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LT500R head spark plug angle
Posted by
Rainman56
on 12 Feb, 2013 15:07
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Bought my Zilla in pieces so i don,t know but is the spark plug off center in the head for clearance reasons?Doing some head mods and if there is clearance I,m going to weld and move the plug hole to the center while modifying the dome/squish are.
Like I said wondering if the plug being offset is for clearance issues?
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#1 Reply
Posted by
Rainman56
on 12 Feb, 2013 17:21
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Anyone?
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#2 Reply
Posted by
Stpltn250r
on 12 Feb, 2013 17:57
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yes its offset. assuming to remove it easier when bike is fully assembled.
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#3 Reply
Posted by
Dezsled
on 12 Feb, 2013 18:11
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It looks like its at an angle to easily remove the spark plug.
Oops it's already been answered.... Duhhh
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#4 Reply
Posted by
Rainman56
on 12 Feb, 2013 19:13
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Is there enough room to remove it if it were to be placed straight up in the center of the head?Like I said my 500 was purchased in pieces so I don,t know how much clearance it has.Basically would the plug be able to be removed and installed if it was dead center straight out?
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#5 Reply
Posted by
Dezsled
on 12 Feb, 2013 19:29
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This pic might give you an idea of the space available
If it was straight up removing the plug might be a problem
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#6 Reply
Posted by
Rainman56
on 12 Feb, 2013 19:38
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Hard to tell in the pic but looks like it may be too tight up against the arch/backbone?
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#7 Reply
Posted by
Dezsled
on 12 Feb, 2013 19:42
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Yeah I'd hate to steer you in the wrong direction.
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#8 Reply
Posted by
Rainman56
on 12 Feb, 2013 19:51
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Checked out a few more pics and beings a cool head has the plug on an angle I,m pretty sure it must be for clearance.If there was room to move the plug to a better location(the center) I,m sure the aftermarket would have done it already.
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#9 Reply
Posted by
Stpltn250r
on 12 Feb, 2013 21:27
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there is way more than enough room for clearance on the plug. the domes in the cool head also turn in any direction but are still at an angle. its fine the way it is. no need to reinvent the wheel. T
The reason its angled the way it is is so when the spark plug fires the flame front does not rock the piston from front to back, it aims it parallel to the wrist pin so there is no rock in the piston. No one wants the piston to rock back and forth at 8k rpms do they??
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#10 Reply
Posted by
Rainman56
on 13 Feb, 2013 07:04
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So does anyone have a clear up close pic of a Zilla engine in the quad to show how much clearance there is?Preferably with the fuel tank off.
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#11 Reply
Posted by
Rainman56
on 13 Feb, 2013 07:16
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[quote author=Stpltn250r link
The reason its angled the way it is is so when the spark plug fires the flame front does not rock the piston from front to back, it aims it parallel to the wrist pin so there is no rock in the piston. No one wants the piston to rock back and forth at 8k rpms do they??
[/quote]
Generally piston rock is dealt with more so by the pin location being offset on the piston itself no???
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#12 Reply
Posted by
Dezsled
on 13 Feb, 2013 10:02
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This is the best I've got atm......
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#13 Reply
Posted by
Rainman56
on 13 Feb, 2013 11:39
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Thanks Dezsled,you,ve been a big help.Looks pretty tight in there.Looks like the angled plug is for clearance issues.Looks like I,ll be leaving things as they are and just fixing the squish.
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...I need to read all these threads before I post.
Seems you guys already have it figured out
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#15 Reply
Posted by
Rainman56
on 13 Feb, 2013 17:23
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...I need to read all these threads before I post.
Seems you guys already have it figured out
Not 100% yet,still all ears.
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#16 Reply
Posted by
Nickisgod
on 24 Aug, 2013 22:39
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hey sorry to gave dig this, but why are the spark plugs offset angled? is the official answer for ease of access? ive always wanted to know
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It's so you know that the cylinder is on the right way.
If the plug is pointing left, you're good.
If the plug is pointing right, you put it on backwards.
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#18 Reply
Posted by
Motoman991
on 25 Aug, 2013 06:56
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It's so you know that the cylinder is on the right way.
If the plug is pointing left, you're good.
If the plug is pointing right, you put it on backwards.
This is the reason why. I put a cylinder on once and thought the spark plug hole was facing the wrong way. Then I noticed the exhaust was pointing to the rear. Ram air FTW
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The only reason the spark plug is angled is so that the spark plug and spark plug cap can be removed. The angled spark plugs have the electrode located so close to the center of the combustion chamber it does do not effect flame propagation. Locating the spark plug in another location other than the center of the combustion chamber will effect burn speed and when the combustion process is complete. We want to complete the combustion process as quickly as possible.
Detonation is more apt to occur as the time for complete combustion to occur increases.
Remember the basics: the pressure front travels at the local speed of sound in the combustion chamber, the flame speed is controlled by the turbulent intensity and heat travels at the speed of light. Flame speed is relatively slow as compared to pressure and heat velocity.
The speed of sound is governed by pressure and temperature. The speed of sound in free air at sea level is approximately 1100 ft per second. The speed of sound in the exhaust at export opening can be over twice the speed of sound in free air. The speed of sound in the combustion chamber at peak pressure and temperature can be many times the speed of sound in the exhaust. Knowing these facts we can see that the pressure distribution on top of the piston is distributed evenly at any time during the combustion process.
Spark plug location has nothing to do with pressure distribution on the top of the piston unless we are strictly being theoretical. The instantaneous effect of the pressure distribution on top of the piston would not cause the piston to rock unless the piston was mass-less. Piston rock is controlled by piston pin offset, offset of the cylinder axis over the crankshaft, connecting rod length, the length of the piston skirts, and piston skirt clearance.
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#20 Reply
Posted by
Kyle T
on 25 Aug, 2013 09:26
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#21 Reply
Posted by
Nickisgod
on 25 Aug, 2013 10:14
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whoa! thats a whole lot of theory right there. i guess i just wanted to know if there would be any benefit to have the plug vertical in the head. i noticed cr500 have there's angled back towards the intake side. anywho, thanks for the info!
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#22 Reply
Posted by
Kyle T
on 25 Aug, 2013 10:26
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Oh yeah. When Jerry speaks, he gives good info.
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...and when Kyle speaks, he gives good head (specifications)
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whoa! thats a whole lot of theory right there. i guess i just wanted to know if there would be any benefit to have the plug vertical in the head. i noticed cr500 have there's angled back towards the intake side. anywho, thanks for the info!
Sorry for such a long answer. This could also be added to my above response.
Manufacturing the dome so the the spark plug is in the center of the combustion chamber is desirable. It also simplifies machining and reduces manufacturing cost.
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