Re: Honda Unicorn Dazzler



Here is the bill. To change the shaft, engine had to be opened and this is the reason for such a long bill.

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Re: Honda Unicorn Dazzler

How does your engine idle? Is it rock stable or does it show minor but continuous fluctuations when idling?
<b> engine idle is not rock stable.it show always minor (+- 100 )but continously fluctuations at hot engine. </b>

How are your cold starts? Do you need to use choke in the morning?
<b> now a days of december it requires little chowk pull . </b>

Do you need to give slight throttle on cold engine to keep it running or once after cold start your engine idles on its own?
<b> after 10- 15 secons engine running on choke, when i turn off the choke engine tends to shut off then i need to give slight throotle on cold engine. After 2 minutes its idle rest on 900- 1000. When i ride it some 5-6 kms its idle goes to 1300 +- 100 </b>

Do you smell a little bit of petrol in your exhaust under engine idle?
<b> almost no</b>

Is your exhaust pipe opening dry and sooty?
<b> dry but very little black on finger</b>

The answer to each of these questions can give you clues about how your carb is tuned.
<b> i think its due to mis tunning of carb. I tried to tune it but not get that perfect point which gives rockstable idling & good mileage</b>
Suggest a method of tuning carb.

Re: Honda Unicorn Dazzler

But, are those diagrams depicting Keihin VM28 Carb?

Re: Honda Unicorn Dazzler


In The above picture u can see a hole near throttle flap. Might be choke's path.

The below picture is taken while top cover & rubber diafram removed.it shows two small holes which supply the fuel to intake manifold.

Re: Honda Unicorn Dazzler

Yes, that's choke bypass.
Among those outlet ports, only one which is clearly visible is controlled by AFR-Screw.

Regarding mileage, you can get carb tuned using a exhaust-gas analyser. Then check mileage using a mileage-test-can after proper warm up.

Re: Honda Unicorn Dazzler

What is exhaust gas analyzer.
Where it is provided , svc or patrol pump stations. ...
I m from hisar haryana. I will try for it

Re: Honda Unicorn Dazzler

Simple internet look up will give more info on "Exhaust gas analyser".

Most SVCs will have it. They measure the exhaust gases at idle-rpm and using AFR screw they tune to meet emission standards.

i.e. your motorcycle will be retuned to stock.

Re: Honda Unicorn Dazzler

Hey thanks a lot..!! Will definitely come in handy since I am going to service center tomorrow.

From your answers it definitely sounds like the engine is running a bit too rich.

Ok so following is a description of how I have tuned my carb. But first ---

Mandatory DISCLAIMER for self protection :P My method is a bit different from what has been described by other experienced members of the forum (for eg. Sibun has a slightly different method than mine but people have used his method and got great results) BUT my method has worked on my bike. So take it with as much salt as you want.

Tools needed - one flat head screw driver. The one which comes with bike tool kit is good enough.

I am assuming you already know where the idle adjustment screw is (if not then refer owners manual) and you know the location of AF Screw - if not then its pointed in one of my older pics posted a few pages back.

I am also assuming that your air filter is relatively new and your spark plug is in good condition. Ideally both should be new. The choke should be completely closed.

Step 0: Turn the AF screw clockwise slowly and count the number of turns. Close the screw till it just seats - don't close too hard or you will damage the end. Write down (or remember) this reading for later reference - if you are unsuccessful you can always come back to this setting.

Step 1: Ride your bike for 10 min in city traffic, get some 5-6 kms done, maybe a couple of 4th gear 40-70 kmph pulls. Basically warm up your engine. Don't warm up by idling for 5 mins on center stand - ride the bike. After you are back at your garage, park the bike on center stand.

Step 2: Turn your idle adjustment screw clockwise and increase your idle to 3000 rpms. It need not be exact 3000, you can go to 3500 rpms as well, no problem. Should not be less than 3000 though.

Step 3: Close your AF mix screw completely. Be gentle about this, do it slow and steady.

Step 4: Did your engine turn off? If yes - then open AF screw to reference position of Step 1, go to Step 2, increase your idle rpms further (if you were at 3000 then go to 3500) and then repeat Step 3. Goal is that your idle rpms should be so high that even after closing the AF screw, the engine should be running. Generally 3000 is good enough as a starting point.

Step 5: Now your AF screw is closed but still your engine is running (probably very unstable and at low rpms). This is because the idle screw has opened the throttle to be in the needle jet range. So NOW - slowly turn the IDLE screw counter clockwise and DECREASE idle rpms. Do this slowly and gently. You will reach a point where the engine suddenly turns off. This point is the reference point of your IDLE screw. After this point any adjustment to IDLE screw should be counter clockwise and not clockwise - i.e. you should only be decreasing idle rpms from this point forwards. If you go clockwise - or increase idle from this point - then you will enter needle jet range and screw any attempt at tuning.

Step 5 is an important step - do this slowly. And stop immediately when the engine stops.

Step 6: So your IDLE screw is SET. And engine is OFF. And AF screw is completely CLOSED. Open the AF screw by half a turn. Turn on engine. Idle will be very low and engine will run unstable. Give some accelerator input and give the engine a few gentle revs. Uptill 2000-2500 is enough. No need to red-line!

Step 7: Now slowly OPEN (turn anticlockwise) the AF screw - quarter turn at a time. So turn the AF screw from half turn open to 3/4 turn open. Now rev the engine gently for 15 seconds and then let the engine settle. Now again open the AF screw from 3/4 turn open to 1 turn open. Again give the engine few gentle revs and again let the engine settle (15 secs wait is good enough).

