Poor Performance Unless On Half Choke

[Commuter_Tim]

If my bike runs without any choke, it has about 10-15mph less top end speed, also when you quickly blip the throttle from idling for a second it has a flat spot before revving properly.
This is after giving it more than appropriate time to warm up, even after a ride.

This has been an issue since I got it, it has been serviced a few times by local mechanics since then, and they have failed to sort the problem.
Granted last time they had it, the monkey had routed/twisted the throttle cable so badly, you couldn't turn steering right more than 3 inches without full revs...
I'm a retard and even I found and corrected that quickly.
There are also no decent mechanics anywhere close to me, so I'm pretty much on my own with this one :/

With it requiring choke to run, but full choke flooding it, then cutting out.
Am i to assume it means too much oxygen is in the mix?

Not that I know which screw adjusts that yet, but I'm sure I can find out, just don't wanna go twiddling screws before I know what to look for.
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The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[Commuter_Tim]

Also is anybody able to vouch for this make of carb?
https://www.ebay.co.uk/itm/New-Honda-CG125-Carburettor-Carb-Carburetor-NEW-/261371452039?pt=UK_Motorcycle_Parts_13&hash=item3cdaf3da87

I'm assuming as with anything, some brands are shit.
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The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[........................]

It's unlikely that you'll actually need a new carb. From what you've described it sounds like the mechanic who you have used in the past is incompetent so don't take their word for anything.

Do you have a CG125? That will have a very simple single carb, try having a go yourself, you'll be surprised how simple it is.

Get a manual and try setting the carb to factory spec, also check your air filter is in good condition.

[Bikeless]

Sounds like a blocked idle circuit/jet,a good carb clean should sort it.

[blurredman]

Have you tried turning the idle screw? It's a possibility that the idle isn't properly set.
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CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k.

[Kickstart]

Hi

Is performance badly affected throughout the rev range or just at the top end? Your comment on 10~15mph off the top speed suggests it is the top end that is badly affected. If you had lost that much power everywhere I suspect it would barely run at low revs.

If it is mainly the top end then that suggests the main jet or something else affecting large throttle openings. Probably worth cleaning out the main jet.

Does the loss of top speed get worse with time, and using the choke just delay the effect a bit longer? Does it have a fuel filter? If so to both then probably clean the filter out (or check that it is a large enough filter to flow sufficient fuel).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Commuter_Tim]

Thanks for the replies.

It is a CG125 W model.
The mechanic who supposedly cleaned out the carbs etc did also happen to leave black grease prints everywhere on the bike, even parts he had no cause to work on, so yeah, I take BCF consensus over his word

I guess I am being a bit of a pansy about taking it apart, it seemed simple on you tube to disassemble the carb.
The same guy lowered the idle speed at the same at as carb "clean" as someone at work mentioned it was too high, admittedly when i got it back comparatively it sounded like it was barely chugging along, is there a good way to measure engine idle timing without any tools?

My air filter is clean as a whistle, even swapped it for a new one not so long ago.

Whole range performance is actually quite good, generally get very good acceleration 0-30, 30-40 acceptable, above that, piss poor in most gears.

I also noticed redoing my CBT the other day, their BR model CG had a decent sized rear sprocket like this...
https://thumbs4.ebaystatic.com/d/l225/m/mcOFkgrSVwvQGbfdNBnjrpQ.jpg
Mine is some pissy little thing about half the size.
at the low end the other learner had trouble accelerating to 30 with me, but above that I couldn't keep up with him, could the sprocket size at least be my top end speed problems?
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The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[lihp]

Just me that read the topic title as:

Poor performance unless on coke?
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covent.gardens: lihp is my most favourite member ever

[Kickstart]

[blurredman]

I also had BR model CG, and noticed that the recommended gearing is something like 45 tooth rear, and the bike doesn't get past 56mph.
I lowered the front tooth (cheaper) to 13, the equivilent of the rear being the standard 42 and the bike was quicker, and indeed reached 61mph. Maybe the Brasilian ones are geared for economy??


