Why do i have to open full throttle when i start my bike?

[crazydj]

Hi all!

 

My bike is like super weird. Whenever i want to start my bike on a cold morning, i just need to open throttle a little bit, hit the electric start. I have to keep the throttle open for about 3 seconds to prevent the engine from dying. This i can live with.

 

However, when i take a long ride and park my bike for about 15 mins onwards, i have to open my throttle to the max. Like electric start then almost open max throttle. Then i can hear the starter motor spin up fast with the engine cranking and all then it slowly comes to life, keeping in mind balanced throttle control.

 

Just changed new about/less than a month ago

1) Carb

2) Stater motor

3) Rectifier

4) Magnetic coil

5) Spark plug and engine oil

 

Any ideas why this is happening?

[kuwaiyert]

Since u had done as what u mention, Probably there is a leakage at ur engine block.. perhaps u need to re-tighten or time to replace the gaskets..

Edited March 18, 2011 by kuwaiyert

[deckard]

check your sparkplug

[ezzyoiler]

Hi all!

 

My bike is like super weird. Whenever i want to start my bike on a cold morning, i just need to open throttle a little bit, hit the electric start. I have to keep the throttle open for about 3 seconds to prevent the engine from dying. This i can live with.

 

However, when i take a long ride and park my bike for about 15 mins onwards, i have to open my throttle to the max. Like electric start then almost open max throttle. Then i can hear the starter motor spin up fast with the engine cranking and all then it slowly comes to life, keeping in mind balanced throttle control.

 

Just changed new about/less than a month ago

1) Carb

2) Stater motor

3) Rectifier

4) Magnetic coil

5) Spark plug and engine oil

 

Any ideas why this is happening?

 

if the engine is hot...and you shut it down...and decided to start engine agian......when you are unable to start engine...

 

get your carb retune.....the fuel mix is too lean..

suggest you retune your carb..

[Raptor]

Mixture is too rich.

 

Your carb is overflowing due to dirt on the carb bowl float high level shutoff valve seat or the valve needle is worn out or the float level is set too high.

[MiddleAgedBiker]

Mixture is too rich.

 

Your carb is overflowing due to dirt on the carb bowl float high level shutoff valve seat or the valve needle is worn out or the float level is set too high.

 

What he said. Also, if your bike has an accelerator pump, excessive opening of the throttle even when the bike is turned off will flood your carbs.

[MiddleAgedBiker]

Mixture is too rich.

 

Your carb is overflowing due to dirt on the carb bowl float high level shutoff valve seat or the valve needle is worn out or the float level is set too high.

 

What he said. Also, if your bike has an accelerator pump, excessive opening of the throttle even when the bike is turned off will flood your carbs.

[MR BIKER]

Or one of the most funniest i ever learn---- your exhaust too much carbon causing some kind of blockage which cause it to just dies of when you are not trottling

[Raptor]

Or one of the most funniest i ever learn---- your exhaust too much carbon causing some kind of blockage which cause it to just dies of when you are not trottling

 

There is some truth in this. There was a Super4 once that had so much carbon coated on the catalytic coverter that it blocked all the perforations so much so that the bike could not rev high nor could it idle properly.. almost everything pointing erroneously to a carb problem.

[crazydj]

The carb is new. Immediately after i changed it, after a long ride and my engine is nice and hot, i can see petrol vapour coming out from the carb overflow hose. If i put something near the end of the hose like a peice of glass or my finger, the petrol will condense and it will start to drip out from the hose for a few seconds.

 

I get about 34km/l as opposed to my usual 40+km/l with my old carb. Also, the bike feels underpowered now. Any ideas?

[Raptor]

The carb is new. Immediately after i changed it, after a long ride and my engine is nice and hot, i can see petrol vapour coming out from the carb overflow hose. If i put something near the end of the hose like a peice of glass or my finger, the petrol will condense and it will start to drip out from the hose for a few seconds.

 

I get about 34km/l as opposed to my usual 40+km/l with my old carb. Also, the bike feels underpowered now. Any ideas?

 

Still an issue of the fuel level in the float bowl being set too high or overflowing due to high level float shutoff valve not seating properly due to dirt or damage.

