Help !! Lost a Cylinder.

[Guest Popeye]

I had my carbs done this summer, with diaphragms, new plugs, etc.

Throttle cable broke & just fixed.

 

My tech told today my scoot is only running on 3 cylinders.....LF exhaust pipe stays cold. He says it can't be electrical & is carb, PERIOD.

 

Engine sounds & performs great, but has always run ~32 mpg.

Tech insists dead cylinder is carb problem [now covered under warranty].

 

LF cylinder not firing, but can't be electrical????? [per tech]

 

Sounds goofy to me, but he sure has no reason to tell me wrong, since he has bike & I want it fixed.

Also, how could I put 15k miles on bike & NOT detect dead cylinder ?

Had carbs, plugs, diaphragms [had big holes], etc., redone & runs the same??

 

Bike has always started super easy & ran sooo smooth with endless power, always 2 up & loaded? It has even sounded 100% for 1.5 years.

 

Bike is at the shop now. What could be the problem if not electrical?

How is it neither tech can figure why cylinder doesn't fire???

I'm not going to bring bike home until one of the shops fixes it.

Once I pay & leave, they won't know me or my scoot.

 

Techs from each shop are going to talk to each other today...how can they NOT know???

This is way too weird.

 

I need some info.

[muffinman]

Popeye it sounds like the carb cables are out of adjustment. Not the throttle cables but if you read the service manual there is a note that says Do Not Adjust This.Dont ask me where it is I just came in from 12 hours of work but when I changed mine on my 84 it was doing the same thing.Look through the carb section of the paper version of the manual and read all of the Notes.

Hope this helps

If they cant fix it ride it down here and I will get it right.

Jeff

[Oldgold]

If this were my 83 with the same problem I'd plug the LF wire into an old plug and ground the electrode, start motor and watch to see if the spark was jumping the gap, nice blue spark would be best, this should eliminate

the electrical side of not firing. If this looks OK, I'd check fuel level, on an 83 they run drain hoses from the bottom of each carb to which you need to add a short piece of 1/8" clear tubing from the hardware store, again on the 83 the level is supposed to be about .55" below the center of the

carb diaphragm cover, there's a small screw at the carb base to open and let the fuel into the hose hold the clear tubing up along the diaphragm cover and see if you're close, now you know you're getting fuel into carb,if this is OK pull air filter and watch the diaphragm slide for that cylinder while operating the throttle, all 4 should be dancing up and down the same, if all this checks and it's still not firing I' be thinking along clogged

jets,or fuel passages in that carb. Did they diassemble and clean the carbs when they did the diaphragms? Just a few things to look at, I would imagine the techs have already done most if not all the above. I don't

know if the float level check applies to your year or not, I'm sure someone

will jump in if it does't.

[FROG MAN]

Fuel,Air,Spark = Vroooomm. First thing I would check is spark. Remove plug wire connect old plug and check for arc against motor or frame. You may have lost pickup coil input for that cylinder ( connector problem). No input means no output spark this is easy to check. Pull plug and see if it is saturated with fuel. Those V4's foul plugs easy.

[Guest Popeye]

Thanks guys, this is good stuff.

No rocket science involved here. I'm taking bike out tomorrow & check for cold cylinder, myself.

 

At present, it has only happened at the shop & never while I was riding it.

If cold, then it will get full diagnostic & I will post problem.

[Squeeze]

Thanks guys, this is good stuff.

... I'm taking bike out tomorrow & check for cold cylinder, myself.

 

At present, it has only happened at the shop & never while I was riding it.

If cold, then it will get full diagnostic & I will post problem.

 

 

That's a good Idea :cool10:

[fixit3546]

And, if it were my 83, I'd put in a new plug. BEFORE i did anything else. $1.50 and go from there.

[Guest Popeye]

I went & got scoot from shop #2 & rode to #1 where carb work is guaranteed...50 miles.

Easy start, but sounded REAL BAD ,no doubt 3 cylinders, but never did it before.

 

After 5 miles, tach quit, then worked intermittently. Seems electrical?

 

No one has checked anything yet, so will wait & see.

 

Idiots at shop #2 left bike out in huge T-Storm last night with 3+ inches if rain.

My house got circuits blown out from lightning, PC modem fried [got a new one today].

 

Scoot was terrible soaked, but they had attitude it wasn't their problem.

I am so NOT HAPPY.

