Can't get the bandit started...

[shidoran]

So... wondering what is next to do with this thing. I did get it in pieces, been putting things together and I think I have everything figured out. It's a 250P (1992) with a GJ47A engine, Mikuni carbs.

- New Battery
- New Oil/filter
- New Sparks
- New HT leads
- New fuel filter

*Has spark, pretty good from what I can see.
*Fuel seems to flow pretty well into the carbies
*I did take the carbies apart, undid the jet screws and cleaned the plungers etc. I didn't fully disassemble though.
*Old spark plugs and inside the exhaust are pretty carbonated.
*Went over the bike electrically, coils are good, stator seems ok, CDI seems to work

What else is there? The thing just won't start. Surely it can't be timing? The advancer is keyed behind the timing cover so I'm assuming it's fixed and can't be adjusted and the CDI controls the spark timing... right?

I'm starting to get concerned about compression, because there just doesn't seem to be anything else left. As I can't start it, any test I do will be cold - not sure if that would be accurate.

So when I go to start it, choke on, no throttle the starter just ticks over and the bike sounds pretty weak and just kind of goes along with the starter. I squirted about 1ml of fuel in each cylinder (through the carby) and tried again and got a bit more life but it was really negligible. Cranked it for about a minute (pretty much flattening the battery, so that's back on charge) and a couple of times it sounded like it wanted to start but didn't have enough behind it to do so very strongly.

So... ideas on what I can do next? How can I diagnose exactly what the compression problem is (assuming that's the problem, I simply can't think of what else it could be...)?

[greg737]

Sounds like you're being logical in your approach to the problem.

Fuel+Air+Spark is the basic formula... then you move into the specifics of each category. 

Take Fuel for example: Is it getting too much fuel?  If it really stinks after cranking, maybe so.  Is it getting too little or no fuel?  If the garage still smells like it did before the cranking, maybe so.

After the 1 minute of cranking did you evaluate the fueling situation?  Did you pull a spark plug and check to see if it was wet with fuel?  After a full minute of cranking without firing the spark plugs an engine that is getting the normal amount of fuel should have wet plugs.  Did you put your nose to the exhaust pipe and sniff to see if you could smell raw fuel?  A wife or sister or girlfriend is a good resource for identifying unburned fuel, their sense of smell is usually better than most men's.  After the cranking is finished call her out and ask her what she smells.

If you're sure the engine is getting fuel but it still won't start, i.e. lots of cranking attempts but nothing ever happens, you might have an engine that just doesn't have any compression.  If it's the piston rings that are bad the engine's oil will begin to smell like fresh raw fuel (because that's where the fuel is going when you're doing all that cranking).

[shidoran]

I cranked it over for a minute or so again. Feels like compression may be an issue somewhere.

Exhaust smells like fuel, could see a misty cloud coming out the exhaust. I took off the engine oil cap for a sniff but couldn't smell fuel there. Took all 4 spark plugs out. Don't know what you consider "wet" but I didn't think they were. Interestingly they were all covered in carbon, which just wiped off. These are brand new plugs so I'm a bit stumped.

[interfuse]

It takes a lot of cranking to fill the float bowls with a vacuum operated fuel tap. I set the petcock to prime for 30 seconds before I start cranking to fill them up. But dropping fuel into the cylinders elimiates a fueling problem. Unless your're not using fresh gas.

One thing I'd check is that you've got the firing order correct with the new leads. Although mixed up leads would probably at least give you some backfiring.

[Squishy]

If it has a spark, and decent compression, then mixture remains. With starter problems I always remove the sparkplugs and clean them with a metal brush.
You said they were marked in carbon? Do you mean they were white? In that case that cylinder isn't getting enough fuel.

Then check all on the carb/airfilter. Could be anything.
Remove tank and airfilter. If you have something like a bottle with fuel to temporarily replace the tank that would be convenient.
If so, plug the vacuum hose that comes from one of the carbs.

