carburettor problems?

[erik]

I was riding the Zeal around today for the first time I've gone for a proper ride (I'd only ridden once around the block on it before), and several times the engine has died as I'm downshifting.
After my first ride, I went out again to try to see what I have to do to make the engine die. I haven't been really scientific about what conditions it needs, and what don't matter, but it seems it does it when you're cruising along with the engine doing about 6000rpm and you quickly close the throttle and disengage the clutch. It doesn't do it all the time, but quite often. And if you do engage the clutch again, the engine will start up (like a push start).
I've got an uncle that's done some work on bikes before, but more on trucks and cars, but he thinks it's probably something with the carbs. I'll take the bike and see if he can help me sort it out later this week, but I was wondering if anyone here could give me any advice as to what might be wrong, and what needs to be done to fix it.
I have almost no experience fixing/maintaining bikes (or cars), but I'd like to learn how to maintain and fix my own.
Any advice would be greatly appreciated.
Thanks.

[Jackrat]

Mate from what you have already told us I would say just for a start DON'T RIDE THE BLOODY THING.If you hav'nt already had them steering head bearing replaced,then do so NOW,And your wheel bearing at both ends.
These things have the potenal to KILL you.
As for your other problem you can have the shop sort that out for you at the same time.Get the bike sorted by a good shop and then you will know what you have on your hands and can start your own maintance learning curve.
Sorry to sound a bit harsh but I would of advised not to have bought the bike in the first place.You have around $150-250 to spend in parts alone just to get the thing safe.Once again sorry to rain on your parade and best of luck.

[erik]

Jeeze, that is pretty discouraging. But I'm still hoping I'll be able to change the bearings and hopefully sort out the engine stopping problem with my uncle.
How bad do bearings have to get before they are really dangerous to ride on? And what happens when they fail?
I got a book out from the library called "Motorcycles: Fundamentals, Service, Repair" that looks pretty detailed, so I'm going to read up about carburetors to improve my knowledge. Even if it turns out I do have to take the bike in to a shop for experts to fix it, at least I'll have a better idea of what they're doing.

I'm still wondering what might cause the engine to die like that. Is it possible to guess, based on my limited description of the problem?

[Slingshot]

It could be similar to a problem I'm having, I'm pretty sure that one or more of the floats in the carbs is sticking open and therefore flooding the engine.
I'm going to pull the carbs off this weekend and see if I can clean them out, I'll let you know how hard it is once I get it all back together.

As for the steering head bearing...I would say if Jackrat thinks you shouldn't be ridding then he probably knows best.

[Jackrat]

Mate I will send you a PM.
Check your messages.

[erik]

Jackrat, I've sent you a PM too.

Slingshot, good luck with cleaning the carbs and sorting out your problem. I'd be interested to know how it goes.

I guess I'll only ride the bike if I have to, like to take it to my uncle's, which isn't far away. The steering head bearings aren't vertically loose, the mechanic said they were tight, but because it still clicked a bit when you hold the front brake and push forwards and backwards, he said they can't be tightened any more and need to be replaced. He went for a test ride on it, so hopefully it'll be ok for the short ride to my uncles.

[erik]

Well, I took the bike over to my uncles yesterday evening. He said he couldn't see anything wrong with the front wheel bearing that the mechanic said was "starting to fail". He said he could help me replace it if I want, he'll help me replace the steering head bearings when I get new ones. But he said the steering head bearings weren't bad enough to be dangerous. They're not loose vertically, and there aren't notchy either, they just click a bit when you hold the front brake and push forwards and backwards on the handlebars. But I'll probably replace them some time next week, or next weekend.

But he said he can't really help me with the carburettor problem, and that I should probably just take the bike into a bike shop and have someone else look at it.
I don't want to do that unless I really have to.
Anyway, I was having a look at the bike today, I pulled the side fairings off and got the soldering iron out and found some old plastic and repaired a cracked bracket thing on it. And I kind of had a look under the tank, but didn't disconnect the fuel lines, so I didn't take it right off. I was surprised how little of what I thought was the "tank" actually held fuel, and how much is just a cover for the airbox.
I haven't touched the carbs yet, except for trying to adjust the idle stop knob, but that didn't help. So I was thinking about pulling them off and cleaning them. But I didn't really like the idea of just pulling them all apart while not actually knowing what was wrong.
But then I remembered a test in the Motorcycle Evaluation Guide that said to check the exhaust pipe temperature near the cylinder head by touching them with a wet tissue. I tried it, and lo and behold, one of the pipes was way cooler than the other three when the engine was idling. If I rev the engine at higher revs for a while (4-5k) the cold exhaust heats up too though.
So I guess one of the cylinders isn't firing at idle. I don't know why though, I don't know if it's the idle mixture for that carb, or maybe it's out of sync with the others, or if there is something else wrong with that carb. But at least I've got a better idea of what the problem is. I think tomorrow I'll have a go at pulling it apart and see if I can learn anything else...

