At a loss... Solved?

I don't know where to go next. I just can't get this thing to get running.
So far I have:
Put the valves in spec
Cleaned carbs, pulled every jet, sprayed air through everything.
Pulled the pms screws, and enrichment circuits. Sprayed air and cleaner through both.
Set pms screws to 2.5 out from bottom
Set floats
Bench sync
New plugs.

I have no change. The bike fires right up, so I'm assuming it's getting fuel. I've gotten it to hold an idle with the choke at about halfway, but if I close it, it dies. Or if I can get it hold idle, it dies with throttle. I've tried adjusting the mixture screws in 1/4 turn intervals, to no avail. New plugs are mostly white, with a faint touch of brown.

I don't know what to do. Help before I pull out all my hair!

 

Re: At a loss...

Also, I noticed my old set of carbs had 205 air jets. I'm assuming this was to compensate for the aftermarket exhaust. I swapped out my 195s for the 205s with no change.

 

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I just ran a compression test. 80 psi across all 4 cylinders....

 

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Still seems like you're not getting adequate fuel...have u verified good supply from the tank thru the petcock? verify the vacuum line to your diaphragm on the petcock is not leaking vacuum and/or try running it with the petcock in the "prime" position. or simply use an alternate fuel source like another fuel container to gravity feed your carbs. Also how did u go about setting the float levels? Once oyuve determined good fuel supply, we can start progressing step by step.

 

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Uh oh, 80 ain't lookin good

 

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80 psi is very low, and it's running too lean too.

 

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I wets set the floats to 3 mm from the flange on the carb body. I had a crack in the vacuum line at the very end where it attaches to the petcock. I cut that part off and refitted it. I have also tried running on prime. Fuel is flowing freely through the bowls when I release the drain screw, so I'm pretty sure I have fuel flow.

I have tried running it with up to 4 turns out on the pilot screw, and still no change on the plugs. Or on the throttle for that matter

 

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I have also flooded the entire carb area with propane, to test for vacuum leak, everything seems ok on that front.

 

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Would the low compression cause the diaphragms to not pull enough vacuum to get it running off idle?

 

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Have you tested the comp' with a spoon of oil in the bores ?
80 psi is well low but they are even, I would try a different gauge.
Couple of silly things to check, are the 2 jets reversed ? throttle cable switched with the enrichment cable, throttle cable getting hooked on the manifold clamps, all these things have been done before.

 

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Cables are correct and not snaggIng. On the top end, the 205 is furthest from the cover screw hole, then a 50. On the bottom end the 110 is screwed into the emulsion tube, with a 40 in the shorter tube behind it.

Oil brought up to around 100 psi

 

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What's the history of this bike? Have you just bought it or has the current running condition been around for a while in your possession?

 

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Bought it about 4 years ago. It ran when I bought it, never really had it on the road. I moved that summer I bought it, put sta bio in the tank, ran it
Then drained it. A year later I picked it up. I started trying to work on, not very seriously though. Then I lost the keys, and couldn't get the drain screws unstuck. So it has been sitting with bad gas through two winters under a tarp.

This year I've finally started attacking it. I went to clean the carbs, and broke a float pillar. I bought new carbs, came home, put them on the bike, pressed the button, and it started up beautifully. Took a break to wrap my head around what it needed next, and came back to it a month later. Replaced the solenoid, and fusebox because of some ignition issues. Then I took on the valves.

After I shimmed the valves, I took the carbs off. I gave them a quick once over, wet set the floats, and put them back on.

The problem either started after the valve shimming, or the first carb "clean"

 

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I've also noticed the petcock is pissing fuel out of its center.

 

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Unles your gauge has a large hose, - - you did it wrong, you need throttle open, plugs out, battery boosted, ignition de-activated.

This is to spin the motor up for the test.

Please re-do the test dry - - re-submit your results.

 

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Had all the plugs out and boots grounded to the frame. I didnt open up the throttle.
By "battery boosted" do you mean hooked up to a charger, or fully charged?

 

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'Boosted' hooked up to a car battery with jump leads.
(car / truck not running)

 

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?? So you're not getting a proper flow to the carbs then?

