83 venture Carb problems or ???

[van avery]

I have an 83 Venture xvz1200. I just cannot get it running correctly. I’ve put around 1000 mile on it this last year.

Under heavy throttle with the rev’s under 3000 RPM the bike “burp and belches” until the rev’s get up higher around 3500 RPM. Also, at idle it will tend to “stumble” a little lower several times them die.

It starts fine some times and then doesn’t want to fire up. Put on trickle charger and later it seems to fire up fine. Some times when trying to start it up after it refuses to start, I have a major backfire. Sounds like a 3006 shot.

Mileage is poor, around 28 MPG. It does not run as smooth as it should, nor have the power it should. Seem like it does smooth out around 75 MPH. History:

Bike sat for about 6 years before I bought it. The gas tank I was told had been drained but not the carb’s. Little wd40 and battery charger and new gas and lots of sweat got it running. Changed the oil and the filter and changed the coolant.

I have replaced Battery and replaced cables from solenoid to starter and the ground line from battery to block with 4 ga soldered ends. Did not replace the braided cable from Battery to the solenoid. I just had to replace the Voltage regulator /rectifier as I started seeing 17 Volts at the battery. Now I get about 13.8 VAC from the stator leads and 13.6 VDC at battery, running at 3000 RPM.

Pulled and cleaned the carbs last year. Sync’d them early this year and went to maintenance day and re-synced them there. Disconnected the YICS by joining the vacuum lines together on the left cylinders and again on the right cylinders.

Replaced the fuel filter last year and have run couple cans of Seafoam through the system (½ can per tank of gas). And replaced the plugs twice and replaced the wires and caps early this year.

Other items re-soldered the CMS (Twice) and most of the time I don’t have warning signals anymore. “Brake and lights” are the ones I see every once in a while.

Have not messed with the TCI but did pull and test the pressure sensor and it checked out.

Checked the float levels on the carbs per the “manual” and each had a gas level between the 3/8” and ½” shown in the book below the diaphragm centers.

I’m considering pulling the carbs and cleaning them again. Getting real close to taking it into a shop, but hate to give up.

Open for suggestions?

[bkuhr]

Mileage is poor, around 28 MPG. Disconnected the YICS by joining the vacuum lines together on the left cylinders and again on the right cylinders.

Have not messed with the TCI

 

My quess for the poor running would be the TCI, and more specifically the glass diodes.

Your YICS disconnect does not sound correct to me and may be cause of poor mileage.

I believe when YICS is removed, all 4 ports should be individually plugged, not sharing vacum with other cylinders.

[bongobobny]

Bkuhr is correct...

[mlew]

Did you note the plug color when you replaced them? A rich mixture will cause the conditions you explain. I agree with the others about the TCI and YICS, I'm just thinking of other possibilities.

[mbrood]

I agree that the first valid check is to look at the plugs, but first you need to correct the plugging of the YICS ports to individual plugs.

 

The 83 was unique for having a "special" TCI and the pressure sensor pulls vacuum from above the venturi. But it sounds like a possible timing issue and that drops to the Pressure sensor and the TCI.

 

The 8 glass, blue/gray, power diodes is a major failure point on the older TCI units, a real pain to remove for repair but sincerely a requirement.

[van avery]

Thanks for the input guy's.

Spent the morning tearing the old girl apart. Tested the TCI and went ahead and pulled it out plan to mount it on the air box.

I have a donor bike that I'm not sure if the TCI is any good but I plan to pull it off the old bike shorthly. That donor bike sat outside for several years, moisture here about 20 miles or less from the gulf might be a problem.

 

I'll plug the old YICS connections seperately since I've got things apart anyway. The method I used was written up in the other "venture" website.

 

Below is a picture of the plugs I pulled out the last time did not pull them this time.

 

I used testing procedure from "FROG MAN" from 5-27-2007 "TCI problems yes or no ?" below my readings are in green. A couple of the readings are out of the bounds See item 5 one reading a little high and then See Item 9 are high but are consistant. Would this be a problem?

 

 

 

Many times we over look the simple and expect the worst TCI failure. Most ignition failure causes are connection issues and not the TCI. Here are the steps I use to trouble shoot an ignition problem on a first gen with suspected TCI problem.