[xXxRatedxXx]

The carb is new. Immediately after i changed it, after a long ride and my engine is nice and hot, i can see petrol vapour coming out from the carb overflow hose. If i put something near the end of the hose like a peice of glass or my finger, the petrol will condense and it will start to drip out from the hose for a few seconds.

 

I get about 34km/l as opposed to my usual 40+km/l with my old carb. Also, the bike feels underpowered now. Any ideas?

 

Ya think what raptor suspect is right.... go ah choong ask him help tune your karpetta... maybe too rich.

[MiddleAgedBiker]

There is some truth in this. There was a Super4 once that had so much carbon coated on the catalytic coverter that it blocked all the perforations so much so that the bike could not rev high nor could it idle properly.. almost everything pointing erroneously to a carb problem.

 

Just curious, how did they finally trace it down to this problem?

[ezzyoiler]

Just curious, how did they finally trace it down to this problem?

 

use your hand...or if you havs a pressure gauge use that.

[MiddleAgedBiker]

No, what I mean is, how did the mechanics even think about the pipes being the cause of the problem?

[ezzyoiler]

one off the item i will check for is compression...for power issues

either from the spark plug hole or by feel at the exhaust...

2 strokes draw back isthat you need to decarbonise at regular intervals..

 

as regards to why mechanics think about this area??

any experience mechanic will eventually trouble shoot this issue..

as to why?? i have no answer why mech think that this is the problem.

[azl-128]

Same problem as me in the cold morning. At Unique, just because I never do carb wash with them before, they constantly ask me to wash. I just wash last August.

[crazydj]

I still have the same prob after my mech changed back all the relevent jets on my new carb. Basically, even though the carb was the same model, the jets on the new carb was slightly larger. He changed all the jets from the old carb to the new one. Still same problem, although my fuel efficiency went up dramatically.

 

How do i explain this problem to you guys? Okay, when the engine is cold, i need to open throttle a little bit. Like early in the morning, no problems. But when i take a ride, about 15 mins ride, whether i park in a cold basement carpark, open space carpark on a hot day or multi storey carpark, (engine is still piping hot to cooling down after 6 hours), i need to open maximum throttle when starting the engine.

 

Let me explain with my "sound effects".

1) Press the electric starter. Engine will almost NEVER start even how long i press it. Nevermind

2) I have to press the electric starter and open the throttle to full. EH-HEH x 5 (Slow) Then EH-HEH x 5(Getting faster), then finally the engine slowly comes to life. I can hear it like 'crank up' about 4 times before i get a 'full starts and the engine will spin by itself'.

 

Ideas?

[ezzyoiler]

do one more thing....clean any thing connected in your air supply and fuel lines

 

ie petrol starting from petrol tank, hoses to the carb..u got the idea..

if still have problem its time to overhaul..

Edited April 4, 2011 by ezzyoiler

[ezzyoiler]

get a carb cleaner...spray it into the air intake while you start your bike...

if this still cannot start bike easily...

well if this is my bike... i will dispose of it..

[crazydj]

Can this be related to the magnetic coil? Its because there was NOTHING wrong with the bike before the magnetic coil went kaput. From what i understand from my mechanic (and i heard this from others before), my bike has 3 revisions of magnetic coil.

 

Rev. 1 -> $30+, Rev. 2-> $60+ and Rev. 3 -> $100+

 

The last time i changed my coil 3 years ago, my old mech changed a $100+ coil. However, now, i just changed to the $60+ coil because my mech's supplier never bring in the $100+ coil. Looking at my problem, could it be the magnetic coil? But since opening my throttle is linked to my carb and engine component itself, what could the problem be? Its not much of an issue la because i know the starting drill of turning on my bike but its just that, its kinda irritating.

[Stylo]

Items to check.

1. Battery

2. Rectifier

3. Plug

4. Engine oil

5. Air filter

6. If above all OK . Carb tuning>>

7. After carb tuning set the idle rpm (about 1200 rpm =/- 100rpm)

No step 6/7 if not sure ask mechanic to do it.

[ezzyoiler]

have you clean spark plug and set the proper air gap....too wide you will have starting issue too.

[damagedigital]

What bike r u riding?

[crazydj]

05' Yamaha YBR125

 

Anyway, now the full throttle issue not so bad. When i engine is hot, i set my idle rpm to almost 2k at about 1.8 to 1.9k. Now when starting, not until so gay must open throttle until so full. Carb too lean ah?