Started My Carbs Yesterday. Couple of Questions.

Well, I went and started to clean my carbs yesterday.

First, Observations.

#1. As I went to remove them from the bike, I decided to drain the tank a bit through the carbs. I installed a clear tube, opened the drain screw on carb 1 then set the tank to prime.... sure enough, here comes the gas. Then, afte a few seconds, the pipe went from solid fuel to fuel with lots of air bubbles in it... and that's how it stayed.

Is this normal, or is this signs of an air leak somewhere?


#2. After the tank was drained, I took it off and proceeded to loosen the clamps around the rubber boots. What's this??? They are already loose. Heck, #2 and #3 clamps weren't even on at the manifold!

Whould this cause my stall at idle and only run at 1/4 choke issues?


Well, once I had the carbs off and apart, I noticed that they weren't too bad at all. I've done the following to #1 and #2 so far.

I've decided to not completely dismantel them and leave them connected together. I'm just cleanning the jets, float bowls, etc.

Oh, and how do I know if I have Hitachi carbs or the other? There doesn't seem to be any name on them.

A question about the jets located under the diaphram. How tight should the be? From the first two carbs I've done, # 1's jets were lose, and #2's jets were pretty snug.

 

The solid fuel was the float bowls draining, then with the air bubbles was the free-flowing fuel. Perfectly normal.

The carb boots not on properly and not tightened will DEFINATELY have an effect on the running - basically a gigantic air leak into the intake.

Most XJ's have Hitachi carbs - only the X models got the Mikuni's.

Jets should be 'hand tight' - no more.

Sounds like you're on the right track there -- check them, reassemble, and check how it's running now.

 

Altus,

Thanks for the info. I've been tightening the gets with a snug turn with the screw driver.

As for the boots, that's good news. I was worried it was something else.

Can you or somebody inform me on where the mixture screws are located? I'm going to order a colourtune plug. I've also noticed that there is no hole of some sort on the head to put a YICS tool. Am I a lucky one???

 

Looking down onto the top of the carbs, on the front side, there is a little tower shaped item.

If there are brass plugs in them, you'll need to drill them out. Search the site for that, there's plenty of info.

If there is no plug, there should be screw heads in the holes. Also search the forum, since there's plenty of info on that too!

 

Canadian models didn't get the brass plugs in the mixture screw holes -- usually they've got little rubber plugs that are easily removed (if they're not gone already).

They're on the top front centre of the carbs - small screw in a small hole - I'll try to find a picture.

If you've got an 1981 or very early 82 engine, it doesn't have YICS.

 

Altus, a picture would be great.

Well, I finished the carbs this morning, put them back on the bike and it's not much better.

before, I could only run it with 1/4 choke on. Now, it's the same, but the throttle lags. In other words, when you give it some throttle, say up to 5000 rpm, it hangs there a sec, then slowly drops down again.

The motor also seems to be misfiring. I've got the seat off, and when it's idealing you can hear some sort of back pressure coming from the air intake box under the seat. It never did this before.

So what's the good news and the bad news? Give it to me straight. I can take it.

 

So at lunch I decide to tinker some more and get it the bike up to running temp. It will idle with no choke now at aroune 1000 rpm. Better then before.

BUT, there is still a definite flat spot right at the beginning of the throttle. You need to massage the throttle up, or she'll stall. Not sure why.

 

Picture (front of carbs is at bottom of picture):



Hope this helps.

 

Crap, that's what I thought. Mine are covered with a brass fitting.

It may not be a mixture issue. Here's what the plugs tell me.

Cyl 1: Black, moist outer with greyish core.

Cyl 2: Black outer with dark core.

Cyl 3: Black, moist outer with greyish core.

Cyl 4: Black, moist outer with greyish core.


Not sure where to go from here.

 

So the carbs are off again, and I bench sync'd them. # 4 was the only one out, but about a hair.

Before I put the carbs back on, is there anything i should do? I don't think I want to mess with the mixture screws. I think my plugs tell me that I'm running almost perfect, with each plug's core a greyish tanish colour except for number 2.

 

Your plugs are telling me that you are running rich.

Since you have the carbs off you may as well remove those brass plugs and set your PMS each to oabout 2.75 turns out. It's no big deal to remove the brass plugs and then you will know for certain how your PMS is set right.

 

well, I went ahead to get those brass plugs out. I think I went too deep on # 4. I drilled in about 3 to 4 mm... and still nothing. Have I gone too far and I've gotten into the screw itself?

 

well after bench sync'ing the carbs using feeler gauges, now it won't start all. I'm upset, to say the least.

It sounds like it's not getting any fuel, but the bowls are full. What the heck am I missing?

 

try a new set of plugs and charge up yure battery really good.
see if that will at least get yu started.

yu may want to check the slides on yure carbs.
be shure they move freely and dont stick or hang up.

keep pluggin.....yu will get er going 8)

how is yure air filter??

is it clean and "in place"

 

did you check the pilot jets for blockage?

you might try ye olde starting fluid right in the cylinders trick.. sometimes that provides just enough vacuum to get those carbs going.

 

I cleaned everything but the mixture screws because I've got those darn brass plugs on. I'll take them off today.

Dan

 

OK,

Had a great conversation with Rick the other night and he set me straight.

Thanks so much for talking me through all that stuff the other night.


So this is what happened. I removed the brass plugs as he directed using a dremel and the mixture screws were in perfect condition. They moved very freely. I removed them, the spring, washer and rubber seal in each. Cleaned and put them back in 2 and 3/4 turns out then a little more.