[bill p]

Popeye you don't need a shop to tell which Cly is not firing. Long nose pliers will allow you to pull off 1 Cly at a time. when you pull off the dead one there will be no change in the sound of the engine. Pull of a live one and you will hear it plane as day. The engine will at least shake and possibly die.

Find out how many are dead. do everything in the above posts,all the info above IS correct. If you have both or one rear Cly dead it may be the ign control unit. But before you buy a new one for 500.00 put the old one in your oven at 150 degrees. Thats just barley warm by oven standards. leave it for a few hrs then install it again. Many have found moisture has entered the unit and caused problems. . The big clue is it was out in the rain. Do you have a shop manual,and are you able to do the testing necessary? Most of the mechanics now will charge you many hours to just get to the control unit. What you basically have to do is test everything up to the control unit and if all else is good replace the control unit. Go to the tech section for more info on test procedures. Let us know how this works out.

 

Bill P

[Guest Popeye]

..... Many have found moisture has entered the unit and caused problems. The big clue is it was out in the rain.

 

They told me it's LF cyl, but techs from 2 shops disagree whether it's a carb or elec problem.

Since carbs have been 100% redone this summer & has guaranty, bike went there.

Strange that neither tech did ANY tests.

 

I would do the work myself, but I can save much more $ by working & remodeling house myself in spare time.

Bike techs are expensive, but building contractors are insane.

 

Scoot was diagnosed, LF cyl, before it was left in T-storm.

However, bike got REALLY soaked 2 rides ago, half way to Eureka Springs, AR but no problems during the trip there or long ride back.

 

Went 55 miles on next ride when throttle cable broke while running great.

 

LF cyl quit while in the shop. [?] Seems a coincidence a cylinder was lost 'while' throttle cables were being replaced.

 

I have often heard of baking the TCI in the oven at 150*F [a little over body temp] & checking solder joints, etc.

[OldNewbie]

LF cyl quit while in the shop. [?] Seems a coincidence a cylinder was lost 'while' throttle cables were being replaced.

quote]

 

Don't remember the reason but i did have to disconnect a coil wire

during my throttle cable replacement getting @ the linkage for cruise

control. forgot to hook it up until after running again.

Moral...check connections to coils. (also was LF)

[Gearhead]

Popeye, your tach intermittent issue is a clue. I've had a problem when water has gotten down by the TCI with just that - the bike runs a little funny, idles rough and sometimes dies, and the tach quits. Might be inside TCI as discussed, and might just be the connections. There are three that are really suspect. Two are on the TCI itself which is hard to get to, but I was able to pull the battery, reach down there and unplug them. Sprayed some contact cleaner, did several plug-unplug cycles, and reassembled with vaseline. The third connection is between the pickup coils and the TCI on the schematic, located behind the LH side cover, right under your left thigh when seated. There are also two connections there for the charging system that you should clean while at it.

 

Jeremy

[Terry Richardson]

Well guys I just picked up an 84 Venture and I lost 2 cylinder and one of the working has weak spark. This bike has been left outside for sometime. I dread tearing down to the TCI unit. Thats a lot of labor on a guess. I also found water and gas in the block. Think maybe that was from sitting up. Flushed and changed the oil... not to work on the dead cylinders. Any suggestions?

[k7mdl]

Caps and wires are all suspect, as well as electrical connectors. I would work back from the spark plug caps to the wires on the ignition coils, the connections on the input to the ignition coils, and at least reach in and wiggle the TCI connector housings. I can just get my hand in over the front cylinders - it is not easy but it is possible to unplug and reconnect them in place with great patience.

 

Reseat the connections, cleaning as required. My 87 was stored indoors, the connections were good, but showed signs of corrosion on teh blade parts that did not have high pressure contact.

 

If that does not do it, you are into resistance and voltage checks. The repair manual has most of the resistance specs for each item. These do not take to long to do. Getting at the coil connectors pretty much requires removing the fairing. If all of that fails, there is elsewhere on the site here measurements for the TCI unit also.

 

I did all of this recently several times, never finding any problem until finally locating a miswiring of 2 connectors. The more you do it the less time it takes - practice does make perfect. Make sure the battery and it's connections are strong also.

 

- Mike

[Terry Richardson]

Mike, thanks bro.. I appreciate the info and will get right on it. Man this ole girl is a pain to get into but well worth the work. Again many thanks my friend.

 

Terry