Trying to run a vacuum test on my bike. Took fuel vac hose off and getting CRAZY suction off left carb (where it's attached)... go to try the right carb and bubkis, nothing.

Aren't they supposed to give the same amount of suction?

The bike is a 2000, I just installed 1 #4 washer on each needle and decided to sync the carbs as well.

When the vac gauge is on the fuel-pump carb I can mess with the throttle balance screw and get it to even out between 12 and 14 vac, however the idle drops from 1750 (where I'm testing) to about 1100... but at that level there is still NO suction out of the right-hand carburetor.

What's the deal? How do I tell if they're balanced if they won't read correctly?

Dan

The right carb casting isn't drilled at that spigot, so no suction there, only the left carb is drilled to provide vacuum to the petcock.  You want to test using the ports on the carb caps, not the ones on the side of the carb bodies.

There are no ports on the carb caps.. they aren't drilled out!

Dan

Quote from: Danny500 on September 18, 2008, 06:05:54 PM
There are no ports on the carb caps.. they aren't drilled out!

Dan

with the tank off, you should see the rubber cap (around thimble sized) on the south east corner of the plastic carb cap.

carefully remove the RUBBER cap, and attach your vacuum tester to each of the carbs there.

hope i made muddy water clearer.

Nope, nothing there... lol. I know exactly where you're talking about but there's simply no rubber cap and no hole in that small spigot. I noticed this as well when I put the washers on the jets; that there is a port going under that nipple/spigot you're talking about... however that nipple itself is not tapped nor capped.

Wtf?

Dan

post a pic that would help alot

No biggie, i figured it out. It must've been a factory mistake because the caps weren't drilled. I just ran a 1/8th inch drill through them and capped them off with vacuum caps I have kicking around, now I need to make the tester.

NEXT HUGE DILEMA:

After I put the washers in, I buttoned everything up and I can't lower the idle past 1300rpm due to the needle height... I try to bottom out the idle screw but it just drops and no longer hits the throttle bar.

So, I was going to sync the mixture screws because it's obviously running rich. Well... where the mixture screws are supposed to be there's just a block-off non-head bolt. It has a SMALL little hole.. almost a punch mark in the center of it... but no adjustment.

Is it possible this bike came off the factory with defective carbs or am I just NOW looking in the wrong spot for the mixture screws? Not to mention that this is a 2000' year bike... shouldn't it have had a maintenance once or twice by the PO or at least the shop I bought it from?

What gives?!?!

Dan

The mixture screws are supposed to be "set and forget" at the factory.  They plug the holes.  Use a small drill bit and very carefully drill out the plug, being careful not to drill into the screws behind.  You can probably just get the bit to bite and then rip the plug out.  Check your throttle cable adjustment also, it could be too short.

By the way, I have an aunt and uncle in Athol.  Used to operate a store, called Longg's, I think.

Hey there,

I think you're looking at a couple of brass caps that cover the idle mixture screws.  If you take them out, I'd recommend using a left hand drill bit cause if by chance you go too far with a regular drill bit, you risk catching the air mix screw and zippin it into the carb body and then it'll be really eff'd up.  Then use an ez-out.  At least that's the way I did mine.

Good luck.

The mixture screws are covered with a "cap" at the factory, in theory they are covered so that a user can't mess with them.  The caps were intact on mine however the carbs were mis set at the factory giving me all sorts of problems.  At least you know that you're starting from the "original" settings.

In theory both screws should be the same number of turns out from tight, but with time that can drift..

Oh yea the factory forgot to make the vacuum spigots ... yea we drill them ... all the time, twice, just today ... wtf ...
I must have seen over 200 carbs, and that is just from you guys, guess how many have not had the top vacuum spigots drilled ... none ... 0 ... not counting the GS'es I stop by the side of the road, jump up and down and drool all over ...
You put pics up of what you drilled ... and you prolly need to get like undrilled ones to replace them.
Cool.
Buddha.

Ok, so I drilled out the brass retainers. Once with a 1/8th and then again with I think a 5/16. One side bit and pulled right out, the other I got the drill to take the top off and then it just spun the cap inside the hole so I had to pry it out with a small allen wrench.

Thanks so much for all the help guys... I was trying to do a 5 minute operation and BAM... look what happens. I still don't even know if the washer trick did anything... lol.

It'll have to wait till tomorrow.

I'll take a pic of the carbs tomorrow to show where I drilled for the vacuum caps, it's in exactly the same place as that video with the 5 dollar vacuum tester, up on the black cap.

I don't know why the mix screws are supposed to be set and forget though... that's a little crazy. I saw that page of a manual that shows UK and other countries with 2 turns, or 1 3/4ths turns and lowly US has pre-set. What crap! Lol.

Dan

Up on the black cap ... You didn't try to remove that black plastic cap
Show me a pic, I've never had to drill that ... ever ... the ocassional screw yea, but not the cap.
Cool.
Buddha.

... there... was... no... black... cap.

The nipple was there, but no hole in it, and no cover on it.

Pics up when i get home.

Dan

No pics of the before, just thismorning after all was said and done.

I used a 1/8th inch drill in my press to do this and used some 3/16ths vacuum caps I got from Advanced Auto a few months ago (thankfully I had a couple kicking around).







Dan

So at least now all is said and done... now I need to go bolt the tank and plastics back on.

I'm currently running:

1 #4 washer on each carb.
Pilot screws out 2 1/4 turns on each carb.
Carbs balanced w/5dollar vacuum tester.

Time to go for a ride.

Dan

Yea ... you're F*(ked ... post back here ... by then you'll know what I mean.
Cool.
Buddha.

Well... I see no apreciable difference in the mod of 1 washer and carb balance. If anything, the exhaust just smells a little richer...

She does run well though, smoother but not a noticeable power gain.

How am I F'd??

Dan

Then, maybe you didn;t drill anything, just cleaned out that hole and didn;t tear the O ring, and you install the caps back on
Cool.
Buddha.

Quote from: The Buddha on September 19, 2008, 05:09:54 PM
Then, maybe you didn;t drill anything, just cleaned out that hole and didn;t tear the O ring, and you install the caps back on
Cool.
Buddha.

What?

Here's what I did...

1: took left side carb cap off, boot stayed with the carb as did a small o-ring that went around a small brass nipple under the bump in the cap. I took the spring off the cap brought it to my work bench and drilled out the bump to 1/8th an inch. there was NO HOLE THERE PREVIOUSLY.

2: Repeat process of right carb.

3: Added washers to the needles, re installed slide and boot, re installed caps ensuring o-ring went back where it was and the boot lip was properly seated before installing cap.

4: installed vacuum caps on nipples where i just drilled holes... previously NO caps there.

5: balanced the mix screws

6: balanced the carbs.

7: done.


What did I do wrong? Is that not where the vacuum lines go, because that's what I thought everyone was saying.. so that's why I drilled them out!

The only thing I can think of other than a factory defect... (which you shot down nicely)... is that someone lost the original caps and used a black liquid nail or gasket maker in the original hole and just did it so well the cap looked as if it was never drilled... But when I ran the press through the hole the shavings spun out like i was drilling through plastic.



No idea... all I know is I think it's fixed... and where it's supposed to be...

Dan

EDIT: Becuase that would've been the first time I've had to deal with bad wrenching on this bike already. The PO liquid-nailed HOT-GRIPS onto the handlebars and gummed up the threaded bar-end receivers...