Very low on power

[tig5]

Hey guys, I've had a good hunt through the threads and just wanted to check whether there is anything else I should consider regarding a recurring problem.

After my bike had sat for a while as a POR-15'd my tank, the first ride I took it on it felt dreadfully underpowered. It wasn't missing or bogging, just felt like it it was trying  to draw air through a stack of pillows. In first gear up a moderate hill it was close to stalling. The bike sounded more like a traditional 4-stroke, it was hard to get the revs up anywhere near the screamy level we all know and love and the exhaust note had definately become more muted.

I'd had the airbox off at the time and figured there may have been a bit of an issue so I checked and found that I had neglected to reconnect the tubes that go from the cylinder heads to the airbox. I reconnected these and the problem seemed to disappear, but returned again a couple of times intermittently. It now seems to be here to stay.

The bike had been sold to me with no air filter installed  >:( and after sifting through the possibilities I'm thinking that the carb is probably clogged. My other theory is that it is running on one cylinder.

So far I have:

Checked fuel flow from tank
Checked all tubes around airbox/carb/Yics
Checked spark plug caps and ignition wires under RH cover

Next I will:

Replace plugs and check for decent spark...maybe in the other order.
Remove gas cap and check tank is venting
Clean carbs
Spray some WD-40 and look for vacuum leaks.

Other notes:

I now have an air filter compliments of Roro, this hasn't made anything better or worse.
I replaced the petcock on my tank around the same time. I have never had an original on there, only a standard yamaha one with an on/off/reserve. Therefore it isn't vacuum operated as far as I'm aware. Would I benefit from an original?
Where is the tube from the top of the airbox meant to go? Mine is cut off about 1 inch. I originally though it was just a vent but have now released that if I suck on it the flapper opens....so this should be attached to something somewhere?
Around the same time of these issues I have also replaced the headlight, indicators, speedo, changed the oil and had the starter apart a couple of times but I can't think how this may have contributed.

Any further thoughts would be appreciated.

[The Prophet of Doom]

Your biggest problem seems to be your flapper.  This should attach to the front carb - see the Intake and Carburetor Modification Kit documentation for a pic
If it doesn't flap open you will get not much air - that won't help matters.  If you can't figure out where to plug it, you may not have an updated carb top. and both carb tops will look identical.

You can check both cyls are firing by wetting a finger and tapping it on the exhaust header.

The aftermarket petcock is good as it stops a jammed float valve from dumping the contents of your fuel tank onto the garage floor.  I don't think it would affect running, though make sure the hose from the manifold is capped off - air leaks there will severely impact running.

[tig5]

Thanks Roro!

I located a stray tube that comes off a top right hand port of the Carb (haven't been able to download that diagram youlinked yet) but it appears this is the tube to the flapper. There is also a port on the top left hand side of the Carb with nothing coming from it...would this have originally led to the petcock?

I tried your finger on the header trick after a short ride. Front headers were hot, back were warm at best. Confirmed only one cylinder was firing by pulling the rear spark plug cap off. It made no difference.Time to get the manual out again!

[The Prophet of Doom]

The front manifold has 2 outlets - one blocked off, one to the fuel pump
The rear manifold has 1 outlet - to the petcock.

When syncing, you normally connect to the blanked off, and the petcock outlets, and set the petcock to PRIME.
If you have the petcock hose dangling and not sealed, you will run very poorly.

Sorry for the bad link.  Try this...
XZ550 (11J) Intake and Carburetor Modification Kit 1982 Models

[Doc Nielsen]

Roro can you take a picture of the one going to the fuel pump for me? I think mine is connected wrong.

[Rikugun]

Doc, the two on the front, one on the back thing may not be written in stone. If they've been removed and replaced front to back (I think that's possible?) then it will be backwards. Also, I think some replacement manifolds may both have come with only one vacuum port each? As long as it goes to one of the ports on the rubber manifolds you'll be OK.  :)

[The Prophet of Doom]

My engine is on the bench with no carbs - some good pics in Haynes though.

Good point about some being backwards - it seems mine was wrong.  On closer inspection of the parts diagrams the factory config is petcock and fuel pump off the double front manifold and the single rear is capped.  I doubt any of the possible combinations would make a substantial difference.  Sorry if I caused concern.

On my rebuild I think I'll use two front manifolds so I can just plug the sync tool in without removing anything.  I'll use some long capped hose so I won't burn fingers on the hot engine.

[cvincer]

Photos of 83'carb

[tig5]

Great pics, thanks cvincer

[pinholenz]

I had the same problem with my bike running on just one cylinder for no apparent reason after I started working on it. I concluded that it was a faulty spark cap after I had replaced the spark plugs, HT Leads and checked out the coils. (If you want some cheap Iridium plugs, PM me, I have some extras.  I also have a spare coil if you need one - postage only.) I got my new NGK spark plug caps from Repco. About $32 for the pair I think.

My guess is that the spark is the problem. But just make sure that the float valve isn't jammed on the rear carb preventing any fuel from getting in. Try opening the drain cap on the rear carb with the tank in place and valve on reserve (or PRI if you have replaced the petcock). It should keep draining freely of course.

