Pulsar 180cc Acceleration Problem

[Wayne D]

Hi.
I have a pulsar 180cc ( the full black verson, i think its the V3, the model just before the pulsar with the digital speedo ) I bought the back in 2006 and it had done 30,000 kilometers.
My father has been using the bike for the last few months so i have not used it recently. When i did take the bike out a few days ago, i noticed while accelerating the bike did not pull as much, the rev meter would go upto 6000 RPM and stop at that point, it would not go further than that.
I gave the bike for service and when i got it back they said that there is a problem with the carburetor ( a rubber piece has to be changed according to them and they did not have that part ) The bike does not pull much at all now.
Further, I have a K&N filter and i've changed the spark plugs.
Can anyone tell me what the problem might be and where i can get it fixed?
I dont think they'll ever get the part that has to be changed.

[aaggoswami]

1) Looks like carb settings are not the way they should be. Work on the carb and if need be, change the carb and see ( if the performance is very bad ). Ask the service center people to get the part and put pressure on them. Bajaj workshops are the industry worst ( I can tell this from my own personal experience ), so pressure will work on them.

2) Spark plugs : Did you check if the heat range was the same ? After the carb has been sorted out, plug in the normal spark plug and see if there is any difference.

3) K&N, if installed correctly, will not harm performance and is not the culprit here IMHO.

[Wayne D]

The thing is the bike use to work fine with the same settings as before, and no one has changed anything since. I will definitely get it checked though.
I wanted to take the bike to a different mechanic if possible to get a second opinion about it.
I did not check the heat range when i bought the spark plugs, they are NGK Iridium 3 plugs, i hope it fits the requirements of the bike.
Other than the carburetor i cant think of anything that would be the problem.

[Wayne D]

What i would like to know is, if any one could point out any other reasons why this is happening.

[Technocrat]

Has the mileage too gone down?

Also how much does the bike rev on tacho now(i.e. after it came back from service)?

Did the service guys check clutch plates?

[arpandiv]

Check with Autoservice (BSK - II)
The rubber part of your carb is called the diaphragm. Must be torn, that's why the bike is not going above 6000rpm. Which spark plugs are you running, hope they are of the standard heat range. Dont expect any performance gain from sparkplugs.

[Wayne D]

I have not checked the mileage as i have not used the bike for a trip more than 4km.
It still revs to 6000 RPM, it just does not go about that, and when it reaches that RPM it slows down a bit ( the kinda of feeling u get when u press the front brakes and ur thrown forward a little)
I dont think they would have checked the clutch plates, because i never thought that would be the problem and i never specified that to them. Generally they wouldnt go out of their way to check something which doesn't come under " paid service"

I think thats the part that he mentioned, i cant be too sure though. I'll have to wait till thursday till they get that part otherwise i'll go to another Bajaj's service station and get it done if they have the required part.
NGK Iridium 3 spark plugs, Looks like Iridium 4 is out now becuase i cant find the lower model on the site. NGK Iridium IX® Spark Plugs

[aaggoswami]

The rubber part of carb might be damaged due to bad quality of fuel.
First of all, IMHO, wait for that part to be replaced. Once that is done, carb is ruled out as the primary source of trouble.
If the bike is not going beyond 6K rpm then surely there is either something wrong with fuel being supplied ( inadequate quantity ) or ignition. Now that you have confirmed about CDI unit changed, I dont doubt that coil is an issue.

[arpandiv]

Well, no fuel reaches the rubber diaphragm, the rubber diaphragm helps in lifting up the slide(on basis of vacuum) so its a normal wear and tear item.
Clutch plates would not be the source for 6000rpm trouble. Did you get your bike washed recently ? then pull out the CDI connector from below the tank and dry it out. Also maybe the HT coils could be kaput but these are VERY RARE cases. My money is on the rubber diaphragm.

[msvg]

Dude Take ur bike to Auto service Banashankari II stage near monotype.
They will fix ur problem.

