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bcfusername
L Plate Warrior
Joined: 02 Sep 2012
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 Posted: 20:56 - 02 Sep 2012  Post subject: I'm stuck. CB125tdc not running! |
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Been stuck on this for ages, sent the bike to a local garage and they gave me a bike back that still did not run. Which was a shame.
Superdream 125, I have modified it slightly, cafe racer style.
Due to the mods (basically - altered back end, hump seat, battery tray moved to where airboxes go) I've used cone air filters. The air box will not fit now.
The bike starts, really well actually, and will rev to 5k. Once it hits 6k it starts spluttering and revs drop. I have managed to rev it over 6k but it was not happy at all.
Plugs come out sooty, left side is a little bit wet, right is dry.
If I hold my hand over right side carb intake (filters removed obviously) Fuel pisses out over my hand. If I hold my hand over the left side, this does not happen.
I have fitted new pistons and barrels, and checked the valve clearances after an hour or so of interrupted running. New plugs, good spark on both sides.
Whilst the engine was apart I decoked the head and valves and cleaned it all up including ports.
Thing is, when I bought the bike almost 2 years ago, I rode home 50-60 miles. It hadn't been used for 5 years, but rode really nicely. Apart from the seized rear suspension..
Before I even started stripping it down it was ridden around at home. And bogged down and died, I thought it was out of fuel.
Stripped the thing down, remodelled it slightly, new cone filters, went for MOT and it got halfway round the block before dying again.
I've had the carbs apart many times, marinaded them in parafin for a week and blown them out with pressured air, and not better.
Pilot jet is standard, screw in standard turnout, needle jet is standard - and I have a range of main jets from standard (98 I think) to fat size 108.
New battery, kept on optimate.
Motad 2-1 silencer.
Please help! I wanted to give this to my wife nearly 2 years ago when she passed her cbt, and we're both pissed off now! |
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Casper
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Matt-
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| Teflon-Mike |
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Teflon-Mike
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| Posted: 21:40 - 02 Sep 2012 Post subject: |
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Personaly, I would make two simple checks before going any further.
1/ what notch is the carb needle in?
(little bet with self you have it on the middle notch; book says one up from middle - a common mistake, middle is default isn't it? But not on the reduced effect Super-Dream! And gives exact symptoms you describe going over rich at 5-6K)
2/ Do the jets have the Keihin star on them?
Mikuni jets fit the PD24... but same number is about eight jet sizes higher! Took me a week of swaps and messing to discover that little gen!
The Motad doesn't do much to the mixture; or power. Neither should the pod filters. If anything they probably flow less air than stock air-box, especially if they are chitty chinky K&N copies. Have a look at the size of the stockers, they are HUGE, and the CB125 Dream has two of them; and its the same filter as used on some of the other small hondas that only have one!
What I WOULD look for on the Motad is a hole in the silencer... seem to go just behind the hanger.... And dents or pin-holes in the headers.
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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bcfusername
L Plate Warrior
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Nope.
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| Posted: 10:25 - 03 Sep 2012 Post subject: |
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| bcfusername wrote: | Hi, thanks for responding so quick.
Carb needles were at 2nd clip (from top) I've now got them at 3rd clip. Middle.
No holes in silencer or headers, a slight blow from the collector.
Filters are indeed shitty cheap little jobs.
Stars on pilot jets, I haven't seen (or looked for) them on the other jets.
Regarding posts made suggesting upjetting, the plugs are sooty - rich already, would a richer jet not make this more so?
And I have googled, for over a year! Struggling to find an answer, many posts lead me here though. Which is how I'm here! |
Post up a picture of your plugs.
I presume you've already stripped and cleaned out the carbs and balanced them?
____________________
Former: Derbi GP1 50, Sachs XTC 125, Suzuki GSXR 400 GK73A, Kawasaki ZX7R, Suzuki DR250, Yamaha RD350
Current: 2011 Yamaha XT660Z Ténéré, 2003 Yamaha YZR-R1 5PW (In Build), 2009 Kawasaki ZZR1400 |
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| karthead |
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karthead
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| Posted: 10:38 - 03 Sep 2012 Post subject: |
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Plug chops might be good in this situation, at different throttle levels (under load) to observe the colour of the spark plug.
