How to compression test with auto decom and LOTS of smoke?

3 replies to this topic
  • Dave Blackburn

Posted February 17, 2008 - 08:13 PM


I have a 97 650L with electric start and auto decompression. How do you compression test with the auto decompression? Is there a PSI I should have with the decom working?
I just got the bike and still don't have a shop manual, so no help there.

Today when I started it there was LOTS of white smoke for about 4 or 5 minutes. It smoked me out of my garage!!!
What's up with that?
It was cold, but I just replaced the rings, piston, and all seals,m total top end rebuild. Everything else on the bike was good.
I rode it yesterday 100+ miles with no smoke at all???
If it is overfilled with oil woll that cause this? I only hav 2.6L in there. I think it was way too much smoke for some bad seals, which are new anyway.
Doesn't smoke when warm??

  • durandal

Posted February 18, 2008 - 08:31 AM



I just got the bike and still don't have a shop manual, so no help there.

If it's an R, the manual is available online for free in several locations.

If it's an L, PM me with your email. I'll send you the PDF.



Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • martinfan30

Posted February 18, 2008 - 11:18 AM


2.7 litres? I thinkl thats too much. Mine only holds 2.07 qts.

  • cleonard

Posted February 18, 2008 - 11:54 AM


+1 on too much oil.

New rings don't seal very well. A lot of smoke before it gets broken in can be normal. With 100 miles it should be mostly broken in.

There is a number for compression with the decomp, but I don't have it handy. I don't feel that it is a very good measure though. You can back off the right side exhaust valve adjuster several turns. This will have the effect of not letting the auto decomp be able to press down the valve. Then you can get a real compression reading. When you are done, readjust the valve to normal specs.

Related Content


93 xr650l Restoration Project by Zigster

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

Supercross Preview 2017 Part 1: Championship Contenders by Chris Cooksey

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  141 replies

Fell Off Trailer by usafxr

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • Hot  43 replies

Would a Young Scott Summers still be Competitive today on an XR600R? What would he ride to be competitive today? by Jayzonk

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  158 replies

DirttyPig 2005 Xr650l Prroject! by braapmebb1moretime

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 22 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.