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Discussion Starter · #1 · (Edited)
Model Year: CBR 250r 2011

Odometer (Miles/Km's): 41,000 Km

ABS model?: No

Description of the Problem:
Start Motorcycle, turns on fine, but will die after about 3 seconds. I can engage the throttle and the motorcycle will stay on. As soon as I let the throttle go, the motorcycle dies. I can ride it, but cannot idle it at all. Have to manually engage the throttle to keep the RPM at 3k, to keep it running.

Operating Conditions when Problem occurs: Pulled motorcycle out of garage and tried to start it, but the problem started.

Service History/Previous issues regarding this bike: Changed Spark plug 1.5k km ago. Do regular maintenance and have been riding it for 8 years. No issues other than transmission plates being replaced at about 34k. I changed the oil 7 months ago, or 1.3k KM ago.

Aftermarket Parts & Accessories installed on the bike: None.

Any other information that may be relevant to the Problem/Issue:
I have fully charged the battery with a trickle charger. The battery is 18 months old. I reset the ECM. I changed the air filter. Checked the air intake for obstructions. Refastened the battery lines.

Other Solutions that involes spending money to find out if it fixes the problem.

Fuel Line Filter.
Running Lean.
Bad compression.
Throttle sensor needs to be replaced.

Other solutions are appreciated. A confirmation of a solution would be astounding.
 

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Changed Spark plug 1.5 km ago
Hey, maybe you should start with that. That the plug is the right TYPE. Check that the plug is screwed all the way in, and its connector sits properly and creates a good electrical contact.
Other solutions are appreciated. A confirmation of a solution would be astounding.
As always, a good mechanic needs a lot of patience, time, knowledge, tools, and a comfortable place to work .with.. if you have all of these you will find the problem, and also fix it. If it is urgent for you that the motorcycle return to normal work, contact a qualified mechanic in your area. As I am impressed your problem is not of the expensive kind, but self-locating can take its time.
Question: If you hold a high RPM with the help of the throttle, in this situation the RPM is stable? Are the engine noises are normal?
 

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Discussion Starter · #3 ·
I meant 1.5k Km. I will check the Spark Plug after work.

The RPM is fine unless it hits just just below 2.5k RPM, then it will putter out and die. I can still ride like any other day, just can't idle.
 

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I meant 1.5k Km. I will check the Spark Plug after work.

The RPM is fine unless it hits just just below 2.5k RPM, then it will putter out and die. I can still ride like any other day, just can't idle.
Excellent, let's move on:
Is the throttle alone capable of stabilizing idle RPM, do not leave the throttle full close, find a balance point and stop there. Are you able to stabilize 1500 rpm with the help of the throttle?
If so, I would clean the hole, the side air passage for idle, or at least check that it is clean. The throttle body must NOT be cleaned with fuel and oil solvents such as: Carburetor cleaning spray(NO), or brake cleaning spray(NO NO), such materials are prohibited**.
You allowed: Air pressure, gentle brush, gentle wiping with a soft rag ...
**Because the throttle body has a molybdenum coating
 

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Discussion Starter · #5 ·
Excellent, let's move on:
Is the throttle alone capable of stabilizing idle RPM, do not leave the throttle full close, find a balance point and stop there. Are you able to stabilize 1500 rpm with the help of the throttle?
If so, I would clean the hole, the side air passage for idle, or at least check that it is clean. The throttle body must NOT be cleaned with fuel and oil solvents such as: Carburetor cleaning spray(NO), or brake cleaning spray(NO NO), such materials are prohibited**.
You allowed: Air pressure, gentle brush, gentle wiping with a soft rag ...
**Because the throttle body has a molybdenum coating
Lowest I can go with throttle is 2.5k RPM. It will not stabilize at 1500 rpm using throttle, as it dies around 2.5k RPM.

Are you talking about the butterfly valve in the throttle body? I'll use CRC Throttle Body Cleaner. That'll be done after work too.
 

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Lowest I can go with throttle is 2.5k RPM. It will not stabilize at 1500 rpm using throttle, as it dies around 2.5k RPM.

Are you talking about the butterfly valve in the throttle body? I'll use CRC Throttle Body Cleaner. That'll be done after work too. No No NO
CRC Throttle Body Cleaner.? NO NO NO
Do NOT cleaned with fuel and oil solvents such as: Carburetor cleaning spray(NO), or brake cleaning spray(NO NO), such materials are prohibited (Because the throttle body has a molybdenum coating).