Do this:
- Plug chop at 1/4 throttle, take plug/s out, take a GOOD QUALITY photo. Put plug/s back in.
- Repeat this step except at 1/2, 3/4 and full throttles for a decent amount of time, then upload the photos for all the BCFers to see, so they can give you a better idea of what you should do next- they can see how rich/lean engine is running at different throttle levels
Good luck  |
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bcfusername
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Nope.
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Posted: 11:23 - 03 Sep 2012  Post subject: |
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| bcfusername wrote: | Yep carbs are nice and clean now, full of shit when I first took them apart though
For plug chop to work, is there a way around riding the bike? It is awkward to ride now, to say the least, I live in a hilly area and it will not get up a hill! Also no tax, mot etc..
Is it doable to run it static, holding against rear brake - bike supported on some kind of stand to keep back wheel off the floor and me out of next door's honuse?, |
Not really. It has to be done under load to get proper results.
____________________
Former: Derbi GP1 50, Sachs XTC 125, Suzuki GSXR 400 GK73A, Kawasaki ZX7R, Suzuki DR250, Yamaha RD350
Current: 2011 Yamaha XT660Z Ténéré, 2003 Yamaha YZR-R1 5PW (In Build), 2009 Kawasaki ZZR1400 |
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| Teflon-Mike |
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Teflon-Mike
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| Posted: 16:24 - 03 Sep 2012 Post subject: |
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| bcfusername wrote: | Carb needles were at 2nd clip (from top) I've now got them at 3rd clip. Middle. |
Drop the needle again then.
Lower the notch the ritcher the mixture will be, & your running rich, aren't you.
| bcfusername wrote: | No holes in silencer or headers, a slight blow from the collector. |
First, are you SURE? I have three of these pipes knocking around, chose the 'best' one to go on last bike I put together, hole can 'hide' in that crap-trap where the hanger tank is tagged on, and under the chrome, go unspotted.
I had to litterally get the bike up and running, and then go over it with a bit of kitchen roll in my hand, feeling for a 'blow' and exhaust soot on the paper, with a close-peg holding the throttle well over tick-over!
Meanwhile collector shouldn't be blowing, that wont help!
| bcfusername wrote: | Filters are indeed shitty cheap little jobs. |
For what they are doing, you might as well ditch them. I've had them on a couple of bikes, and they are just wamp.
I've run one or two completely filterless; OK small particulates may mean premature bore wear, but?!!?! Carburate better.
Stock air-boxes are pretty useful. Even without filters, giving the air a chance to draw from a still reservoir and sort itself out into a lamina flow down that fairly long 'trumpet' before the carb-mouth, makes the 'pick-up' as teh throttle is opened a lot crisper.
You said you have removed the air-boxes, and have relocated the battery in a new tray where air-boxes were, hence cant use stock filters / boxes, becouse battery is in the way.
Stock set up, the battery tray is formed in a recess between the two air-boxes.
Why cant you go back to the original air-boxes, and use the battery tray they form?
If you cant, then I would probably try at least using the original intake trumpets that used to go into the air-box, if not the air-box itself, or a filter.
| bcfusername wrote: | Regarding posts made suggesting upjetting, the plugs are sooty - rich already, would a richer jet not make this more so? |
Yes... and you dont need to rejet for the Motad pipe. Done that one to death, which was when I discovered the little leaf-hole niggle and the Keihin star jet anomoly.
My money would be on the pod filters being your main problem.
They are horrible little things; fasionable back in the olden days, but they dont have the intake area to flow big air, and sucking around the perifery of the carb-mouth AND so close to the carb-mouth, they can actually provide significant flow restriction, making the air turn through 90 degrees right in the carb-mouth....
| bcfusername wrote: | And I have googled, for over a year! Struggling to find an answer, many posts lead me here though. Which is how I'm here! |
Yup, becouse BCF is top ranked UK Bike Forum, I'm one of its more prolific posters, and bottom of every one of my posts, it says "'CB125TD (4 of em!)'" and I've blogged rebuild of one of mine on here, my Girlfreind another, seeding other Super-Dream-Believers to the fould!
