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Firing on two of four!


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Neal, yes jumped the switch, when I got to fire up, it had a slight nock in that #4 cylinder (sounded a little noisy). Walked around the bike to check it out and the right pipe began to smoke pretty good, started smelling like I was burning it up and I got concerned and shut it down. After shut down I checked the pipe and it was HOT! After a few minutes I figured I was just burning off the buildup in the cylinder, started it again and it never got hot again. Wet plug just as before jumping the main switch. I will say, the readings I measured on the ignition circuit side of the switch were too high (265 ohms at best, mostly in the kilo/mega ohms) that is too much resistance for a switch.

 

I plan on going through the whole wire harness Saturday.

 

My friend told me to start the bike and let it run for a few and check the coolant filler for bubbles (head gasket leak). He said it might be causing the wet plug condition. I did so and watched tiny bubbles come up every so often. It seemed that every time the #4 cylinder would pop, I had a reaction in the level of coolant in the filler neck Rise quickly and go back down. I wasn't really sure if it was from the bike moving or not.

 

Pulled both cold cylinder plugs and they were wet, smelled them and they had no odor of gas or coolant. I don't know what to think, I can see if I can get an adapter for a coolant tester I have access to and test for a leak.

 

My original post back in 10/13 starts out with a complaint of a cylinder not running at high end and low compression on #4. (160, all others in the 180s)

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I had a similar issue on my 91. Coils tested OK, but when I pulled them 2 of them was cracked on the bottom. I bought 2 used ones and went with new plugs and wires. Fixed the problem. When it got hot the coils were not working. Next time I pull them I will be getting 4 new coils tho.

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I do not understand you descriptions. of the resistance readings for the switch.

If when using an ohm meter to check for either the resistance or the continuity of a circuit essentially one side of the devise being tested must not be connected to anything that can provide a parrell path back to the devise. Ie one side must be an open circuit.

If testing a switch set the ohm meter to the highest value scale, connect the ohm meter across the devise to be tested and with the switch in the open position the meter should read an infinity amount of resistance , ie 10 meg ohms or more.

then set the meter to the lowest value resistance range , close the switch and if the switch contacts are good there should only be a very low value ohms reading which is equal to the residual resistance that is caused by the resistance of the test leads.

You can test the test leads by touching them together and seeing what the ohm meter displays, this is their residual resistance.

A zero or very low value displayed ie one ohm or less being displayed when the switch is closed indicates that the switch contacts are in good condition and that the switch is OK.

I hope that this means something to you.

Cheers ,

Winston66 ,

Northampton , Western Australia

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Winston66,

 

There are two sets of contacts across the switch, one for lights ect and the other for ignition. I removed the switch from the circuit, meter was on auto. I got 1.5 ohms across the "power contacts" & 264 ohms & kilo (thousands) & mega (millions) across the ignition contacts, the meter fluctuated around depending on where I move the key in the cylinder.

 

The very lowest resistance I could get was 264 ohms, too high! PO had a long rat tail leather thing hanging off the key, looked cool but the whipping around in the wind did not help the lock cylinder.

 

That aside, I jumped the switch only to get the same results (two wet plugs).

 

Appreciate the feed back Mate!

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You may have the needles stuck wide open allowing the fuel to flood the cyl. If your taking the carbs off Sat check to make sure they are moving freely. and shutting off the fuel when closed. you can hook up a fuel line to the carbs when their off and check for proper operation.

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Which needles? Float needle? Needles hooked to the slide valve? I could locate anything on what position (circ clip notch) the slide valve needles should be in? They are all the same and only two carbs are wet so I suppose it doesn't matter.

 

Thanks.

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I'll start out by stating that I'm no further along on finding out what the problem is with this bike than before I spent the 6+ hours looking at it.

 

Pumped up the coolant system with a tester, engine cold and shut off, I have a very slow leak off (14 to 0 psi in 1.5 hrs). The flip side of this is if I leave the tester on the fill cap and start the bike, after it gets warmed up I get into the warning pressure range 25 to 30 psi. I know the bike is supposed to operate in the 17.5 range (filler cap rating). I have no external leaks. Cracked head or bad head gasket? Is this what is fouling my two plugs? When I run it with the regular cap I have no leakage or bubbles coming from the overflow tube (you think I would if I had 30+ psi in the system). When the bike cools down, and the cap removed, I have to add about 2=3 cups of water to bring it back to the top. No steam coming from either pipe.

 

Did another cylinder leak down test, all pass, less than 5%, the worst one at 5% is the hottest cylinder...go figure. I also performed a compression test, unlike last falls testing (160-165 on #4) I now have 180-185 on all four cylinders. The latter reading is with oil added. Test performed on a warmed up engine, plugs removed and wide open throttle. My manual calls for 180 psi minimum.

 

I now have a slight knock that is prevalent around the #4 cylinder at idle, I can make it quieter by pulling the choke out one notch, don't know what effect this has on it but that's what happens.

 

I ran the engine at about 1800 rpms, a loud pop became steady, one every 1 to 2 seconds (right bank only).

