'86 vfr750 carb fix

I picked this bike up yesterday, and it showed signs that the carbs needed cleaning -- only run on choke and seemingly run fine in upper rpm. I went to pop the carbs off, and I noticed that someone has been into these before. One of the ports in the mouth of one of the carbs is snapped off, and a piece of one off the carbs is cracked on the side of the assembly. How bad is this? I look forward to riding the bike, and I'm hoping this isn't a big ordeal.



My guess is that the guy I got this from started to go into the carbs and quit after breaking a few items.

I did find some vac hoses that are cracked, and it looks like someone removed some of the emissions pieces once upon a time as there are some other open hoses that go nowhere.

And I need to source some carb boots. Where is the best/cheapest place for these?

 

it is hard to see the broken port. here is another pic:



Is that being oversized going to cause a prob?

 

Your hosed. The brass air tube is missing, no good way to fix that and with the broken ear to boot I would look for another set. Both problems are common when the manifold is removed and then the carbs pulled off the bike. Never want to do that, remove and install the manifold and carbs as one unit. Bike Bandit has the boots, Honda P/N 16212-MBO-770, Bike Bandit P/N 590140. $13.84

 

So what all carbs will work?

 

how many times does daddy have to tell you kids not to do that !!!!!!?

 

I wish someone would have told the last guy. I read Toe Cutter's thread and another thread where you were telling an MMI student not to do that before I went to tinker today. For a second I thought I might have somehow broken the tube, but 1) I didn't do anything that could break it and 2) I don't have any carb pieces sitting in the intake port. Oh well. These things happen.

What does that tube lead to? Would a much larger hole in that spot lead to the symptoms mentioned earlier? The carbs, while not pristine, did not have too much gunk in them.

The hunt is on for some carbs.

 

Yessir, i'd try building up the missing stuff with JB* before i'd scrap anything, ever.

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*Not a paid endorser.

 

If you lived near Sacramento, you'd be riding already !

 

I contemplated that. I'd be mighty annoyed if that JB worked its way out and found its way inside the engine, but I suppose I could put some dimples in the sides of the hole before I mush the JB. That should help it stay put. Then I'd only need to drill the blob out to the .080" or so the others show to be.

 

Sure, you might even find a more suitable aerospace material better than JB.

Seems like the biggest issue is the strength of the bond between the pot metal carb and the JB.

 

It occurred to me while I was digging through my drill bits for something a bit undersized to start the hole... I have those really sweet screws with the retaining tabs about an inch from the thing I'm worried about falling out. I can easily enough make a bonus bracket/tab to cover the JB (or JB alternative) in the hole so it can't fall out. I obviously won't be covering the whole thing, but as long as the entirety of the mess doesn't fall out, we should be good. As you said, it should be able to stick to itself well enough; we just don't want it coming out of the hole in one piece. I used a center punch on the back side of the hole since that is about the only place I can access, so the hole won't be a smooth bore at least. And I did have some epoxy left over from a fork leg that I filled a pit in. If only I can find it. Considering that repair on my KTM is holding from last year, that stuff should work here. We used to use devcon's stuff to fill/reshape intake ports on engines back when. None of the stuff we installed ever fell out that I know of, but I have seen other intakes from different shops with chunks missing. Back to the shop!

 

For better or worse, it is done. Before I made an .080" hole all the way through, I noticed that my .040" drill bit did not fall through the other tubes. That was the smallest I had so I'm not sure the exact size it needs to be where it necks down right at the very end. I ended up using a grease needle that also measured .040ish and pushed through the semi solid epoxy. After I pulled it out, the hole is smaller than .040, and I can push a strand of wire through it so that is that.

As much as I would prefer not dealing with this in the first place, I sure with I was the one to have snapped this off. At least I could attempt epoxying it back in instead of creating this odd looking hole...thing.



I'm still looking for a set of carbs (for anyone that may have a set to sell), but I'll try this in the meantime. I doubt it will be falling out on its own so I might skip the bracket too.

Anyway, I ordered my boots. Now we wait.

 

All 86-87, 700-750 carbs will work.

 

Will I need to rejet (which should not be an issue as I have the originals) or will the 700 be a bolt on?

Thanks for all your help. I was hoping one of you two would be popping in on this thread, and I end up with both helping out.

 

NO rejetting necessary unless Groveton is above 4000 ft., you're running no airbox lid, or straight-through exhaust.

 

Same jetting for both.

 

Good to hear. So far it looks like it is going to be $200ish for a cleanable set. I'm holding out to hear what a few other places have to say, but I guess I'll pull the trigger sometime this week. Aside from the broken carbs, the bike seems very clean. I acquired it in an even trade for an '04 400ex that I never used, and even with this fiasco, I'm happy with the trade. I guess it is a good trade when both people think they got the better end of the deal?

 

I admit I did that to my bike in my first attempt to remove the carburetors, not realizing they are intended to be removed as one unit. At the time (about three years ago) I found a replacement set on E-Bay for under $100.00. Here's a set for $90.00: Honda Interceptor VFR700 700 35MM CARBURETOR CARB CARBS | eBay The description does say fire damaged, but you only need the castings, so it may be worth a shot. tearing them down and rebuilding them isn't that difficult. There's even a set all rebuilt and ready to go for $400.00: HONDA INTERCEPTOR VFR 700 F 1986-7 SET OF KEIHIN CARBS CARBURETORS | eBay

 

I had looked at both of those possibilities. I'm not ready for the $400, and I'd hate to go for fire damaged carbs without being able to see them with my own eyes first. I made an offer on a set, and I'm waiting for the answer.

 

If no luck on the set you're dealing on, I have a rebuildable set with plenum, very good condition, complete as removed, for $90 shipped CONUS. They appear to be California plumbed, but that's removable. I can get you some good photos.
joe.nelson@ymail (dot) com