You say you have cleaned the carbs, and soaked the bodies in parafin..... BUT, something that is nigling me is description of petrol pouring from Right hand carb, when you choke it.
AND the pariah of manky carburettor inlet rubbers, often ripped by people pulling carbs off without removing air-box first, then repairing them with super-glue and insulation tape under the huse clamps.... becouse replacements are pure unobtanium..... ring any alarm bells?
Anyhow; three bikes, five pairs of carbs.... every one of them has done this at one time or another, one or two, more or less regularly;
Turn the petrol on, and fuel runs to the float-bowl; float needle lets fuel in, float lifts, BUT needle doesn't 'seat', and fuel kees flowing in, flooding the carb.
NOW, there is an over-flow pipe running up the middle of the float-bowl, and any excess petrol OUGHT to drip out of the over-flow nipple on the bottom of the float bowl, to which a vent pipe ought to be attached... (if you don't have one, attach one, or petrol puddles on top of the gear-box, and makes diagnosing next bit more awkward)
However, there is also a breather vent in the carb-body.
If you look at the Left-Hand carb, where the choke cable outer sleeve is clamped by a little plate...... THAT plate, is covering a little brass nipple... that's the breather vent.... there's one on the other carb, but doesn't have a bracket in the way, but its harder to see nestled between the carbs.
On first float-bowl fill, fuel will often spirt out of that breather... NOT the over-flow...... And it can spirt for quite a while.
I have cleaned carb bodies, tried different float needles.... on old PD24's it seems inevitable that the float needle is a 'bit' sticky, and will take a little while, to find it's seat and start working.
If you turn fuel on, wait for spirt, to tell you float bowl is primed, then turn fuel off, start engine, let it idle, then turn the fuel back on, wait for it to spirt, then off, and let floatbowl drain, making the float needle move in the tap... by the time bikes warm, often finds its 'seat'.
THAT may be the phenomina you are seeing, when you choke the carb...
However; the 'I've Cleaned the Carb' comment....
Lol comment for you; we have had newbies who have been told to remove & clean the carb, and have done exactly that... taken the carb off, got a washing up bowl of soapy water and a tooth-brush and scrubbed the carb.....
Never took it apart or looked at floats or jets, but TO THEM they 'cleaned the carb'...... and wondered why it made bog all difference!
Dont presume you are so at fault, BUT, these PD24's are annoying buggers, and the primary air-ways ARE prone to firring up, and a simple parafin soak and blow through on an air-line may not get them properly cleared.
Getting the carb Ultrasonically Cleaned, CAN, and if you get the jets done so that the emulsion tube vents are also properly free, and that float needle seat, as clean as you can get it... stand a MUCH better chance of eliminating possible problems.
Oh:- ponder point ref no tax or MOT.
Engines only shiove bike along; hence usually last thing I tackle on them. I like to be sure they stop and steer before they start!
MOT man is little concerned with the motor. All the equipment on a the Super-Dream runs off the battery, so you dont even need the engine running to test lights. He only has to see that it runs, make sure that the exhaust ent too noisy or chucking out great plumes of black or grey smoke.
If you get the thing 'legal', then you can do all the road-testing you need, after, and not have that hassle that a bike with 'problems' or being pushed is more likely to attract attension of plod... and even if it does, they cant do bog all, 'cos its taxed & insured & legal!
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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| bcfusername |
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bcfusername
L Plate Warrior
Joined: 02 Sep 2012
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| Posted: 16:36 - 04 Sep 2012 Post subject: |
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| Teflon-Mike wrote: | | bcfusername wrote: | Carb needles were at 2nd clip (from top) I've now got them at 3rd clip. Middle. |
Drop the needle again then.
Lower the notch the ritcher the mixture will be, & your running rich, aren't you.
| bcfusername wrote: | No holes in silencer or headers, a slight blow from the collector. |
First, are you SURE? I have three of these pipes knocking around, chose the 'best' one to go on last bike I put together, hole can 'hide' in that crap-trap where the hanger tank is tagged on, and under the chrome, go unspotted.
