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I need to replace shims, should I replace cams while I'm at it?


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My exhaust valve lash is too tight. Just a bit under 0.203 mm, but the spec is 0.2 mm, and valves only get tighter, so I'm going to go ahead and get the lash well back into spec. (The intake valves are both on the high side of the spec.)

Question is: since I'm pulling the exhaust cam anyway, should I go ahead and upgrade either or both cams?๐Ÿคฃ

Mostly stock DRZ400SM. Non-stock bits:

  • 3x3 mod
  • K&N filter
  • JD jet kit
  • E-sized Scorpion-brand "stainless steel" header (currently connected to the stock muffler--long story ๐Ÿ™‚)

๐Ÿ‘ I'm thinking maybe the Hotcams stage-1 intake, with stock exhaust, or Hc stage-1 intake with Hc stage-2 exhaust. Though, I'm also thinking any gains would be so small as to be pointless. :applause:

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Some googling indicates that you can get a new, OEM E-model exhaust camshaft for $200-ish. And the intake for $150-ish. So, maybe that's an option, too--though, they were designed for an FCR, weren't they.... ๐Ÿ‘

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My exhaust valve lash is too tight. Just a bit under 0.203 mm, but the spec is 0.2 mm, and valves only get tighter, so I'm going to go ahead and get the lash well back into spec. (The intake valves are both on the high side of the spec.)

Question is: since I'm pulling the exhaust cam anyway, should I go ahead and upgrade either or both cams?๐Ÿคฃ

Mostly stock DRZ400SM. Non-stock bits:

  • 3x3 mod
  • K&N filter
  • JD jet kit
  • E-sized Scorpion-brand "stainless steel" header (currently connected to the stock muffler--long story ๐Ÿ™‚)

๐Ÿ‘ I'm thinking maybe the Hotcams stage-1 intake, with stock exhaust, or Hc stage-1 intake with Hc stage-2 exhaust. Though, I'm also thinking any gains would be so small as to be pointless. :applause:

Its not a difficult or long job so that is not a reason to change cams. I'd leave it if thats your only motivation, save the money for something else.

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.2mm, (which is equal to .200mm), and .203mm are really close. It is kinda tricky to measure thousandths of an inch and be really accurate for most of us, thousandths of a milimeter would be really tough, so am i missing something here? either way, if your clearance keeps tightening up, a valve job is in the near furure. btw, I have the stg 1 Hotcams, and like them.

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.2mm, (which is equal to .200mm), and .203mm are really close. It is kinda tricky to measure thousandths of an inch and be really accurate for most of us, thousandths of a milimeter would be really tough, so am i missing something here?

My feeler gauges are inches first, metric second. So, the closest I've got to a .200 mm is a feeler labeled .203 mm. The .203 will fit under the cam, but I have to force it, and there's a lot of drag when sliding it. The next feeler down, labeled 0.173 mm, slides freely.

So, all I can say with 99.73% (k=3) confidence is that the clearance is between 0.203 and 0.173, +/- whatever the error on the feeler gauges is. My SWAG is that the lash is just a wee bit under 0.203mm.

[Note: I'm playing silly buggers. To actually be able to make a k=3 confidence statement, I'd need to take a lot of measurements, rolling the engine over between each measurement, recording the temperature of the cam and bucket each time, somehow control or correct for the properties of the engine oil, etcetcetc. And I prefer to not even think about all the error involved in off-the-shelf feeler gauges.... ๐Ÿ‘]

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If you decide to reshim ,you must take the cam out anyway , so dropping in a new one doesn't take any extra time.

If you go for hotcams ,beware of that they shall have a smaller lash than the oem cams.

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