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Author Topic: The Bad Idea - VF750F Interceptor restoration  (Read 32686 times)

Offline Worst cb650 ever

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The Bad Idea - VF750F Interceptor restoration
« on: Mar 24, 2014, 23:09:55 »
So I seem to have a bike hoarding problem, as a fourth orphan Honda has followed me home.

This one is a 1983 VF750F Interceptor, apparently the second fastest bike in the world in 1983.  No, I don't know what the fastest bike was. 







This is what it looked like new:



I responded to a Craigslist post for this bike, as the tank and fairings looked in good shape, and I've always loved the '80s looks of the Interceptors.  After some back and forth, the previous owner and I agreed on a price, and I picked up the bike a couple days ago. 

The problems were pretty much the standard laundry list for an '80s Honda that sat for a year+:

-No clutch action
-No front brake action, but both calipers frozen on the rotors
-No rear brake action
-Starter doesn't work when button is pressed
-Stiff rusty chain
-Old Metzler tires
-Throttle turns, but doesn't snap back closed
-Unknown condition of the top end - these motors are know to have "chocolate" cams (thanks PJ  ;D) that end up with excessive wear on the cam lobes due to poor oiling and improper adjustment
-Dead battery - bone dry
-No turn signals - probably bad flasher relay

Other than that Mrs. Lincoln, how was the play?   :o

I attacked the brakes and clutch first after I brought it home, as it was late and this would determine how many hundreds I'd need to spend on seals and rebuild kits.  However, I was able to get the front brakes and clutch working without changing anything other than the hydraulic fluid.  Well, and drilling out the seized screws holding down the cover on the brake master. 

I had to "exercise" the pistons in the front calipers by pressing them back in with channel lock pliers.  I also took the opportunity to remove the pad pins and clean and lube them as well as the caliper slider pins.  Sil-Glyde is your friend. 

The secret of getting the air out of these '80s Honda clutch and brake systems is to start bleeding at the banjo bolt where the hose attaches to the master cylinder.  Put a paper towel under the union, fill the reservoir, and pump the lever 3 or four times and hold it.  Then, crack open the banjo bolt at the master cylinder.  You may or may not get some air or fluid out.  Repeat until you are only getting fluid out of the union.  Then, move on to the caliper or slave cylinder, and attach your length of clear tubing going into your clear jam jar to the bleed screw.  It will take a while to bleed out all the air, and make sure you don't let the reservoir run dry or you'll have to start over. 

Once I had pressure to the front brakes, I was able to "exercise" the brakes by running out the pistons, press them back into the bores, run them out again, and so on until I was happy with the action.  I ran a lot of fluid through the system until the bubbles were gone and the fluid coming out was the same color as what I was putting in.  The clutch slave started working with a "pop", after following the same bleed procedure. 

The rear brake bled out ok, but the hose between the reservoir and the master cylinder is leaking like a sieve.  Ebay to the rescue - a foot of hose is about $4 shipped. 

Heartened, I moved onto checking the cams.  I pulled off the valve covers to reveal absolutely beautiful cams.  I mean, the metal under the covers was spotless and the cam lobes and everything else under there looks brand new.  The only issue I saw was that everything was dry from sitting.  Some oil can action with my favorite Rotella 5w-40 helped alleviate that issue.  I also added a couple of tablespoons of ATF to each spark plug hole to help free any stuck rings.  I really dodged a bullet here. 

Also, the coolant I drained to remove the upper radiator (to remove the front cam cover) looked perfect.  The oil looked like it had been changed yesterday, and was full.  Someone took care of this bike at some point. 

Next, I moved on to getting the starting system working.  After some testing, I determined that the starter solenoid was clicking on as soon as the ignition was turned on.  The solenoid itself was fine, but someone was triggering it without the starter button being pressed.  I determined that the neutral safety switch was working, but the clutch safety switch was not.  Still, when the bike was in neutral and the start button was pressed, the headlight went out but the starter did not crank.

Bridging the starter terminals made the motor turn over, which meant that even thought the solenoid was being triggered, but not enough to spin the starter.  Some tracing back pointed to the starter clutch diode.  I removed the diode, and the solenoid clicked off.  I tested the diode with my multimeter, and found the thing was conducting electricity poorly both ways.  It's cooked!  Hello Ebay...