I had to litterally get the bike up and running, and then go over it with a bit of kitchen roll in my hand, feeling for a 'blow' and exhaust soot on the paper, with a close-peg holding the throttle well over tick-over!
Meanwhile collector shouldn't be blowing, that wont help!
| bcfusername wrote: | Filters are indeed shitty cheap little jobs. |
For what they are doing, you might as well ditch them. I've had them on a couple of bikes, and they are just wamp.
I've run one or two completely filterless; OK small particulates may mean premature bore wear, but?!!?! Carburate better.
Stock air-boxes are pretty useful. Even without filters, giving the air a chance to draw from a still reservoir and sort itself out into a lamina flow down that fairly long 'trumpet' before the carb-mouth, makes the 'pick-up' as teh throttle is opened a lot crisper.
You said you have removed the air-boxes, and have relocated the battery in a new tray where air-boxes were, hence cant use stock filters / boxes, becouse battery is in the way.
Stock set up, the battery tray is formed in a recess between the two air-boxes.
Why cant you go back to the original air-boxes, and use the battery tray they form?
If you cant, then I would probably try at least using the original intake trumpets that used to go into the air-box, if not the air-box itself, or a filter.
| bcfusername wrote: | Regarding posts made suggesting upjetting, the plugs are sooty - rich already, would a richer jet not make this more so? |
Yes... and you dont need to rejet for the Motad pipe. Done that one to death, which was when I discovered the little leaf-hole niggle and the Keihin star jet anomoly.
My money would be on the pod filters being your main problem.
They are horrible little things; fasionable back in the olden days, but they dont have the intake area to flow big air, and sucking around the perifery of the carb-mouth AND so close to the carb-mouth, they can actually provide significant flow restriction, making the air turn through 90 degrees right in the carb-mouth....
| bcfusername wrote: | And I have googled, for over a year! Struggling to find an answer, many posts lead me here though. Which is how I'm here! |
Yup, becouse BCF is top ranked UK Bike Forum, I'm one of its more prolific posters, and bottom of every one of my posts, it says "'CB125TD (4 of em!)'" and I've blogged rebuild of one of mine on here, my Girlfreind another, seeding other Super-Dream-Believers to the fould!
You say you have cleaned the carbs, and soaked the bodies in parafin..... BUT, something that is nigling me is description of petrol pouring from Right hand carb, when you choke it.
AND the pariah of manky carburettor inlet rubbers, often ripped by people pulling carbs off without removing air-box first, then repairing them with super-glue and insulation tape under the huse clamps.... becouse replacements are pure unobtanium..... ring any alarm bells?
Anyhow; three bikes, five pairs of carbs.... every one of them has done this at one time or another, one or two, more or less regularly;
Turn the petrol on, and fuel runs to the float-bowl; float needle lets fuel in, float lifts, BUT needle doesn't 'seat', and fuel kees flowing in, flooding the carb.
NOW, there is an over-flow pipe running up the middle of the float-bowl, and any excess petrol OUGHT to drip out of the over-flow nipple on the bottom of the float bowl, to which a vent pipe ought to be attached... (if you don't have one, attach one, or petrol puddles on top of the gear-box, and makes diagnosing next bit more awkward)
However, there is also a breather vent in the carb-body.
If you look at the Left-Hand carb, where the choke cable outer sleeve is clamped by a little plate...... THAT plate, is covering a little brass nipple... that's the breather vent.... there's one on the other carb, but doesn't have a bracket in the way, but its harder to see nestled between the carbs.
On first float-bowl fill, fuel will often spirt out of that breather... NOT the over-flow...... And it can spirt for quite a while.
I have cleaned carb bodies, tried different float needles.... on old PD24's it seems inevitable that the float needle is a 'bit' sticky, and will take a little while, to find it's seat and start working.
If you turn fuel on, wait for spirt, to tell you float bowl is primed, then turn fuel off, start engine, let it idle, then turn the fuel back on, wait for it to spirt, then off, and let floatbowl drain, making the float needle move in the tap... by the time bikes warm, often finds its 'seat'.