Step 8: Check idle rpms reading and note it for reference. Here on out your tuning starts!! The carb tuning will be in the 1 Turn out to 2 Turn out range, not less and not more.

Step 9: Open AF screw by 1/8 turn and again give a few revs and let engine settle. See the behavior of rpms needle. Keep doing this till you go to 2 turns out from complete close.

Step 10: So for example if you see that at 1 and 1/4 turn your idle rpm is at 1600 and then till 1 and 3/4 turn it remains at 1600 then you should choose a setting where the needle stays the most stable and shows least fluctuations. If it is equally stable at 1-1/4 and 1-1/2 then choose whatever you like.

If you are getting confused at some point then you can leave the AF screw at 1-1/2 turns OUT from complete close. This is stock setting from factory. Don't go more than 2 Turns OUT. My personal setting is 1 and 1/4 turns OUT.

Step 11: Now take a break. Turn off engine. You can let it cool for a few minutes or so. Turn on the engine - check that its turning on smoothly - without any accelerator input. Just thumb start should work. Without giving any accelerator inputs just observe the rpm needle. Remember - goal is stable rpms and easy engine starts.

Step 12: Ok good job, tuning is mostly done!! Now what has to be done is to check that tuning has been done correctly. So go home, watch TV, go to sleep. Wake up next morning and go to your bike. The engine will be stone cold. Keep the choke closed. Thumb the starter. Don't touch accelerator. Engine should start on first thumb press (assuming healthy battery). If the engine starts immediately at first crank then Awesome..!! But probably without choke and accelerator input the engine will immediately die. No problem, again thumb start the engine and rev it at 1500 rpms with slight accelerator input for 30 seconds. After that the engine should idle in the low 1000s. Take the bike for a ride. Ride gently on the cold engine. The engine should warm up in 1-1.5 kms. After 1-1.5 kms you should see a stable 1200-1300 rpms.

Now ride your bike normally for a couple of days. Observe idle rpms on hot engine - your hot engine idle rpms may be 1600, 1700. Don't worry about that - just ride the bike for a couple of days and get a feel of how its running. You should not worry about the value of the rpm needle but rather behavior of rpm needle. It will show fluctuations - but fluctuations should be minor and infrequent on hot engine. There should not be continuous fluctuations on hot engine. Warm engine starts should be quick and without accelerator and choke. Engine warm up time should be 1kms - 2 kms max. Cold engine idle rpms should be rock stable. When you rev bike till 4000 rpms on neutral and close throttle then rpm needle should fall down to idle rpm quickly and smoothly. Engine should respond crisply to 1/4 accelerator input.

So observe all this for a couple of days, if you want you can go 1/8th turn more or less from your setting as well and fine tune it further. Understand that observing how your engine is behaving is the real tuning - not closing and opening screws.

If you are happy with how bike is performing then go to FINAL Step -->

Step 13: This step is basically adjusting your idle to 1400 rpms. BUT ONLY TURN IDLE SCREW ANTICLOCKWISE. During tuning mostly your hot engine idle rpms would have exceeded 1400 rpms. Turn IDLE Screw anticlockwise and bring idle rpms down to 1400. If they are already at 1400 then don't touch IDLE screw. If idle rpms is lower than 1400 then mostly it means that you did not do Step 5 correctly. But mostly you will be in high range - about 1600-1700 rpms. Under NO circumstance should you turn IDLE screw clockwise. Otherwise all effort till Step 5 would be waste and you will have to start from Step 1.

So that's about it. Simple enough. For me its more about being in tune with the bike.

Even after this if your mileage does not improve - then you are not riding correctly - and a HOW TO for that is a topic for another post

Re: Honda Unicorn Dazzler

Tuning your bikes carb can be done in various ways. It depends on bike to bike. And mileage not only depends on carb tuning. Also idle fluctuations depends on other factors also.

Some of the major factors depending mileage and idle:-
1. Air filter- the most simple thing,
2. Valve clearance- This is important as tight valves will lead to compression leaking
3. Worn out valves.
4. Compression in engine,
5. Choke piston stuck.
6. Clean carburettor.
7. Carbon on piston- Less carbon is not good nor more carbon.

When all this things are correct then the carburettor tuning will be correct.

My extreme idles at 900 rpm when cold and 1100 rpm when hot. And choke need not be touched.

Re: Honda Unicorn Dazzler

Hi guys.. can you remember your odometer when you changed your chain sets? Mine is just 18T KMS thanks!

Re: Honda Unicorn Dazzler

Mine was changed at 15000 kms... But second set still going nice and strong at 33000 kms...

Re: Honda Unicorn Dazzler

Mine first one was changed at 18k and second set needs to be changed after 41k.

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Re: Honda Unicorn Dazzler

how to identify a worn out chain???I watched a video related to it the person said that the chain should be in contact with more than half the number of teeth on the rear sprocket and should not wobble or move left-right. Is this the way to check the condition of the chain???
Odo reading is 21270 Km.Till now I have not changed my bike's chain.

Re: Honda Unicorn Dazzler

Number of kms don't matter. There is a marking on the swingarm which shows how much of a chain's adjustment is left.

Re: Honda Unicorn Dazzler

first one lasted only 12K Kms and the present one has already worn out at ~24K Kms (as per the chain adjustment mark)