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Old 30th January 2009, 17:08   #1
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Question Twin Sparks: A doubt

What will happen if you remove one spark plug and leaving the hole open, try to start the bike?
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Old 30th January 2009, 17:13   #2
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The bike will not start. The open hole will let the fuel mixture escape. If by any chance it starts then you will have yourself a fire breathing bike.
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Old 30th January 2009, 17:49   #3
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+1 man.

All the compression will be lost so the cycles will not complete.
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Old 30th January 2009, 17:54   #4
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What if one hole is blocked with a Dummy spark plug
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Old 30th January 2009, 17:54   #5
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So if we somehow get the spark plug out when the bike is in motion.
Say by loosening one and riding on extremely bad roads.

How do we find a volunteer to do this?
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Old 30th January 2009, 17:56   #6
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Even in this case the bike will stall or at least it should stall.
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Old 30th January 2009, 18:08   #7
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what if 1 spark plug is dead/disconnected?
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Old 30th January 2009, 18:11   #8
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Quote:
Originally Posted by vikram_d View Post
The bike will not start. The open hole will let the fuel mixture escape. If by any chance it starts then you will have yourself a fire breathing bike.
tried oen with 4 sparks, 2 were off, and hence blew the engine
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Old 30th January 2009, 18:12   #9
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Quote:
Originally Posted by bblost View Post
What will happen if you remove one spark plug and leaving the hole open, try to start the bike?
Should not\will not start.

Quote:
Originally Posted by reddy6980 View Post
What if one hole is blocked with a Dummy spark plug
Will start.

Quote:
Originally Posted by bblost View Post
So if we somehow get the spark plug out when the bike is in motion.
Say by loosening one and riding on extremely bad roads.

How do we find a volunteer to do this?
Will stall and harm the engine.

Quote:
Originally Posted by ms001 View Post
what if 1 spark plug is dead/disconnected?
Will start and run.

Better question how do we find out both Spark plugs are firing/sparking?

Last edited by Spitfire : 30th January 2009 at 18:13.
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Old 30th January 2009, 18:14   #10
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one spark not working will have no impact on the bike.

I personally don't understand the funda behind the twin sparks.
IMHO: One is as good as two in this case.

However was surprised to hear that the RE TBTS returns a milage of 50+.
I however attribute that to lesser transmission losses than the extra plug.
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Old 30th January 2009, 18:34   #11
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i removed the lead to the second spark plug once on a friends bike at idling ,it made no difference at all , i dont know at high revs , he didnt let me experiment further.
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Old 30th January 2009, 19:02   #12
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Only advantage the plugs wont foul as much.

A good spark on a single plug is better then 2 plugs.

Logically 2 plugs better combustion, but it isnt as straigtforward as that.

Coming to the TBTS returning 50+ you must be kidding me..
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Old 30th January 2009, 19:59   #13
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The purpose of two or more spark plugs is to reduce the amount of potentially un-burnt fuel-air mixture in the combustion stroke.

When you have one spark plug, it is mounted (generally) at the top-center of the cylinder. When it fires, the fuel burns in a conical form. So, there still is stuff near the sparkplug that does not full burn.

Having multiple plugs, reduces the amount of unburnt fuel by affecting more volume in the cylinder. The result is lesser un-burnt fuel, which means better power, torque and improved mileage.

If If in a TBTS or a pulsar DTSi, you remove one of the multiple plugs, and do not cover the hole, the engine would not run, as the compression, expansion and exhaust strokes would not do their job.

If you remove one of the plugs, cover the hole properly, the engine would probably still run, but would be very inefficient.

Hope i have answered your queries, atleast partially.
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Old 30th January 2009, 20:17   #14
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If we disconnect one plug, then the bike will run.
The real function in relatively small engines having two plugs is to reduce the fluctuation in power and torque curve and make the throttle response more crisp.

Once I had read an article where one of the plugs in DTSi engines was disconnected and they did dyno test. The test revealed that rather than improving power and torque, it evens out the power and torque curve.
In case of 150cc/200cc engines, one good spark plug is more than sufficient to produce good results.
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Old 30th January 2009, 20:38   #15
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Quote:
Originally Posted by bblost View Post
What will happen if you remove one spark plug and leaving the hole open, try to start the bike?
Engine will never start.

Quote:
Originally Posted by bblost View Post
So if we somehow get the spark plug out when the bike is in motion.
Say by loosening one and riding on extremely bad roads.

How do we find a volunteer to do this?
When the engine is running and if you try to remove a spark plug you'll injure yourself and probably blow a hole in the fuel tank. As you loosen it there's a very good chance that the sparkplug would shoot off like a bullet.

Quote:
Originally Posted by bblost View Post
one spark not working will have no impact on the bike.

I personally don't understand the funda behind the twin sparks.
IMHO: One is as good as two in this case.

However was surprised to hear that the RE TBTS returns a milage of 50+.
I however attribute that to lesser transmission losses than the extra plug.
Well, if you asked all that to come to the conclusion that twin spark is not worthwhile since the bike will run with one spark plug, it's a wrong approach to take. If it's to make an engine just run then you're right, one is as good as two.

Twinspark is a much refined engine and it has enough pep in it compared to the older AVL. I don't know if it will give 50+ on regular riding, but it will definitely yield 40+.

I found a marginal difference in performance when i converted my CI350 to twinspark.
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