You may have already read this but Chacal's comments re cleaning jets is worth repeating:



http://www.xjbikes.com/Forums/viewtopic/t=8918.html

 

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I've already done all that. Probed passages with a guitar string, and sprayed cleaner and air through everything.

The bike starts with the choke. So I don't think that's the problem.

 

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That one is worth alot

When you do the "wet test", use the same amount of oil, 12CC's
The combustion chambers are 23 CC's

The volume in the hose for the gauge factors in also.

 

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Ok. I just kinda poured a capful in each bore. The hose is pretty long too. It's a harbor freight gauge if that means much... I've been trying to
Track down another one to test against as well.

 

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Did you REMOVE the jets, all of them, and clean them?

Did you REMOVE the EMULSION TUBES and clean them thoroughly, inside and out?

Did you REMOVE the float valve seats, and check the condition of the "beanie screens" and replace (or remove) them?

It sounds to me like you've shortcut your carb service. If the bike starts/runs, it's making more than 80psi and you just goofed the compression test is all. Unplug the TCI next time (easier than grounding the plugs) and if you do the compression test with the carbs OFF, you don't need to worry about holding the throttles open.

SLOW DOWN, back up and do it right. Carefully. Thoroughly. Or sign up for the "I've cleaned my carbs five times" club. Your choice. Oh, and if your petcock is peeing gas, you might want to fix that before too long.

 

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I pulled everything, short of breaking g the rack. Pilot screws, every jet, emulsion tube, needle seats, and enrichment plunger. Twice. Confirmed air and
Fluid flowing through every port.

Beanie screens were rough. But I did clean them best I could. Can it be run without them?

 

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Could setting my floats too low cause this?

 

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Could there be loose stuff undoing your good work each time? Ie rust or similar re blocking the jets? Might pay to fit a fuel filter...

 

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If the "beanie" screens are rough, either replace them (recommended) or go ahead and pull them. You CAN run without, but they are the last line of defense against a hunk of crud getting lodged in the float valve seat.

Low float levels can cause all sorts of wackiness. Float level tolerances are only a millimeter or two each way, the more accurately you wet-set them, the easier the rest of the process will be.

 

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Adrian, I've already fitted an in line filter.

Fitz, I guess I'll pull the carbs again(I'm getting real good at that) and check the fuel levels. It's the only thing I haven't quadruple checked at this point

 

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Save me some typing and read my most recent response to this thread: http://xjbikes.com/Forums/viewtopic/p=3 ... tml#338615

 

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Thanks. That's the way I did it last time. I may have measured wrong though.

 

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Time to ride, I just tried the compression test again, this time with the throttle open, and battery boosted. No change. My hose is about 3 feet long. I'll try to track down another gauge maybe?

The plugs are looking a little better though.

 

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Is it just me or do those plugs look... off..

No carbon at all around the base of the threads and a shiny brownish black insulator? What do ya think guys?

 

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Frightening.

Those plugs tell us there is something seriously wrong.

NO carbon on the flame ring, and NO carbon on the ground strap?

Something is really not right.

Maybe we need to revisit the valve clearances, and figure out the compression thing.

 

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They are also brand new plugs as of yesterday. This was after running with oil and seafoam in the bores.

 

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So, just got home and double checked the valve clearances

Exhaust has: .007(kinda loose) .008 .007 .007
Intake has: .005 .006 .006 .005

About to pull off the carbs to check the floats.

 

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Aaaaannnnddd........


Fuel levels are drastically low

 

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Ok, so got the floats set. Put the carbs back on, and it's running. Seems to be holding an idle. At first it was pretty touchy on the throttle. I had to give it a few quick blips before I could rev it. Now it seems to be revving ok. It hovers around 2k on the way back down for a sec.

The plugs are a lot darker. Not really sure how to read em. Here's plug number 1

 

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Making progress! Hooyah! After its warmed up, how does it run? If you enrichen it slightly with a small amount of choke how does it respond at idle? Good persistence!!