 

At idle, I held a piece of thin cardboard about 1/4 away from exhaust pipe on the right side, cardboard was sucked back over the pipe outlet in a hard and steady manner, the left pipe pushed on the cardboard and never sucked it back. Stuck exhaust valve?

 

I would point out that the bike does not pop when you first start it up, only when its brought up to temp.

 

I hooked a small clear tube to the carb bowls and opened the drain to measure the float level, two are at the bottom of the diaphragm cover (about 1" below cover center line), this is within specs, the other two (right carbs) are lower than spec. I would point out that the relation of the two that are out of spec, only one has a wet plug.

 

Here is my question..is this a measure of how much fuel is in the bowl? or what the level is? The bike is not running during this test to make up the fuel I just drained out, so it must be a measure of how much is drained out. My tube was slightly larger than the Yamaha tube, so I would expect a lower level in the tube.

 

Why is it that when the key is turned on and the bowl drain open, I don't have a steady flow of fuel coming out? Why is it that the pump does not stay on? I started the bike with the bowl drain open and did not get a flow of fuel, but when I shut off the engine and pull the plug, I have a wet plug?

 

I shut off the idle screws on #1,3 & 4 and bike idles with no problem with the #2 carb idle screw open 2 turns. If I try this with #3 cylinder, cut off #2 and open #3 (the only other hot cylinder I have) the bike wont run. In or out on all but #2 makes no difference, on a cold cylinder, I can see this, but the #3 that is firing? Is this screw adjusting air or fuel?

 

I ordered a Colortune and will test for over-fueling when it coms in from the UK.

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A couple of things.

On my 96 XVZ the radiator overflow is a coolant recovery system and the radiator overflow goes into a recovery bottle adjacent to the battery. (no dribbles from the resivour outlet)

The fuel pump will only run for a short time at the ignition turn on and then stops until the motor is started and the ecu sees a signal from the crank position sensor that the engine is running.

With the liquid gauge to test the float bowl level , turn the ignition on and off a few times in order to prime the carbs. properly and to establish that the float valves are working properly. This test is not to establish how much fuel the float bowls will hold, but at what level the fuel will obtain when the motor is running.

I believe that with the carb. diaphragms and attached long needle there is supposed to be a small O ring in the throttle body for the needle to sit in in order to properly regulate the fuel delivery. can you research this and check.

 

I SUSPECT THAT YOU SHOULD CHECK AND ADJUST THE VALVE TAPPET CLEARANCES IF THEY ARE OUT OF SPEC.

 

After all of this why do you not get the ignition module either checked or replace it with a known good one for a test as to weather it is the major cause of the miss fire problems as stated in the workshop manual.

 

I hope that this helps,

Cheers , Winston66,

Northampton, Western Australia

 

:fingers-crossed-emo :mytruck1:

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Winston,

 

That is what is odd about my whole troubleshooting, I try to put two & two together and I can never seem to nail it down.

 

I have the same coolant recovery system, If I pump it up and lose pressure one would think a leak. If no external leak, than internal....I'm not making oil, not steaming or dripping at the pipes. OK than must be a leak in the tool, but when tool is left on and the bike and it is started. I build up too much pressure (30 Lbs). One would think that there would be dripping or bubbles from the overflow tube when the 17 Lb cap is installed...thus indicating a head gasket problem or cracked head or something....NO, no bubbles or dripping (tube is not plugged). I don't understand it??

 

I have spark on the two cold cylinders, a friend dropped by to take a look and told me its plenty of spark. Is it at the right time? Don't know, I guess I will buy a $50 ECU from eBay and swap it out. I just hate to replace parts when I don't know for sure it will solve the problem.

 

I will bring up a parts drawing to check for an O-ring you mention, I will pull carbs as well. I have a Colortune on the way from the UK, this will tell me if I'm rich or lean.

 

Will keep you up to date.

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I suspect your problem is in the carbs - no real reason I can explain - I just do.

 

I agree with V7Goose, but I think I might be able to explain. The problem is with the carbs. I had a similar problem with my 97. While the bike was sitting on the side stand only 2 cylinders would fire consistently. The other two would only fire occasionally causing the bike to spit and sputter with the occasional after fire that would cause my neighbor to become very Irate. (he works at night). If I stood the bike up in the vertical riding position the engine would eventually fire on all 4 and smooth out. Anyway, I reset to float levels following this thread and everything cleared right up. http://www.venturerider.org/forum/showthread.php?t=75252 If you have good spark on all plugs, it's a lack of fuel. The floats are closing the needle too soon and the pilot jets are not deep enough in the fuel to run correctly. Just something to check.:fingers-crossed-emo

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That was a quick response,

As you probably have the bike partially dismantled I would seriously consider checking the valve tappet clearances. That should not be a big job at this stage. Too little clearance can contribute to hard starting and some other problems. (ie. the exhaust popping)

Adding a teaspoon of oil to a cylinder and then doing a compression test will indicate that if the compression pressure increases, that there is some blow by of the rings.

You indicated that you did this and the pressure increased.