[merv]

But he said the steering head bearings weren't bad enough to be dangerous. They're not loose vertically, and there aren't notchy either, they just click a bit when you hold the front brake and push forwards and backwards on the handlebars.

If they aren't notchy they might be OK to tighten up a little bit more. Are you sure its the bearings clicking and not something else like the brake pads when you move back and forth? You are putting your finger on the top of the steering stem and the bearing housing to feel if its moving or clicking and likewise at the bottom of the steering stem when you are trying this?

A few years ago I was silly enough to think while I'm getting new tyres put on the bike I might as well get the shop to do the WOF. I got told "your steering head bearings are a bit dry". I asked how could you tell that? Got spun some bullshit - but really most of any feeling turning the steering side to side is all the cables and whatnot moving around. So I said don't be so bloody stupid, give it the warrant and I'll go home and dismantle them and check them. I did that and found they were beautifully greased and the bearings were still in good nick. I just rotated the races a bit so they wouldn't be working in the same spot as before, regreased them and put them back together. Then I rang the shop (think I sent a detailed e-mail too) and told them they were fine.

Moral of that story is getting a WOF from the guy that would benefit from you having to get work done at his shop is to be avoided. I take my bikes to the local car workshop or VTNZ and don't have problems with either of those places being picky about bikes that I maintain in new condition.

But then I remembered a test in the Motorcycle Evaluation Guide that said to check the exhaust pipe temperature near the cylinder head by touching them with a wet tissue. I tried it, and lo and behold, one of the pipes was way cooler than the other three when the engine was idling. If I rev the engine at higher revs for a while (4-5k) the cold exhaust heats up too though.
So I guess one of the cylinders isn't firing at idle. I don't know why though, I don't know if it's the idle mixture for that carb, or maybe it's out of sync with the others, or if there is something else wrong with that carb. But at least I've got a better idea of what the problem is. I think tomorrow I'll have a go at pulling it apart and see if I can learn anything else...

Sounds like that could be an electrical problem as another option - coil, plug lead or something like that. If the cylinder is cutting out it won't necessarily be due to carb problems

[erik]

Are you sure its the bearings clicking and not something else like the brake pads when you move back and forth? You are putting your finger on the top of the steering stem and the bearing housing to feel if its moving or clicking and likewise at the bottom of the steering stem when you are trying this?

I haven't tried putting my finger on the bearing housing, but I'm pretty sure it's the bearings. I'll try checking it with my finger on the bearing housing after I've got the tank etc. back on the bike.

I take my bikes to the local car workshop or VTNZ and don't have problems with either of those places being picky about bikes that I maintain in new condition.

It's a bit of a worry that mechanics would do that. I'd like to think most of them are ok, but I guess when I need to renew the wof, I'll take your advice and go to VTNZ.

Sounds like that could be an electrical problem as another option - coil, plug lead or something like that. If the cylinder is cutting out it won't necessarily be due to carb problems

Thanks for that tip. I stopped by at Henderson Motorcycles yesterday, and the guy there told me that it might be the spark plug. So I pulled it out and checked it, but it looked ok. It was a pain trying to clean the grit out from around the plugs before I took it out.

After checking the plug, I thought I'd have to pull the carbs apart and clean them out. So I spent the rest of my saturday pulling the bike apart to get to the carbs. At the end of the day I had them off the bike, but hadn't started to disassemble them yet. Yep, I'm a slow worker. But it was fun, I think I must've spent as much time standing around looking at the bike and grinning as I did actually pulling it apart.

