CG125 idling issues, and other teething problems

CG125 idling issues, and other teething problems

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Baryonyx

Original Poster:

17,034 posts

115 months

Thursday 29th May 2014
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Evening all,


As discussed elsewhere, I've recently bought a CG125 for getting to work on. The brief background on this was that my 106 Rallye was fked, and wouldn't be taking me to work again. I decided to make use of my CBT and buy a Honda CG125, spurred on by various biking friends who thought it sounded like a great idea.

For the most part, I've enjoyed riding it and getting to work for next nothing, cost wise, is a boon. A few issues have reared their heads though, rapidly developing from little niggles into real issues.


The first thing to address is probably the idling issue. For the past three journeys, the bike has been a real pain to start. Ever since I put a fiver's worth of fuel in at a BP garage the other day. The tank is now full again. Idling the bike when it's cold is a fking nightmare. Tonight, I couldn't get it start at all when I left work. After plenty of kick-starting, it finally fired. I should note though that, no matter where I left the choke lever, I couldn't take my hand off the throttle, if I closed the throttle the engine would promptly cut out. Shortly after putting it on full choke, I heard the revs rise and I moved the lever to half choke, thinking the bike was ready to come off full choke. It cut out.

I managed to ride out of the office car park, onto the main road and reached a set of traffic lights. The bike cut out just as I passed the traffic lights, and took another few moments standing at the roadside trying to kick start it, and then get it to idle without assistance. Eventually, I just rode off as it was, stopping down the road and taking all the choke off. The engine was generally fine after that, for the most part. I should note that when the bike is having trouble idling, the throttle occasionally feels extremely lazy, like opening it wide gives very little response, typically before the bike cuts out. I've also had more luck starting and running on the reserve position on the fuel tap rather than the main position, though I don't know if this is genuine or if it's just something else I'm doing when I'm fiddling with the bike trying to get it to go.


It's been cooler this week than it was last week, but I thought last week the bike warmed through pretty quickly, even when it needed some choke to start. This week, I don't know if it's just not warming through quickly, or if there is a deeper issue at play. After a few miles riding the bike, it generally feels okay. That is, except for the other issue I'm having.





Twice tonight, the bike cut out just as I passed through a junction, leaving me stranded on the wrong side of a now-red traffic light. As if this wasn't bad enough, I've had issues pulling away this week, primarily related to finding first gear. Now, trying to shift a 15 stone bloke with 11hp would challenge any bike, but I've categorically discovered that this bike just won't hill start in second gear. The issue being that often, I'm kicking down the 'box as far as it will go. Sometimes, I'm able to gently let the clutch out and press the gear lever down and find first, but a lot of the time it just won't happen. I've got away with this a few times in the flat, piling on the revs and feathering out the clutch until I can get the bike to pull away, but first is so often elusive. A few times over the past few journeys, I've stalled trying to pull away. Sometimes, I'm stuck at traffic lights on a hill, feeling that I haven't got the bike in first and can't pull away in second, so I have to paddle the bike to road side, let the traffic past and stall the bike to get back to first gear. I've been lucky so far, to find drivers behind me who are patient or happy to drive round me as I stand trying to kick the bike into life, but I am wondering if this is a phase that will pass.




So, to consolidate these issues:


1) The idling problem, does the bike just need ages to warm up? Like, a good ten minutes of holding it on a steady throttle? Would adjusting the idle screw to speed the idle up be worth a go?

2) How can I get round this issue of finding first gear? I know the CG 'box is renowned for being a slop-fest, but being locked out of first has put me in a few dangerous situations this week. Is there some technique to getting from second to first, when the box is effectively locking you out, without stalling the bike, letting the clutch out and putting it in first gear?

3) Can an electric start button be retrofitted to these bikes? Mine is a 2001 model with a kick start lever. It's easy to use in the dry, but with wet boots, on a hill, it can be tricky. Certainly, the most dangerous situations I've found myself in this week have involved stalling, whereas on my CBT I found the CG125 with the push button start was useful for quickly tidying up any fk-ups I made with the bike.


NB: The problems I've experienced above tend to occur in the first half of my ride home, through urban and suburban areas. Once I'm out in the country and riding down B roads, the bike feels fine. It'll even (usually) find first quite easily when approaching a slow corner.


In general, I've enjoyed riding the bike. This week's rides should have been the best so far, finishing work at midnight and getting a quiet ride home. I don't do short journeys on the bike, my commute is 24 miles a day and I never just jump on to go to the shops. The bike only has 5000 miles on it and has a good service record, and is stunningly cheap to run and easier than cycling. When I've had a good day, I feel like my riding is really coming together and I'm looking forward to getting back on when I put the bike away. These past couple of nights, the bike has felt like it's fighting against me, I've felt like paying attention to the problems the bike was suffering, or worrying about what was going to happen at the next traffic light, was putting me off really concentrating on the minutiae of my ride, which was worse off as a consequence. I've been happy just to get home these past couple of nights and put the bike in the garage, satisfied that I am at least home if not content with the way things have went.



I am hoping these teething problems can be resolved, as I mainly just want to get on and enjoy riding the fking thing.

