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Carb Noob Epilogue

  • Thread starter Thread starter MisterCinders
  • Start date Start date
M

MisterCinders

Guest
Now that I have cleaned the carbs, replaced the intake o-rings, and set the valves, bench synched the carbs and set the idle, I took the old girl for a spin around the neighborhood. Total distance of about 5 miles in the city.

A few issues.

1. In the garage, the idle was steady at about 1,000 - 1,100. On the road, the idle climbed to 2,500 - 3,000 with no choke. Obviously, I will re-set the idle screw to bring that down. What would make the idle change so dramatically.

2. The bike has heartburn? Perhaps related to the idle situation, the bike runs hot. Indeed, to get her home, I would kill the engine at red lights, etc. to lay off the heat. Once I shut the bike down, there was smoke (grey?) coming off the front of the cylinders at the exhaust pipes. Not huge clouds, but more than just wisps. Couldn't tell the smell exactly, smelled a bit like plastic , maybe?

Checked the oil level, it is solid at F.

I am not seeing smoke from the back end of the exhuast.

Not sure how the power level is. With the idle issue, I was hesitant to try and open up the throttle very much. At the low end (idle to 1/3), she seemed responsive enough.

Like I said, I will pull the tank and adjust the idle down. I have tried to fine tune the air jets per the instructions on BassCliff's site, but the rpms don't seem to change much when I turn the screws, and it is hard to detect any sweet spot.
 
First thing that comes to mind is an air leak. Bike is running hot due to a lean condition.

Did you replace the intake o-rings (the ones underneath the carb holders)?

Since you are running a VH exhaust, did you rejet for the pipe?

You running pods or a stock airbox?
 
I did replace the intake o-rings with fresh ones from bwringer.

I have the stock airbox. The rubber seals on it are tight, but I may go ahead and drop some weatherstipping in there as well.

The V&H were on the bike when I bought it. I switched the main jets when I rebuilt the carbs because the old ones were pretty mangled. I have 102.5s in place. But the main jets should not be messing up the idle. Since I was driving in the city, I doubt I even hit the main jets. My throttle never went above 1/2.

I did spray to check for air leaks when I reassembled the bike. Nothing turned up.

When I cleaned the carbs, the old settings were suspect (3/4 - 2), so I put them at 1 turn out. The air screws are at about 1.5 turns out.
 
When the bike is at idle, if you blip the throttle, does the tach needle rev up and hang before returning to baseline OR does the needle return to baseline quickly?

I'm not that familiar with VM's but air screw should be about twice as far open as the fuel screw.

What is the stock main jet size? I would think for a pipe you would want to bump the main up 2-3 sizes.
 
The stock main jet for my bike is 100.

I'll double check the throttle blip, but I'm pretty sure it did not hang.
 
When you set up the carbs, did you check the float height and the level of gas in the bowls (service fuel level). If your float height is not correct, this will have an effect on all throttle positions. I usually set the float height with a calipers but do my final float tweaking by checking the service fuel level. Its not hard to do, you just need a piece of clear tubing and adapter for your fuel bowl drain screw.
 
I checked float height dry (with a ruler). Don't have the adapter to do the other test. Hunting down air leaks now. Really don't want to check the valves again.
 
The stock air box sucks. Pain in the ass to wrestle on and off, and looks like it must be leaking like crazy.

Oddly enough, when I run it on idle and spray carb cleaner or WD-40 around the boots, no change in engine run. Seriously wanting to switch to pod filters just to ditch that damn box.

Pulled the air box and carbs. Double checked the intake boots and their new o-rings. All is well. Put some anti-seize on the intake bolts (new Allen head, natch). Turned the fuel pilot screws out a half-turn. Put her back together and fired it up.

She idled at 1,200 or so. I dialed that down to 900-1,000. Blipped the throttle and she wound back down to idle with no hang. Maybe a little slow to ease back to idle, but not enough to say it is hanging on the revs.

Tried again to adjust the air jets to dial in the idle. Still cannot hear any change, but I ended up turning the air screws in about 1/4 to 1/2 turns to err on the side of rich.

The smoke at the head is still there. Not heavy, but more than I like to see. It seems to be coming from the No. 2 exhaust.

I have not vacuum synched them yet because my new synch tool is short one adapter (supposed to have 4, only came with 3). Not sure that this would be a synch problem though.

Absent other ideas ITT, I will try and take a ride tomorrow to see if the idle creeps up again.
 
Once you get the carbs synced the bike will run better. Without doing a sync you can't really tell if all the intake tracts are pulling the same amount of vacuum.

Checking float height with a ruler will only get you so close. Since there are variations in floats, fuel needles..etc the wet method is the most accurate way to set your floats. Whenever I rebuild carbs thats the way I set the floats, takes a little longer but its worth it.

Take it for a ride and see its still running hot.
 
I agree that I need to do a wet float test and vacuum synch. Just waiting on parts in both cases.

The air box is a thing of the Devil. I cannot find and leaks, but it looks so raggedy. The air box boots are soft but they seem to flop around in their ports in the box. Spraying those areas does not reveal any leaks. I know that the WD40 test is not perfect, but as crappy as that box looks, it should pick up the kind of huge leaks I'd expect to find.

