engine sound check

[HunterCubNL]

Hi all,

Just joined the forum as proud owner of my CT125 for about a year now.

I've been changing some parts here and there, but now I feel like there is a sound that shouldn't be there. Might be my paranoia as I'm just started working on bikes, but would greatly appreciate it if you guys and gals could perhaps have a listen to the video I took.

This is the YouTube short I uploaded of said engine sound

Last weekend after I used the kill switch, when turning it back in the engine check that occurs got stuck and didn't work until I started it up again some times. I also noticed today that when I turn on the engine the check engine light also blinks for less than a second.

I hope it is all in my head, but better save than sorry. Planning on camping coming weekend and need to know if I can take the cub or not.

All help would be great appreciated.

Regards,
Nick

 

[m in sc]

sounds normal to me.

 

[vintagegarage]

Sounds normal to me too.

 

[Kev250R]

I think you're fine. Remember, these are air-cooled engines so they are going to be little noisier then a liquid-cooled mill.

 

[dmonkey]

What parts have you changed, anything engine related?
If you are running the engine in a garage, next to a wall, or anything like that it will sound different than out in the open and you'll likely pick up on valvetrain noise more than you otherwise would.

The check engine light should illuminate when you switch the ignition to on, and then it should clear a second or so later. If it's doing anything more than that, then it might be giving you a DTC (Diagnostic Trouble Code) to look into.

 

[m in sc]

keep also in mind, this motor uses rocker arms to work the valves, they will add to 'normal' engine noise. don't sweat it you're fine.

 

[HunterCubNL]

First of all, thank you for all the responses.

The chance is high that it all was in my head and I'm worried about nothing. Just thought that there was a low, irregular sound mixed with the normal engine sound.

I've changed the following of the engine:
Exhaust to SP Tadao
Big throttle body + intake SP Takegawa
Cam shaft SP Takegawa
Air filter SP Takegawa
Oil cooler Morin (added extra oil as specified)
Oil pump NK racing (150% more output to compensate for the cooler)
Enigma subcon (currently using settings taken from SP Takegawa)
T-rev mini

After the last upgrade I rode about 300-400 miles I think, but might be more or less. Living in Tokyo so making long distances isn't that easy to do.

Of a DTC is thrown, how can I read this out? It turns on at turning the key and goes off like normal, but yesterday when cranking the engine I saw it flash for a split second, adding to my worries.

I will go for a ride again and keep an eye on performance. At the next oil refresh I might also open it up to clean the oil screen and check the insides.

 

[dmonkey]

IIRC a DTC wouldn't flash when cranking, it will flash when the key is turned to the ignition on position. The only thing I've ever caught while cranking the electric starter is that the illuminated lights, ABS and Neutral, may dim for a second and the headlight may flicker due to the power draw of the starter.

Here is info on checking DTCs:

The codes themselves are listed in the Service Manual which can be found here.

 

[HunterCubNL]

I checked the DTC by shorting the blue and green/black cable using a pin. After turning on ignition the engine light stays on. this would mean there are no stored DTC codes?
I remember resetting the DTC + o2 sensor when installing the new throttle body, as well as resetting the EMC when the subcon was installed.

I also checked oil levels which are fine, the oil also flows through the radiator without any issues.

After installing the new camshaft, sometimes the starter has difficulty with the first rotation, but after looking into this it probably has to do with the new camshaft not having a decomp on it.

I think I just need to ride it again and if nothing feels off then there probably isn't any need to worry further.

 

[dmonkey]

The check engine light or malfunction indicator lamp should not remain on. It sounds like it may have been shorted for too long based on that behavior and what's in the service manual.


Does the stock cam's decompressor fit the Takegawa cam that you're running? If so that might be an easy solution to just move it over, otherwise that sounds like it would be hard on the battery and you might want to consider a battery with more cold-cranking amps, or kickstarting it.

 

[HunterCubNL]

I removed the pin within 5 seconds of turning on. Might try again tomorrow with a different cable. If I leave it in and there is a recorded DTC, will it tell me by blinking while it is shorted?

Going to check if I can put old decomp on new camshaft. don't like the struggle it sometimes has to crank the first revolution. Thanks for the tip, until I installed decomp I will use kickstart.

 

[m in sc]

dont sweat it and dont worry about the starter . just bump it. if that bothers you, you can get a high torque starter, but most aftermarket cams wont allow the decompression lobe to be installed.

 

[inroads]

First of all, thank you for all the responses.

The chance is high that it all was in my head and I'm worried about nothing. Just thought that there was a low, irregular sound mixed with the normal engine sound.

I've changed the following of the engine:
Exhaust to SP Tadao
Big throttle body + intake SP Takegawa
Cam shaft SP Takegawa
Air filter SP Takegawa
Oil cooler Morin (added extra oil as specified)
Oil pump NK racing (150% more output to compensate for the cooler)
Enigma subcon (currently using settings taken from SP Takegawa)
T-rev mini

After the last upgrade I rode about 300-400 miles I think, but might be more or less. Living in Tokyo so making long distances isn't that easy to do.

Of a DTC is thrown, how can I read this out? It turns on at turning the key and goes off like normal, but yesterday when cranking the engine I saw it flash for a split second, adding to my worries.

I will go for a ride again and keep an eye on performance. At the next oil refresh I might also open it up to clean the oil screen and check the insides.

Lots of engine changes..how fast does she run now ?

 

[HunterCubNL]

Lots of engine changes..how fast does she run now ?

Haven't had chance to really test her as I can't go on the highway in Japan and mainly ride in the mountains.
Managed to reach 110km/h on a flat road once or twice. But most important for me is that hills are less of a challenge.
When riding in the mountains it's easier to climb up and the cooling helps with maintaining power on hot days when pushing her to the max. as we are headed to the winter I will have to install a thermostat to keep the oil from cooling too much, especially because I won't be riding to the max but more errands and stuff.

Last weekend I rode about 380kms (236 miles) and didn't have any issues with starting or performance. Most of the times starts with 1 kick and after getting up to temp the backfiring of the custom exhaust stops immediately.

Seems like there is no problem at all, thanks again all for the help