Mystery rough-running problem - please help

Hoping for some help from the Brains Trust to get my Bandit running right.
 
It’s a long story, but the important points are:

• It’s a 1997 Bandit 1200 with some modifications.
  
• These problems only show up when the engine is HOT.
  
• It won’t rev above 6k RPM, at which point it fits and farts like it’s hitting a dodgy rev limiter or something.
  
• At lower speeds it runs rough, as if it were only on two cylinders, and this symptom clears somewhat when the throttle is opened wider.
  
• One of the modifications is an Acewell digital dash, on which the gear indicator behaves weirdly, giving a reading that I’m in 8^th gear.
  

 
The mechanic at the moment is looking into the possibility that there’s something going wrong with the relationship between the Throttle Position Indicator, the Gear Position Indicator, the CPU and thus the timing.
 
Is there anything I can tell him that is a known trouble spot on these older Bandits?
 
I’ve already spent an eye-watering amount of $ chasing this problem, from a Dyno run (where the bloody thing behaved perfectly), a new (S/H) air box and K&N filter, new coils (they were arcing across to the engine) and leads & plug caps & Iridium plugs.
 
While it’s nice to know that the bike has some new bits, none of them improved the problem.
 
Any help would be appreciated.

I've put this up on the FB page too, and i'll probably be able to check that more frequently, because this forum is really hard to read on the phone.


Matt

All the watercooled guys have immediately thought - you need Gus  :   https://nswbandits.forumotion.net/t1379-fuel-pump-fix

Your symptoms absolutely fit this filter problem.

Wait for an oilburner owner to confirm the filter setup for the 97 model.

Thanks Tag.
I had a good read of Gus's solution, but as far as i can tell we oil burners don't have fuel pumps. The fuel is gravity fed into the CV carbs from the tank tap directly above them.

Thought as much, but was referring  to the 97's filter setup (not pump) and attempted to not put my foot in my mouth

Hi Mate, I guess lets start from the top.

Before and after latest mod and tune. Is it exactly the same as it was, or have you now got more problems.

So when it was on the dyno, the bike was running right?
When you rode it home directly from dyno, was the bike at any point, still running well, or was it a pig straight away? 

From what I understand, you only had problems under 4000rpm pre airbox, and upper revs where fine, but now not?

Now you have problems everywhere?

I`m assuming when fitting the airbox, all the vacuum lines have now been reinstated, and none have been knocked off, as it sits at your place right now? (just doing check list)

All the feed wires to the coils are mounted correctly and not loose?

Just curious, is the peat cock valve, now vacuum operated with the airbox now reinstated, or is the peat cock valve on prime?
How were you running it before with no airbox? 

Got to start somewhere here.....


P.S...You haven`t accidently got the choke on?

Have the carbs been synced? I top reckon the bike is starving for fuel if it won't Rev

Hi Mate, I guess let’s start from the top.
 
Before and after latest mod and tune. Is it exactly the same as it was, or have you now got more problems.
It was slightly worse. Though I must clarify - the bike was running rough only on smaller throttle openings and only up to about 4k RPM, after which it sort of cleared.
I will add though that initially the roughness 'felt' like a carby issue. But after the airbox was fitted the roughness was worse, but took on an electrical 'vibe'. I'm not an expert, just giving you my intuitive vibe of the thing...
 
 
So when it was on the dyno, the bike was running right?
When you rode it home directly from dyno, was the bike at any point, still running well, or was it a pig straight away?
It ran smoothly on the dyno but was just the same when I rode home. I later thought that perhaps the problems only showed up when the bike was hot.
There were two dyno runs, one was only slightly rough, then the guy removed the pod filters and it ran more smoothly, all the way up to 9k RPM.
That was late December, and I booked it in with him for a tune in the new year. At the time he threw my "crap" pods in the bin and told me to come back the next day after he'd ordered "proper" ones. I did, but they didn't arrive for a week, and when they did they wouldn't fit. By then I had taken a dislike to the guy and decided to search elsewhere for a solution, so I was riding around with no air filtration at all. Also by then I had been advised by so many people that it would never run right with pods, so I had determined to get an air box and take the arrangement back to standard.
 
