SuzukiSavage.com - "wasted spark"?

sillydilly

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"wasted spark"?
05/07/11 at 10:46:29

hey quick question. I was talking to a few 'mechanic' friends of mine about my bike. We were on topic of installing the cams and I mentioned there was 2 TDCs for the piston and which one I need to use for cam install.

One claimed my bike is most likely a 'waste spark' 4 stroke, which means it will spark after the compression stroke AND the exhaust stroke?

By saying this it doesnt matter how you install the cam as long as the pistons at TDC it will spark either way, but to make sure you install cam lobes down so that the valves are both closed making it true TDC for the whole engine?

This makes sense to me but am I missing something here?

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: "wasted spark"? Reply #1 - 05/07/11 at 11:05:16 true, it's a wasted spark engine and as long as the cam is timed to either tdc, you're good to go.
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sillydilly Full Member Offline SuzukiSavage.com Rocks! Posts: 231	Re: "wasted spark"? Reply #2 - 05/07/11 at 11:10:51 thanks!
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CalisOsin Senior Member Offline Rather die, than live down on my knees. Posts: 297 Orange County, Ca Gender:	Re: "wasted spark"? Reply #3 - 05/09/11 at 08:44:56 Then how come everything we do, we set the bike to TDC on the compression stoke?
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sillydilly

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Re: "wasted spark"?
Reply #4 - 05/09/11 at 09:19:53

because the compression stroke sets the CAM to TDC. I believe the piston (crank) rotates 2 for everytime the cam goes once. so if your on the wrong TDC, your cam will be 180 degrees out of rotation which means lobes straight up and valves open. TDC on compression stroke ensures that the pistons at the very top, and more importantly, your valves are both closed with the lobes facing straight down

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CalisOsin

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Re: "wasted spark"?
Reply #5 - 05/09/11 at 09:24:59

sillydilly wrote on 05/09/11 at 09:19:53:

because the compression stroke sets the CAM to TDC. I believe the piston (crank) rotates 2 for everytime the cam goes once. so if your on the wrong TDC, your cam will be 180 degrees out of rotation which means lobes straight up and valves open. TDC on compression stroke ensures that the pistons at the very top, and more importantly, your valves are both closed with the lobes facing straight down

duh, thanks! I'm having a problem with rectal-cranium inversion this morning.

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: "wasted spark"? Reply #6 - 05/09/11 at 09:27:53 Simple solution.. PLexiglass belly button implant.. You can see where youre going,
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sillydilly Full Member Offline SuzukiSavage.com Rocks! Posts: 231	Re: "wasted spark"? Reply #7 - 05/09/11 at 09:29:38 the oil check glass on the clutch cover works good too
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CalisOsin Senior Member Offline Rather die, than live down on my knees. Posts: 297 Orange County, Ca Gender:	Re: "wasted spark"? Reply #8 - 05/09/11 at 09:43:29 justin_o_guy2 wrote on 05/09/11 at 09:27:53: Simple solution.. PLexiglass belly button implant.. You can see where youre going, HA!
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verslagen1

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Re: "wasted spark"?
Reply #9 - 05/09/11 at 10:16:48

Quote:

Then how come everything we do, we set the bike to TDC on the compression stoke?

sillydilly wrote on 05/09/11 at 09:19:53:

because the compression stroke sets the CAM to TDC. I believe the piston (crank) rotates 2 for everytime the cam goes once. so if your on the wrong TDC, your cam will be 180 degrees out of rotation which means lobes straight up and valves open. TDC on compression stroke ensures that the pistons at the very top, and more importantly, your valves are both closed with the lobes facing straight down

On a stock cam, at both TDC's the valves are closed. So you could be tempted to adjust the valves at any TDC. But don't. Check this out, won't take long promise. Next time you adjust your valves, before you close up, rotate the engine a bit and reach in and feel the gap on the rocker (lift and press, repeatedly) see as you progress in rotation the gap gets larger, not by much, but it does. The reason behind this is mfg tolerances. Thru the compression stroke you want to guarranty full valve closure, so after TDC on the compression stroke they releave the cam so there's more clearance, just to cover all bets.

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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28651 Tucson Az Gender:	Re: "wasted spark"? Reply #10 - 05/09/11 at 10:49:51 I hate waste.... ...any ideas on whet we can do with the other spark?... ... ...
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ralfyguy Serious Thumper Offline Posts: 932	Re: "wasted spark"? Reply #11 - 05/09/11 at 10:51:25 So when I did mine, I had the piston at TDC and intake and exhaust valve rockers I could wiggle a little up and down before I adjusted. I take it that I did it correctly?
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28651 Tucson Az Gender:	Re: "wasted spark"? Reply #12 - 05/09/11 at 10:56:21 ralfyguy wrote on 05/09/11 at 10:51:25: So when I did mine, I had the piston at TDC and intake and exhaust valve rockers I could wiggle a little up and down before I adjusted. I take it that I did it correctly? Very likely, yes... Find TDC the easy way...
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CalisOsin

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Re: "wasted spark"?
Reply #13 - 05/09/11 at 11:02:28

Serowbot wrote on 05/09/11 at 10:56:21:

ralfyguy wrote on 05/09/11 at 10:51:25:

So when I did mine, I had the piston at TDC and intake and exhaust valve rockers I could wiggle a little up and down before I adjusted. I take it that I did it correctly?

Very likely, yes...

Find TDC the easy way...

Serowbot, I just used this trick this weekend and it worked beautifully, thanks a million!!

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MotoBuddha Serious Thumper Offline Let's roll! Posts: 1416 Charlotte, NC	Re: "wasted spark"? Reply #14 - 05/09/11 at 11:43:48 Serowbot wrote on 05/09/11 at 10:49:51: I hate waste.... ...any ideas on whet we can do with the other spark?... ... ... Let's see, you could wire I'm a big azz capacitor, use the wasted spark to charge it, then use it to shoot lightning bolts at bad drivers.
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