Also thinking about carburettor, the main needle too low on slide? Maybe it needs to be up one notch?
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k.

[Fizzer Thou]

Spray some WD40 or 'Dampstart' around the inlet manifold between the engine and the carb with the engine running.If the engine revs rise noticeably,then you have an inlet leak.This is allowing the mixture to run too weak,so that using the choke on at least half-setting makes the mixture richer to compensate.

If you have to ride with the choke set to halfway,then top speed will be affected as it will stop correct airflow over the needle jet.
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Just talk bikes.What else is there?

Always have a 'Plan B'

[Commuter_Tim]

Sorry to drag this thread back from almost Necro workshop, but I do appreciate any help I can get.

I checked and it seems sprocket rear smaller size is standard for the Turkish CG's.

So seems it may well be a carb issue, but have yet to have a day free where it wasn't pissing down and I could get out there and try your suggestions, I use it every day for work so need to do it all in 1 day ideally.

Just wondering tho it seems I may be able to clarify the situation, to help you lot help me.

It seems you are correct Fizzer, the top end problem is purely down to riding on half choke, it seems to have full speed If choke is off.
The main issue being even after a decent ride, I go stationary, choke off, If I then whack on the throttle it cuts out, yet I chuck it back on half choke, and it happily revs the tits off from idle.

Now next chance I will be ripping the carb off to clean, this being the first time I've done this tho.
Is there anything else in particular I should check? or just the jets and engine idle screw?

Also Blurredman you mentioned the main needle, saw which bit you mean on youtube, is adjusting it purely trial and error?

Tried the WD40 thing, seemed ok, no change to revs :/
____________________
The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[Commuter_Tim]

OK so I tried playing with the idle speed, didn't seem to make a lot of difference with it cutting out when hitting throttle from idle.

I noticed when I whack the throttle on, the exhaust made a popping noise (more of a pop than a bang, but it is only a 125...)

https://i1274.photobucket.com/albums/y439/Timothyallen85/IMAG0219_zps43b50cdd.jpg

https://i1274.photobucket.com/albums/y439/Timothyallen85/IMAG0223_zpsf4b11f90.jpg

The exhaust is leaking a lot as in the photo below, not sure if its petrol or stanky moisture??

Also the rubber air inlet from filter to carb looks like the rubber hook at the top of it is rotting, not sure if its just the hook on top or if that hole goes right through, didnt care to push too hard on it.

Is it possible I could just be expecting too much of the bike?
Am I stupid to think I should be able to just turn the throttle to max and back, in neutral, without it cutting out?

Annoyingly for some reason my choke switch keeps throwing itself full on, but not every time, and I've already checked that the screw on the choke hinge is tight.
____________________
The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[Commuter_Tim]

I finally got the chance to remove my Carb, strip it and clean it.
Turns out this was the problem all along.
So a digital 12 pack of beers for you all for helping steer me in the right direction!

Just to update for all the noobs like myself who may encounter this problem...

The loss of power was purely down to the fact I was riding on half choke at those times, as lately it wouldn't ride any other way.

It's hard to say *exactly* what the cause of the stalling was, as there were so many problems:
Sticking throttle slide (covered in black shit)
black shit on the throttle needle too
caked on yellow oxidation throughout the entire carb bowl
caked up jets
the list goes on, but it all revolved around shit caked everywhere

It seems that it all may have stemmed from the "mechanic" who has been the only person besides myself working on the bike, has thrown away my rubber gasket from the airbox (probably 6 months ago when he was meant to clean the carbs...), causing it to cake up, then the filters which were covered in what I can only describe as a mixture of Piss and Jizz.

But I cleaned it all up and refitted it, started fine first time, sounds healthier too (not that I would really know).
I can rev the tits off it now tho, so here's hoping its all good in the morning.
____________________
The above post is most likely nonsensical.

I ride a Bandit 600... badly.