THAT may be the phenomina you are seeing, when you choke the carb...
However; the 'I've Cleaned the Carb' comment....
Lol comment for you; we have had newbies who have been told to remove & clean the carb, and have done exactly that... taken the carb off, got a washing up bowl of soapy water and a tooth-brush and scrubbed the carb.....
Never took it apart or looked at floats or jets, but TO THEM they 'cleaned the carb'...... and wondered why it made bog all difference!
Dont presume you are so at fault, BUT, these PD24's are annoying buggers, and the primary air-ways ARE prone to firring up, and a simple parafin soak and blow through on an air-line may not get them properly cleared.
Getting the carb Ultrasonically Cleaned, CAN, and if you get the jets done so that the emulsion tube vents are also properly free, and that float needle seat, as clean as you can get it... stand a MUCH better chance of eliminating possible problems.
Oh:- ponder point ref no tax or MOT.
Engines only shiove bike along; hence usually last thing I tackle on them. I like to be sure they stop and steer before they start!
MOT man is little concerned with the motor. All the equipment on a the Super-Dream runs off the battery, so you dont even need the engine running to test lights. He only has to see that it runs, make sure that the exhaust ent too noisy or chucking out great plumes of black or grey smoke.
If you get the thing 'legal', then you can do all the road-testing you need, after, and not have that hassle that a bike with 'problems' or being pushed is more likely to attract attension of plod... and even if it does, they cant do bog all, 'cos its taxed & insured & legal! |
Lots of post! Thanks frying pan dude.
Ok, first, this is why the battery tray is where the airbox should be..
https://i606.photobucket.com/albums/tt146/iamcaptainsmelly/IMG00519-20110715-1559.jpg
https://i606.photobucket.com/albums/tt146/iamcaptainsmelly/IMG00518-20110714-1527.jpg
Battery doesn't fit under the hump, if there was a kickstart I'd use a smaller battery but there isn't. So I can't.
MOT man is a couple of miles away, don't have a van. It's downhill to get there, but rather less downhill getting back!
I've been running with and without the little filters, no difference in running. They may keep out small animals and children, but you're right I wouldn't expect them to filter small dusty stuff that well. Despite a liberal oiling of filter oil.
I strongly believe that there are no air leaks into the carb rubbers, engine to carb rubber tested by squirting with wd40 or equivalent showed no difference to enigine note, (tested this by loosening the clamp and then squirting, found engine revs to rise)
Carb to filter rubbers, largely irrelevant I guess when it's run with an open intake! But hoses do deform under vacuum/hand choking over ends.
I'm going to examine the carb overflows and float valve. Fuel flows from the bottom overflow when the drains are loosened, and not when they aren't, which is good, but possibly not from topdrain which I did not know about
Will report back! |
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Teflon-Mike
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bcfusername
L Plate Warrior
Joined: 02 Sep 2012
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| Posted: 19:10 - 04 Sep 2012 Post subject: |
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| Teflon-Mike wrote: | https://i178.photobucket.com/albums/w269/teflons-torque/Little%20Dreams/imag0781.jpg
Battery, in OE air-boxes, is under the seat-rails, so I don't really see, how changing the seat would stop the battery or air-boxes being fitted. |
Bollocks! A bit of wasted time and money for me it would seem!
Well I've been working on it this afternoon, running much nicer now I'll take it out tomorrow on my 'private test track' to see what is happening
Balanced the carbs, they were pretty far out.
Made sure all the overflows were unblocked - achived by tilting the carbs in multi directions and observing petrol pissing out where it should.
Cleaned the float valve hole as best I could, they were quite grubby already.
One issue, probably not a good thing, after a fire up and warm up, if I take the carbs off (again) there's fuel in the intake rubbers. Carb to head rubbers I mean. Which isn't good I think!
Also left sparky plug was fouling, it isn't now and I'm not really sure why. Both looking quite rich too. But it's only been run without load so far so that may influence stuff. |
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The last post was made 14 years, 33 days ago. Instead of replying here, would creating a new thread be more useful? |
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