Gareth9702

206 posts

88 months

Thursday 29th May 2014
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Poor idling when cold on my outboard motor is a sure sign that water is accumulating in the carb. Turn off the fuel tap. Using the drain screw to empty sediment from the carb might give you a simple fix. It takes a couple of minutes and cannot make matters worse. In any case, if you catch the fuel that comes out you will be able to see if there is any problem. You might then need to strip the carb fully.

graham22

3,079 posts

161 months

Thursday 29th May 2014
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Whip the carb off & make sure the choke flap itself is still there - worked on one years ago where the choke flap broke and disappeared, found half of it in the top of the piston, the rest had gone out the exhaust port.

The old boy I worked for knew exactly what the poor start pronlem was before we even looked at it, understood it was a regular problem. Replaced with a small stainless flap & locktighted screws.

Your problems sound choke related if it runs OK when warm.

With respect to the gear selection, try going down one gear at a time rather than trying to get to 1st from 3rd or 4th, letting the clutch out between selections. The gearboxes usually need movement to help the cogs mesh. If you find you're stopped in 2nd, try either rocking the bike or geting the clutch to biting point before pulling back in again to select 1st - if that makes sense.

Edited by graham22 on Thursday 29th May 10:00

spoodler

1,444 posts

111 months

Thursday 29th May 2014
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Not meaning to sound at all patronising, just trying to help...

Sounds like you don't know much about your own bike, I'd suggest getting hold of a manual and setting up the bike as per the spec's in there. It's the best starting point and you may find that a properly adjusted and lubed chain (with your weight on the bike so as not to be overtight), cables and correct oil level may sort out your first gear problem. Ditto choke cable.
If not, I'd be inclined to check for air leaks at the carb', the previously mentioned choke flap as they had a habit of coming adrift, and in the old days the points would have been suspect but I can't imagine even a CG still using points at that age. Water in the fuel would likely show itself when you tried to rev as it blocks the jet cutting the fuel supply.

Again, not being sarcastic but a CG shouldn't be difficult to kick over, probably a case of stalling, feeling vulnerable and being the centre of attention - take a moment to relax and compose yourself before getting in a flap (if you're in a panic desperately trying to start it at the head of a line of traffic it may be better to move it to one side and take your time). Panic could also be the reason behind struggling to find first gear, the CG box isn't a "slop fest" as you put it but may benefit from selecting first before coming to a halt.

Best of luck with it, I worked on loads of these when they were the learner/commuter of choice years back and sorted they are a cracking little bike - above all don't let it get to you as it's supposed to be enjoyable and you'll never enjoy it if you're getting wound up.

Baryonyx

Original Poster:

17,034 posts

115 months

Thursday 29th May 2014
quotequote all
It's a doddle to kickstart when it's warm. You could turn the engine off and consistently kick start it once it's warmed through. The issue being, that for the first part of my ride home from work it's all gently uphill towards the city and the interchanges I need to get home. So the bike is going through lots of periods of idling at traffic lights and on hills, perfect time for it to cut out and then it's a bugger to restart, more than likely linked to whatever problems the bike is already suffering. Pressing a button over and over until it fired would be easier than jumping on a greasy kick start lever though!


I've been out and had a fiddle with the idle speed screw just now, albeit not for long as I'm just about to go out. It didn't seem to make much of a difference, indeed just before putting the bike away it held an idle for about 30 seconds before slowly spluttering and dying out. The missus was furious as all the exhaust fumes blew back into the garage and made the kitchen stink. curse

I think the suggestion that the choke is malfunctioning could be bang on the money, as the issues are mainly experienced when the bike is cold and get better as the ride goes on. Looking at the outside of the assembly, it appears to be working though I can't say what is going on inside the bike. Looks like it could be a couple of hours work to strip down and rebuild. I'll have another fiddle tomorrow, with the exhaust pointing away from the house...

graham22

3,079 posts

161 months

Thursday 29th May 2014
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You just need to be able to look into the end of the carb, disconnect from the air box. the choke is simple on those, just a flap - can't remember if it's airbox or head side of the slide, if it's the latter you'll need to open the throttle when looking.

The flap will either be there or not.

Hooli

32,278 posts

156 months

Thursday 29th May 2014
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Sounds like you need a mate who's got more experience of bikes to help out.
Cleaning the carb out is probably a good idea, doesn't take much dirt to block the enrichment jet (which stops the choke working). Check/replace the plug, check the valve clearances, check the points (if it has them, they are in a crap place so get ignored) etc
A decent service should sort it really, they are such simple engines.

Roadrunner23

539 posts

151 months

Thursday 29th May 2014
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Have a quick look at the plug to see what colour it is, should be a nice biscuit colour. Get a Haynes manual or go online and re-setup the carb mixture. I think it is 1 and 3/4 to 2.5 times out from fully seated but can't remember 100%. To check for a carb air leak spray a small bit of wd40 around the carb manifold. If the revs rise or fall you know there is a leak. As someone else said remove the carb and give it a good clean as old fuel may have gummed it up. Is it points ignition or cdi?

