CBR250 Forums banner

1 - 20 of 24 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
I was just wondering correct me if i am wrong:
If an engine was running slightly lean with a normal octane say 91RON fuel could you tune it with a higher octane fuel say 95RON. Its just a thought i am no expert so go easy with me.
 

·
Registered
Joined
·
7,411 Posts
If your engine is running lean you should try tuning it by adjusting your pilot screws, the washers under your diaphragm needles and your main jets. If the intake system on your bike is stock however and your exhaust mods are equivalent to a slip-on or less, then you should really only need to turn your pilot screws out by a quarter turn at a time. Or use a colortune plug.
 

·
Registered
Joined
·
747 Posts
That colourtune is not great really. I bought one out of curiosity but its not really suited to the job. Its fine for tuning idle mixtures but tbh, you can do that just as well by listening to the engine. It can only be used to look at the mixtures on a free revving engine, you cant tune the engine under load with it so essentially your back to relying on the seat-of-the-pants method.

I know its pricey but a wideband O2 sensor and gauge is a much more accurate and if you set it up right it can be used on every bike you ever own essentially.
 

·
Registered
Joined
·
7,411 Posts
That's true. But for the average noob who hasn't got the knack for tuning by ear nor the justification to spend hundreds, its a cheap invaluable tool that's hard to cock up.
 

·
Registered
Joined
·
747 Posts
My point is though that even for the noob who doesnt want to dish out for a wideband, the colourtune is still next to useless for tuning as it willonly be good for tuning idle and off idle mixtures. You wont be able to use it to tune the top half of your rev range which is the most important in a 250.

On top of that, they are very awkward to use on the cbr because of clearance issues above the head of the engine.
 

·
Registered
Joined
·
1,816 Posts
Humbug said:
Oh wait, dayeve is running habib spec, so his only runs stoichiometric on hummus.
:lol:

yeah i've got a colortune plug too. haven't got around to using it cos of the awkward placement, but haven't got rid of it either :D

to see it with different revs, i thought of using a rubber padded gopro (or style) camera to fit above the plug or next to a mirror above the plug to watch the colour change in synced time with another camera on the tacho. or just put it on a dyno. the deep plug well is a pain though. dunno how accurate the tune is, but still an interesting tool.
 

·
Registered
Joined
·
298 Posts
My first question would be how do you know its running lean?????
 

·
Registered
Joined
·
298 Posts
Aduro said:
Running hot. Backfiring. If you know your bike you can even hear it.
Very true, but that could also be other problems... and no offense to Zafar (and I might be completely wrong), if he is not mechanically minded enough to know that increasing the octane is going to make it run richer, i would be surprised that he knows that it is running lean....

Hence I was asking how he knew it was running lean, so we can be sure he is on the correct path fixing the problem... :)
 
1 - 20 of 24 Posts
Top