View Full Version : Cold morning, blocked carbs and whoops unscrewed idle!
Juniper
29th May 2014, 09:34
Hey so I had an interesting morning yesterday so thought I would post it. Maybe get some ideas.
Yesterday morning I went to go start my bike and it had totally frozen over (Left it outside as was at a mates place...she usually sleeps inside) and obviously it wouldn't start.
Used choke and wound the idle right up (or so I thought) and would start and then rev off to a stall. Figured it was cold and after some phone calls a mate thought that maybe one of the jets had frozen, so there I was heating my bike up with the hairdryer on the battery, in the engine as much as I could see without taking the tank off and down my air intake pipes (which actually lead nowhere) but I figured it would heat up the airbox and whatever else down there.
Got it going with the choke still in, and it heated up so much the fan kicked in. But it still wouldn't run without the choke and every time I even slightly twisted the throttle the revs would drop and it would either stall or when I let it off it would rev higher and then settle down to its fluctuating 3-5k. My bike idles at 1-2k depending on the weather, I ride at between 6-10 commuting and eco mode motorway (6th) and it redlines at 19. Open road is usually 11-14k.
I figured applying gas was flooding it so it would stall or when I let off it was revving higher to burn it off.
By then I had accidentally unscrewed my idle. Called George MD and he said I would need to take the carbs out to put it back in. Now bear in mind I'm at my mates house, no tools and typical girl knowing fuck-all about fixing it (or so I thought)
Made a few posts on Facebook and phone calls, everyone said carb problems. Mate came round and another guy from Facebook turned up with some tools. (Thank you biker community you ROCK!)
We took the fairings off and the tank (full tank of 98!!) the airbox and the thingy under the airbox that connects to the carbs. Started it up and watched the throttle turn open the float thingies (when looking down at the carbs in the bike the things that move up and down/open close by suction) and watched the bike drop revs and die.
When we choked the carbs (thats what FB Friend called it) by putting hand over each one so it sucked against our palm creating pressure it worked when the throttle was turned, the bike reved up and not down. Figured we'd fixed it so put it all back together and then it stopped working and went back to first paragraph problems. Took it all apart again and when extra fuel was dumped into the carbs by either choking them or blowing down the intake pipe to push fuel up it worked. Now this is the part we don't quite know how we fixed. The seals need replacing as each of them have been cut to make them fit and some silicone was applied to a couple of them which I think caused a problem in the first place by fouling them. We decided that it was a loss because the carbs weren't sucking fuel.
Mate figured out where the idle screw was meant to go in (without removing the carbs!!) and suddenly that fixed everything. We could take the bike off choke and now when the throttle was turned the bike reved up instead of down.
Other than coming to the conclusion that carbs are run on black magic and pixie dust. I want to know why and how they fouled and how/why we fixed it by flodding them with our hands over each one at a time.
I think that I understand that you can't run the bike with choke on when its warm..... but why? And that the idle is needed so that you can take the choke off and turn the throttle. Without the idle its got nothing from stopping it from stalling.
Ideas?
Cheers,
I'm a complete rookie when it comes to mechanical things, but to my understanding the bike will die with choke on at normal running temperatures because the air/fuel mixture is off. By choking the carbs you're blocking air thereby increasing the fuel in the mixture. Incoming fuel and air have gotta be at the right ratio for the sparks to ignite the mixture.
As for diagnosing the problems I wouldn't really want to comment because carbs confuse the crap outta me too. I took apart the one on my old car once and I told myself never again.
I'm glad I no longer have any carbed vehicles for this exact reason.
unstuck
29th May 2014, 10:06
Maybe there was something stuck in there that got forced through when you choked them. Carbs can be so much fun.:banana::banana:
Juniper
29th May 2014, 10:11
Yeah I'm thinking maybe that Sicilian crap?
But what would cause it to happen because it froze over?
Big Dog
29th May 2014, 10:49
Could be water. Droplets sink. Without significant pressure they don't fit through carb needles.