Roadrunner23

539 posts

151 months

Thursday 29th May 2014
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As someone else said when coming to a stop from 5th gear go down the gears using the clutch, don't just pull the clutch in and kick down until you find first as sometimes it will get stuck in a gear. If it does don't panic and slowly pull the clutch out until you feel a bit and that will unlock it and you should be able to find 1st gear.

Mastodon2

13,090 posts

121 months

Thursday 29th May 2014
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It sounds like there is a lot of good advice in this thread. A workshop manual for the CG125 can be found here in PDF form:

http://die-kleinkraftrad-ig.de/wissensdatenbank/re...

I would imagine that being 13 years old and only having done 13,000 miles, it's probably suffered more from under-use than over use, and could probably do with a bit of TLC to get it back to happy health, especially since the bike sat for a few months to a year without even starting.

I'd knock up a jobs list, get the tools together and spend a day on the driveway in the sun working through them one by one.

1. Do a leak test with WD40 on the carb, spraying small amounts on to the joints where a leak might occur. If the idle speed rises, it's sucking in WD40 and there is a leak. I'm not sure if there is a gasket where the carb mates onto the engine itself. If you do have a leak I'm not sure what the next step is, other than possibly remove and refit the carb to try and get it seated properly. The manual will probably tell you what to do. If you do have to remove the carb, you may as well clean it. At this stage I believe you can flush it with carb cleaner. Don't get it on the paint! If necessary, strip, clean and rebuild the carb if it looks ropey. Check your choke flap valve is present and intact. Refit the carb. Check the air filter, clean or replace.

2. Drain the fuel tank into a jerry can, inspect petrol for tank crap. If the fresh petrol that went in the other day shows signs of fouling, remove the tank and flush it. This will be useful for clearing the main tank and reserve petcock spigots that feed fuel to the carb, incase they've been partially blocked by tank gunk.

3. Check the fuel tap filter for dirt which might be blocking it, or holes. Clean and replace, be ready to order and fit a new filter if necessary.

4. While the petrol tank is off, you might as well sort the leaking rocker cover gasket, and double that up with doing the valve clearances. On most engines this has to be done when it's stone cold to prevent it expanding under heat, so you might need to leave the bike for a few hours. Check the clearance and adjust if necessary, put a new gasket on and reassemble.

5. Unscrew the spark plug and check the condition, there are diagrams in the manual for this.

6. Do an oil and filter change.

7. Reattach the petrol tank, fill with fresh fuel.

8. Whip the chain guard off, give it a good clean with the petrol you drained off in step 2 and an old toothbrush, wipe dry with a rag and then apply some new chain oil. Check the tension, adjust if necessary.

9. Reattach chain guard. Unless I've missed something, at this stage the bike should have a spark plug showing the mix to be ok, it's valve clearances within tolerance, a new rocker cover gasket, a cleaned carb, leak free and with an intact choke flapper valve, a freshly-cleaned petrol tank, clean fuel filter in the petrol tap and a tank full of fresh petrol. Set the mix using the manual.

10. Take it for a ride.

These jobs are mostly just routine maintenance jobs, but I think that doing these will probably solve the problem, as well as making you more confident at diagnosing and working on faults in the future. Make yourself a short shopping list of the things you'll need, namely WD40/GT85, carb cleaner, new oil and filter, a jerry can full of fresh petrol and some chain oil. Get this stuff in advance and don't do the job the day before you need to go back to work on the bike, do it when you've got a few days off so you don't feel tempted to rush or get stressed. Alternatively, take it to a garage and have them do the above if you're not confident, I know it would be more stressful if it's your only transport to get to work.

Edited by Mastodon2 on Thursday 29th May 16:54


Edited by Mastodon2 on Thursday 29th May 17:06

Baryonyx

Original Poster:

17,034 posts

115 months

Sunday 1st June 2014
quotequote all
The problems I've had with the gearbox have certainly been resolved to some degree by counting my way down through the gears, letting the clutch in and out as I go. When I first got on the bike, I was giving too much concentration to other things, but now I'm more familiar with the gears, and their respective speed/noise/throttle response relationship, so I normally know where I am. Coming down to junctions, I've largely solved the issue of not being able to find first by slowly trailing to a stop in second and clicking down to first just as I come to stop, or go. I've learned not to be timid with the throttle when pulling away, especially on hills, as it really needs some!


It's still stalled at junctions, usually just as I come to stop or pull away. I suspect this is still due to the running issue. It was marginally better on Saturday monring, in that it only cut out twice, both close to home and when the roads were deserted. Coming home from work on Monday afternoon, I was expecting a tough ride. Mechanical issues mixed with rush hour traffic weren't an appealing mix, so I wasn't especially thrilled to be heading home on it after a long day at work. That was a surprise, as it started and idled fine first time, and gave no trouble on the way home. Despite heavy traffic on the way out of the city, the ride was good fun. I did have an issue with the N/S mirror blowing down to point at my knee in any sort of wind, a probably that first only appeared on NSL roads with a headwind, was now happening at 30mph. I went for a replacement mirror today, but the Honda garage was shut. I've pulled the gaiter down and glued the edge of the ball joint, which should hopefully hold out.