From what I understand, you only had problems under 4000rpm pre airbox, and upper revs where fine, but now not?
As a 'returning rider' I must confess that I was riding around fairly gingerly, not often getting the revs up into the upper range. So I’m tempted to say that yes, pre-airbox the bike revved better, but I can't say for sure because I wasn't riding it that hard.
 
Now you have problems everywhere?
So it would seem. After the airbox, air filter and spark plugs (and an oil and oil filter change for good measure) I collected the bike and it was worse. I'm not sure whether to be pissed off at the mechanics or not; I had asked them to fit the airbox and filter then balance the carbs and do any re-jetting as necessary. But after fitting the airbox and taking it for a (cold) test ride they pronounced it "fixed" - no changes to the carbies. I collected it and gave it a hard time on the freeway. After it was properly hot the low-end symptoms returned, a little worse than before, and trying to rev it out in 3rd gear on the freeway showed up this top-end trouble.
I returned to the mechanic and told them it was worse. They then started leaning towards the electrical side of things, and next day called me up saying that the coils tested as 'bad' and were arc-ing to the motor, and the spark plug caps were dodgy too. They ordered new ones and only today called up to say that after fitting the new coils and caps the problem remains the same.
 
I`m assuming when fitting the airbox, all the vacuum lines have now been reinstated, and none have been knocked off, as it sits at your place right now? (just doing check list).
It's still at Midlife Cycles in Richmond, where it's been since the 6th Jan, busy consuming new part and labour for no result. I have to confess to not having had a good enough look at the connections before and after the fitment of the airbox.
 
All the feed wires to the coils are mounted correctly and not loose?
I hope so, but again I haven't seen the bike with my own eyes for a week.
 
Just curious, is the peat cock valve, now vacuum operated with the airbox now reinstated, or is the peat cock valve on prime?
How were you running it before with no airbox?
Another excellent question I’m afraid I don't know the answer to. I ran the bike out of fuel on the "main" setting once and flipped it around to "Res" then back again when I’d filled up.
 
Got to start somewhere here.....
 
P.S...You haven`t accidently got the choke on? Nope, that one I CAN answer.
 
Just to rule it out, is there any relationship between the CPU (and thus the spark timing) and the Gear Position Indicator?
 
So, to summarise some of the things to check into from your post:
·         Check that the vacuum lines are all correct for the airbox.
·         Check that the vacuum lines are all correct for the fuel tap.
·         Check that the feed wires for the coils are snug.
 
I also put this question up on the FaceBook Bandits page, and some suggestions from there are:
·         Check that the Throttle Position Sensor is set to the correct impedance.
·         Check for loose electrical connections up around the head, as they are prone to corrosion.
·         Check the float heights on the carbs, as Bandits are very sensitive to these being out.
·         Check that the carbs are in sync.
 
As you can imagine, I’m still stumped.


In theory if I can only get an accurate diagnosis then the problem can be confronted. But until then I just have my friendly mechanics replacing parts and see if that works. An expensive way to go about trouble shooting.

I`m no electrical wizz, I`ll make that clear right now, but my gut feeling its all carb tuning. It may have something to do with the said Gear Indicator, but if there`s interference going on there, then disconnect it, and see if it helps? (My opinion, you don`t need it- do you need someone to tell you, you`ve got an itch)

In this case, I`d be starting from scratch, ripping the carbs off, and going through the check list.

1-Float levels. 14.7mm( as per factory)
  
2- Are the "Needle Jet (Emulsion tubes), and the "Jet Needles", in good condition.     
(The Gen1 carbs are a bit temperamental, and if these are worn, will make it run rough, but not to the degree that your talking about, but as a combined thing, if everything else isn`t tuned right, wont help.) 

I`d like to know what needles are in your bike right now??????? Are they factory ones now back in, or are they after market, with a different tapper?????

With the pods on, you really should have had different tapper needles , as the stock ones wont help your tune. But if they weren`t ever changed,( maybe why it ran bad down low to begin with) and you still have stock needles in, what main jets are you now running? were they changed to back to 102 mains now???  What was in them to begin with? 

3-What clip, are the needles on now?, as this determines how the bike runs in your transition from pilot circuit, to main jet,(which effects the main torque and feel of the bike) and if these aren`t on the right clip for tune, will make the bike run like shit too, taboot. 