This morning, I went looking for carb cleaner. In the bike maintenance book I've got it said that decarbonising solvents (also called cold soak cleaner) was what to use for cleaning the carb, and that you needed to take all the rubber, plastic and fibre bits off, and then immerse the carb in the stuff. Repco didn't have any of it, and neither did some other auto parts shop. So in the end I just bought myself a spray can of CRC carb cleaner.
But the carbs were all covered in dirt/grease on the outside, and my uncle suggested that I should have used an engine degreaser while they were still on the bike, so that I didn't have to deal with so much outside dirt when I was trying to clean the inside of the carbs.
He also said I should try just adjusting the idle mixture screw before pulling the carbs apart. Now, I know I should've tried that before pulling the carbs off the bike, but I'm new at this, and I guess I was kind of looking forward to pulling it apart.
So I figured I'd put the carbs, airbox and tank back on the bike and try cleaning it and at the same time try adjusting the idle mixture screws. Before I put the carbs back on the bike, I checked the screws to see how far they were wound out. The carbs for the three good cylinders all had the idle screws set at about 2.5 turns out. BUT! The screw on the cylinder that wasn't running at idle was only screwed out about 1 turn.
Anyway, the carbs are back on the bike and I've cleaned the outside of them, and tried adjusting the idle screw for the cylinder that wasn't going, and then did the wet rag on the exhaust header test and all the cylinders were going. It was idling a bit faster than before as well, so I tried adjusting the idle stop screw to get the revs down, which worked, but I'm wondering if I've got it set too low now, because when I checked the exhaust header temperatures with the wet rag, the two inside ones seemed cool and the outside ones were hot. I tried adjusting the idle mixture screws a bit more, but I couldn't tell if they made any difference, so I've just left them where they were, at about 2.5 turns out each.
So now I guess I need to read up more about tuning carbs. I'm wondering if they need to be synchronised, and also what the proper way to get the idle mixture screws set just right is. And I need to know where the idle stop screw should be set.

Anyone got any links/know any good books where I can learn this?

It wasn't a total waste of time pulling the bike apart, aside from it being fun, I discovered there wasn't any airfilter in the airbox, so I'll be getting one of those as soon as I can. Hopefully running without one hasn't damaged it.

[Jackrat]

Try this.
http://www.cyclemaintenance.com/fuel/fuel_trouble.htm
I know what you mean about looking an grining,It's fun Aye!
You will probably find the bike will run a bit rich when you put in your new air filter.Good luck mate,your doing well
Oh yeah,The idle seting only effects the idle nothing else.All things being correct you should be aiming for about 1200rpm at idle.

[PeteThePom]

eric [img]file:///D:/Docs/stop.gif[/img] before it's too late!!
It sounds to me like your sufferng from too much enthusiasm and not enough knowledge. I don't mean to piss on your parade but jap multi's are notoriously sensitive to having their carbs messed with and it can turn into a nightmare if you dont now what your doing! Anyway enough of the constructive criticism and onto something more helpful.

Yes your carbs will need synchronising, especially after they've been take apart, you need a set of vacuum gauges to do this, failing that a shop shouldn't charge you any more than an hour's labour to balance them assuming that is all that is needed.

As for the mixture screws they shouldn't need moving from factory setting but the fact that you mention no air filter means the engine would have been running lean, this CAN lead to melting pistons but only if you thrash your bike everywhere or do a loooong motorway cruise at high speed/revs.

If I were you I'd get an air filter, balance the carbs, reset mixture screws to factory setting and then see what you have at least you are then starting from a known point.

It sounds to me like you may have a blocked pilot jet in one or more of your carbs from what you describe, which combined with no air filter and the fact that the carbs have been off the bike means that your carbs will be all over the place hence the dodgy tickover, you may also have an air leak between the carbs and engine!!

You say you dont have any experience of bike maintenance and I'd say that this is probably a bit advanced for you at the moment, take it to a 'good' shop and get it fixed then you can hopefully deal with easier stuff as it crops up, learning is a gradual process. Having said that I'd love for you to prove me wrong and fix it yourself!
Kepp on fiddling with your bike, it is rewarding, just one note of caution, know your limits and don't be afraid to ask!

[erik]

Well, I spent all afternoon yesterday synchronising the carbs, setting the idle, and putting the bike back together. But when I went for a ride in the evening to test it, the engine was still stopping near idle. This morning I tried richening the idle mixture. It seemed to fix the dead cylinder so they were all firing at idle. But when I went for a ride, it was cutting out worse than before.
I've noticed it sounding a bit weird while I was riding before, not just at idle, and I got dad to listen to it sitting in the driveway this morning. He said it sounds a bit like there might be an electrical problem. So merv, your suggestion might be right.
I've recorded the engine sound, with the bike sitting on the driveway. I was revving it up to about 4000rpm. I don't know if you can tell anything from the (zipped) wav file, but I thought I'd post it just in case.
I'm going to go and read all I can from that bike maintenance book about electrical stuff. Pete, I don't know about me having too much enthusiasm, sometimes I feel like giving up completely. But you're definately right that I've got a lack of knowledge. I think I'll keep reading stuff, and hopefully I'll learn enough to sort it out myself, or learn enough to know that I need professional help .

It looks like I'll be taking the bus to uni for a while...

[erik]

http://www.kiwibiker.co.nz/forums/at...tid=1090&stc=1

Ta Da!!!

