How can you tell if you're running on one cylinder?
 

Ok, heres a silly question. How can you tell if the bike is only firing on a single cylinder? I'm sure you'd see a loss of power, rough running etc., but that would probably describe a whole raft of issues.

Can you tell just from the sound - if so, what would it sound like?

The reason I'm asking is that I'm just getting the bike (2002 SV650 naked) back out after a few months off over the winter. I'd warmed it up a few times before, but yesterday it was hard to start initially. After it warmed up the idle had dropped to about 500rpm. I took it for a ride which seemed to generally be ok, but running about 35 at ~4000rpm (I think it was in third gear) I noticed that the power delivery was sort of pulsing - like it was firing about 3times /second 'ish.
Anyway, I'll put a can of carb cleaner through it sometime this week and check the plugs, WD40 the HT leads and see what happens, but I was just curious about what symptoms single cylinder operation would give.

Cheers,
Vic

Re: How can you tell if your running on one cylinder?
 

extremely poor pickup, rough as old harry, smell of unburn petrol from exhaust and one cold down pipe (DON'T ACTUALLY TOUCH IT TO FIND OUT!!!!).

Re: How can you tell if your running on one cylinder?
 

Ever been karting? If so you'd recognise the noise.

Re: How can you tell if your running on one cylinder?
 

Slightly smoky method... spray some WD40 on the exhaust header for each cylinder, if the cylinder is running (and so the pipe is hot...), lots of smoke.

Re: How can you tell if your running on one cylinder?
 

spot on descriprion,:thumbsup: in my case it was a bad connection on the rear cylinder HT lead

Re: How can you tell if your running on one cylinder?
 

Easy way round that, it may be a bit of a filthy habit, but spitting on them is better than burning your fingers. See if it sizzles.

However the SV rear downpipe is a bit hard to spit at:rolleyes:

Re: How can you tell if your running on one cylinder?
 

When spitting make sure its not a greenie they tend to dry and stick on :(

Re: How can you tell if your running on one cylinder?
 

Peasant!:smt082

Re: How can you tell if you're running on one cylinder?
 

I usually try something a bit more sanitary and flick some tap water onto the headers.

When running on one cylinder the bike doesn't have enough power to maintain 55 MPH up a modest hill unless you downshift so that the engine is revving at around 8K.

Most likely you've got a carburetor that is acting up. Lift the tank and pull the airbox and start the engine briefly. If you see gasoline dripping out of one of the overflow lines (the hoses between the two carbs that have open ends on them) you've got a stuck needle valve in the carb attached to that hose. Pulling the carbs and cleaning the contaminants under the needle valve should fix that.

If you're not seeing any gasoline you've probably got a clogged jet. You can test that by placing your hand loosely over each carb throat and restricting the air flow. If you do it on the one that's firing the engine will stall almost immediately. If you do it on the one that's not firing the engine will actually start running better (i.e., running on both cylinders). This is because the additional vacuum is pulling a bit of fuel into the intake. If that's the case you'll have to clean the jets and all the little orifices to restore normal operation. Fun!

Re: How can you tell if you're running on one cylinder?
 

Thanks everyone.

Some good tips. I'll check some of that out tonight.
Incidently, I was talking to one of the dealers looking for some carb cleaner - It's quite common here for people to park the bike up over winter then have the crud in the carb come spring time. They were telling me they'd been having a lot of customers with carb probs since the petrol companies switched over to E85 fuel (here in Oklahoma). Sometimes with just 6weeks of not being run! She suggested taking it for a long run (2 to 3 hrs) and see if that will flush the carb and burn some of the crap out. I'll have to find time to do that before long (It'll be fun even if it doesn't help :-)

Re: How can you tell if you're running on one cylinder?
 

Lesson - winterise the bike. Drain carbs or run bike regularly through winter. Keep tank full though, stops it rusting. Best solution is a weekly 20-mile run, although your weather may make this a bit hazardous! :pale:

Re: How can you tell if you're running on one cylinder?
 

True enough. I draw the line at riding on 6" snow. Mind you, it's the ice underneath that that'll get you.
How do you drain the carb though, since theres no shut off **** [edit - c*ck]?

Re: How can you tell if you're running on one cylinder?
 

This is just a word of wisdom from someone who's been there and done that and got the tee shirt. I'd be real careful about taking it for an extended ride when the bike is running on one cylinder, especially if you have a suspected crud-in-the-carb problem.

Take it easy on this ride and if the other cylinder begins firing just keep taking it easy for the first several days afterward to give the fuel system plenty of time to clear its arteries.

If you don't you could suffer my fate from awhile back. I thought everything was hunky dory and took my bike to the drag strip to practice a few launches (in anticipation of an upcoming race weekend). Mid-way through the 2nd run the rear piston "detonated".

It turns out that if the cylinder running way lean (because the carb still isn't completely cleaned out or other issue) the piston head can get overheated. The incoming spray of fuel/air from the intake helps cool the piston head.

Here's how my piston looked when I dug down to it. The shiny round places are where chunks of piston head blew off. You're looking at the piston rings. Fortunately the pieces of piston made it out the exhaust port without doing further damage (other than to un-gap my spark plug).

http://i648.photobucket.com/albums/u...t/SV650CCT.jpg

Re: How can you tell if you're running on one cylinder?
 

One way to do it is to lift the tank, pull the vacuum line off the bottom of the fuel supply valve (the smaller hose), then start the engine and run it until it stalls. Without vacuum the supply valve will remain closed. You may want to plug the end of the vacuum line when you do this to keep the engine from sucking any contaminants from the air into the intake during this procedure.

ETA: As an alternative you could pour some Stabil into the tank and run the bike for a few minutes (long enough to get the Stabil into the carb bowls) and shut it off. We've had pretty good luck with Stabil for winterizing our training bikes for the program I work with conducting MSF classes.

Re: How can you tell if you're running on one cylinder?
 

A 2002 SV has carbs I think, if so the carb float bowls have drain screws. A short piece of fuel hose can be fitted to the float bowl drain stubs and lead to a jar. Then open each drain screw in turn and see what collects in the jar. Probably a lot of water from the offending carb.
Riding a twin running on one cylinder can have fatal results if the 2nd cylinder chimes in when you arnt expecting it.

Re: How can you tell if you're running on one cylinder?
 

I changed the plugs this weekend, though the others were still in pretty good nick. Doing the squirt test on the exaust I found I was running on both pots, though still a little rough. Took it for a run and burnt through some of the old fuel. After sticking in fresh fuel with some fuel additive and running for another 50 miles it seems smoother now.
Hopefully things will improve a bit more when I go through this new tank (and the additive's will have had a chance to sit in the carb for a while).

Thanks everyone for some good advice - I know what to do now next winter :-)