 

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Didn't run it too long tonight. It was about dark, and I have some serious holes in my collector box, so I didn't want to piss of the neighbors. But, when it warmed up it got a lot more responsive. Cold, it is still weird. It will rev and then drop down a lot like its trying to catch up. Im gonna try a running sync soon if it will hold an idle.


In other news, setting float levels sucks. I feel high as sh*t from all that gas.

 

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If you have "Serious holes" in the Collector, ... THAT presents a detrimental effect on BACK PRESSURE.

The lack of BACK PRESSURE will affect your Tuning.

Patch-up the Collector.
You can over-lay sections of Sheet Metal and Braze the Patches n too stop the leaks.

A talented Welder using a Low-Heat M-I-G Welder should be able to save the Collection Box.

Otherwise, ... the lack of Back Pressure will change the Tuning to be Lean.

 

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yeah, its on the list. ive got a buddy who is a pro welder. I plan on bringing it up to him after i get this wonkiness sorted out and get my front end back together.

 

Ok so I just ran it a bit after work. It was acting up a bit, stumbled and died. I adjusted the idle speed and fired it up(warm no choke) and it holds an idle. Seems pretty responsive to the throttle. The plugs are looking better too. Maybe a little rich? I do need an air filter.





I don't if this will work. Here is a video so you can hear how it sounds.

http://i1243.photobucket.com/albums/gg5 ... d9eddc.mp4

 

Air filter is a must, unless you're running pods.
Those plugs are ok, better than being too lean.

 

No pods. I have a filter. It's just older than dirt.

 

Sounds like your missing firing on a couple cylinders, sounds more like a v twin than an inline 4

 

I was suspecting something like that. How do I go about diagnosing/fixing something like that?

 

Start it up and put feel the headers in front of the bike when it idles. The ones that don't get warm are the ones that aren't firing. You can also let it idle and take off a spark plug cap. The idle should decrease if that cylinder is firing because you're removing its spark.

 

Ok so I just went out and messed with it a little more. If I pull any of the caps off the plugs, the idle does go down, some more drastic than others. I did notice the number 4 header pipe stayed pretty cool. I could actually grab it, while the other 3 where too hot to touch. The engine actually dies when I pull the cap off of that plug.

The plug also looks pretty weird.

 

DON'T PULL THE SPARK PLUG CAPS OFF OF A RUNNING ENGINE!!!!!!!!!!!!!!! YOU CAN FRY YOUR TCI BOX!!!!!!!!!!

Sorry for the yelling, but that is bad advice. Your ignition system is a wasted spark system. Pulling one wire actually stops TWO (2) cylinders from firing, as the high voltage current goes down one spark plug wire, across the gap in the plug, through the engine head, across the other gap in the plug, and up the other spark plug wire to complete the circuit.

Not only are you not just testing "that" cylinder, but the high voltage signal needs somewhere to go, and can end up in your TCI box where it can arc across the delicate (and closely spaced) solid state circuits. If you want to verify spark, (bike off) you pull the plug, GROUND IT TO THE ENGINE, then turn over the bike.

For only one cylinder to not fire, you've either got a fuel delivery problem (sync off, mixture off, air leaks, sticking slide, clogged jets, SOMETHING is off on the fuel delivery), or there's no spark (gap or something else with the spark plug is wrong, coil would cause 1 AND 4 to not fire), or the copression is very low in that cylinder (did you retest compression with a new gauge?).

I would wager, give your (very bad) spark plug cap removal test, that your sync is way off, and #1 is pulling along #4, and maybe even the other cylinders. When you took it out of the mix (by pulling #4's plug cap), the engine died because it's strongs cyldiner stopped firing.

 

Just re-read an earlier post, a 3ft long compression tester hose can make it difficult to test your compression. There should be a valve at the bottom of it, and really should be under 12 inches long.

 

Cool, thanks for the info. I'm starting to think(hope) it's just a sync problem. I have only done a bench sync on it so far. The slides all seem ok to me. They all raise with minimal effort, and drop back down at te same speed. They all went clunk when I put them together. Every passage and jet in the carb seems to be free and clear as well.

In previous testing, i did pull that plug out and saw that it was sparking.