Scratch on block under intake

[ap73]

I've been chasing a vacuum leak for a while and in desperation pulled the carbs thinking I botched something in the rebuild.  I just noticed these gouges in the block mating surface.  Is that bad enough to cause a leak?  Just put on new viton o rings.  What are my options on cleaning it up?  Think sanding it smooth would be too much material to remove?

[Pluggy]

Have you leak tested that location?  Many of us would put the bike back together and spray carb cleaner around that area.  A propane torch with the flame turned off also works.  Set the engine to idle and if the idle changes, it has a leak path.  If a leak is found, we can discuss a few possible fixes.

[ap73]

Actually I did check it with starter fluid.  First thing I did was douse all the joints with it trying to find the leak and didnt find anything.  Thats why I came to the conclusion I did something wrong in the rebuild.

[98valk]

I would definitely sand that down to a smooth finish 800-1000 grit like the rest of the machined surface. An o-ring will not seal those gouges.
when installing a new o-ring into the intake manifold u would see it doesn't sit to far above the smooth surface machined surface.

that would be your vacuum leak right there.

[ap73]

Sounds good, guess I'll try that.  High grit sanding was my first inclination, just making sure I wasnt going to make things worse.

[TTG53#1717]

Time for the farm equipment guy to check in... I'll also preface this by admitting to 57 glorious years of precision machining.

That is clearly a job for a "German Milling Machine".
A "Mill Bastard" FILE.
Buy a cheap 6 or 8 inch file at the local hardware store. Even the lowest East Asia variety is fine. Put it in a vise and snap it off in the widest section to a length about a half inch per side longer than the intake flange. If you can grind a groove in the file where you want to snap it, even better.
Put a well greased paper towel in the port. Wearing mechanic's gloves to get purchase on the stub file section, rotate the file in the cutting direction of the teeth to very carefully create a flat surface on the face of the flange where the gouges are. You'll be surprised how quick and accurate this can be. Even for a novice.

Sandpaper or Emery may create undesirable abrasive tailings that need to be avoided. The stub file will only create aluminum shavings that are much less worrisome. Hopefully the grease catches most of them.

You're more concerned with shaving off the high burr spots than removing enough material to totally remove the low points. A quick spray of high solids aluminum paint can adequately fill those in. Another light pass with the file and you'll be a happy camper.

I would not put something together looking the way it does.

[ap73]

You're more concerned with shaving off the high burr spots than removing enough material to totally remove the low points.

This is what I was aiming for.  If I get a chance Ill do a picture after while, but I started with 800 grit and worked my way up to 1500 grit just to knock down the high points and used a vacuum set up to keep up with the dust.  It looks far far better than when I started.  Got everything back together and the vacuum leak is 99% gone.  Or maybe that's just me hearing things.  This is my first Valkyrie and I don't have much of a baseline.

At any rate I got it all back together and it runs amazing.  Thanks for the help.

[h13man]

Time for the farm equipment guy to check in... I'll also preface this by admitting to 57 glorious years of precision machining.

That is clearly a job for a "German Milling Machine".
A "Mill Bastard" FILE.
Buy a cheap 6 or 8 inch file at the local hardware store. Even the lowest East Asia variety is fine. Put it in a vise and snap it off in the widest section to a length about a half inch per side longer than the intake flange. If you can grind a groove in the file where you want to snap it, even better.
Put a well greased paper towel in the port. Wearing mechanic's gloves to get purchase on the stub file section, rotate the file in the cutting direction of the teeth to very carefully create a flat surface on the face of the flange where the gouges are. You'll be surprised how quick and accurate this can be. Even for a novice.

Sandpaper or Emery may create undesirable abrasive tailings that need to be avoided. The stub file will only create aluminum shavings that are much less worrisome. Hopefully the grease catches most of them.

You're more concerned with shaving off the high burr spots than removing enough material to totally remove the low points. A quick spray of high solids aluminum paint can adequately fill those in. Another light pass with the file and you'll be a happy camper.

I would not put something together looking the way it does.

REVEREND BROTHER! 

[rug_burn]

    I can't see your picture for some reason, but I'm familiar with the problem- 
    If the gouge is on the head where the intake tube seals to it, you're right, you don't want to remove that much material.  better is to take about a 1/16" pin punch, and tap the aluminum back to where it's flat with the rest of the sealing surface, at least where the o-ring groove is.   get a pair of close-up reading glasses, some bright light and using very light taps, coax the aluminum back down to flatness.   Then i'd use a thread sealer that hardens up a little bit (loctite 5772) right where the groove was to fill in any teeny tiny voids; but this could well be oveerkill.