 

1. Remove battery and battery compartment.

 

2. Unplug both connectors from TCI box

 

3. With a digital ohm meter connect the black neg lead to the black battery cable. Do not connect to frame or chassis for a ground. Now measure with the red lead of ohm meter to a frame bolt or engine bolt. You should have O ohms or slightly higher.The ground connection to chassis is good.Now we are ready to measure TCI connectors. I had 0.2 OHMS

 

4. On the smaller 6 pin connector measure the black wire. It should read 0 ohms or slightly higher. This is the gnd output from TCI to the pickup coil center taps. It may be easier to insert red test probe into the back of the connector plug to take these readings. NOTE: The ground comes from the TCI. You won't have a ground connection on the stator side with connector unplugged. The main ground to the TCI comes in on the output connector from the frame and loops through the TCI to the pickup coil input connector then through the pickup coil connector along lower frame next to stator. I had 0.3 OHMs

 

5. Now measure the Orange,Gray,White/Red,and White/Green wires one at a time. These are pickup coil inputs to TCI.They should read 115 -125 ohms normal. If you don't have this or loss of one or more the most common cause is connector failure. (see white connector plug along frame above stator and clean contacts). My readings were 124, 115.5 , 126.5, 115.5 respevtively

 

6. The Black/White wire is the Emergency Inhibit line. If it measure 0 ohms or has a low resistance the bike willl not start. Normally this measurement is done with the battery hooked up via jumper cables and ign switch on. Various sources through energized relays can inhibit this line. Such as emergency killl switch,side stand relay,tilt switch.clutch switch,etc.

 

7. With battery unhooked lets move to the 8 pin plug. measure the black wire should be 0 ohms system ground. I had 0.2 OHMs

 

8. With the battery unhooked move the black lead of ohm meter to the Red + battery cable and turn on ignition switch. We are now going to measure the resistance back through each Primary Ignition coil to the battery positive lead.

 

9. Measure the Orange,Gray,Yellow, and White wires. Each should read 2.5 to 3 ohms ref the red battery lead. I had 3.4, 3.4, 3.5, 3.4 These are the induction output wires that fire the energized ignition coils, The Red/White wire is 13.8 volt supply line and should read 0 ohms. I had 0.7 OHMs Thats it for the dc continuity test of connections to TCI. The Black/Yellow,Black/Red wires are from the pressure switch and should only be measured with engine running. The pressure sensor converts pressure into voltage which varys the timing advance with changes of pressure caused by rpm increase. These timing changes can be viewed with a Oscilloscope measuring the pickup coil input pulse and the corresponding output pulse for each cylinder.This is not something you need to worry about now.

 

If all is well to this point and the obvious has been checked including Spark plugs and plug wires it's time to check the TCI. Before removing it (a patience trying task) I would plug in a spare unit. Every first gen owner should have a working spare or know where you can borrow one. If the TCI is defective remove from bike, open the case by removing the 4 phillips screws exposing the soldered side of circuit board. place in oven at 100 degrees for 30 minutes to remove any moisture in module. You can remove any corrosion from solder side of circuit board with gentle strokes of an old tooth brush and an electronic contact cleaning spray. If you have soldering ability and a low wattage iron resolder all connections below the heatsink nuts on the circuit board. These are the contacts leading to the out side connectors. The heatsink nuts hold the switching transistors that fire the ignition coils. Resolder the 3 terminals of each transistor. with a magnifying glass carefully inspect the remaining solder connections on the board. Anything that has a dull color or hairline crack should be resoldered. You have now fixed probably 95 % of TCI failures. Actual componet failures are rare and can only be accomplished by electronic techinicians with specialized desoldering stations and a schematic of the TCI. Not to mention parts availability for a 20 year old technology. Watch used TCI's can be bought on Ebay ocassionally for $50 bucks.

 

10. The best way to check a TCI is on the bike but I have plans for bench testing later.

 

 

__________________

[van avery]

I did put things back together enough to start the bike back up with the existing TCI that belongs in that bike, and w/o the air box on. Noticed that when I rev the bike the right rear carb slide is moving much more than any of the rest of them. Really I don't see the rest of them moving much at all. They all move freely with approximately the same amount of resistance when pushing them back with a finger. Doesn't seem right?? Also, remember previously when I get blowback when trying to start the bike, the right rear is the one that normally "spit back".

I did plug all the YICS vacuum ports independant of each other as suggested.

I'm still working on getting the TCI out of the donor bike due to stripped screw heads etc. Sprayed them with Pt Blaster for the night and will pick up in the morning.

Figured I would install the TCI out of the donor bike and run the same tests and make sure the bike will still start before I cut up the TCI box and try to replace the diodes.

[bkuhr]

Noticed that when I rev the bike the right rear carb slide is moving much more than any of the rest of them. Really I don't see the rest of them moving much at all. They all move freely with approximately the same amount of resistance when pushing them back with a finger. Doesn't seem right??