Bench sync'd the carbs using the business card trick. 1, & 4 were off a fair bit.

Installed the carbs and she started!!!!! Now, before we get out the champaign, it will only run with choke and it runs rough at that. What should I do to get it idling before I start messing with the idle mixture screws?

Also, I looked high and low, and I don't think I have a YCIS port. Another member said that the canadian 1981 models don't have one.

 

Update,

The good news. After setting all 4 mixture screws to 2 and 3/4 turns. It will start and idle without choke.

The bad news. It runs like crap. I studders and if you bring the throttle up to 4000 rpm or so, it stays there for 2 seconds then slowly drops down. Took it out for a spin in the parking lot, and it does the same thing in motion too! Bit scary. I let go of the throttle, and she kept on going.

Help!

 

Dan:

You're looking good. You're just a little-bit of Fine-tuning away from having her on-the-money.

You may wind-up needing to clean-up the Inside Diameters of the Bores that the Diaphragm Pistons rise and fall in.

(Do it anyway -- Search: "Clunk Test")

At 4,000 rpm -- the bike is taking Fuel from the MAIN JETS. The MAIN JETS can be as clean as a whistle ... But, if the EMULSION TUBES (The Brass Cylinders that the Main Jets are screwed into) have anything plugging-up their 18 -to- 20 Metering Holes ... what happens is:

The Bike will run like it's possessed because the Mixture can vary from Rich to Lean and Rich again ... because the Butterys are doing the job of breaking-up the Fuel Stream AND Regulating Mixture.

Here's the 64-Thousand Dollar question?

Do you KNOW if the EMULSION TUBES Metering Ports are ALL Clean, Open and letting-in AIR from the Main AIR Jet?

You cannot successfully do any Fine-tuning until you can answer that question with absolute certainty ...

YES!

 

Rick,

Oh man. How do I get those emulsion tubes out?? I saw a brass fitting down there, but it wouldn't budge. I figured they were set in there. Damn, off come the carbs again.

EDIT.

In the picture below, are the items circled in red there? Becuase when I took mine out, there was just the small threaded jet only. No long needle looking thing.

 

This schematic is a Complete exploded view.

Note the bottom of the "Piston Valve" (Diaphragm Piston).
Just under it is a part labeled "Main nozzle"

The Main Nozzle = Emulsion Tube

The Emulsion Tube is best extracted this way:

From inside the Float Bowl.
Remove Main Jet
Remove Main Jet Washer (Exposing bottom of Emulsion Tube)

Remove Top Cover of Carb
Lift-out complete Diaphragm Piston Assembly taking care not to damage the attached Needle.

From inside the Float Bowl.
(Using a small bolt with threads that match the MAIN FUEL JET threads ... screw the bolt into the exposed bottom of the Emulsion Tube)
Tap lightly on the bolt driving the Emulsion Tube UP through the TOP and out through the Bore of the Diaphragm Piston.)

When the Emulsion Tubes are Out.
Refinish the Inside Diameters of the Diaphragm Piston Bores.
Search: "Clunk Test"

Clean Emulsion Tube Exteriors with ScotchBrite Pad until shined.
Clean small center hole up through Emulsion Tube with Q-tips
Pull-off a little bit of the Cotton so they fit.
Lots of Carb Cleaner.

Clean EACH individual, little, tiny hole in Emulsion Tube with the proper fitting wire tool from a Welders Tip Cleaning Set.

With BOTH Diaphragm Assembly and Emulsion Tube extracted ...
Blow Out Main AIR Jet Passage with Carb Cleaner.

 

Rick,

OK, we're on the same page! I was just reading mine differently, that's all.

Everything is clean and set to go. I've ordered a colortune plug, and I'm off to partsource to pick up a vacum gauge. I'm going to do this right. I'm going to read up on float levels because I want to make sure everything is sound.

 

Are you tuning-up for Casual Riding or The Gran Prix of Newmarket?

I know ... I know!

You are going to Tweak until you can "Push the outside of the envelope"
Get to the next light before the other guys get out of second.

"Til it's so tuned-up and goin' so fast you'll be going-back in TIME!!!

 

LOL.. too funny.

OK, checked all the float levels, and they are perfect. One more thing off the list.

I got a vacuum gauge for 29.00 bucks and I'm going to get that going right now.

I double checked the pistons, and they all drop perfectly. Nice and smooth. I'm going to put the carbs back on and go for the sync again before I mess with the mixtures. besides, the colortune won't be here for a few days. ;-(

 

Make a "Restrictor"

If you don't ... the Guage won't show true.
It will be too busy "Fluctuating all over the place."

The restrictor will settle it down.

Put the restrictor in the line close to the Manifold.

11-hundred rpm's

Read - 3
Mark the Guage with a sliver of tape at 3's Max Vacuum

Plug - 3
Read - 4
Adjust 4 to the Max reading you got on 3

Plug -3
Read -2
Mark - 2 (Mark -- don't adjust it.)

Plug -2
Read - 1
Adjust - 1 -to- Match 2

Plug - 1
Read - 2
Adjust - 2 to Match 3 -&- 4
(#-1 is married to #-2 and gets adjusted when you Match 2 -to- 3!

 

Thanks again rick. I'll give it a shot. An inline valve would do as a restricto wouldn't it?

 

Might.

I like the restrictor because there's not error factor.
Built-in consistency.

I got a feeling that when you crack-open the valve ... it's still going to be too much.