using comp. release to roll start?

10 replies to this topic
  • 426fireman

Posted July 24, 2002 - 05:14 PM


while riding on a local MX track last sunday, i killed the motor in 4th gear, i simply feathered the clutch and comp. release and restarted while still in motion. My question is will this dammage the motor in any way?

Life is to short, RIDE HARD AND FAST

  • bigdrtrdr

Posted July 24, 2002 - 05:34 PM


cant answer your question but,I do it too and she always fires right off!

  • Mark_Cantrell

Posted July 24, 2002 - 10:59 PM


Not at very low speeds. I drop the clutch, and then feather the compression release. That minimizes how long the decomp gets used.

Good luck,

  • Thumpty_Dumpty

Posted July 25, 2002 - 03:27 AM


I did exactly the same thing in a race last Sunday. Stalled on a descent into a right hander (too much rear brake), so pulled clutch in while coasting in gear, brought engine over TDC with decomp, kicked it, it fired up and I carried on. All without reason why it should do any damage to anything....other than your mid-race pride... :)

  • cornbread

Posted July 25, 2002 - 03:37 AM


Read NEW HEAD? Posted yesterday..

This could be the reason for my problems...


Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • bashn

Posted July 25, 2002 - 04:02 AM


I do it ALL the time. Whenever I can start the bike on a slope, or whatever. Pull in the clutch, click it into 2nd or 3rd, pull in decomp and let out the clutch, then pop the decomp out. The decomp will not open the valve to the point it will contact the piston. I've never seen any damage or wear on my cams, and I do inspect them every 40 hours.


  • OTBC_yz426f

Posted July 25, 2002 - 06:18 AM


I use this starting technique as well. At slow speed and with the engine off, I don't believe it is a problem. But beaware of how this system works.
The depression shaft has a half moon that rotates and pushes directly down on the valve butch, which opens the valve. The valve butch will be damaged if the decompression shaft is turned pulled while running. I know from experience, my buddy pulled it on my old bike and the valve stuck open. Had to pull the head and replace the valve butch.

  • 426fireman

Posted July 25, 2002 - 07:08 AM


thanks to all who answered, in my understanding this should not hurt anything if done only ocasionally. This may only happen during a crash prevent and I have only done this a very few times and also if she does'nt fire right off you will have to stop anyway and do the drill. You guys have came through for me once again, thanks and RIDE ON......

  • John_Lorenz

Posted July 25, 2002 - 07:41 AM


I have been able to bump start the beast no worries, by getting the bike to compres stroke and just using the comp rel to get over TDC, just as you would on the starting ritual.

A run and bump works everytime if warm or hot, or better if your rolling.

It just worries me that if the timing is off you will damage the valve...

BTW thumpity did it the way I described

[ July 25, 2002: Message edited by: E.G.O.**** ]

  • Kirtwell

Posted July 25, 2002 - 08:59 AM


I just applied a little common sense and concluded that if you kick the engine over manually witht he decomp lever in....then how in the world could the valve be damaged if you bump started it? It won't!!!!!
I've done exactly what you did many times and it never gave me any problems at all.

  • Boit

Posted July 25, 2002 - 09:52 PM


Kirtwell: Exactly!

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