 

Most likely in bad need of sync, but could be vacum leak (sync nipple caps, yics nipple caps,carb boots leak,holes in diaphrams, missing diaphram cover oring), or plugged vacum passages in the carbs.

 

Suggest start with static sync, remove sliders (good time to look for holes in diaphrams and cover oring) adjusting per sync procedure until as you see same barely open butterfly on all 4. Reassemble and due vacum leak detect with (diff of opionion-sprayed flam gas ie:ether, LP {have fire ext very near by}or non flam gas ie:wd40) and listen for change when running to pinpoint sorce of vacum leak. Use either gas in moderation at small pinpoint suspect areas. Keep in mind does not run well with airfilter off, but sliders should respond about the same.

[Venturous Randy]

Gotta ask, when you cleaned the carbs, did you take the metering block off and remove the pilot jets and clean them? Did you check the diaphragms for holes? Did you make sure the passageways were open that pull vacuum to the diaphragms. Did you do a temp check on all the pipes after the bike ran for a minute. Did you check to make sure the spark plug caps were not corroded inside where the resistor is located?

RandyA

[van avery]

Most likely in bad need of sync, but could be vacum leak (sync nipple caps, yics nipple caps,carb boots leak,holes in diaphrams, missing diaphram cover oring), or plugged vacum passages in the carbs.

 

Suggest start with static sync, remove sliders (good time to look for holes in diaphrams and cover oring) adjusting per sync procedure until as you see same barely open butterfly on all 4. Reassemble and due vacum leak detect with (diff of opionion-sprayed flam gas ie:ether, LP {have fire ext very near by}or non flam gas ie:wd40) and listen for change when running to pinpoint sorce of vacum leak. Use either gas in moderation at small pinpoint suspect areas. Keep in mind does not run well with airfilter off, but sliders should respond about the same.

 

BKUHR you originally suggested possibility that the TCI needed the diodes replaced. With the reading I gave above do you not think that is part of the problem? Syn'd carbs several times now

 

Gotta ask, when you cleaned the carbs, did you take the metering block off and remove the pilot jets and clean them? Did you check the diaphragms for holes? Did you make sure the passageways were open that pull vacuum to the diaphragms. Did you do a temp check on all the pipes after the bike ran for a minute. Did you check to make sure the spark plug caps were not corroded inside where the resistor is located?

RandyA

When I cleaned the carbs I did pull the block and cleaned the jets and tried to open and clean every hole I could find. Not sure which port went to the diaphrams. It's been a year since I cleaned them. Put about 1000 Mile on since then. Never have felt the bike was running "right".

A couple weeks ago I sprayed WD40 around the carbs and intake manifold and did not get a increase in rev's.

I replaced the diaphrams a couple of weeks ago. Is there a way to induce a vacuum on the back side of diaphram check for vacuum leaks between the diaphrams and slider connection?

In the manual it say's to fill the the slider and diaphram with gas to check for leaks. There is an additional hole at the bottom of the sliders that is not plugged with the small "washer with a nipple" on the needle that sticks through the small hole. Guess you just put finger over that hole. Question is won't that hole relieve the vacuum?

Begining to think I should pull the carbs and clean them again might have missed something. Have not checked temp on back two exhaust pipes. I will check that.

 

Thanks again guys for the help.

Jerry

[bkuhr]

BKUHR you originally suggested possibility that the TCI needed the diodes replaced. With the reading I gave above do you not think that is part of the problem? Syn'd carbs several times now

 

I went back and looked at the test you conducted, and you #s do look good for the most part-nothing suspiciuos to me, but keep in mind that all those test were for wiring and components external the TCI, not the TCI itself.

 

To be frank, I think you have multiple proplems, as I did on my 83. The 27 year old TCI is always a suspect for poor eninge preformance, with no real test for good or bad, but if you open it up and look at the diode side you will likely say " Ya thats got to be the problem", the get fustrateted after fixing it and still not quite right. YES I still think you have TCI problems.

 

I found the idle jet in the bottom of the jet block to have a very,very small port, and very easily plugged. I had my carbs off 5-6 times and tried to run .020 stainless lockwire thru jet which was to big of a wire, and ended up reaming out the jet-and ordering a new one.

 

Need to be 100% every port is open and running clean fuel thru new filter to avoid new dirt in carbs.

 

spark plugs with couple hundred miles on them can be good indicators of how the carbs are working.

 

Dont give up, I find it challenging if fustrating to get it running right but enjoy it- spend about 8 months on mine and its starting to act up again- I think TCI again as I have lost tach above 1500rpm-thinking about jumping into the $200 igntiteck unit.

 

good luck.

[van avery]

Pulled the carbs this evening while removing them I checked the vacuum advance line and it had a couple of pin hole in it. I'll replace it.

