Problem with the Bandit - electrical?

[El Dopa]

There's a problem with my bike. I strongly suspect it's electrical, and the searching I've done on this forum seems to support that. It might be something else, but before I put in a lot of time and effort narrowing the fault down, I want to make sure I'm doing it right.

The bike had an intermittent problem a month or so ago. I thought I'd fixed it after Pitter suggested checking the connectiors on the coils.

Last week, the bike wouldn't start. I took the battery out and charged it, and ran a bit of fuel through the carbs in case there was water in the tank. Battery charged and replaced, she fired first time. Problem appeared solved.

Then, at the end of a long ride yesterday, which had been completely problem free until that point, the bike starts intermittently firing. I check the connections at a friends house as well as you can without taking everything apart. No problems apparent.

After that, all seems well until about 2 miles from home. The bike dies at a traffic lights. 15 minutes of swearing later, it restarts. I try to keep the revs high so as to actually keep the engine running and ride home. Unfortunately I hit every red light on the way, and it proves impossible to keep the revs high all the time - bike stalls again approaching a set of lights and won't re-start.

It's currently in the garage waiting for me to fix it.

Now, I think its probably a faulty coil and/or coil connection. However, my searching suggests it might be carbs, or vaccuum, or something else mechanical. I don't think it is, because she was running sweet all day up until the final stretch.

I'm going to take out the plugs and check for spark as a first step.

Question:

If I DO get a spark on every plug but it still isn't firing, would I be correct in thinking that indicates a mechaical problem - e.g. carbs or fuelling?

If I DON'T get a spark on every plug, would that indicate e.g. a problem with the coil? If so, how do you check whether a coil is 'good' or not?

Cheers,

Rich

[interfuse]

You don't even need to take the plugs out to test... when you bike is acting up touch the headers and see if they're all the same "hotness" if you've got two pipes that are colder then  the others that are linked to the same coil then that's your problem....

if its only one pipe that isn't getting hot, or they aren't linked to a coil then  its probably carb related or something else...

[PitterB4]

I'm betting electrical.  Your symptoms are EXACTLY like when I was having the bad connection to the right coil.  If it were fuel, it would most likely only be one cyl, and it'll run better than that on 3.  It really sounds like you're running on two.  Like Mike said, check the pipes when it's running poorly.  I'll bet 1&4 or 2&3 are cooler.  The easiest way to check the coils is to swap them.  If the problem follows one of them, it's bad.

[El Dopa]

Thanks for the replies. The trouble with the 'pipe-temp' checking method at the moment is that it won't do anything more than turn over on the starter - it does 'harrumph' occasionally, but it won't fire. So the pipes won't be getting hot.

My money's on electrical, too. I had a quick look at the coils at lunchtime (bikes garaged at work), and one of the connectors on the RH coil seemed really loose - it was kind of jiggling around. I'll have a closer look when I get a chance.

[Bartjan]

my guess would also be a coil.

loose wire can be the problem, or to much water around it.
cilinder 2 wont work right if my bike is swimming through the rain, after some spray (on the coil) that removes water (dont know the english name) it runs perfectly again.

also do you remember what the top speed was the B4 could go to, when it was running bad?
if its around 60-80km/h it probably runs on 2 cilinders and if its around 100-120km/h it probably runs on 3 cilinders

[erik]

To check the coils, you can use an ohm meter/multimeter. The manual says the primary coil is supposed to  be 2.5 to 3.8ohms, the secondary (plug cap to plug cap) 30 to 50 kilo ohms.
If you haven't got a multimeter, they're cheap. Or I could come over and you could use mine.
I wouldn't mind giving you a hand with it, although I don't know if I'd have any more luck than you at figuring it out.

[PitterB4]

I had a quick look at the coils at lunchtime (bikes garaged at work), and one of the connectors on the RH coil seemed really loose - it was kind of jiggling around. I'll have a closer look when I get a chance.

Uh... I think you may have found your problem!  Pull it of and gently squeeze it with a pair of pliers, put it back on, thumb starter, smile.  

[El Dopa]

To check the coils, you can use an ohm meter/multimeter. The manual says the primary coil is supposed to  be 2.5 to 3.8ohms, the secondary (plug cap to plug cap) 30 to 50 kilo ohms.
If you haven't got a multimeter, they're cheap. Or I could come over and you could use mine.
I wouldn't mind giving you a hand with it, although I don't know if I'd have any more luck than you at figuring it out.

I might take you up on that. Thanks. I'm going to try and narrow the problem down a bit more - fixing the loose connection didn't help.

The battery is on charge. If the bike fires up with a fully charged battery (which is what happened a couple of weeks ago when it wouldn't start), then I'm guessing it's either a problem with the batery or the reg/rec. Anyone agree/disagree?

If that doesn't fix it, I'm going to get the plugs out and see if they've all got spark and take things from there.

BTW Erik, I got a set of sliders from the same guy. I might pick your brains on fitting them.

[pmackie]

Sounds like you need to check the battery first. A bad battery can cause some of the symtoms you describe, and may not have allow the bike to fire while it is turning the starter.

Have the battery load tested and ensure it is good, or replace it.

[erik]

The battery is on charge. If the bike fires up with a fully charged battery (which is what happened a couple of weeks ago when it wouldn't start), then I'm guessing it's either a problem with the batery or the reg/rec. Anyone agree/disagree?

If it starts after charging the battery, that would indicate the battery isn't being charged while the bike is running so I'd guess either the reg/rec or the alternator might be faulty?

I'll pm you about coming to take a look at it.

[El Dopa]

OK, so here's an update and a request for some more help.

I took the battery out to charge again. It charged very quickly. That suggests to me that it isn't a duff battery - it's still holding a charge well.

I finally managed to get all the sparkplugs out to check for spark. There is spark on all four, but one or two of them look a bit old and cruddy. I don't think they were fouled, but I don't really know how to tell. They didn't look overly sooty. However, the metal bits of the bodies on at least one of them was looking pretty rusty.

I put them all back in, ran a bit of fuel through the carb nipples (again), and turned the engine over. After a couple of false starts, it fired and ran.

Now....

I had the choke open to start the engine. When it was running/idling with the choke open, the rev needle was 'bouncing' a bit - the engine would rev, then drop a couple of hundred, then gain a couple of hundred, sort of intermittently. When I closed the choke, the engine nearly stalled.

If I had to guess, I would possibly think it was a spark plug problem - intermittent spark on one plug, so running on three cylinders, then on four, then back to three, and so on.

Does this sound feasible, or am I talking rubbish?

If it isn't that, then what is it? CDI? How do you tell if the CDI if futzing up? I don't think it's the coils or a loose connection to the coils as there was spark on all four plugs.

Anyone?

[gsxr400 racer]

buy new plugs  

[El Dopa]

buy new plugs  

Yeah, you're probably right, but 4x new plugs = $$$$

New plugs won't be a bad thing either way, but I just wanted to canvas opinion to make sure that would actually solve my problem.

[gsxr400 racer]

Just buy the single electrode ones

[interfuse]

Check your charging voltage. When my voltage regulator went bad, after a long ride the battery would fry and the bike would almost refuse to idle (I can remember having to keep the idle up around 2500 rpms to keep it from stalling).

Eventually the battery would appear to be "full" but didn't have the juice to crank the motor.

It's a simple test, it's free, and if its all working then perfect.

Heres a linky
http://forums.banditalley.net/viewtopic.php?t=5831&highlight=regulator