Also, yay for the motor spinning over! 

That's as far as I've made it with the work so far.  I'm waiting for parts to arrive to get the bike cranking over on its own, and I'm also going to build a testing fuel tank for the next step.  Stay tuned...
DTT Blue (cause Winter is Coming) CB360 Club.

1995 CBR900RR - a winter flip not worth a DTT writeup - Sold

1986 Yamaha SRX600 - mailed to me from California - build coming soon?

1983 VF750F

1976 CB360T

1993 CBR900RR - Sold

1979 CB650 - Sold

Offline teazer

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #1 on: Mar 25, 2014, 00:26:27 »
That's good progress and I love to read that I'm not the worst at picking up orphaned bikes.  I almost feel better about the amount of scrap iron in the garage pretending that they can go back together as great running bikes for minimal outlay. 

Offline Worst cb650 ever

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #2 on: Mar 25, 2014, 00:40:28 »
Sometimes the orphans are the most interesting bikes! 

I'm pleased at how far I've got with so little money spent.  I haven't started in on the fuel system, however, and looking at the carbs makes me uneasy.  Maybe they'll just need some fuel to start working?  Hah!
DTT Blue (cause Winter is Coming) CB360 Club.

1995 CBR900RR - a winter flip not worth a DTT writeup - Sold

1986 Yamaha SRX600 - mailed to me from California - build coming soon?

1983 VF750F

1976 CB360T

1993 CBR900RR - Sold

1979 CB650 - Sold

Offline interceptor

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #3 on: Mar 25, 2014, 07:51:05 »
I love these bikes.  Just look at my username  ;D
Opinions are like farts... they stink and no one wants to hear it except yourself.

Offline Maritime

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #4 on: Mar 25, 2014, 08:40:52 »
A good cleaning an new tires and it sounds like you will have a fun bike, That model 750 is my favorite of the old interceptors.
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Offline Cafe-XV750

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #5 on: Mar 25, 2014, 08:56:50 »
One of my favorite 1st gen sport bikes too.  Instead I picked the fastest bike of that era  ;)

There are few nice VFs rolling around our Peoples Republic area ... spotted at Depot Town bike nights, downtown and in other parking lots.  A co-worker has one that he brought back from neglect too ... daily rides it when we have hospitable temps.

Cam oiling was a weakness ... IIRC there is a relatively easy mod to improve it - was part of the VF->VFR update.
« Last Edit: Mar 25, 2014, 09:01:26 by Cafe-XV750 »
'82 Yamaha XV750 - cafe conversion
'72 Suzuki T500 - rough, but going cafe
'79 Honda XL185 - dirt bomber
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Offline Worst cb650 ever

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #6 on: Mar 25, 2014, 23:16:17 »
The cams look perfect in this bike.  I have no idea why, other than perhaps they have been replaced already?

I did remove the carbs to clean them, as the float bowls were full of some nasty ass gas, and found that the plastic pipes between the carbs were all shot to hell.  Someone had glued them back together with JB Weld, and it had cracked and fallen apart.  Good thing I didn't try to put fuel to the thing or it would have all come out the bottom of the carbs. 

The carbs look ok inside, other than some normal goop, so I ordered up some brass tubing of the same ID of the broken plastic pipes.  I'll glue it to the inside of the broken plastic, and hopefully that should be a more permanent and cheaper repair than the $50 aftermarket pipes.  It should also help hold the unbroken pipes together.

I'll also pick up some Allen head screws to replace the carb screws and the screws that hold the lower air box to the carbs.  One of these air box screws was missing.  Hmm, maybe I should check in the cylinders...

Pictures!







DTT Blue (cause Winter is Coming) CB360 Club.

1995 CBR900RR - a winter flip not worth a DTT writeup - Sold

1986 Yamaha SRX600 - mailed to me from California - build coming soon?

1983 VF750F

1976 CB360T

1993 CBR900RR - Sold

1979 CB650 - Sold

Offline Worst cb650 ever

  • Posts: 1491
  • You can always get it running with time or money.
Re: The Bad Idea - VF750F Interceptor restoration
« Reply #7 on: Mar 28, 2014, 14:43:59 »
I've started digging into the carbs, and other than a couple of the expected stuck screws, everything's going well.  They're in pretty good shape other than the float bowl goo. 