I spent most of yesterday evening carefully pulling the carbs apart. Before I had to stop for dinner, I'd managed to get them all in bits.
I haven't cleaned them yet, but the only thing that I've found wrong with them was there was some plastic dust on the outside vent part of some of the diaphrams, and there was a missing o-ring at the bottom of one of the plastic slide guide things, but I don't think either of those things would cause much of a problem.
Earlier yesterday, I'd bought some new plugs to try. I got some slightly hotter ones, because the old ones were a bit carboned up, and I read an article on the net saying that manufacturers often recommend too cold plugs, and one of the symtoms of cold plugs is that they don't get hot enough to stay clean.
They didn't seem to make any difference either. The engine still sounded like it was misfiring, and it still stopped when I accelerated up the drive then let it go to idle and grabbed the clutch.

So this morning, I was wondering what else it could be. I had a look at the alternator/timing sensor thing, but it can't be adjusted, so I just put it back (it's lucky it can't be adjusted actually... ).
Then I thought I'd have a look at the ignition coils, leads and plug caps.
After pulling them off the bike, I tried testing the resistance of the primary coils (2~3 Ohm), the secondary coils (~15k Ohm), the HT leads (0 Ohm), and the plug caps (~10k Ohm.... mostly).
In the first coil I looked at, one plug cap had 10k Ohms resistance, the other had 39k Ohm resistance! So I checked the other two plug caps, and they were both approximately 10k Ohm.
I think I found the problem!!!!
http://www.kiwibiker.co.nz/forums/at...tid=1091&stc=1

I've gotta admit I feel a little silly for not checking the leads and caps earlier. But I guess I've learned more about my bike this way, than if I'd just straight away found the problem .

I did some googling on the net for info about resistor plugs and plug caps, and found a thread where a guy suggests taking out the resistors in the plug caps. I haven't opened the caps yet, but I think they have a slot in them, like the guy describes, so I'm guessing one of the resistors is stuffed (the sparkplug that cap connected to had some corrosion on it, so maybe that contributed to it failing, or was related to it).
The guy actually suggests completely removing the resistors from the caps. I'm wondering about this, because the spark plugs already have a 5k Ohm resistor in them, plus the 10k Ohm resistance in the caps makes me wonder if there is too much resistance? Thoughts anyone?
I guess I'll leave the resistors in the caps and try replacing the dodgy one, and then see how it runs.

[Jackrat]

Yeah,I would just replace the dodgy one.
Ain't it odd,it's always the last thing you check.
Well not really huh!!

[erik]

Just in case anyone's intersted:
I think I've got the engine sorted. I replaced the spark plug cap and two of the leads, I was going to replace all 4 leads, but it was such a mission just doing two (getting them into the clip that holds them into the ignition coil) that I figured I should probably go by the old saying of "if it ain't broke, don't fix it" since there wasn't actually a problem with the old leads.
I haven't tried the old spark plugs in it again, but I'm guessing it was probably a waste of time replacing them.
And I think it wasn't necessary to clean the carbs. The jets all seemed clean enough when I pulled them apart. I did end up replacing 1 of the seals in each carb (the one that goes between the jet assembly thing and the rest of the carb, inside the float bowl), because they looked old and kind of hardened. They're shockingly expensive, $11 bucks each. Still it wasn't as expensive as a simple o-ring that goes at the bottom of the plastic guide thing for the throttle slide, the guy said just one of them was $25, which is nuts, because it's just a plain o-ring. One of the carbs didn't have one in it, but because they were so expensive, I figured I'd leave it out, I don't think it had much, if any effect.
After I'd got the carbs back on and synchronised, and the new plug cap and leads on, I tried adjusting the idle mixture. I found that if I richened it (I had the screws up to 3.5 turns out at one point), the idle seemed a bit smoother, and it seemed ok when I just revved it sitting still on the drive. But if I got on the bike (sitting on the pillion seat since the main seat wasn't on it ) and accelerated up the driveway and then cut the throttle and disengaged the clutch, the engine would die. So I tried leaning the mixture out (it's at 2.25 turns out now) and it seems to be ok, it doesn't die anymore. I guess maybe the stuff I found about setting the idle mixture in this post: newsgroup post applies more to when the engine is under load.

So far I've only been on one short ride on it, but the engine didn't die once (except when I pulled up at the post office and put the stand down before putting it in neutral I'm a newbie, and a rusty newbie at that!).

I changed the fork oil too, and I think the front suspension feels a bit better now. The old oil had a fair bit of black silt-like stuff in it.

Hopefully that's all the problems I'll have with the engine for a while! Thanks everyone for your help/suggestions.