[Randhawa]

Originally Posted by KK RE Lover

Hello Randhawa. No it's not the cold start sound I'm referring to. On running in, I did it the way the manual asked me to. First 500 kms did not cross 50 and made sure at least 400 of it was in open roads / highways. Haven't abused the bike during running in or for that matter even now. I have till date taken the bike to RE ASS only of who I have no hope. Any carb setting done is just by those guys and I'm not a DIY person so I'm just about to start my search On a good bullet mechanic.

Now the strange thing is, this sound is not audible when the bike idles not even a bit. Even if I open the throttle in neutral not much can be heard but I can hear 😊. It's still difficult to understand the noise in neutral. It's pretty pronounced when I shift each gear and open the throttle - comes at the beginning and as the bike gains momentum fades away.

Yesterday I tried very sedate driving and there is a particular position in the throttle where the sound won't come and if I open the throttle further it starts. But this position is very low from the close position so practically not possible to keep driving this way.

Let me know what you think.

I knew what you gona say Ok, now the serious stuff is that nothing bad is going to happen and RE can not resolve nor would they help you on this(If your bike is under warranty then may be with some fighting with RE they might change it). Just get this clear in your head that if you want to get rid of this noise then only solution is a new piston, barrel kit. Or just a new set of piston and rings might do. But if you opt for this then you have to change your running in style and riding also to get rid of this noise. Otherwise you can change the barrel and piston but without change in running in method you will again end up with this noise around 2K+. Its the piston slap and you can not do anything by changing fuel/plugs or setting up the carb. You can ask me the procedure for running in but its way different from RE manual guidelines. In my time the kit was around 8k but don't know the price of it now. It hardly takes 30min to change it. You can take as many opinions on this and try whatever people say but you will just loose your sleep over it without any results.

[VW2010]

It's pretty pronounced when I shift each gear and open the throttle - comes at the beginning and as the bike gains momentum fades away.

Just the sound of pinging. Running lean or poor petrol. Try a load of 97 and see if that changes so you can eliminate fuel as the reason.

Piston and barrel change may not fix this issue if the bike continues to ride lean and you are wacking the throttle.

[swami69]

After reading through, i related this sound to the one I had in my old Thunderbird. This sound comes when the throttle turn and the bikes momentum does not match. Or, when there is load and you want the bike to go fast and turn the accelerator. In simple lay man terms like myself, i would call it the bike struggling till it reaches the optimum speed for that throttle position. This sound comes only very momentarily and calms down once the vehicle gains speed. I think it is just a engine struggle not matching the speed. Recently I test drove few Classic 350s at RE showroom and they also had similar characteristics - load vs speed vs throttle input case.

What I did to overcome - I started using the throttle much more gently to match up with the speed gain and got rid of this irritating noise to a large extent. See if this helps.


Swami

[Crankpin]

What kind of running has the bike done? What grade/ make engine oil do you use? Are you using a free-flow exhaust?

Using higher Octane fuel wont help much as the compression ratio of the bullet 500 isn't very high (approx 8~9:1)

I recommend shifting over to a round slide VM28 Mikuni kind of carburetor eventually and up-jetting to 140 mains and about 25~30 size pilots will help correct the lean engine issue.

[smuniswami]

Dear sir,
The photograph showing the effect of lean, rich and optimal air fuel mixture ratio on the spark plug is very informative and useful.
Thanks.

[Crankpin]

I'm glad its helpful.

[Racer911]

Did this knocking sound start in between services suddenly while riding or immediately after you got back the bike from a service?? if it's the latter, then even I'd first check the carburettor tuning. I've observed regularly that RE mechanics normally tune the carburettor a little lean. although i didn't have any knocking problems in my Enfield, the engine used to heat up more than it should. So I tuned my carburettor on my own with improved throttle response.

To eliminate the possibility of a carburettor tuning issue, you don't really need to know the tuning process. I think you already must've figured out what the fuel screw is in the carburettor. Just turn it Anti clockwise very slowly, while precisely noting the degree of turn. I'd recommend just about 1/8 turn at a time then checking for the knocking issue.

If the problem disappears after whatever amount of turns you've made, voila, if not, then turn the screw clockwise again exactly as much as you'd turned Anti clockwise.

