auto compression release issues?

6 replies to this topic
  • wickedsprint

Posted July 22, 2004 - 01:14 PM


How exactly does the auto compression release work ont he 650R? Is there any way to bypass it so that ONLYuse of the manual lever is possible? I hate pretty much anything automatic and if it is anything like the arangement my XT350 had, I would again, rather stick tot he manual release. How does it stay in adjustment so it is not bumping the exhaust valve open while you're riding??

  • qadsan

Posted July 22, 2004 - 02:29 PM


I thought I was hitting the rev limiter at higher RPM and my bike was intermittently becoming hard to start (very suddently). I verified my ignition, fuel and then suspected the auto decomp mechanism. Sure enough, that was the culprit (intermittently lifting the exhaust valve) so I had planned to remove it and then had the bright idea to install a stage one HotCam while I was in there. I bought my HotCam for ~$90 and it works fine with the stock rockers & springs since it's a machined billet piece and not hard chrome welded like some of the other cams that requires a matching surface on the rockers. I removed the cam retaining sprocket from my old cam and put it on the new HotCam, then put things back together and broke it in. It was a nice mod and worth the money IMO.

To remove the auto decomp mechanism from the stock cam, you need to remove everything between the cam sprocket flange and the first lobe. There will be a hole in the cam underneath the auto decomp mechanism to lubricate it. Without the auto decomp mechanism in place, the oil will take the path of the least resistance and go right back down into the engine via the cam chain cavity. Rather than losing potential oil pressure to everything important in the valve train, you'll want to close up this hole. The best way to do it is to weld it closed, but you could probably also use JB Weld, QwikSteel Epoxy, etc. All you need to do it quickly tack it with a mig welder and its closed (very quick & simple) if you have have access to a mig welder. Since the HotCam is designed 'not' to use the auto decomp mechanism, you don't have to worry about welding any holes closed. You'll also see a little spring loaded pin in the head that actuates the auto decomp mechanism. You won't find HotCams mentioning anything about this springloaded pin in their instructions, but they do recommend removing this pin & spring if you talk to them on the phone, so you may want to also remove this if you're removing your auto decomp mechanism. It's held in with a retaining clip and I left mine in because I forgot to take it out, but I also think it's pretty secure as is. The most important thing you'll have to remember without the auto decomp mechanism is to always kick your bike over when it's slightly past TDC, otherwise there's a small chance you may end up with a kick start lever broken off and stuck in your leg if you kicked from the middle of the cycle and the bike kicked back and the lever broke. The auto decomp mechanism prevents the bike from kicking back hard by lifting one of the valves, but I'm glad I have that sucker out of there. I still have full use of my manual decomp lever & its function and I don't have to worry about the auto decomp mechanism coming apart and pieces falling into the engine. There's also a little less rotating mass and my bike has never had any further starting issues since then.

  • wickedsprint

Posted July 22, 2004 - 05:23 PM


Thanks for the advice, luckily I DO know how to properly kick over a big single with the use of a manual lever only, or none at all. I have heard alot of horror stories. I greatly appreciate the info you just posted, so basically I have to slap a hot cam in there and make it simpler..sweet! Nice to see someone else who also knows the proper drill for a manual release only :thumbsup:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • smashinz2002

Posted July 22, 2004 - 06:07 PM


Yeah I know what you mean, I hate the auto decompressor on the 650R also. I could never get the bike to start just by kicking it over (auto-decompressor). Fortunately, the 650R also includes a decompressor lever, so you can do it manually with no prob. But still that auto thing sometimes gets in the way when you're trying to start it manually, and makes for several dead kick throughs before you feel it come up on compression.
I don't know what kind of sissies Honda was thinking would be riding this bike. I mean, if someone is big enough to handle the 650R, surely they are big enough to start the thing with a manual decompressor lever.

  • wickedsprint

Posted July 22, 2004 - 07:18 PM


But it is not the weight, even when i was a skinny 140 lb kid I could kick over a DR650 with ease..all about technique baby!

  • frils

Posted June 09, 2008 - 12:34 PM


i have 87xl600r i love this bike i just got this toy, but now im finding out i cant start it due to a broken ankel injury 4 years ago it keeps kicking back at me when starting my ankle cant take it what the hell is the mater with this thing

  • martinfan30

Posted June 09, 2008 - 01:12 PM


i have 87xl600r i love this bike i just got this toy, but now im finding out i cant start it due to a broken ankel injury 4 years ago it keeps kicking back at me when starting my ankle cant take it what the hell is the mater with this thing

Try starting a new thread. Did you notice the last post date before you?

BTW, welcome to TT!


Related Content


Engine Loping/Sputtering by tcaldwell

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 2 replies

93 xr650l Restoration Project by Zigster

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 17 replies

Which thumper motor for a street tracker? by woz

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • * * * * -
  • Hot  29 replies

2015 XR650L Squeaking noise by Crayjay

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 3 replies

What was your path to Beta? by officialhopsof

Dirt Bike   Make / Model Specific   Beta
  • Hot  79 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.