cam timing confused


15 replies to this topic
  • apriliars250

Posted October 21, 2011 - 08:49 AM

#1

just done my cam timing on my drz 400

when i rotate my engine to top dead center once the timing marks do not line up at all (miles out) the one on the intake points up and the 4 points up on the exhaust valve (if there was a 4 marked) . then rotate it agen to top dead center the marks line up fine,,then rotate it agen it dose not line up. then rotate it agen and it dose line up perfect.

is this right i have searched and read the manual and cant find anythink about it

  • E.Marquez

Posted October 21, 2011 - 08:59 AM

#2

just done my cam timing on my drz 400

when i rotate my engine to top dead center once the timing marks do not line up at all (miles out) the one on the intake points up and the 4 points up on the exhaust valve (if there was a 4 marked) . then rotate it agen to top dead center the marks line up fine,,then rotate it agen it dose not line up. then rotate it agen and it dose line up perfect.

is this right i have searched and read the manual and cant find anythink about it


The timing marks on both cams and the flywheel will only align when the piston is at top dead center on the compression stroke, at all other positions things will be misaligned.

have you read though the FAQ article?
DRZ Valve Clearance Check and Adjustment plus Cam timing
Erik Marquez
Published by E.Marquez
08-10-2009


If not, please do so, it should help you understand the procedure.

  • apriliars250

Posted October 21, 2011 - 09:08 AM

#3

The timing marks on both cams and the flywheel will only align when the piston is at top dead center on the compression stroke, at all other positions things will be misaligned.

have you read though the FAQ article?
DRZ Valve Clearance Check and Adjustment plus Cam timing
Erik Marquez
Published by E.Marquez
08-10-2009


If not, please do so, it should help you understand the procedure.


yeah i have read though the FAQ article

it does line up at top dead center every other turn is that i dont under stand why

  • William1

Posted October 21, 2011 - 09:16 AM

#4

The cams turn at 1/2 crank speed. Meaning the the crank rotates twice for every revolution of the cams.

  • apriliars250

Posted October 21, 2011 - 09:20 AM

#5

The cams turn at 1/2 crank speed. Meaning the the crank rotates twice for every revolution of the cams.


that means i have done my timing right then..just a bit confused becuse it done not say that in the manual

  • DrzDick

Posted October 21, 2011 - 09:31 AM

#6

If you look up the basics of a 4 stroke engine it'll all become clear. The piston goes up once to compress and once to clear (exhaust) so the top end has to turn at half the speed of the bottom end to operate the valves in sequence.

TBH I would have thought that would at least have warranted a foot note in the manual..:thumbsup:

  • E.Marquez

Posted October 21, 2011 - 09:34 AM

#7

that means i have done my timing right then..just a bit confused becuse it done not say that in the manual


:thumbsup: Good you now understand.
One thing to keep in mind.. Service manuals, technical write ups and the like assume the reader has a basic understanding of how the machine they are working on works, the basic principles.
In example, the writer of a service manual for a 4 stroke motorcycle engine assumes the mechanic reading the manual understands that an engine of this type, is a 4 stroke design, intake, compression, power, exhaust, and that the overhead cams, turn at 1/2 crank speed.

  • apriliars250

Posted October 21, 2011 - 09:52 AM

#8

cool so now i know.. i have never worked on a 4 stroke before

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  • Joester

Posted October 21, 2011 - 06:33 PM

#9

does the DRZ400 engine use a wasted spark like my YFZ450 engine did? (i figured this thread was relevant enough to ask this question in because its not a worthy question to start a separate thread over :thumbsup:)

  • Noble

Posted October 21, 2011 - 06:37 PM

#10

Yes. As is very common in most 4 strokes these days.

  • Joester

Posted October 21, 2011 - 06:56 PM

#11

i figured it did, but when the time comes for my to do my timing (haven't had to do it yet) It sure would be useful to know, lol.

  • E.Marquez

Posted October 21, 2011 - 08:06 PM

#12

i figured it did, but when the time comes for my to do my timing (haven't had to do it yet) It sure would be useful to know, lol.


Not really.... you’re not adjusting or setting spark timing, just cam timing in relation to the crank. It is so easy, some folks over think and make hard.
The DRZ has only one timing mark on the flywheel, that’s TDC, spin the motor over till TDC mark is centered in the window, put the cams in, aligning the marks to the head surface, check lobe position as a back up and your done…

If you talking about timing the cams, as in aftermarket cams with adjustable sprockets. That’s a little more involved, but still nothing to do with the wasted spark ignition system.

  • Joester

Posted October 21, 2011 - 08:59 PM

#13

The DRZ has only one timing mark on the flywheel, that’s TDC, spin the motor over till TDC mark is centered in the window, put the cams in, aligning the marks to the head surface, check lobe position as a back up and your done…



without a wasted spark you need to make sure you are at compression TDC before installing the cams. because spark only happens at compression TDC, so if you install yours cams as though you were on the compression TDC, when you are really on the exhaust TDC, your spark plug will fire when the cams are in the exhaust position, and it WONT fire when your cams are in the compression position, which would mean a no-start, obviously.

with a wasted spark, you can just set it to any ol' TDC (the mark on the flywheel to which you refer), and just throw the cams in in compression position, and it wont matter, because it sparks at every TDC.

  • E.Marquez

Posted October 21, 2011 - 10:24 PM

#14

without a wasted spark you need to make sure you are at compression TDC before installing the cams. because spark only happens at compression TDC, so if you install yours cams as though you were on the compression TDC, when you are really on the exhaust TDC, your spark plug will fire when the cams are in the exhaust position, and it WONT fire when your cams are in the compression position, which would mean a no-start, obviously.

with a wasted spark, you can just set it to any ol' TDC (the mark on the flywheel to which you refer), and just throw the cams in in compression position, and it wont matter, because it sparks at every TDC.


Right, umnmm thought that was what I just said.....:ride:


I get it now, you were assuming or just not sure if it was a wasted spark design or not.. As most every common modern motorcycle is a wasted spark design, I would assume it WAS a wasted spark design.
Just a point of reference deal.
:thumbsup:

Edited by E.Marquez, October 21, 2011 - 10:52 PM.


  • Noble

Posted October 21, 2011 - 10:28 PM

#15

Joe - stop and think. There are only 2 places on a 4 stroke motor to take spark timing: off the cam or off the crank. If it is off the cam, you automatically get spark timing with cam timing (except for some old Hondas). If it is off the crank, very TDC is a spark. The "stroke" is defined by the cam not the piston. You really can't go wrong.

  • Joester

Posted October 22, 2011 - 04:28 AM

#16

Right, umnmm thought that was what I just said.....

sorry, i thought you were trying to imply that even if it wasnt a wasted spark that it still doesnt matter how you set timing, and i was like uhhh, scwhat? :thumbsup::bonk:


There are only 2 places on a 4 stroke motor to take spark timing: off the cam or off the crank.

you can have a gear off the crank with a .5 ratio, that activates spark every other revolution, even though it would be stupid to design it like that, not every company designs things 100% logically, haha

regardless, i know what to do when timing my DRZ now. thanks guys. i dont want to get in a huge internet fight about this. :ride:





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