4- Was the pilot circuit checked to see if the pilot Jets are now factory?

5-The airbox that was just put on, has it still got the original snorkel in it, or removed?  Has it got any extra holes in it, for what ever reason?


I`m still thinking the thing hasn`t been set up right.  Find out EXACTLY, what is going on inside the carbs.

What exactly, did the latest hands that touched it, actually do to it. Did they just fit the airbox at your request, and didn`t address everything that goes along with it?

You need to find out all specifics to know where you stand, and understand, what`s going on here.

Don`t worry about the peat cock question, as you must still have the vacuum line from your carb to the peat cock valve, so that's all good.

As Reddog has said, make sure the carbs are balanced.

TPS.. I can disconnect mine, and it still runs fine, That's both on my Gen1, and Gen2( I can only speak for the 1200`s, not the 1250`s)

Thanks so much for taking the time to help me out. I'm getting quite an education here.

The bike came with pods and allegedly has a Dynojet kit installed, standard headers and a Remus muffler.

You're right, i don't need the dash to tell me what gear i'm in - i was just wondering if the CPU needed to know what gear the bike is in for any reason.

The air box i bought from a wreckers, it had no extra holes in it and i didn't see a snorkel.

When i took it to the mechanic initially i gave them the air box i had bought and told them to install it and tune the carbs. They called me and said that they had installed the air box and taken it for a ride and it ran great, so they didn't do ANYTHING to the carbs.

I'm going to let the mechanics have one last crack at it next week, and i'm compiling a list of your expert advice to set them on the path to righteousness. If your gut feeling is carbs then that's where i'll get them to start.

I`m no expert!!!!!,  but have played with the carbs on Gen1 and Gen2, and if any one thing is out of sync, they do run like shit.

They told you the bike ran great??? you get on it, and it runs like shit??? hold them accountable, and if they chuck something back at you as an extra, prove what the problem was/is!!!!

Ask them what the settings are.    Jet sizes, needles clip height, what needles are in them, before and after.

They would have had no choice, but to pull the carbs apart, to tune it back to an airbox setting. If they never did that, and said it ran great, I call bullshit on their behalf!!


I have only recently, totally rebuilt my Gen1 carbs: 

 Totally stripped the carbs apart, and soaked them in a carb cleaner solution 
 New O rings through out.
 New float bowl needle and seats
 New diaphrams
 New emulsion tubes and needles

I put everything back together at factory settings, and straight away, the thing ran sooooo much smoother, and it was near factory settings to begin with. I then dynoed for A/F only, not to re-jet for more power, just to smooth out, the best an old style carb can be(they will never be any where near as smooth as FI. The fuel mixture screw is so touchy, that an 8th of a turn on the screw, is enough to make it run like shit from idol to take off.

It maybe not your cup of tea, but if its not your main source of transportation, you should have a crack at pulling them apart yourself. A few reasons for this, its educational, so you know and understand how and what`s going on, also you are a witness to what is actually in your carbs. You`ll be saving a lot of money too!!!  Its really not that hard.
When you pull things apart, you lay them all out in order, and reverse the process when putting it back together.

I hear you, and thanks.

I agree, pulling them apart myself would be educational, and it is my cup of tea to learn how to take care of things myself.

I bought this bike after moving back to Melbourne after being overseas for a while. It was intended to be my only vehicle, and it is, but i live close to work and can tolerate a while longer on public transport.

I don't have very much in the way of tools or space to work, but i guess it wouldn't be too much of a hardship doing the work in the kitchen... It's not the whole bike, only the carbies.

Part of me thinks i should make them do what i asked in the first place, and to stop looking everywhere BUT the carbs for a solution. In light of your advice i'm beginning to think they're 'carb-ophobic' and it seems a few bike mechanics are.
But there'd still be tons of labour to pay for, even if they discount the price a little.

I've been without the bike for ten days already, maybe i should just take it back and have a crack myself. Let me ponder that a little over the rest of the weekend.

I have a workshop manual, and from you posts i guess i have the factory settings.

I've decided that I'll give Midlife Cycles one more shot at the bike this week. I thought i'd maybe bring the bike home and begin my carby education on the kitchen table, but i just remembered i have a landlord inspection this Wednesday!
So I've written them a long email, compiled from your expert replies to thsi thread, and we'll see how they go.