I'm still fighting with the starter system - it is acting strangely.  As soon as I turn on the ignition, the starter relay clicks on.  However, the starter motor doesn't run.  When I press the starter button, the headlight goes out, but the starter does not run.  Bridging the solenoid terminals makes the starter motor run, but not well, and it doesn't make a full rotation. 

I can freely turn over the motor with a wrench, so I know it's not locked up.  I tried replacing the starter circuit diode and solenoid, but neither one of those helped.  The next step is isolating the issue by unplugging the starter button / right control harness.  I imagine something's gummed up in the control "pod" or a wire is pinched, but I'd like to make sure that there isn't an issue with the body harness.  The starter motor will probably need to be rebuilt or replaced, but it could also be the starter clutch jamming up. 

There also seems to be a "clacking" noise from the front cylinder bank when the engine is turned over by hand, which sounds suspiciously like a chain tensioner doing something naughty.  It could also be the starter or starter clutch hanging up.  I'm interested to hear the thoughts of the learned Interceptor owners...
DTT Blue (cause Winter is Coming) CB360 Club.

1995 CBR900RR - a winter flip not worth a DTT writeup - Sold

1986 Yamaha SRX600 - mailed to me from California - build coming soon?

1983 VF750F

1976 CB360T

1993 CBR900RR - Sold

1979 CB650 - Sold

Offline teazer

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Re: The Bad Idea - VF750F Interceptor restoration
« Reply #8 on: Mar 28, 2014, 15:37:48 »
Sounds almost like a crappy ground at the solenoid or the starter, but they usually just ground through the mounting bolts.. I was going to suggest checking that there were enough electrons reaching the solenoid from the button, but if. it's clicked into action, that's all it needs. 

How about the motor ground strap and battery ground?  Are they both 100% hunky dory or are they a bit dodgy?

Mine was a VFR so can't comment on the chain, but sounds like it could be loose.  I'd adjust it to be on the safe side, but I'd guess it's starter clutch

Offline Worst cb650 ever

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  • You can always get it running with time or money.
Re: The Bad Idea - VF750F Interceptor restoration
« Reply #9 on: Mar 28, 2014, 21:41:30 »
Yea, I think I'm going to add a supplemental ground to the starter after I reinstall it.  I really tore into the bike this evening, however, and found my problem. 

I first dumped the oil and took off the clutch side cover and put a ratchet on the starter clutch.  Spinning it forward caused the starter motor not to spin, and spinning it backwards caused the starter to spin, which is what I expected to happen. 

I then removed the starter and bench tested it, and it seemed to spin over quite happily.  I mentioned previously the clacking noise I was hearing, and I was able to isolate it to the front cylinder bank. 

In for a penny, in for a pound, so I drained out my fresh coolant (into a clean container, I'm cheap!) and pulled the radiators off.  After digging under the front valve cover, I found the cam chain seemed to have a lot of slack, and the chain was moving funny. 



I managed to remove the cams and other various bits and then extracted the tensioner.  Which wasn't.  You had one job tensioner, ONE JOB!



It's hard to see in the picture, but the spring is missing from the tensioner.  This is part #4 (and #9) in this diagram:



It is nowhere to be found in the front cylinder, so I guess I'm pulling the oil pan off and hoping it is down there.  It's a shame, because this tensioner has almost no wear on the guides, the chain is in good shape, and there's no "notching" of the tensioner where the lock rod rubs the tensioner frame.  It's in great shape other than the missing parts  :-\

Ebay seems to have a good collection of tensioners available, and I can always transfer the spring from an Ebay unit to my unit if mine is in better shape otherwise.  I'd rather give one of you guys the money though, so if anyone has a spare tensioner gathering dust, my Paypal is ready!

I'm waiting for CrazyPJ to give me the business about this bike - you were right PJ, now I gotta fly you up to the frozen North to help fix it, right?  ;D
DTT Blue (cause Winter is Coming) CB360 Club.

1995 CBR900RR - a winter flip not worth a DTT writeup - Sold

1986 Yamaha SRX600 - mailed to me from California - build coming soon?

1983 VF750F

1976 CB360T

1993 CBR900RR - Sold

1979 CB650 - Sold