* Check if choke moves properly and returns to off position
* Check of throttle valves are closed with no throttle and move properly.
* Check the vacuum hose on the carb to the tank.
* Make sure the pilot system is clean (the 2 small holes on the airbox side of the carb + pilot/main jet).

Try starting with a little throttle to see if the idle adjuster isn't off.

[shidoran]

Thanks for the insights guys.

I took the head off yesterday to have a look at the timing and it seems to be OK. More than anything now I'm starting to suspect compression. Strange for a bike with only 30,000 kms to have compression problems though?

I've ordered a proper compression tester kit so hopefully in a week or so I'll know for sure. It couldn't hurt for me to some more cleaning on the carbies either I suppose, just to make sure.

[ventYl]

NO! Don't fiddle with engine internals just because you have feeling you have compression problems. From what I have seen, even abused engine will have usable compression after twice as much km than yours still having 1* idle and running stable on all four cylinders. Await compression loss after 120000+ km.

You stated that:
* you bought new sparks. Which sparks? Are the *EXACLY* by service manual specification?
* you have pretty good spark. What does it mean? Suzuki suggest that ignition system in good condition *MUST* be able to fire spark between two nails with 8mm gap
* CDI seems to work. How you can tell? Did you do scope measurements on HT driving wires? Without scope you can tell pretty much nothing about health of CDI itself.

Some carbonation in exhaust pipes is normal. Carbonated plugs means either that they are too cold, engine runs too rich (now irrelevant after carb cleaning, carbs are now setup completely different) or that engine was run mostly for short periods of time and didn't heat up properly. Carbonated sparks may easilly cause your engine to run on less than 4 cylinders.

This type of engine needs quite exact air:fuel ratio to be able to run. It is not hard to get this ratio with clean carbs, but nearly impossible with some passages clogged. So clean your carbs once again and clean them properly! Also pay attention for basic setup.

I've had similar problem with my B400 after two partial cleanings of carbs, new spark plugs, repaired CDI and still unable to start. After complete 4 hour cleaning of carbs and basic setup it cranked on first try.

[Squishy]

Agreed..
My b400 runs fine.. but when one of the pilotjets was clogged it would need 30s of cranking to start up.
And this is with an engine that had been used only 3 weeks before.

I would imagine with an engine that hasn't run for longer, and might even have 2 cylinders clogged it will never start.

[shidoran]

So... compression test today (all units PSI)

Dry 125-125-125-125
Wet 200-135-185-165

Confirming my fears that compression is a bit of an issue. From what I can tell, each cylinder should be between 163 and 192 PSI with a difference of less than 28 PSI and the "use limit" (I suppose being the minimum compression for the engine to run) should be 113 PSI.

NO! Don't fiddle with engine internals just because you have feeling you have compression problems. From what I have seen, even abused engine will have usable compression after twice as much km than yours still having 1* idle and running stable on all four cylinders. Await compression loss after 120000+ km.

You stated that:
* you bought new sparks. Which sparks? Are the *EXACLY* by service manual specification?
* you have pretty good spark. What does it mean? Suzuki suggest that ignition system in good condition *MUST* be able to fire spark between two nails with 8mm gap
* CDI seems to work. How you can tell? Did you do scope measurements on HT driving wires? Without scope you can tell pretty much nothing about health of CDI itself.

Some carbonation in exhaust pipes is normal. Carbonated plugs means either that they are too cold, engine runs too rich (now irrelevant after carb cleaning, carbs are now setup completely different) or that engine was run mostly for short periods of time and didn't heat up properly. Carbonated sparks may easilly cause your engine to run on less than 4 cylinders.

This type of engine needs quite exact air:fuel ratio to be able to run. It is not hard to get this ratio with clean carbs, but nearly impossible with some passages clogged. So clean your carbs once again and clean them properly! Also pay attention for basic setup.

