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-   -   Pulsar: No spark on the right plug? (https://www.team-bhp.com/forum/motorbikes/136283-pulsar-no-spark-right-plug.html)

Hello experts,
My full black Nov 2005 Pulsar 180 has clocked close to 19K kms and is generally in good condition. Even though the running is low, I stick to the recommended maintenance schedule and perform most regular servicing tasks at home. Few months back while checking the plugs, I tried to check the strength of the spark and to my surprise, found that the right-side plug was not producing a spark at all. Had few local mechanics look at it; most of these blokes do not seem to think this is a serious issue and some did not even understand what the heck I was talking about. As for Bajaj service I've had such horrid experiences with them, I don't want to let these morons anywhere within 10 feet of my bike.
Even though I could not find any discernible difference in the bikes running character, this was still at the back of my mind all the time and one weekend, I decided to investigate this on my own. Below are the details:

1. Possible spark plug problem? Ran to the nearest auto shop, got a set of new plugs and checked spark again - spark produced only on left. Interchange the plugs, still spark visible only on the left
2. Possible HT coil problem? Interchanged the HT coils. No change in behavior - spark produced only on left
3. Possible HT lead problem? Again, interchange the leads. Still spark produced only on left
4. Possible CDI unit problem? Got a new one and plugged it in - no change in behavior again
5. Wiring harness problem? I was suspecting the wire that runs from the CDI unit to the HT coil. Checked continuity with a multimeter - found OK.
6. As far as I understand, the TPS reed switch should not control whether the right plug works or not. But to make sure I manually bypassed the reed switch and tried both open and closed modes, but neither made any difference.

Otherwise, the bike picks up well, runs perfectly fine and hits 100+ comfortably even riding two up (never pushed her beyond that) and averages between 42 and 48 depending on driving conditions. If I hadn't opened up the plugs, guess it would've been a long time before I found out.

I will be grateful to the experts to guide me with further steps. Prefer to fix this at home unless it requires special tools/skills.

Mods: looks like this hasn't been discussed anywhere else hence the new thread. Kindly merge if I'm wrong.

Hi friend, have you tried a new spark plug boot ?
regards adrian

Yes, when I interchanged the HT leads, it was along with the boot to rule out exactly that possibility. Forgot to mention that, sorry. But thanks and any other ideas?

The DTS-i tradeoff is that only a single plug works for sparking duties (which is more than enough), and the second plug comes into play only and only if there is a requirement for extra spark, such as high revs or whatever the Cdi unit determines as requirement for the second plug to be sparked.

isiv

As Ford5 mentions, your motorcycle controls which spark plug fires based on the engine speed.

Quoting from the Maintenance Manual:

"These engines are capable of of reviving very high, quite easily.
To keep them mechanically safe, a engine rpm limiter has been
incorporated in the Digital CDI. This curtails the sparks to the
spark plugs thereby limiting the engine rpm Max upto 9000 and
thus keeps the engine mechanically safe.
There are 2 spark plugs. LH spark plug fires at 350 rpm and then continues to
give spark till at 9000 rpm of engine. The spark is cut off from
LH plug 9000 rpm to protect engine from excessively high
speed.
RH spark plug gives spark at 750 rpm and then continues to
give till 6000 rpm of engine. If engine rpm exceeds 6000 rpm
then RH plug is cut off. This is done to reduce combustion
noise created in engine."

Notice that the RH spark plug does not fire until a engine speed of 750 rpm is reached.
Depending on your method of cranking the engine during your test it is possible that this 750 rpm speed has not been reached thus there would be no spark at that plug.

If you have Adobe on your computer so you can read a pdf file you might wish to download the following link to the Maintenance Manual.

http://www.bcmtouring.com/imp/pulsar...ers-manual.pdf

At the risk of upsetting someone, I'll say that in my opinion the concept of using two spark plugs in a cylinder is unnecessary.
It is used as a sales promotion to make a vehicle more attractive without really adding any noticeable benefit. This also applies to the Royal Enfield which touted the dual spark plugs on some of their models. (My 500cc fuel injected UCE only has one spark plug which works very well after I threw the Bosch plug that the motorcycle was supplied with away and replaced it with a NGK).

My old 1975 Honda CB400F Cafe Racer would readily rev to over 11,000 rpm using a single sparkplug.

Have a good day! :)

I agree. This is a marketing gimmick. Internal combustion engines only require a tiny bit of spark (as is always been) to fire the air-fuel mixture.

Infact having an extra plug only adds cost. The Honda city 2nd generation in India had the i-Dsi engine with 8 plugs!

And according to Bike guru Dilip Bam, twin spark plugs reduce engine life :eek: The Royal Enfields fire both their plugs simultaneously. So that doesn't do much damage. Please check his website for more details.
Regards adrian

That explains it. Thanks a lot for the info and PDF, which also talks of the effects of one plug failing to fire - none of which I am experiencing. I can guess the answer to this one, but still I shall ask - my bike happens to be the DTSI with the analog console, which I presume is UG2. The manual seems to be written for UG3 so would this detail be applicable for the earlier model too?

Also wondering how I could verify that that the RH plug indeed starts firing as the RPM crosses 750. I did think of stupid: unplugging the LH HT cable once the RPM reaches say 1000, but afraid to touch the cable with the engine running. If anyone can think of a safer/more scientific approach, do let me know.

As for the superfluity of the second plug, I tend to agree too. But I believe if a bike is specced with two plugs to fire in tandem, it must & should work according to that spec. Else we have a problem...

Thanks once again to ArizonaJim

Just unplug the right plug and rev the bike to about 2-3k in idle to check if its producing spark.

Disconnect the right hand sparkplug wire from the engines spark plug and install it on a spare sparkplug.

Making sure the spare spark plugs body is grounded to the engine, start the motorcycle.

Your idle speed is probably higher than 750 rpm so you should see the spare sparkplug firing. If it is not, increase the engine speed a bit. 1000 rpm is easily attained with very little throttle opening.
Your spare spark plug should be firing with a nice blue spark.

Shucks! Why didn't I think of that? Guess I'm losing touch :D Will try over the weekend and write again.
So long

Disconnect the working plug. The bike should start on the plug which you suspect is not working.

Its a fail-safe mechanism that Bajaj uses which will enable this. Such a thing helped me when I had water enter the primary plug and the bike refused to start. As soon as I disconnected the wet plug, the bike started without any drama off the second spark plug!

Easier done than said! Indeed I could see the spark on the RH plug once the engine was at idling speed. With the RPM a shade below 1000, the plug was sparking beautifully. Thanks once again!

If one of the plugs is not sparking there will be a noticeable drop in power when you ride. If you are curious you can disconnect one of the plugs and ride to see what happens. I have experienced this unintentionally when someone had pulled off the cable while the bike was parked.