[Wayne D]

Today morning i went to the bajaj service station on 100 feet road, when the mechanic took a test ride he said there is not any problem, probably because he did not go past 6k RPM, i asked if the carburetor had to be cleaned and he said yes. I also enquired about the clutch plates which he said would cost Rs 900 and the pistion rings which would cost Rs 800. He told me he did not have the piston rings so he asked me to come tomorrow morning.
I wanted to get the bike fixed today so i went to this place called Tuner Kraft on 80 feet road. The mechanic there told me i had to get the carb cleaned ( i did not get anything done at the bajaj place) so he did that and i came back after one hour and he was almost done. After that, he put it back and put a different rubber pipe from the carburetor to the airfilter. He said the old pipe was not properly attached or not suitable for this filter. So that was changed.
After all this was done the problem was still there, he even checked the rubber diaphragm and said there was nothing wrong with it.
He then took the bike for a test ride and decided to check the spak plugs as he said there was an electrical problem. He cleaned the spark plugs and tuned the bike. After that the bike accelerates much better and goes upto the red line ( 9 K RPM ) but the thing is that i dont feel it pulling like it use to.
He told me the timing chain has to be replaced as he could tell by the noise that it has worn out. Would the timing chain have anything to do with the bike's pick up? By the way, the total cost came upto 450 , 200 for labour, 75 for the K&N filter oil which i asked him to put, 80 to clean the carb and 95 for the new rubber pipe to the air filter.
I also wanted to know if i should replace the clutch plates and the pistion rings as alot of black smoke comes out from the bike when i rev.
The bike has done 32,000 km and i think i've pushed the bike to its limits most of the time.

[arpandiv]

Originally Posted by Wayne D

I also wanted to know if i should replace the clutch plates and the pistion rings as alot of black smoke comes out from the bike when i rev.
The bike has done 32,000 km and i think i've pushed the bike to its limits most of the time.

Please take the bike to a good workshop and get the following things done :-
1) Compression test
2) Valve leakage test
3) Put bike on roller test machine and check 0-60 and top speed figures.
Piston rings cost <500, clutch plates pressure plates cost <800.
Labor charge would be around 500.
If you lift the head you will also need to examine valves, get valve lapping done, check condition of the camshaft.
Timing chain, timing chain adjuster should be changed as a set.
You are looking at a bill of around 3K.

Please take the bike to a good workshop for this kind of work.
and sell that K&N off.

[aaggoswami]

Originally Posted by arpandiv

Well, no fuel reaches the rubber diaphragm, the rubber diaphragm helps in lifting up the slide(on basis of vacuum) so its a normal wear and tear item.

Might be my misconception. In case of my Zues, I dont know if it was the same part. The service center used this word so thought. Actually the float was problem in my Zues case.

Can you update me on this : Is there any rubber part in touch with fuel ? I have opened engine once, but carb is complex so yet to work on it more.

[arpandiv]

I have attached the exploded view of a Mikuni BS series CV carb.
Parts no. 16- 32 are ones which are in direct contact with fuel.(Excluding the parts which are outside the carb body)
Due to bad fuel, fuel deposits, gum formation in carb, all O rings are susceptible to damage.

[greatmana2000]

Since you mention that black smoke is coming , I suspect that the valves are not properly closing and because of that your bike might not be getting full compression .

Do a compression test ..check if valves are stuck ..probable chances are that they might be stuck since you have not used the bike for a while .

Since the time you stopped using the bike , did you put some oil in the bore through the spark plug hole and try circulating the oil by kicking the kick starter ? This is a normal maintenance procedure and you must do it if you are not going to use your bike for extended period of time .

Did you check the oil level ? After you have checked the oil level , try adjusting the tappets .. since the 2nd mech said there was timing chain noise , I highly suspect that the tappets need to be adjusted .

I dont think the motor needs a new set of rings or timing chain as timing chain should easily last atleast for a lakh kilometers .