In case anyone's interested, here's my email. It might be too polite...

Good Morning Shane.
 
Over the weekend I consulted the Brains Trust of the NSW Bandits Forum, and the Facebook Bandits page.
 
I got a lot of replies, some well thought out, some just silly.
 
The consensus from those that seemed most knowledgeable is that the problem will be found with the carburettors.
 
Here is the list, in order of priority and likelihood of being the problem:
 
Fuel:
1.    Float bowl heights – Bandits are very sensitive to having the correct float bowl height. Factory setting is 14.7mm.
2.    Balancing the carbs – another known problem where small imbalances can have a drastic effect on running.
3.    Mixture screw – I’m told that even a 1/8^th turn in the wrong direction can make a Bandit not run at all.
4.    Emulsion tubes and needles – I have a new set of emulsion tubes here at home.
5.    The needle clip that the needles are supposed to be set on from factory is 0.5mm, many owners shim that up to 1.0mm and find more torque.
6.    The bike came with pods and an alleged Dynojet kit installed (102 mains are the factory ones). Now it has an airbox, so it presumably needs re-jetting, but try the above first.
7.    The fuel filter, up near (or inside) the petcock, is prone to becoming kind of glazed over with a clear film, and can need a proper scrub with a brush to clean it properly.
8.    And naturally the vacuum tubes that go into the airbox and the fuel petcock need to go back to standard, now that the bike has an airbox and not pods.
 
Possible electrical things to check, once all the carby issues above are checked:
9.    Electrical connectors up near the rocker cover are prone to corrosion due to the extra heat they experience.
10. Ignore the fact that the gear indicator on the dash isn’t working, there is apparently NO relationship between the gear selector and the ECU, the gear selector has no effect on timing, it can safely be disconnected (I know what gear I’m in).
11. Throttle Position Sensor (TPS) set to factory-correct impedance.
 
I have to say that so far I’m not a happy customer. I came to Midlife with what I believed to be a carburetion problem, That was the consensus on the Bandit forums when I first asked then over Christmas. Yet to date the carbies are yet to be cracked open. I believe we wasted last week chasing an electrical problem that turned out not the be the problem. You’ve had my only form of transport for 12 days now and the carby tuning I asked for is yet to be done – balancing, mixture, float heights and jetting (if needed).
 
Sure, the bike is better off with new oil, filter, plugs, plug caps and coils. But they’re not the problem I came to Midlife for a solution to. I understand that all these things are improvements to my bike. But you must understand that from my perspective I’ve burned through over $1,000 and the initial carby work I was asking for has not been started.
 
I sincerely hope that my bike is firmly on the ‘priority’ list for work this week. Please send me a quick email to confirm that you’ve read this email.
 
Cheers,

Matt Waite

I think you should change that to 'Probable Problem"
Also, I`d be ditching the term "expert"   We`re all inthusiast`s.   I`m not a paid professional, only adivising on my experience, unless of coarse, you`ve been given expert advise from a paid professional, from some site.

If they did the necessary changes, and put it back to factory settings, then the carb won`t be your problem.

But if the situation is, as you say, that the carbs have "not" been pulled apart, and put back to airbox settings, then this must be addressed.

i have a 1250 that did similar things a while ago and i took it to the mechanic - it was a dud spark plug cap

After my email Midlife Cycles called me.
Apparently the float levels, mixture and balance were indeed looked at back two weeks ago - they just didn't tell me and it was not on the invoice.
Even so, standard factory size main jets and emulsion tubes have been ordered and should arrive for installation today.

So to re-cap, the work done so far:
Changed from cheap pods to standard airbox (no snorkel).
K&N filter in the airbox.
Vacuum tubes re-attached in light of now having an airbox.
Float levels checked.
Carbs balanced.
Mixture adjusted.
Diaphragms and slides checked and cleaned.
Petcock and fuel filter checked and cleaned.
New coils, plug caps and plugs.

While waiting on the new jets and emulsion tubes, the mechanic was telling me he's concerned about the wiring. It's apparent that a previous owner has cut into various wires in the loom at various points, then re-connected them. They've been soldered, but he found plenty of corrosion on most of the connectors he opened up. He also found corrosion inside the TPS.

