak. Don't know how much of that can be attributed to residual oil on the cylinder walls skewing the "dry" numbers, but positive none the less.

 

IN 0.13 mm (0.005 in)
EX 0.20 mm (0.007 in)

http://pkarwowski.pl/moto/wp-content/uploads/2014/01/Honda-VFR-750F-RC24-Service-Manual.pdf

 

Intake: I’ve gone down to .0015 and it still won't insert on all 1-4

Exhaust: 1-4 (.006 is a little tight and .007 will not go)
.152 (.006)

 

never saw a feeler that thin (.0015"), u sure that's right ?

so, with standard tolerances, .005" means .004-.oo6" is OK and .oo7 means that .006-.oo8" is OK.

 

Feeler by Dr.Инженер posted May 29, 2019 at 6:00 AM

yes sir here is a pic of it. I wasn't confident I did this right, because I usually just send the heads off for inspection if I know the bike is worth it. But its not hard to put a cylinder TDC and check lobe vs rocker with a feeler. Once I seen that no gage would fit I slowly inched the crank and checked multiple different location as long as the lobe wasn't putting pressure on the rocker. No feeler would fit at any point on any intake valve.

If one of you are up for it I can video it this afternoon and post it to my YouTube channel. Or if one of you have facetime or skype we can go over it that way.

I do appreciate the time you guys are taking to ensure this is done properly.