I've had similar problem with my B400 after two partial cleanings of carbs, new spark plugs, repaired CDI and still unable to start. After complete 4 hour cleaning of carbs and basic setup it cranked on first try.

I don't have a 250 manual. If you know where to get one that would be handy. I've been running off the B400 manual, the japanese website (http://www1.synapse.ne.jp/s-hara/bandit/ban-spece.html#maint-eg) and some help from forums like this.

CR8E's for the plugs, as per the website above and that is what the old plugs were.

Poor spark is still spark, and it should still run (albeit poorly, or at least make some sort of effort to run). From what I can see, it's got pretty good spark. Can't see why it couldn't do 8mm but I could check it if it's that important.

The whole ignition system seems fine. If it's getting spark at the right timings from each coil, tells me the CDI should be OK. I can go through and test it all but I think I'd be looking in the wrong place.

I could clean the carbies again, and I will. But they were bone dry. Nothing in them. No build up, absolutely spotless. Checked the jets too - nothing. When I put a few drops of pure fuel into the plug hole and she didn't at least fart then that tells me no matter what I do to the carbs I don't think she will go. She sounds so low on compression the test I did today kind of confirms it.

I've cooked an engine before on a car that lost compression and the thing sounded like it would shake itself to pieces when I tried to start it up but it didn't go. Like it was trying to but couldn't. Nothing like that happening on this bike though.

Do I continue with my suspicion and start to dig down towards the pistons?

[ventYl]

So... compression test today (all units PSI)

Dry 125-125-125-125
Wet 200-135-185-165

Confirming my fears that compression is a bit of an issue. From what I can tell, each cylinder should be between 163 and 192 PSI with a difference of less than 28 PSI and the "use limit" (I suppose being the minimum compression for the engine to run) should be 113 PSI.

125 psi dry equals 8,6 atp. Quite similar to mine compression pressures. This should not be an issue ,motorcycle must be able to run even with one ignition coil disconnected. You have quite a huge difference between them indicating that service should be done, but not that engine shall not crank. I've seen machine running without no problems with compression pressure around 90 psi and lower limit for gasoline mixture to be ignitable is even lower, around 65psi. But you can expect power loss of course, yet nothing strongly critical. Machine should still be able to operate.

NO! Don't fiddle with engine internals just because you have feeling you have compression problems. From what I have seen, even abused engine will have usable compression after twice as much km than yours still having 1* idle and running stable on all four cylinders. Await compression loss after 120000+ km.

You stated that:
* you bought new sparks. Which sparks? Are the *EXACLY* by service manual specification?
* you have pretty good spark. What does it mean? Suzuki suggest that ignition system in good condition *MUST* be able to fire spark between two nails with 8mm gap
* CDI seems to work. How you can tell? Did you do scope measurements on HT driving wires? Without scope you can tell pretty much nothing about health of CDI itself.

Some carbonation in exhaust pipes is normal. Carbonated plugs means either that they are too cold, engine runs too rich (now irrelevant after carb cleaning, carbs are now setup completely different) or that engine was run mostly for short periods of time and didn't heat up properly. Carbonated sparks may easilly cause your engine to run on less than 4 cylinders.

This type of engine needs quite exact air:fuel ratio to be able to run. It is not hard to get this ratio with clean carbs, but nearly impossible with some passages clogged. So clean your carbs once again and clean them properly! Also pay attention for basic setup.

I've had similar problem with my B400 after two partial cleanings of carbs, new spark plugs, repaired CDI and still unable to start. After complete 4 hour cleaning of carbs and basic setup it cranked on first try.

I don't have a 250 manual. If you know where to get one that would be handy. I've been running off the B400 manual, the japanese website (http://www1.synapse.ne.jp/s-hara/bandit/ban-spece.html#maint-eg) and some help from forums like this.

CR8E's for the plugs, as per the website above and that is what the old plugs were.

Poor spark is still spark, and it should still run (albeit poorly, or at least make some sort of effort to run). From what I can see, it's got pretty good spark. Can't see why it couldn't do 8mm but I could check it if it's that important.

