NO 1 ....FUEL TAP FILTER IN TANK !! if its half caked up with rust or dirt you wont get enough fuel flow...just a thought..judging by the silt in the new inline filter...???👍🏻☮❤
Not a bad shout. I did think about it, however the flow is really good when opened. So I didn't bother with another tank. Will try it tho again! Cheers!
I recently restored an old (1986) cg125 had exactly the same symptoms as you’ve got, it was the fuel tap in the end, the fuel was just trickling out to feed the carb. Good luck mate.
If it runs with the choke on cuts out with choke off the mixture is lean, lots of air not enough fuel. Try gravity feeding the carb from a bottle or funnel, bypassing the tank, as you have the same issue with both carbs.
The first things that came to mind for me, were possible blockage of the petcock filter inside the tank, gas cap venting blockage, or kinking/vacuum collapsing of the fuel line from tank to carb. Very much seems like a fuel starvation problem, not a matter of carb settings per se. When my CBR125R is extremely low on petrol, I can still ride with zero issues on gentle throttle, but cause it to instantly gag, cough and stall out via a large handful of throttle. Best wishes to sort it out!
MackieBass I received my Cambridge pinstriping sticker today the 29/3/19 It's going to look awesome in the inside of my lid of my airbrush tool cabinet thank you very much 🤘and have a beer check the height of the needle in the carb and good luck
Hi Mackie, Im not a mechanic this what I would try next first fuel air/fuel mix, then check the timing points (not sure if it has old style points but its worth checking) 3rd pull the fuel tap out and check/clean filter and the inside of the tap. DO NOT drill the butterfly valve on the new carb! your new carb is a full power (15bhp i think) model whereas the old is a restricted (12.5bhp I think) model. personnally i would also dump the nylon spacer but thats me. If i got any thing wrong please say quickly as I dont want Mackie wasting his time. Thx
The small Honda's run very lean and sometimes the muffler baffles will start to break away if it is an older bike or depending on the climate where it stays.The slight restriction at the air box sometimes is all it needs.I did not watch the whole video but I see you have a lot of comments I would expect that one or more suggested also to check the carb holder for leaks via a aerosol spray with straw.Hope this helps.
Problem with carbs is... cg is a single, so each suck (induction) charges a 125 cc cylinder... the ca is a twin, so each suck charges a 62ish cc cylinder, hence the different bore size. I would forget that and look to the original problem... the symptoms sugest that there is insufficient fuel flow to keep up with a rapidly opened throttle, but apparently enough to maintain proper mixture with a progressively opened throttle. Which to my mind would suggest a partially blocked jet or drilling in the carb. Remove any jets/tubes etc and get the carb cleaned ultrasonic is best, then dry with an airline. Hope that helps, difficult to diagnose remotely. (retired mechanic).
Try running it with the fuel cap off if that doesn’t help then remove the fuel tap and check for crap in your tank that would obstruct the fuel flow,also make sure that there is no air leaks on the rubber hose that connects to the carb and that it is secured tightly to the carb as this would fuck up your fuel and air mixture
Before you start taking the new carb apart make a note of how many turns the air screw is turned out from being fully in. I suspect they are set to be "in the zone" when they are assembled so the carb is basically plug and play. Use that original setting as your baseline.
Hi Mackie,sounds like its running too lean on the main jet to me. I think its worth removing the float bowl and taking a look at both the pilot jet and the main jet. if you remove them and look closely you will see numbers stamped on them which will tell you what size they are,for example the main jet might be size 105 or something similar (if you have a Haynes manual for that bike it will tell what the standard jet size and needle positions are) its worth comparing the jet sizes from both carbs just in case the original jets are bigger,I doubt that they are though, given that the new carb has a significantly bigger bore size. More airflow requires more fuel,you might need to go up one or two sizes on the main jet so if its say 105 then a 115 or 120 size might improve matters. It's also worth checking the float level on both carbs because if that's too low it can cause fuel starvation too. (The manual should show you how to set the float height) Fresh fuel also helps too,modern fuel goes off quite quick and some bikes are more sensitive the these things than others,I once owned a honda cr500 and if the fuel was left in it for more than 2 weeks It wouldn't start at all! Hope this is of some use to you,carbs can be a pain in the ass sometimes,at least that bike is easy to work on,unlike some modern bikes. All the best mate.