Since with the throttle you can not stabilize the RPM at 1500(idle), then the problem is NOT in the throttle body. You asked about the hole through which air passes when the "butterfly valve" is closed? This hole is on the right side of the throttle body, the entrance is near the IACV, the exit after the butterfly valve.
Automotive lighting Automotive design Rectangle Motor vehicle Font


The ignition is strong, the battery is powerful?
Because the next option I would check is is there a charge?
 

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12.7V OK Feel free to check again, this is a simple check, I recommend you check it again.

The 12.7V tells only part of the story. I recommend you to check the dynamic tests:
1. Voltage when the motor is at 5000 rpm, should be around 14.1V.
2. Voltage drop. When starting the voltage should be above 10V.
(3. At 1500 rpm should read around 13.9V, but at the moment you can not measure because of the problem with the rpm).

vacuum leak?
Check the rubber that connects the throttle body to the engine inlet (INSULATOR 16211-KYJ-901). Is it cracked? Check that the clamping rings are tightened (maybe the screws are loose)?
 

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Discussion Starter · #12 ·
CRC Throttle Body Cleaner.? NO NO NO
Do NOT cleaned with fuel and oil solvents such as: Carburetor cleaning spray(NO), or brake cleaning spray(NO NO), such materials are prohibited (Because the throttle body has a molybdenum coating).

Since with the throttle you can not stabilize the RPM at 1500(idle), then the problem is NOT in the throttle body. You asked about the hole through which air passes when the "butterfly valve" is closed? This hole is on the right side of the throttle body, the entrance is near the IACV, the exit after the butterfly valve.
View attachment 45350

The ignition is strong, the battery is powerful?
Because the next option I would check is is there a charge?
The battery is in functioning order and it starts on first turnover.

I wasn't going to use the CRC on the throttle body. I was going to use CRC on the butterfly valve. Maybe it's gunked up and not moving properly.

Why is it bad to use CRC on molybdenum?
 

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Discussion Starter · #13 ·
12.7V OK Feel free to check again, this is a simple check, I recommend you check it again.

The 12.7V tells only part of the story. I recommend you to check the dynamic tests:
1. Voltage when the motor is at 5000 rpm, should be around 14.1V.
2. Voltage drop. When starting the voltage should be above 10V.
(3. At 1500 rpm should read around 13.9V, but at the moment you can not measure because of the problem with the rpm).

vacuum leak?
Check the rubber that connects the throttle body to the engine inlet (INSULATOR 16211-KYJ-901). Is it cracked? Check that the clamping rings are tightened (maybe the screws are loose)?
I'll check those voltages too. I will also check the rubber too, and see how that goes.
 

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I wasn't going to use the CRC on the throttle body. I was going to use CRC on the butterfly valve. Maybe it's gunked up and not moving properly.

Why is it bad to use CRC on molybdenum?
Please DO NOT!
CRC will ruin your coating. The coating important otherwise it would not be there.
Try not to destroy it (These are the manufacturer's instructions)
 

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Why is it bad to use CRC on molybdenum?
My mistake
The CAUTION about the molybdenum can be found at Haynes book(No' 5919):
Page 4 * 16(Chapter 4 Section 7)
and NOT in Honda's book.
I add my recommendation, that CAUTION is correct and accurate!
 

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There is "Throttle Body Cleaner" designed for cleaning the TB.

I would try adding a strong fuel system cleaner like Techron Concentrate (1oz per gal) to the fresh gas.

If there was old gas in the tank when you added the new gas, it could still be a problem. Checking the Throttle Position Sensor (TPS) may be something to try.

Checking that your voltage goes up when the engine is running isn't a bad idea either.

Then there's always the possibility of a bad fuel pump (common). As noted, check that the tank is free of rust.
 

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Fixed. Dirty Air Filter caused the Spark Plug to get gunked up. Occurred after only 1.5km with new Spark plug. Filter and Spark Plug replaced.
Run a strong fuel system cleaner like Techron Concentrate (1oz per gal).

That cleans the fuel system, injector, intake valves, and combustion chamber. It's possible that carbon build-up can cause detonation and eventual engine damage if excessive.

I run it once a year in all my vehicles.
 
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