There are treatments you can buy. In the nineties I used to use a tablespoon of diesel or a teaspoon of white spirits, paraffin or some other thinners to about 17 litres ( or a tank).
Stupid phone / Tapatalk, apologies in advance.
Big Dog
29th May 2014, 10:57
Or if already caught out, shaking the bike side to side by turning the bars whilst stood astride. If that did not work get a mate to steady the back while jumping up and down in the pegs.
Others have since told me but only done once, tried draining the float. Warm your carb. Turn off the fuel tap. Drain carb via little screw. Do up screw. Check it does not leak when you open the tap. Should work.
Stupid phone / Tapatalk, apologies in advance.
Ribit
29th May 2014, 13:58
Juniper
Used choke and wound the idle right up (or so I thought) and would start and then rev off to a stall.
Is it possible the idle screw was unscrewed at this point? therefore all the problems stemmed from this?
Juniper
29th May 2014, 15:06
Is it possible the idle screw was unscrewed at this point? therefore all the problems stemmed from this?
I thought that, but Nah. the screw came out after I had pushed it to the end of the driveway. Which was after about an hr of trying.
Ribit
29th May 2014, 15:31
I thought that, but Nah. the screw came out after I had pushed it to the end of the driveway. Which was after about an hr of trying.
It would explain why it went wrong and everything came right after reinstalling it, but anyway....
and would start and then rev off to a stall
This would indicate a partial fuel blockage. as the fuel in the float chambers are used the mixture leans out (runs out of petrol) and the motor stops. ya crank it back over and because your not using fuel as quickly the floats can refill. 'Choking' the carbs may have cleared the blockage by the extra suction put on the carb, sucking the blockage through.
ducatilover
29th May 2014, 16:20
Not enough skids.
pete376403
29th May 2014, 21:08
water (wouldn't take much) freezing would block the passages, and even after the engine heated enough to thaw, the water would still remain blocking the passages. Bear in mind that the only thing normally pushing fuel through the jets is the difference between atmospheric pressure above the fuel in the float bowl, and the less-than-atmospheric pressure in the carb venturi - i.e. not much.
When you blocked the carb inlet, all the vacuum in the carb throat was applied to the jets and passages, which would have sucked the obstruction through.
Juniper
30th May 2014, 08:59
water (wouldn't take much) freezing would block the passages, and even after the engine heated enough to thaw, the water would still remain blocking the passages. Bear in mind that the only thing normally pushing fuel through the jets is the difference between atmospheric pressure above the fuel in the float bowl, and the less-than-atmospheric pressure in the carb venturi - i.e. not much.
When you blocked the carb inlet, all the vacuum in the carb throat was applied to the jets and passages, which would have sucked the obstruction through.
Yeah thats kinda what I was thinking!!
What do you think of this: http://litetek.co/Carb_Kit_Kawasaki_ZXR250.html
I've got my old carbs at home so am going to check to see the seals are in good condition. The ones in there atm have been cut to make them fit.
ducatilover
30th May 2014, 09:18
I doubt you'll get it cheaper anywhere else :2thumbsup that's around $65nz?
Juniper
30th May 2014, 09:21
I doubt you'll get it cheaper anywhere else :2thumbsup that's around $65nz?
Yeah about that. But I'll try my old ones first though. And for some reason first time we took it apart I cleaned out a lot of dirt from them. When we put it back together and took it apart again it was dirty again. Not as bad as the first time but still had git and stuff in there.
Is my air box not working properly? Or dirt in my tank? Or the seals letting it through?
Mate said my air filter wasent any dirtier than it should be.
unstuck
30th May 2014, 09:22
Fuel filter clogged or you do not have one installed. :msn-wink:
ducatilover
30th May 2014, 09:42
Could be either a perishing air filter, or what unstuck said.
Usually a perishing air filter will leave a bit more evidence though (filter spoof everywhere)
Just give up and swap it for my Bandit :niceone:
Big Dog
30th May 2014, 10:16
Grab an inspection mirror when your tank is empty. If your bike has ever been stored with an empty tank there may be various oxides. If you don't have an inspection mirror drain some fuel from the fuel tap. Allow to sit in a glass or pour through a white coffee filter. If there is no trace repeat test below fuel filter.