Fingers crossed that the new standard-sized jets make a difference, and that any more dodgy bits of wiring are rectified.
We shall see...

Mechanic called, he cleaned up corroded electrical connectors above the engine, replaced the mains and emulsion tubes to standard, cleaned and re-assembled the carbs and .... no change!
I gather he's a little frustrated too, though not nearly as much as i am.

Next on the to-do list is to disconnect the side-stand kill switch thing, just in case it's going silly once the engine is hot and the bike is up to speed.
If that doesn't work it might be time to try another CPU or TPS or both.

He said he'd given the fuel petcock a good look at everything seemed fine, but on the test ride, after the bike cut out altogether, it would only start on reserve. He's thinking of changing it out just to see.

All fingers seem to be pointing to electrical.

I see you`ve said that the "Main Jets, and Emulsion tubes are new"?( the emulsion tubes will only bring it back to a new state)
So I see the Jets were never changed with the airbox. It wouldn`t have run properly anyway, even if it wasn`t an electrical problem, as it seems to be.

You haven`t said if the Needles are now Factory, or if at all they were different?
If there was a Dyno Jet Kit in it when you purchased the bike, the kit may have had different needles?

Example: If you buy a Holeshot Jet Kit, for an open airbox, or pods, the kit comes with...

1-New and different tapper Needles, with shims
2-Different Pilot Jets
3-Different Main Jets         This is all to cater for a different operating atmosphere, with a removed airbox.

I`m just double checking.
I`m sure your Mechanic checked this anyway, as it would be too rich with Sharper Needles, at a Factory clip setting.

If I heard the mechanic correctly, all the jets and settings were standard, only the main had been changed.
So I believe now that the carbs are back to factory settings.

Assuming the search is now on in earnest in the electrical department, and knowing that the corroded connections have been cleaned up, the coils-caps-plugs are new, can anyone suggest a short list of electrical thingmabobs to investigate?

Has he actually had a meter on the tps and checked it is in spec?

Has the bike has a timing advance plate added? Does the bike get really hot?

I just saw you said, that after a test ride, it cut out, and would only start on reserve. The peat cock valve may need a kit through it.

Some people through out the world with 1200 Bandits, do suffer from problematic peat cock valves, that do need a rebuild kit through them.

An easy way to tell if its the problem is to put it on "prime",  the setting between reserve and on.

This will by pass the vacuum action of the peat cock valve, and become a straight dump of fuel.
This will not effect anything, as long as your float bowl Needle and Seat, are working properly.

I have a Pingle Straight dump valve, which eliminates the problematic vacuum system.

So before pulling it apart, its an easy quick test.

Had a long talk with Charlie, the mechanic at Midlife Cycled who is working on my bike. We talked about the petcock but he's certain that it is not the problem.
he spent the day going all over the bike's electrics with his meter and found:
The ground connection's resistance increased as the bike got hotter.
The alternator is pumping out 15 volts.
The TPS has it's factory correct impedance.
The crank ignition pick-up measured 200 ohms, which is way above factory setting of 130 ohms.
He took it for another test ride with the side stand switch bypassed and the bike was still the same. Given the above he wants to change the ignition pick-up for a 130 ohm one and test again. Suzuki want $260 plus freight from Japan, so i've bought one from Vic Motorcycle Wreckers for $60 and it's being couriered to Midlife tomorrow.

bloody hell mate...this is going to be a $10 000 Gen1 by the time you`ve finished with it!!!

So..when you first bought the bike and went for a test ride...what did the bike do?

Did it at any time run well, or was it always like this?

Yes mate, i'm at my wits' end!

The bike ran fine when i first bought it, and behaved well for about four weeks.
Then it started to just feel a little rough in the mid-range on modest throttle, sort of hunting and feeling like it was only running on two cylinders.

But as the weather heated up in December the problem became more pronounced. I spoke to a few people who told me that the pods would definitely be the cause and to put the airbox back on.

So when i first went to the mechanic i gave them an airbox and told them i wanted the airbox installed and the bike tuned to suit.

It's been downhill ever since...

plenty of people in the world with pods, and no issues, and by what your saying, it ran when you bought it,
 so its definitely pointing to something else....and a mystery at that!!!

Timing chain/ tensioner?