Luke, thank you so much for your suggestions here. Much appreciated. It all makes perfect sense. I will explore all the above and report back with my findings! Cheers.
Hi Mackie as others suggest it could be the fuel filter, also worth checking the flow from the petcock itself. Also changing the carb for one with more airflow its worth checking needle height but may also need a rejet possibly later on. Im no expert but worth a go. Hope you get it sorted soon.
Had the same problem on my 650 Deauville mate, turned the idle speed down a touch, and all is now fine, strange how carb's play up! But fair play, you sorted it buddy. Ihope anyway, not watched all the video yet lol
The plastic spacer is athermal insulator. It resuces heat transfer from engine to carb. you should bore it to matchthe new carb.. this isnt your problem in regards to tuning. Is the new in-line filter more than half full when running you may have a blockage in the line or petcock? Goodluck
I think you nailed it...I will inspect it again. The petrol was flowing smoothly from the petcock, so I wasn't worried about that. But I will double check that all.
Bad fuel, You know the answer. Just get on and thoroughly clean the whole fuel system put in fresh fuel and next year store the bike empty. Put the old carb back on, it's probably ok. Nice Garage.
Hi Mackie! ..great little bike this one. .. So, not an expert,..but service people are telling if you're engine won't run without choke, then look to your pilot jet screw... My thinking about everything is.. When you believe it to be a carb problem...it might be an electric problem as well.. and vice versa... ...did you see to a new spark-plug..? Coil-amps..might test it..? ..really hope that you get this little bike running,.. cheers!..:)
My initial assumption was the same as yours but you have the same symptoms on both carbs - so I'd rule out that as the source (for now). Check the fuel flow to the carb - can you bypass the tank? If that doesn't work, and I'm not sure it will because you can nurse it up to full revs so it has good enough fuel flow into the carb (otherwise it would run the carb dry), and fuel through the jets. The issue seems to be on hard acceleration (accelerator pump and needle position are replaced in the new carb) and if you've ruled out fuel delivery into the engine, I'd be thinking about points advance - are you just flooding the engine with the accelerator pump and the spark isn't keeping up? Good luck! Skäl David
Here’s my 2pence worth I think is sounds most definitely fuel related ie fuel staving I look simple first and I’d look at the fuel tap if it ran before it was stored I can’t see it being major you’ve put 2 carbs and still same issue so work back hope you get sorted 🤞\m/
You said it was stored outside with a cover over it. You changed the air filter you said ? How does the airbox get its air before the filter. Is it clear ? Is the exhaust (muffler)clear ? When you store a bike, especially outside, critters (mice) can get in and make a nest and block intake and exhaust passages. If that happens the bike wont run properly.
Crap in fuel tank maybe, partially blocking the filter over the tap on the inside, if it sat for a while, this new bio fuel is crap if its left a couple of months, its kind of goes mouldy for want of a better description. Also, make sure the rubber from the airbox to the carb is not split, or not fitting properly, that wont help either. Good luck buddy.
Yes, I know, modern fuel is crap indeed. But I've got fresh one in the tank. And the flow is smooth, so I was hoping it'll be ok. I will double check that for sure!
Was just about to put that very suggestion forward, feeding 2 carbs from 1 source has never worked successfully because it's a shit cost cutting excercise!
Listening to it run and watching your second attempt, it looks and sounds like you have a fuel issue, not getting enough to the engine. It runs much better on full choke. I would look for some sort of restriction in fuel flow to the carb and eliminate that from the equation first. Is there something floating around in the fuel tank? Is there a fuel line pinched? Is the fuel filter plugged ? Not knowing anything about any of the 125 cc models, I would have to think that they would be jetted and adjusted the same since they have the same displacement. That would get me to thinking that there shouldn't be too much to adjust with the new carb. But, what do I know, I'm from the States and don't ride motorcycles.
Definitely sounds like it's starving for fuel ...the fuel lines and the valve at the tank is where I'd start after learning it's the same with both carb's... good luck with it my friend
@@CaptainScarlet1961 Well the valves would contract and expand with the change of the temp's but the timing not sure, however it could be one of the issues. Anyway just some thoughts I had I don't know for sure.
That's probably the only thing I didn't do...but I'm on it this afternoon! Plugs were fine, I replaced them anyway, but they looked just right in my opinion.
