My friend has a little honda cbr 125cc motorbike and when he starts it he always lets it tick over for about 5 minutes before driving because it runs lumpy and has no power if he drives straight off. This is annoying having his bike running outside mine and other friends houses when he leaves at night! I've suggested him trying a different grade spark plug to see if it helps. Do you guys think this could work and if so,does he need a hotter or colder rating plug (I can't remember) ps. he doesn't really do many long journeys,I've heard colder plugs are better for long journeys but I don't know which is better for cold starts. Im guessing hotter plug but really can't remember.

 

always let your bike warm up before running mines is never ridden until its warmed up, your even learned that way, has he a loud can the way you hear it?

 

http://www.bikechatforums.com/viewtopic.php?p=2960116

My old Suzuki Bandit 600 used to run cold from a start. If it's like that bike, it set to run lean for emissions. I'd suggest the choke trick the guys in the forum link above do. I had to run my bandit at half choke for a mile or 3, but it allowed me to get moving alot faster then waiting for it to warm up. The fix for the bandit was to re-jet the carbs for a richer mix. I assume the CBR 125 may be similar.

IMO, I'd be afraid to change the plugs as it probably runs fine once warm. You may fix the start up and do bad things to when its warmed up.

 

It's a 2 stroke so his air fuel mixture will be out
Has he tried modding it
Like sticking a K&N on it changing his exhaust etc etc
Is it carb or FI?
Or worse case because it's a two stroke , the rings have gone or poss just 1
, creating hard starting , as the metal gets hotter & expands the cracked rings uniform allowing the bike to work ( time bomb )
But don't worry that's worse case
One last thing , if he has been fiddling with it , if it's reed valve , they may not be inserted correct
Go change the plug first & let us know how you get on

 

I not sure if it's standard pipe,its not what I'd call a loud bike but loud enough to annoy neighbours late at night. If it has to be warmed then so be it,but if anything can help then I'll suggest he tries it.

 

I'll mention this to him thanks,but it seems some of the guys in this link think its normal forc a cbr to need warming,also by the sound of it he might have to hold the choke to stop it springing back so therefore couldn't ride it.

 

I'll have to ask him about mods (probably has mods knowing him lol) hopefully not his engine! What rating plug would you go,hotter or colder?

 

I wouldn't , it's a 125 two stroke
Return it to stock if it's been tampered

 

CBR125 has always been a four stroke. It's the NSR that was two stroke.

 

I'm 46 years old
& when I was 17 we used to play around on RDLC 125, 250, 350
All two stroke
I assumed the CBR was this days equiv
I ride a 4 stroke fireblade sure , but that's big cc
My app
Honda , what shame taking the castrol R away from the kids ... Tut tut

 

Yes your right laupy, jst googled it
How horrible ,

 

I don't think he would've tampered with engine but may have aftermarket exhaust and air filter,I'll ask him. As laupy says it's a 4-stroke so hopefully engine is ok. I don't think he struggles to start it,just won't run properly if he drives straight off. Hotter or colder plug for cold start guys?