PS: if by the above process the problem has to go away, it should go within a maximum of 2 turns unless it's set way too lean. if it doesn't, i don't think theres any point going any further. turn the screw back to its original position.

[gauravanekar]

Originally Posted by Randhawa

Its the piston slap and you can not do anything by changing fuel/plugs or setting up the carb. You can ask me the procedure for running in but its way different from RE manual guidelines.

I can relate to this problem since I owned a desert storm for 3yr/36k km. That bike had a fuel injection system yet similar problem was there albeit to a lesser extent. So I think it has nothing to do with fuelling. @Randhawa could you please share your running in method for REs? . When I did run in for my Desert storm I used to accelerate smoothly and try to maintain constant speed between 70~90kmph, it did not produce any good result in engine behaviour. The engine sounded as it was on day one until one fine day I attempted saddle sore ride at more than 10k km on odo (yes I succeeded).
Also one my second bike that is Bajaj pulsar AS200 I did breaking in as propounded by this thread here http://www.mototuneusa.com/break_in_secrets.htm . I'm very happy with the results now.

[tikku.dk]

Originally Posted by Crankpin

This image is a good enough reference for you to read your plugs.

The picture you have posted is absolutely wrong. The plug with tan colour(extreme left)should be of optimal mixture. The one with white colour in ceramic portion(extreme right) indicates lean mixture

[alpha1]

Originally Posted by KK RE Lover

Hello Bullet Gurus - I own a standard 500 and have done just about 3500 kms. In the past one month or so, have been hearing a weird knocking kind of noise - may be like a clutter ( something like tak tak tak) when I try to accelerate. This knocking sound appears when I just open the throttle at any speed. I get this when I try to accelerate at 20 KMPH or even at 50 KMPH. It then fades away and when I shift gear and open the throttle again, I get to hear that.



No luck at the authorised service centre as I was told to just keep riding and in fact I was also told that this is very common in Standard 500. Wasn't convincing and reaching to you all to seek your inputs and guidance.

Looks like the engine is not able to generate sufficient torque for the given acceleration demand at the particular gear.
The solution would be to shift one gear down so that the engine revs at an RPM that can generate sufficient torque.

If the sound exists at all RPM range and all gears - then it is not a concern, your ears just need to get used to the Bull't sound.

[Crankpin]

Originally Posted by tikku.dk

The picture you have posted is absolutely wrong. The plug with tan colour(extreme left)should be of optimal mixture. The one with white colour in ceramic portion(extreme right) indicates lean mixture

Check again...! It's absolutely correct

[tikku.dk]

Originally Posted by Crankpin

Check again...! It's absolutely correct

Iam quoting a sentence from the tuningmatters.com website, the same place you sourced the picture if spark plugs. They have posted wrong picture but correct information

" In the optimal setting the spark plug tip will be slightly wet but clean. The tip should be grey to brownish and generally clean"

[Crankpin]

I am referring to the picture...only the picture. And yes in optimal condition, the tip and sometimes even the first few threads could be wet but not dirty. The insulator looks clean. I can share more pics of the same if you want.

Also, this is a probably a two-stroke scooter's plug and that too a performance one. In our case, our 4-stroke carburetted engines are highly lean set from the factory for emission reasons.

Anyways, from the post on Tuning matters its obvious that many others have commented on the picure being incorrect so I can understand why you too have commented the same....!

[Cool_leo_guy]

The Bullet's engine is not a free revving unit. When you are at lower speed and abruptly turn the throttle, the engine sounds like horses galloping on a tin roof or a demented blacksmith on performance enhancing drugs let loose on a metal piece.
This is not a big issue and readjusting the carburettor for a bit richer mix may alleviate the problem. However the best course of action would be to ride it like a Bullet and not a Pulsar, which means gentler throttle inputs and gradual building of speed. After a few thousand more kms on odo, the engine will run smoother. Also try shifting gears at a bit higher rpm and do a bit of rev matching.

[tikku.dk]

Crankpin, Iam attaching pictures of spark plug that had optimal carburetor settings. Iam only saying this because my splendour is optimally tuned by myself, as i have removed catalytic converter and blocked secondary air injection system and a slight upjet . You will have a clean ceramic tip if you are using a platinum/iridium plug, they tend to remain in white, but the electrode will be in tan brown colour. Hope this helps