My purest hatred of the air box emerged this morning. Dismayed at the findings, I went out to put the tank back on and go for a ride. Flipped the petcock to check the idle one more time, hear the gurgling, and look down to see that the fuel line had gotten knocked off over night.

Why does this make me hate the air box? Because I cannot get to the f***ing fuel port without pulling the m*****f***ing air box AGAIN!

I hate that box with every ounce of my being. It mocks me. I hear it whispering behind my back. CURSE YOU AIR BOX!!!

Will get back to it and give her a spin. Fingers crossed.
 
I know what you mean - mine is a bear as well. It got much better this year when I replaced the intake rubbers (which I think you already have done) and then I replaced the airbox itself (they sell the kit, which has everything). The softer rubber boots coupled with an undistorted plastic box finally made the job bearable. But I still hate to even think about touching it.
 
And when you are ordering some parts, spend a few more dollars and get the proper fuel line. New, proper, OEM fuel line is SO much nicer than anything you will find at Auto Zone. Will not pop off accidentally and you don't even need clamps to hold it in place.

If you decide to go with pods, start planning right now how much money and time you want to spend on the project. :-k

If you go with the more-expensive K&N filters, please also get the DynoJet Stage 3 jetting kit. It's almost plug-and-play.

If you go with the cheaper EMGO filters, you can still get the DJ kit, but will still have to make some adjustments for the cheaper filters.
And you should plan on spending a lot more time to fine-tune the jetting with this setup.

Not sure what you might have gotten from bwringer, but the air leaks that are common are the o-rings between the intake tubes and the cylinder head. Just spraying something around the area to listen for a change is not good enough. If those o-rings have not been changed since you have owned the bike, assume that the previous owner did not change them and do so. It will make your life so much easier. They are also very inexpensive if you need to get them, just ofder them from cycleorings.com, he is a member of this forum.

.
 
I just changed the intake o-rings.

I have new fuel lines but they are 1/4 inch. They fit pretty snug. It popped off because I had it attached poorly.
 
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Took another ride. Think I went too far on the idle. Now it stays at 900 or so, but feels a bit sluggish at lower speed. Struggles off the line.

Didn't see as much smoke from the cylinder, maybe a touch. Will check these symptoms and do more tuning.
 
There is no Stage 3 for my bike. Will look into the pricey pods and new jets.
 
How did you ever get the 1/4" line on there? The fittings are 7 mm. 1/4" line is 6.25 mm, 5/16" line is 8 mm, which requires a clamp.

Most of the fuel hose you get from an auto parts store is also very thick-walled and pressure-rated. The OEM fuel hose is thin-wall and very easy to use.

Don't be put off by the price they charge when you get some, though. It's about $12-15, depending on where you get it, but you get about 6 feet of hose and you need less than one foot to do the bike, so you have plenty of extra.

.
 
Took another ride. Think I went too far on the idle. Now it stays at 900 or so, but feels a bit sluggish at lower speed. Struggles off the line.
Click to expand...

Not much more you can do until you vacuum sync the carbs. Once you sync them take it for a ride.
 
Steve said:
How did you ever get the 1/4" line on there? The fittings are 7 mm. 1/4" line is 6.25 mm, 5/16" line is 8 mm, which requires a clamp.

Most of the fuel hose you get from an auto parts store is also very thick-walled and pressure-rated. The OEM fuel hose is thin-wall and very easy to use.

Don't be put off by the price they charge when you get some, though. It's about $12-15, depending on where you get it, but you get about 6 feet of hose and you need less than one foot to do the bike, so you have plenty of extra.

.
Click to expand...

It was a struggle to connect the 1/4" line, and my half-assing it caused it to jump off. It pops right onto the petcock though. v0v It was too fat to fit the vacuum port, so I stayed with the original line that came with the bike.

I don't mind shelling out a couple bucks for OEM line, where can I find it? Z1 had the 1/4 inch stuff.

Current Status

After the wild swings in performance so far, I pulled the carbs again to check the needle settings. I know that one slide was missing a piece (the flat 3-hole washer within the slide) and now I have some spares, so I can tighten that up and check the needle clip positions.

Pods/Jets

I am going to order K&N Pods and some bigger jets and plug those in while the carbs are off. I noticed that the both sets of pilot jets (the ones in the rebuild kit and the ones on the bike before) are indeed #15. The ones on the bike, however, have visibly larger side holes than the kit jets. They almost look like the holes expanded with wear. I kept the old jets for 3 of the 4. The forth jet was a bit banged up on top. Seriously, it looks like the last person to pull apart these carbs used an impact driver on the different jets, as all the screw heads are trashed.

With pod filters and VH exhaust, I think I should go up a size or two in pilot jets. Any ideas how many sizes to go?

For mains, I am thinking 120s, per the recommendation ITT.

Even with new o-rings, the drain plugs seem to be leaking fuel a bit, so I am going to root around there and try to tighten those up as well.

Head Smoke?

Although not as bad during the second ride, I am still seeing light wisps of smoke from the head/exhaust connections, especially off the No. 2 exhaust. I know the valves are shimmed to spec. The smoke troubles me, and I fear that I may end up going deeper into the rabbit hole to sort out (or pay someone else to sort out) piston rings. When I get the compression tester, I'll know more.

In the interim, what exactly does this smoke indicate? Bad exhaust connection? Bad mixture? A ticking time-bomb?
 
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