Still no trace up the anti and try filtering the whole tank. A perished diaphragm caused issues similar on an old bike of mine. But oxide in the tank or perished fuel filter are more likely.
Stupid phone / Tapatalk, apologies in advance.
Juniper
3rd June 2014, 08:14
So I took her apart in the weekend. All by myself!!! (Well I did have someone help me take the tank off) and replaced the gaskets with my old ones that were in good nick. And cleaned them out again.
I need to do my air filter but need air filter oil for that. When I do that I'll check if the stuff is in my fuel tank. How do you clean a fuel tank?
I'm quite chuffed with myself!!
ducatilover
3rd June 2014, 14:42
Good work!
Drain the tank, take the filter out, bit of kero, slosh it around. Repeat.
If it's a bit rusty, ball bearings and kero
Juniper
3rd June 2014, 22:07
Good work!
Drain the tank, take the filter out, bit of kero, slosh it around. Repeat.
If it's a bit rusty, ball bearings and kero
Where's the filter? I don't remember seeing one. Would it be before or after the reserve tap?
Thanks for all the advice guys!!!
pete376403
3rd June 2014, 22:14
The fuel filter might be in the tank, part of the fuel tap assembly. Is the tap assem. held on by a couple of bolts? If you can remove it, you may find a filter as part of the fuel intake.
Juniper
4th June 2014, 10:59
The fuel filter might be in the tank, part of the fuel tap assembly. Is the tap assem. held on by a couple of bolts? If you can remove it, you may find a filter as part of the fuel intake.
Ummmm, will have to reply when looking directly at bike. I think its held on by some bolts......
unstuck
4th June 2014, 17:10
If it has no inline fuel filter, my suggestion is you fit one, piss easy and cheap to do. But make sure you clean the one on the petcock too, it will either be sticking up inside the tank, or inside the actual tap.
ducatilover
4th June 2014, 21:29
Where's the filter? I don't remember seeing one. Would it be before or after the reserve tap?
Thanks for all the advice guys!!!
The filter is in the tank, attached to the top of the fuel tap.
You don't need an inline filter if you have an in-tank one
neels
4th June 2014, 21:54
You don't need an inline filter if you have an in-tank one
Sometimes you do.....the in tank filter is usually just gauze to stop the big lumpy bits getting through, doesn't stop the fine bits that hold your vacuum fuel tap and needle valves open in order to empty the fuel tank on the shed floor:facepalm:
Anyhoo, with regard to the original post. The bike worked fine when you parked it, it didn't work after it was frozen which is not hugely surprising given the number of tiny parts involved in a 4cyl 250, if you'd left it to defrost by itself it probably would have worked fine.
Now that you've buggered about with it you need to work backwards through everything you did, until you undo whatever it was that caused your current problems.
Icemaestro
4th June 2014, 22:03
Kero? I thought meths as it combines with the water. Would have thought kero would leave a residue (good for rust, bad for carbs I would have thought?)
Sent from my iPhone using Tapatalk
ducatilover
4th June 2014, 22:11
Sometimes you do.....the in tank filter is usually just gauze to stop the big lumpy bits getting through, doesn't stop the fine bits that hold your vacuum fuel tap and needle valves open in order to empty the fuel tank on the shed floor:facepalm: The Kawasaki ones are fine :yes: and don't restrict flow as much as most inline filters (sucks not having a fuel pump!) I hate it when they decide to piss on the floor! I've used kero many times without issue, I also flush the tank again with a wee bit of petrol.
Juniper
4th June 2014, 22:32
Ok I am going to have to check this out now!! Weekend task though.
Another carb related query (I think)
I want to know why and how to fix this problem. I have had 2 sets of carbs now (old shitty original ones that spectrum fucked and the new second hand ones that now work fine....unless I freeze them)
Start bike on side stand as I usually do and revs to idle revs, about 1.5-2k. Sit the bike upright and the revs drop a little. Now while straddling bike lean it to the right about 45degrees and the revs will drop so low the bike can stall if I leave it there.
