Hard starting CBR

[nleitao]

Hey Guys, pretty nice community here

Well i'm facing some starting issues with my Cbr125R from 2005
I bought it last week and i'm using it for commuting.
It has an Malossi cilinder, increasing his size to 166c, and also an aftermarket exhaust. Can't really identify it.

The main issue is a hard start.
All the week in the morning, i had almost a minute of continuous start button, every day, for it to go; that's terrible for the starter and for the battery. At 16:30h it starts almost well. She sleeps in a underground garage during the night and during the day is also in a closed garage at the work.
Yesterday i changed the spark plug for a new one although the old one sparks really nice; picture below of the old one. It has a standard gap of 0.7, and Malossi recommends 0.8 to 0.9. The measuring tool is already ordered to fine tune it.
Since when i choke it a tiny bit it's really worse i imagine the mixture is to rich, so i thought i would look for the air filter box to see how the air filter is; No air filter inside! Also already ordered.
In conversation with the guy from the spark plug shop, he suggested one of those start sprays. Bought one and i really notice a difference. it starts almost instantly compared with before.
I guess i have to open the Carb tomorrow and give him a cleanup, no air filter might put dirt inside, i'll change also the fuel filter, you never know and its really cheap.

Any other thoughts?

Picture and Youtube video below

https://lh6.googleusercontent.com/-Yj5TUIREVrk/VExH9_capUI/AAAAAAAATlQ/t2IwDjgl3AM/w596-h805-no/IMG_20141025_092912.jpg

https://www.youtube.com/watch?v=JSLawPk1jCs&list=PLRd9q9Uf0C6LnPZ1AHvIfVnWsZllx-64w

[monkeybiker]

If you take out the spark plug and look at it then look for picture of spark plugs online. The condition of the plug will give you an idea if it is rich or lean.

With it having no air filter I would have thought it would be running lean. Or it's running very rich and the last owner took out the air filter to lean it out.

How to fix it? I have no idea

[nleitao]

https://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

Great source!

I would say my spark is like the Lead Fouling

[Clutchy]

I'm fairly sure poorly checked valve clearances could also cause this issue, how many miles has it done?



But yeah, clean carbs, replace filter and see where you are after that.
____________________
Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
*33 BHP restriction up on 10/12/14* Current bikes/car: SV 650 S/ MKIV GOLF
Guide to pass your test with no lessons!

[nleitao]

[prawny1]

is the bike fuel injected or carb?

if it is fuel injected then you are gonna be lean for sure and relying on the ecu for cold start enrichment. as I don't think they can be mapped.

There are probably fuel rail pressure mods and different injectors available for these bikes as well as "black box" type things to trick the ecu into over fuelling, but it is all going to get expensive for not a lot of gain.

far easier to start putting things back to standard.

Are you confident enough to check the cam timing? it might have been set wrong,

do you get any fault light? are all the sensors plugged in?
____________________
hellkat wrote:

Some people are only alive cos its against the law to kill them.

[nleitao]

[prawny1]

heating needle = temperature gauge?

with a carb you will want to check your pilot mixture settings (may well be electronically controlled on a newish bike) and check for air leaks around the manifold or disconnected pipework.

Does the bike have a manual choke for cold starting? perhaps the cable is broken or slack.
____________________
hellkat wrote:

Some people are only alive cos its against the law to kill them.

[MaybeGuy]

It's probably jetted wrong. You've increased the capacity by 30%, so probably need both mains and pilots to compensate.
____________________
Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[nleitao]

[wr6133]

Get a range of jets and set the carb up properly that plug looks black it should be more a nice chocolaty brown. I'm guessing the previous owner just tossed in a bigger jet, realised it was way too rich so then removed the filter to compensate, still had issues and instead of trying some smaller jets just sold it to you.

[prawny1]

your cooling system should be full too, lack of coolant suggests a leak, a faulty water pump or head gasket issue.

the expansion bottle is only an overflow /reserve tank for the main system.

When the coolant gets hot it expands and the radiator cap allows the excess pressure to escape preventing blown pipework and splits in the radiator, when the bike cools down again the coolant creates a negative pressure drawing the fluid back from the expansion tank.

The jetting can only be altered by physically replacing the jets or enlarging the hole in the centre with micro drill bits (only good if you are running lean as you can't make the hole smaller this way), the numbers on the jets tell you the flow rate, higher number = higher flow.

Different jet makers use different sizing schemes so the numbers may not match between brands.

To adjust the idle mixture you will have a small screw with a tapered end and a spring with a small washer and o ring beneath it for sealing.

Usually somewhere towards the front of the carb by the inlet manifold, screwing this in will weaken/lean the mixture screwing it out will richen it up,

but like I said some bikes have an electronically controlled idle mixture that will be controlled by the engine temperature circuit (cold = richer warm = leaner).


Your plug being black suggests rich running but the fact you need easy start spray suggests you are lean.

Perhaps you are lean low rpm but rich high rpm,

try turning the idle mixture screw all the way in then back out 2.5 turns and drop the diaphragm needle down by raising the little clipone slot at a time and see what your plug colour does.
____________________
hellkat wrote:

Some people are only alive cos its against the law to kill them.

[chris-red]

A few points,

Don't hold the starter you shouldn't use it for more than a few seconds at a time.
Does it start ok with the spray?

By the sounds of it the carb isn't set right.

First off once it is warmed up and running take it out for a blast and see how it feels open the throttle fully and gradually reduce how it is opened. If it feels like it gets faster when you come off the throttle, you probably need a bigger main jet.
There is no point trying to set the rest of the carb untill you have the main jet sorted.

I've recently set up a carb for an old triumph using this.
https://www.hitchcocksmotorcycles.com/monobloc-how-to-tune-up

It is written for than specific carb, but applies to all cabrs.
____________________
Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando.
WANTED:- Fujinon (Fuji) M42 (Screw on) lenses, let me know if you have anything.

[nleitao]

You guys are great, I really appreciate the help. When I arrive home I'll digest this new info.

Thanks again
Nuno

[nleitao]

[chris-red]

That click can just mean the battery is flat.
____________________
Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando.
WANTED:- Fujinon (Fuji) M42 (Screw on) lenses, let me know if you have anything.

[nleitao]

[iooi]

[chris-red]

[nleitao]

[prawny1]

next step should be a cooling system pressure test or have the radiator tested with a gas sniffer to see if you are getting products of combustion in the cooling system.

It is starting to sound like the bike has a head gasket failure (or wrong head/gasket for the big bore kit)

A lean running bike or one with an intake air leak will pop a little on the over run.
____________________
hellkat wrote:

Some people are only alive cos its against the law to kill them.

[nleitao]

[nleitao]

Starter removed, opened, cleaned and closed. it's running. Tomorrow it's going to it's place.
Took the advantage that tomorrow I'll not run the bike and bringed the battery with me, it will spend the night and tomorrow's day charging to be sure it's ok for tomorrow's evening tests.

[prawny1]

[nleitao]