ajordan9
Two Stroke Sniffer
Joined: 24 Jul 2018
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 Posted: 19:45 - 24 Jan 2019  Post subject: CB125 TD Left Side Noise and smell |
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Hey all,
So having an issue with my CB125 TD.
Heres a video but really listen to the audio: https://youtu.be/Oy3CnsSgP1c
So I just finished sorting out a starter motor issue which saw me replacing the starter outright. When re-fitting I had to open the left side case because the chain and cog which attaches to the starter fell into the case, but pulled it out and sat it back on the starter no issue.
I had also attempted to re-sync the carbs as the throttle was a lit laggy. Did have some issue with that but everything appears to run alrite now.
But in the midst of firing it up and re-syncing carbs by ear and throttle responsiveness this strange noise started occurring, listen for a high pitched hollow-ish noise. Mostly on lower rpms but can't be certain not on higher. ALSO, there is a very strange type of burning smell going on, mostly only on the left side which makes me sure its that side.
Im gonna open left side up tomorrow but just wondering if anyones ever experienced this or if theres anything I should look out for?
Thanks in advance! |
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Grubscrew
Scooby Slapper
Joined: 23 Dec 2018
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ajordan9
Two Stroke Sniffer
Joined: 24 Jul 2018
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| Posted: 20:44 - 24 Jan 2019 Post subject: |
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Thanks for the reply! I can't seem to see a tensioner on the parts list but yeah could well be so i'll have a look tomorrow.
thanks mate. |
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Nobby the Bastard
Harley Gaydar
Joined: 16 Aug 2013
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ajordan9
Two Stroke Sniffer
Joined: 24 Jul 2018
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Riejufixing
World Chat Champion
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WD Forte
World Chat Champion
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Teflon-Mike
tl;dr
Joined: 01 Jun 2010
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| Posted: 06:29 - 25 Jan 2019 Post subject: |
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| Nobby the Bastard wrote: | Brace yourself, darling. You're about to get the teffing of your life...
Sounds like it's knocking. Bottom end is fucked. |
Sounds pretty 'wopity' to me.... which is normal... not that I could tell much from the vid, and not much more from the OP's post... crank goes round... that's a good start.... nothing to really suggest that the pressed up crank be kerfkered.
| ajordan9 wrote: | So having an issue with my CB125 TD. |
Y-e-r-s......
| ajordan9 wrote: | Heres a video but really listen to the audio |
I did... learned less than I did from words in post.... sorry.
| ajordan9 wrote: | So I just finished sorting out a starter motor issue which saw me replacing the starter outright. When re-fitting I had to open the left side case because the chain and cog which attaches to the starter fell into the case, but pulled it out and sat it back on the starter no issue. |
Y-e-r-s... they do that... sounds like a case of RTFM... it does warn.
Chain runs loose, and gets looser with age. There is a metal guide, on the backing plate sandwhiched between cover and crank-case, but thats all. Noises are usually the starter-clutch in the back of the generator rotor. Its three rollers on ramps un the shaft; as the rollers and ramps wear and or rust, then they get a bit sticky and loath to dissengage, which normally results in a horrible loose fan belt like 'screech' when the engine catches, and the starter doesn't disengage properly. No noise like a loose fan belt in vid... so perhaps OK.
What DOES need to be watched for though is that starter motor backing plate sandwhiched between the crank-case and genny cover. The starter motor is usually held in the thing better by rust and crud around the kneck of the starter, than it is the bolts into the crank case.... hence RTFM.... ISTR it says remove the genny cover first, slip the chain and sprocket off the starter shaft THEN undo starter motor bolts... and you 'may' wiggle and twist or do any other gymnastics you preffer, I suppose, to pull starter out the plate.... possibly aided by a 'light' bit of smkacking with ever bigger hammers until the plates manged to bludgery, and you resort to the hack-saw.... and start wondering where you can get another plate from.... and if you can live without an e-start... and cursing honda removing the kicker from earlier models!!!
When re-assembling.... if you have dislodged the starter from plate.... good chance that its not properly sat 'fluch to the crank-cases, and or the cover isn't sat fluch to the plate when sandwhiched.
See Snowies 'Pup' thread... this had us on one for ages, with the starter plate holding the genny cover 'just' far enough off the crank-cases that the lugg on the genny rotor completely missed one of the two ignition triggers, so it fired up reluctantly and only on one pot....
Go re-visit and pay particular attension to cleaning up the faces a) for the plate to crank-case b) genny cover to plate, and c) the state of the location dowels for the genny cover, which OTMH go through the plate, in a couple of instances, and often get stuck there.
| ajordan9 wrote: | I had also attempted to re-sync the carbs as the throttle was a lit laggy. Did have some issue with that but everything appears to run alrite now. |
There's a handy How2 on this very subject on this very bike linked in my profile....
Syncronising the carbs is the last thing to be done to a GOOD engine....
There's also two syncs that need to be set. The idle rest position of the carb-slides, then the lifted position of the slides. Idle far too often set by numpties on just one carb, and wioth similar numptiness to try screw the idle stop in to lift the slide, resulting in a dinges and stucl slide, and no change of idle....