This happens when bike is hot/cold freshly started or after a ride. The first set of carbs it was WAAAYY worse. With these ones it's a lot less, but I still don't think it's normal.... I could be wrong.
If I figure out how to load a video from my phone I'll post it up.
ducatilover
4th June 2014, 22:37
That's normal, it's the effect of the fuel level being on an angle, either dropping the float and richening up, or taking the jets out of the fuel, and just stalling from no fuel. One major draw back to carbs.
Juniper
4th June 2014, 22:46
That's normal, it's the effect of the fuel level being on an angle, either dropping the float and richening up, or taking the jets out of the fuel, and just stalling from no fuel. One major draw back to carbs.
I like you!!
ducatilover
4th June 2014, 23:02
I like you!! Can I have your bike?
unstuck
4th June 2014, 23:58
Can I have your bike?
You shameless hussy. :nya:
Juniper
5th June 2014, 07:32
Can I have your bike?
ummm....no
I love her too much.
ducatilover
5th June 2014, 17:43
ummm....no
I love her too much.
:weep:
Worth asking
Had the exact same thing happen the other week - bike wouldn't run except on full choke. reason was blocked carbs from rust scale in the tank. to clean it had to put rocks in the tank and shake it around with fresh fuel and rinse a few times. if you clean the carbs, use a very thin wire down the jets and especially the idle air passages from the intakes. there's some good solvent based carb cleaner spray that dissolves most of the crap that can block it
:scooter:
ducatilover
7th June 2014, 23:24
Had the exact same thing happen the other week - bike wouldn't run except on full choke. reason was blocked carbs from rust scale in the tank. to clean it had to put rocks in the tank and shake it around with fresh fuel and rinse a few times. if you clean the carbs, use a very thin wire down the jets and especially the idle air passages from the intakes. there's some good solvent based carb cleaner spray that dissolves most of the crap that can block it :scooter: Don't use wire unless it's very soft, you don't want to scratch the jets
matrox02
11th June 2014, 21:41
after reading all of this, I can only say this... Im glad I had a 89 CBR250 that had little to no carb issues, and I'm damn happy that I have now got a bike with Fuel Injection...
imdying
12th June 2014, 11:13
EFI can block up just the same, the difference being you probably won't be able to fix it yourself.
Drew
12th June 2014, 13:26
EFI can block up just the same, the difference being you probably won't be able to fix it yourself.
Youtube search it. Bloody simple and effective method for cleaning injectors.
matrox02
13th June 2014, 03:00
EFI can block up just the same, the difference being you probably won't be able to fix it yourself.
HA HA! , I wouldnt be able to call myself a Genuinely certified back yard mechanic if I couldn't fix it! ( that or i find more tools and ask uncle google for help )
though admittedly, I still have a bike with a carb, its a bit of a paperweight with out half it assembled at the moment though
Juniper
30th June 2014, 08:04
Now another carb based query.
After riding in the rain my bike won't start. I stop and turn it off and then have to wind the idle up and pull the choke in and keep trying it for ages before it starts.
I've just gotten into work from riding in the rain and let it idle for a minute or so to try and maybe burn whatever water has gotten in there and nope still had the same problem. Once it finally started I turned it off again and it started first time after.
?????
unstuck
30th June 2014, 08:07
You sure it is not water getting at the electrics?
awayatc
30th June 2014, 08:53
Spark plug lead cracked/poor condition...?
also in regards to getting water in fuel when it rains....
when you ride and use petrol, air gets sucked into tank, so make sure it sucks dry air (i.e no foam ring under filler cap )
Drew
30th June 2014, 09:01
If it comes right as soon as it dries out, it's something electrical getting wet. If it takes quite some time to come right after it's dry, it's in the tank/carb.
So, replace the plug cap and you will prolly be sorted.