I only got one carb opened and cleaned this evening.

But when I opened the float chamber noticed bunch of crud in the bottom of the chamber, amazing afer one year. The jets were still clear on this carb including the pilot jet. pulled and cleaned anyway.

I did not open and clean the pilot screw last time. Did pull it this time and cleaned passage.

I also opened the "coasting enrichment valve" and noticed a small rip in the rubber part of the diaphram, the "back up material" was still intact but looking at it with a bright light I could see pin holes. How critical is this valve? I'll try to steal one off donor bike if they are still good. This was the slider that was basically not moving when I rev'ed the motor.

[van avery]

OK, been on vacation (still there) but before I left I pulled the TCI off my donor bike and installed it in the running bike and it ran . But not as well as the original TCI. So, I cut the box and purchased the new diodes and replaced them on the TCI from the donor bike. These were definately shot. Two of the diodes were completely disinigrated. While replacing the diodes, I noticed I also have a bad capacitor ( top of the attached picture). It's a 400V .047UF and the Radio Shack does not carry them. They do carry a 50V .047UF capacitor.

Since this is a 12 VDC system will the 50V .047 uF work instead of the 400V .047 Capacitor?

Thank for any help.

[frankd]

No, you need the 400 volt unit. It is a 12 volt device, but because the TCI switches the ignition coil primary, there are pulses that are higher than 12 volts. Have you found the correct capacitor yet? If not, I'll look in my parts stash.

 

You also were wondering if your trigger coils were out of tolerance. One of yours is 126.5 ohms, and the specification is 115-125. I wouldn't worry about that. Did you measure them at the TCI plug or at the plug just before they go into the left side engine cover?

 

If 2 of your diodes were open, you may have done some damage to the switching transistors. I would use an analog ohmeter (Simpson 260 or Tripplett 630 or similiar) and measure the transistor junctions. If you need help here, let me know and I'll explain what I mean.

 

BTW, have you ever checked for spark at all 4 cylinders?

 

Frank D.

[van avery]

I did get the correct capacitor and installed it in the old TCI. The bike would not start with it. So I whet ahead and bought an aftermarket "Ignitech" TCI and installed with the plug and play program from Inteltech. The original TCI for the bike still works and the diodes were all good in it so did not replace them.

As for your other questions: I checked the coils through the TCI plug with digital meter.

And yep I have spark at all of the spark plugs. Thinking about it I have not checked them lately out of the bike but all the exhaust pipes are hot so pretty sure they are all working yet.

 

Bike still dioes not run correctly. Hired a mobile bike mechanic rode the bike tried adjusting the carbs a little and then did a compression test and I have 180 PSI on both of the back cylinders but the front two only had 80 PSI. The front two spark plugs also had a oil odor to them. Said the rings were bad. He told me he probalby would not fix it if it was his but just run it. I'm thinking it needs to be fixed. He did not put any oil in the cylinders and recheck by he was sure that was the problem. Still burps and belches several times during acceleration till about 3000 to 3500 RPM's and when ideling will do fine for awhile then will stumble several times and then die if you don't rev it back up.

Not sure yet what the repair cost for him to replace the rings on the front two cyliners as he was going to check materials cost first but figured it would be around $700 in labor alone.

Thinking of tackleiing this myself. Need to do alittle more reading. Not sure I'm equipped to do all this with the valves, etc.

Guess I'm looking for a little advice here from the group.

 

Thank Again for the input. This is a great group and there is a wealth of information and advice.

[bkuhr]

I had a bent valve and paid $200 for valve job, but I would not expect that to be normal as PO had seriously abused motor.

 

I would more likely suspect you need to do a valve shim check, common reason for low compression, especially when on more than 1 cylinder.

[Dragonslayer]

Before I had done the valve shim thing on mine reading the articles made it seem scary. But when I did do it with RandyR's help it was not as bad as it seemed. Synching the carbs without the Valve shims correct does no good because the valves shims need to be within tolerances before the sych is accurate.

 

With the Valve shims and carb sync correct the performance on my bike increased about 30%. It looks like most if not all of the other possible contributing causes have been covered. RandyR is a good source of information and help on the Valve shim adjustment proceedure.

[van avery]

Thanks guy's.

Going to either buy or borrow a good compression tester. Then put cylinder at top dead center and put about 5 psi through the plug opening and listen for air at the carb, exhaust, and the oil filler.

Need to make sure if its valves or rings.

If it is the rings do you have to open the case disconnect the rod and push the piston out and connecting rod out, or can you rotate the motor and will the piston come up far enough pull the pin and pull the piston out and replace the rings?