If there is no increase , from the initial measurement, in pressure and the cylinder remains considerably lower than the other three it indicates a possible valve problem.

However I would still check the tappets for the proper clearances.

A vacuum leak on the cylinder side of a carb. can also contribute to popping on the respective exhaust particularly on deceleration.

If you are considering a replacement ecu iginiter unit I would seriously suggest that you invest in one of the Dyna dk3 units that is made especially for these bikes.(plug and play)

believe me, I invested in one even though the original unit was working , the difference that it made to my Royal Star was amazing.

Do a search on the forum for some more information and specifications on that product.

For me it was well worth the $300.00 it woke my bike up.

 

Cheers , Winston66, Northampton, Western Australia

 

 

:detective::fingers-crossed-emo:backinmyday:

Edited by winston66
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Gents,

 

I looked at this video last fall and set the floats up accordingly. If I were "starving" for fuel, how would that explain the two wet plugs? When I have the carbs out I will double check the measurement, maybe go the other way (lean out) the two that are flooding. My coolant pressure test did not pan out, the bad thing is I cant tell whether its antifreeze or fuel that is on the plugs??

 

As for the valve clearance check, I'll pop the cover and give it a check, I have nothing to lose. I have looked over the intake for a leak on this side of the bike and do not see anything wrong, what other place can a vacuum leak be? Somewhere in the head?

 

Thanks for the input, I really do appreciate it.

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The needle on the slide. it could be the slide is not going all the way down shutting fuel down and flooding the plugs. If you think you may have coolant leak into cyl try putting a piece of cardboard at the exhaust pipe to see if it's getting wet. still think your problem is carb related.

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Gents,

 

I looked at this video last fall and set the floats up accordingly. If I were "starving" for fuel, how would that explain the two wet plugs? When I have the carbs out I will double check the measurement, maybe go the other way (lean out) the two that are flooding. My coolant pressure test did not pan out, the bad thing is I cant tell whether its antifreeze or fuel that is on the plugs??

 

While you have the carbs out to check the float levels, (set them close to 9 mm) remove the needle seats. There is an O-ring around the seat. Mine got hard and dry and started to leak even when the float was up and the needle was seated. This could explain why you have wet spark plugs on the cylinders that aren't firing. The o-ring is not available through the parts list however the dealer in my area had them and I could replace them for about two dollars each. Also check the needles themselves I had one that the rubber tip was broken but you couldn't see it until you try to flex it side to side.

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All,

 

I removed the carbs for a third inspection, this time I found a few things, to my defence, one item I inquired about and never could get an answer for, the other I cannot explain except I must have over looked. Here it goes...

 

#1 & 4 have a wet plugs and cold cylinders, #1 carb has two good size holes in the diaphragm for the power needle , you cannot miss this. When I had these apart in October, I did not see this. This cylinder was "damp" but cold. #4 cylinder was really wet and I found the slide needle was set at the third notch up from the pointy end, all other carbs were set at the second. This is a large difference in the carburetor world. I moved it to the same notch as the rest.

 

One other finding: None of these needles have a stop fit on their mating seat (they do not close off any thing that I can see). There is a small amount of space all around the needle.

 

Also, I looked up the parts illustration for the slide valve, the order in which they show the parts does not seem entirely right. The illustration shows needle, plastic spacer bushing, circ clip plastic spring receiver (non threaded), spring & plastic screw. I think it should be needle, circ clip. plastic spacer, spring receiver, spring & plastic screw.

 

This is when I discovered I have an additional part..an extra spacer, very thin metallic washer. Metal, slightly corroded, I'm thinking this is some modifications from a previous owner trying to get more from the carbs (shimming). I will remove this washer on each carb.

 

Floats are set at 8mm, I will move them to 9mm

 

located a NOS slide & diaphragm on eBay. Will let you folks know how it works out after I effect repairs.

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Does anyone know what position the power jet (slide needle) is supposed to be set at? I found one carb not like the others, moved it to the same position but wanting to know what is the correct position is. I think there are 5 positions, if you know and reply please list from what end of the needle, thanks

 

My factory manual does not cover this at all.

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Flooding on #3, fuel is poring in from the power jet at idle, a little fuel is on #4 in the same place put not like #3.

 

Should these jets be dry at idle?

 

I have set floats to 9mm, new diaphragm on #1, power jet needle set to #3 position from pointed end (with a shim).

 

Help!!

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  • 4 weeks later...

Don't knowing you've figured out anything it not, but when I found a couple if my carbs pouring out gas when they shouldn't, I found that I had at least 3 of 4 carb overflow/vent hoses clogged.

I thought to check them when another fellow had mentioned that he had a flooding carb and found a pinched vent hose.

 

My bike had set up for several years and dirt daubers had infested my hoses.

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  • 2 weeks later...

Taz man sent a #3 & 4, changed out and set up carbs with #1 & 2, all good now.

 

Many hours spent trying to figure out why they were flooding, now Mr. Taz man will get a shot at it. I'm sure he will keep us informed.

 

My hat is off to him for bailing me out.

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