Juniper
30th June 2014, 10:29
I'm not sure stop-start-stop and start again would dry out electrics. It turns just doesnt turn over (I'm not sure of the right terms there) just like if I was trying to start it cold.
I don't think I've ever touched the spark plugs or the cables. Are those the same as the timing things where its meant to be 1342 or 1243. If it's that then I already know something is wrong there as its set up 1234 which is wrong no matter what order, but it seems to work that way and I've tried putting it in the correct order (as per the manual and lord google) and it wont start. so 1234 it is for now.
Are spark plugs expensive?
Drew
30th June 2014, 10:39
Oh right, you're on a zxr. Carb rubbers/airbox rubbers is my first guess then.
scumdog
30th June 2014, 10:52
Spark plug lead cracked/poor condition...?
Happened to me on a trail-bike I had.
Plug lead had a crack just where the spark-plug boot was, right in line for any water thrown up by the front wheel.
Took ages and some nasty words before I found the culprit.
Juniper
30th June 2014, 11:19
Happened to me on a trail-bike I had.
Plug lead had a crack just where the spark-plug boot was, right in line for any water thrown up by the front wheel.
Took ages and some nasty words before I found the culprit.
I shall have to look into this.
I did however sheer off a screw in my carbs when I was putting them back in last time. People have said I could drill it out but I'm not sure I want to be drilling so close to my carbs.
AllanB
30th June 2014, 11:54
Kero? I thought meths as it combines with the water. Would have thought kero would leave a residue (good for rust, bad for carbs I would have thought?)
Sent from my iPhone using Tapatalk
Correct - meths is the magic stuff to displace water out of a fuel tank. I've always used it over winter in my tanks to avoid the risk of rust setting in the low spots.
matrox02
5th July 2014, 06:44
I'm not sure stop-start-stop and start again would dry out electrics. It turns just doesnt turn over (I'm not sure of the right terms there) just like if I was trying to start it cold.
I don't think I've ever touched the spark plugs or the cables. Are those the same as the timing things where its meant to be 1342 or 1243. If it's that then I already know something is wrong there as its set up 1234 which is wrong no matter what order, but it seems to work that way and I've tried putting it in the correct order (as per the manual and lord google) and it wont start. so 1234 it is for now.
Are spark plugs expensive?
You have a Wasted spark plug setup, determined by the CDI on when which bank of plugs fire, IE, your firing order may be 1-3-4-2 but when the plug for 1 is needing to fire 4 also fires and when 3 fires 2 is firing as well, it gets a bit confusing to think about it, but it is right, you would barley be able to get the bike to run let alone move only running on 2-3 cylinders on a stock setup , otherwise, the issues sound either electrical or, that you have a vacuum seal issue with the carbs, replace the carb boots and see how the bike runs after that, and get a tarp to put over the bike in the rain, and also, get the bike warm and set the idle then leave it as is(1500 rpm i think would do fine ), the throttle plates create vacuum that helps draw out fuel for the bike to start properly, hence the no start condition when no idle stopper screw was in place, also you need a nice seal from the air filter to the carbs on the air box as well as that also helps with cold starts
All the crap I learneded the hard way on my old CBR250Rh :S
Juniper
9th July 2014, 12:54
Ok, so I'm getting to and seeing what I can do about my spark plugs this weekend!!
Will also check the seal around the carbs and the airbox. I have a feeling it could be that screw I accidentally sheared off be letting air and whatnot in.
What are carb boots?
unstuck
9th July 2014, 14:15
What are carb boots?
Things they put on when go to see bands.:headbang::headbang:
298995
Things they put on when go to see bands.:headbang::headbang:
Those are what I call 'manifold rubbers', or 'manifold blocks'. What I call 'carb boots' are the ones that go between the air box and the carbs. Cunt's of things on those old 250s, as they shrink with age and never seem to fit properly. Since the bikes rev so high, a good seal is so so important to keep things working right through the rev range on CV carbs.
Have a look on Ebay for a set of flat slide carbs that will fit. More power, and much less hassle.
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