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**Honda_CBF** · 04-19-2011, 06:48 AM

here's the picture of the spark plug's electrode, which shows the deposits of last 500km.
and guys all next images scared my s#*t out of me yesterday....

look at the thread of spark plug's... there's some liquid, brown in color... what's that?

that can also be seen at spark plug hole...

**princesirohi** · 04-19-2011, 02:18 PM

by the colour of your center electrode, it appears to be running lean.

regarding the liquid, tell me is it oil? ?? but if its oil, it should be black in colour and there is no oil near the electrods, so it may not be oil, as i think.

it appears that either your plug is not tight and something is leaking from outside or your plug is faulty, try replacing your plugs.

**Honda_CBF** · 04-19-2011, 04:03 PM

It's kinda gummy, but its not oil. And the plug is almost new (2000km done) & was perfectly fitted.
You still think i should change the spark plug?

**princesirohi** · 04-19-2011, 04:56 PM

before refitting the plugs clean them thourougly with a cloth-- both plugs and the thread in block. then check again after a few hundred kms.

**Honda_CBF** · 04-19-2011, 07:48 PM

Originally posted by princesirohi View Post

before refitting the plugs clean them thourougly with a cloth-- both plugs and the thread in block. then check again after a few hundred kms.

ok. Will do that, just after posting... And any guesses how can i tune it richer. I think carb have to be removed.

**princesirohi** · 04-19-2011, 09:43 PM

Originally posted by Honda_CBF View Post

ok. Will do that, just after posting... And any guesses how can i tune it richer. I think carb have to be removed.

i have not seen any two-wheeler till date, in which carb has to be removed to tune it.

just called my mechanic, he said there are 3 models in stunner and company has made some changes ineach of them. the A/F tuning screw is accesible from left side in some bikes and from right side in other models. may be stunner has its own generations like we have in our pulsar UG-1,2,3,4 etc.

my mechanic said, there will basically be only two screws in carb that you can move, all other screws will be fully tight, so, out of the two screws, try to unscrew/screw each screw carefully by counting the number of turns. the screw which has drastic effect on idling RPM is the idling screw, so obviously other one is A/F screw. gotcha. eureka...!!!!!

**Honda_CBF** · 04-20-2011, 12:15 AM

Originally posted by princesirohi View Post

i have not seen any two-wheeler till date, in which carb has to be removed to tune it.

SAME WAS MY THOUGHT UNLESS I GOT THE REPLY FROM "SKLD" CHECK THAT ON PAGE 2.

my mechanic said, there will basically be only two screws in carb that you can move, all other screws will be fully tight, so, out of the two screws, try to unscrew/screw each screw carefully by counting the number of turns. the screw which has drastic effect on idling RPM is the idling screw, so obviously other one is A/F screw. gotcha. eureka...!!!!!

answer in caps above.
i haven't located the afr screw, so i can't do that.. The only screw available in idle screw which is long and spring loaded.

**Honda_CBF** · 04-20-2011, 06:30 PM

Originally posted by skld View Post

Based on what you said, I also tried getting some more information about Stunner's carb. Here's a site that describes a similar carburetor: Constant Velocity carburetor . This is a picture of the carb (from that site) viewed from bottom with the float bowl removed:

The tube on the right side goes towards the engine's intake. Unfortunately, the AFR screw is positioned facing inwards towards the bike. You can feel the screw with your finger on the back of the carb, just below the tube that goes towards the engine. On my bike, it seems impossible to get to the screw unless there's a special tool for it

@skld, as labeled on the image posted by you.. It says IDLE AIR/FUEL MIXTURE ADJUSTMENT. so, does that mean it only adjust idle mixture i.e. Sent by pilot/slow jet??

**skld** · 04-21-2011, 12:46 AM

I don't have any practical experience in that, but from what information I have read, you are right in saying that it only adjusts the fuel mixture going in from the pilot jet. The pilot jet's contribution is only significant up to 25% of the throttle opening (refer Dan's Motorcycle Carburator theory and Tuning). But from what I have seen, while riding in the city the throttle position is within that range for a good amount of time. Hence, the AFR screw may have a big role to play. Maybe you could experiment over the weekend with different screw adjustments and let us know what you found

Edit: Also, it is almost certain that your mechanic only tuned the carb by using the AFR screw. The other methods of carb tuning seem to be changing the jets, adjusting the float level and changing the level of the needle for the needle jet. In Stunner's carb, the needle's position can't be changed and the floats are made of plastic, so they too cannot be adjusted. It also seems unlikely that he changed any jet inside the carb.

**princesirohi** · 04-21-2011, 01:42 AM

AFAIK, there should be an idling screw and another Air/Fuel setting screw. there will not be any idle air/fuel screw.

**Honda_CBF** · 04-21-2011, 06:41 AM

Guys, i need to take the carb out of the bike to tune it, its confirmed. So i need a how to guide for it.. Plz tell what to disconnect and unscrew and etc, etc.
Note: i need to REMOVE the carb, NOT DISMANTLE it.
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**Honda_CBF** · 04-22-2011, 01:26 PM

Guys, I'll be out of city for next 3-4 days. Will check highway (i.e. long ride) performance and post my experience. I haven't done any afr adjustment yet.

**Honda_CBF** · 04-26-2011, 05:03 PM

I'm back guys and I've shocking update.. Bike burned some oil, around 50ml on 300km trip (150 one way). Its unfit for highway use..
Plz tell me how to remove the carb and to which way I've to turn the AFR screw?

**princesirohi** · 04-26-2011, 10:38 PM

take pictures of your carb from both sides, without taking it out and post it hear.

**cmahajan** · 04-27-2011, 01:41 PM

Originally posted by Honda_CBF View Post

I'm back guys and I've shocking update.. Bike burned some oil, around 50ml on 300km trip (150 one way). Its unfit for highway use..
Plz tell me how to remove the carb and to which way I've to turn the AFR screw?

Sorry bro...I won't be able to guide you on this problem.

Why don't you take your bike to some experienced mechanic in your city who can adjust the AFR for you?

I know HASS people are idiots in most cases which is why you should take your bike to some experienced mechanic. Since you have a carb version of the Stunner, I believe any good mechanic should be able to fix your problems. Cheers !!

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AFR Setting on Stunner

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