False! You are trying spark under normal atmospheric pressure and with a lot of air. In cylinder you have much higher pressure and different mixture of "athosphere" so conditions for spark are drastically changed. Don't assume that if you see spark outside it also happens inside, much more that even if it happens, it is able to ignite mixture. So once more. Suzuki suggests that ignition system should be able to fire spark with two nails over 8mm gap. Does your's? Does it at least over 4mm gap? How specifically did you check ignition system? What measurements did you do with what results? Be more specific to get more specific help.

The whole ignition system seems fine. If it's getting spark at the right timings from each coil, tells me the CDI should be OK. I can go through and test it all but I think I'd be looking in the wrong place.

I could clean the carbies again, and I will. But they were bone dry. Nothing in them. No build up, absolutely spotless. Checked the jets too - nothing. When I put a few drops of pure fuel into the plug hole and she didn't at least fart then that tells me no matter what I do to the carbs I don't think she will go. She sounds so low on compression the test I did today kind of confirms it.

I've cooked an engine before on a car that lost compression and the thing sounded like it would shake itself to pieces when I tried to start it up but it didn't go. Like it was trying to but couldn't. Nothing like that happening on this bike though.

Do I continue with my suspicion and start to dig down towards the pistons?

No, let it be as it is! Make the rest of bike top condition and if even after this it won't start you can always return back to engine itself and break it up. If you disassemble it, you have to make all steps prior to close it which could be expensive.

Did you clean not only jets but also emulsion tubes of main system? Did you clean thin air and fuel passages? Are all tubes inside carb freely passable?

[shidoran]

The issue to me is not necessarily the low compression, but the variance between the dry and wet test. That immediately indicates a ring or piston problem. In terms of the ignition system I've tested the resistance of both the primary and secondary windings on both coils and they are fine. The HT leads are brand new. Plugs are new. I haven't looked at the reg/rec but I did test the stator phase windings resistances and do the short test and it looked fine.

I took the head off to have a look at the timing and honestly I'm not entirely sure but gut feel is that it is ok. When #1 is at TDC , arrows 2 and 3 are pointing upwards on the cogs and according to the B4 manual that looks correct. The disk is aligned with one of the marks too.

I did replace the flywheel, but being on the opposite side to the disk I couldn't see how the flywheel needed to be timed to the stator. It wasn't keyed and had no markings on it I could see - I think it must run independent of the timing... is that a correct assumption?

Here it is kicking over

http://youtu.be/CHVXFTBjXEU

[ventYl]

i've seen that bike with dry compression pressure around 6 bar and wet compression of 8,5+ bar was running fine until carbs started to leak heavilly.

Manual itself says that ignition coil resistance measurement is only orientational and coil still can be dead. One of my B400s have coil which' primary and secondary resistances are within tolerances set by manual, fires spark if tested outside but bike runs only on two cylinders. Spark is just too weak. But coil is formally in good condition.

[shidoran]

Ok sorry for the delayed response, got hit left right and center by work so haven't had time to look closer.

I'm soaking the carbies at the moment, all the bowls were filling fine last time I was cranking. I did the compression test again and got similar readings.

It's a fair enough argument with what you're saying about the spark so I'll have a closer look at it. I'll put up some videos or something of what kind of spark I am getting at the plugs. My gut feel says even with weak spark the bike should still sputter, but due to the consistency during cranking I'm doubting that's the problem. I may have to dig deeper and look at the rings... but where the heck would I get new rings or a head gasket for this bike if I needed them? I can't seem to find them anywhere...

[shidoran]

Well I'm giving it another crack. New pistons and rings, compression test and she's very low at about 75. Timing's out. Can someone clear up what TDC is on the restricted (GSF250P) rotor please? Is it the "T" mark or the mark after the "T"?

16 pins between the relevant teeth and I'm almost there. So close.