And its worth leaving the battery on charge overnight just to make sure that isn't playing silly buggers.

Cheers

[Rikugun]

On my rebuild I think I'll use two front manifolds so I can just plug the sync tool in without removing anything. I'll use some long capped hose so I won't burn fingers on the hot engine.

I did something similar. I installed a "T" fitting in the petcock vacuum hose and capped off the third leg. To sync the carbs, just uncap and use that "remote" port and run the bike normally with the petcock "ON". The cap is easier to get to. Also, it always bothered me to carefully sync the carbs then plug the petcock into one cylinder. This way, the carbs are sync'd with the petcock influence accounted for.

Yes, it's overkill.  :-[  Later tests revealed it makes no never mind but it is easier to get to and you don't burn your fingers. :P

[tig5]

Thanks for the thoughts guys. I went to check for a spark and I seem to have lost my electrics  >:(
When I hit the starter button I could only hear a click, then the neutral/oil/highbeam lights started flicking on and off. I had a fiddle around the ignition area etc and couldn't find anything loose. I pulled out the instrument bulbs and they were still lit but only a tiny tiny bit. After a while they went out and I couldnt get them back. I recharged the battery but it hasn't helped. Any idea what would show as very weak power? A loose connection? Battery connection is fine, fuses seem ok. I have a multimeter but I'm a bit of a novice with it. The bike just weathered a pretty serious storm down here in wellington. I think it was the only bike on the street to stay upright. It's possible that water got in to something.

[QBS]

A fully charged battery should show approx. 12.6 volts DC at its' terminals with the key off.  Your multimeter should be able to test for that.  Put it in VDC mode and touch the leads to the battery terminals and see what you got.  Connection polarity isn't an issue for this test.  If you're low on voltage charge the battery up and try to start again.  A good charging system should show approx. 13.2 volts DC for this test with the engine running.  Anything less is indicative of a failed stator.

[pinholenz]

Glad to hear that you survived the worst storm since the Wahine disaster. Reports up here were that you had 15 metre waves and 200 kph winds and that the power outages have been pretty serious for a lot of people. If the battery is charging OK and your multimeter shows 12.2 to 12.6 volts at the battery terminals, start checking upstream if the lights are dim. I would start with you main fuse and make sure its not corroded, then trace the black earth wire to the frame/starter to make sure its not loose/rusty.

OT, I was at a photography Conference this weekend in Auckland. One of our keynote speakers was Ingvar Keene who, with another beginner rider, did a 2 year world trip on his motorbike. Mostly photographed portraits during his trip. Thought you might be interested in a fellow traveller of the less explored highways.
http://www.ingvarkenne.com/ingvarkenne_personal.html

Cheers

[The Prophet of Doom]

A fully charged battery should show approx. 12.6 volts DC at its' terminals with the key off.  Your multimeter should be able to test for that.  Put it in VDC mode and touch the leads to the battery terminals and see what you got.  Connection polarity isn't an issue for this test.  If you're low on voltage charge the battery up and try to start again.  A good charging system should show approx. 13.2 volts DC for this test with the engine running.  Anything less is indicative of a failed stator.

Digital meters will just show negative volts (eg -12.3) if you get the polarity wrong.  Connection polarity can be an issue if you have an old fashioned analog meter - the gauges only work one way, and will burn out on higher reversed voltages.  It's generally good practice to identify your polarities and use them correctly.  There are plenty of multimeter tutorials on youtube.

Check the electrolyte levels before charging.

[tig5]

Yeah it was a pretty gnarly couple of days. The coast took a hiding. I have a friend who lives near the beach and she found a 6 inch seahorse in her back yard...Lots of power lines down, I was lucky not to walk into one at waist height in the dark.

A scooter on my street had its seat blown off so I wouldn't be surprised if something on my bike has come a little loose.

Thanks for the tips on the multi metering, I'll try that when I get home. I did notice that there is a single black wire under the RH side cover that isn't connected to anything. It has a single connector on the end so it hasn't come out of one of the multi-block connectors. Can't find anything for it to plug in to. When Pinholez mentions the "black earth wire that runs to the frame/starter", this is not the black wire that leads to the terminal on the starter, correct? The earth for the starter is the frame itself? I haven't bumped into the earth/frame contact point yet, could someone point me in the right direction?

Cheers

[QBS]

A frame ground point is under the gas tank at the spark coil mounting point on the frame.  Use the multimeter to find out what the black wire might do.  + or _ key off, key on.

[Rikugun]

Use the multimeter to find out what the black wire might do.  + or _ key off, key on

I'm fairly certain all black wires are ground on the Vision. If it's a factory wire in the factory position it may be ground for the left rear turn signal. There should be a dark green that runs adjacent to it.

[Walt_M.]

Is it the rev limiter! Disconnect the yellow/black wire from the TCI and see if that is the problem.

[tig5]

I have no speedo on the bike at the moment so I don't think the rev limiter is the problem