Its also an utter waste of time, if the choke flex-link between the two carbs is either not connected, or as is oft the case, wobbly as feck, and one of other choke butterfly wobbling around like a fifty year old joggers bum....
| ajordan9 wrote: |
But in the midst of firing it up and re-syncing carbs by ear and throttle responsiveness this strange noise started occurring, listen for a high pitched hollow-ish noise. Mostly on lower rpms but can't be certain not on higher. ALSO, there is a very strange type of burning smell going on, mostly only on the left side which makes me sure its that side.
Im gonna open left side up tomorrow but just wondering if anyones ever experienced this or if theres anything I should look out for? |
As said, couldn't really tell a thing from the vid sound, other than sounds pretty usually wopity.
Oil on left hand side... I ASSUME that's as you sit on the bike. Opposite side to oil fill.dip-stick.
Daft question... does this particular Super-Dream have a side stand? It should be on that side, if it has one, so bike leans to left when parked, away from the filler cap... but lean does mean that oil in the rocker cover will tend to puddle to that side when parked, and seep down the stem-seals, which are normally perished to bludgery on a bike this age.... and or, and more usually and, weep past the sprocket shaft oil seal, which curtecy of over-enthusiastic chain tensioning, is normally kerbluggered, if it's not gone hard and horrible and started cracking up with old age.... leaving the accumulated gunk in the sprocket cover to stem any out-flow..... which it actually seems to do rather well, a lot of the time!!! And they start leaving pee-drips when parked after some-one has had the notion of 'cleaning' in there when they have replaced the chain and sprockets..... but still.
MOST likely cause of oil burning smell, though will be a knackered, misfitted and or misshapen chinky replacement rocker cover seal, letting oil pooling that side, drip down onto upper cooling fins of the head and or exhaust flange to get burned off when engine run. If any-one has had the possibly not so grand idea to take the rocker cover off and do the tappets..... cos its a buggers tight wiggle fit under the frame top-tube! Other one of course is that sprocket shaft seal, and oil dripping past that onto the mid-section of the exhaust by the foot-rests.
Calve stem-seals are really an engine out and top-end rebuild job, done as part of rather than as a job in thier own. And have to say it, but with, far too many of these little bludgers kocking about; I tend to cut to the chase, and pull the motor and do a full top-end as 'course', now, with a chinky barely and piston kit, cos they are cheaper than a re-bore at local M/C shop and debate with machinist over the tiny size of the holes, and whether he has stones that small.... personally I think he's just boasting.... but still.... getting barely kit through the mail also saves trecking to and from with oily bits.
BUT... motor gets a top end, whether it 'seems' to run or not. These moped sized pots that can spin up to 14,000 rpm, which is pretty audacious for a two-valve air-cooled engine of any vintage, let alone one thirty odd years old, LIKE sharp piston rings, and when the bore is only, 43mm bore, a few 1/10ths of a mm wear are a much bigger proportion of the gap, and far less discerneable than they may be on a 54mm bore or bigger single.
They are particularly sensitive to bore and ring wear, and you can waste so much time and effort, chasing starting and running niggles presuming carbs or ignition or echaust, that for a week-end and £120 or so... far far easier to cut to the quick, and do it at the beginning, lapping in the valves for a good seal, fitting new stem-seals, assessing the state of the cam-chain... hint, if the cam goes in even moderatelty 'easy' it kerfkered.... timing in the cam critically, setting the tappets properly... with proper tappet key, and probably new tappets, again to save stupid questions and extra work later, for the sake of a fiver...
But, all that remedial done, engine be base lined for any further diagnostocs.... like looking to see if the rotor missing the ignition inductor cos starter plate sat cock-eyed!
Your call.... how much muddling in the middle hoping to luck in on a problem are you prepared for?
| WD Forte wrote: | Did you replace the oil when you put the covers back on? |
He 'should' have only had to remove the magneto cover, whoch shouldn't hold oil, so no oil drain and replace required.
IF there is/was oil in there when opened.... it got big problems. Means main crank/crank-case seal gone, and a total tear-down to renew.
| WD Forte wrote: | Burn it send it to hell |
Tempting... very tempting... but they all seem to end up here in my back garden in the Super-Dream-Saniterium.... I think that they know that its a smokeless zone, and that after futtering up the drive, belching blue, the council WILL be watching lol!
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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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bikenut
World Chat Champion
Joined: 21 Nov 2011
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Fizzer Thou
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| Posted: 17:14 - 25 Jan 2019 Post subject: |
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What does the engine sound like once the plug is inserted and tightened?In my mind that hollow sound is just windage inside of the crankcase as the engine is revved and is nothing to worry about.
There is no starter chain tensioner.Once the engine has started the sprague clutch disengages and the chain stops rotating
https://www.fowlersparts.co.uk/parts/4754893/cb125tdc-1982-e/starting-motor-1
Under that side cover is the rotor and stator for the electrical charge circuit
https://www.fowlersparts.co.uk/parts/4754892/cb125tdc-1982-e/left-crankcase-cover-generator
As for the smell of oil,with that access plug removed I would not be surprised to smell something oily.Once the plug is put back in place the smell should stop.
As for the difference between the UK and Continental versions,it would only be minor and nothing to do with the engine.Why would there be???
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ajordan9
Two Stroke Sniffer
Joined: 24 Jul 2018
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