OzVMX Forum

Clubroom => Tech Talk => Topic started by: Ktm181 on September 01, 2013, 10:57:15 am

Title: auto decomp
Post by: Ktm181 on September 01, 2013, 10:57:15 am


Hey Men,

auto decomp on  500 2st, who uses them?  How do you find them as far as sticking etc?  What are you finding as best type to retro-fit to air cooled cylinder, i just looked at one with a Stil chainsaw type fitted, nice neat job?

cheers,
Kt.
Title: Re: auto decomp
Post by: b490 on September 01, 2013, 11:11:20 am
  Got one fitted  to my 500 Husky .
(http://i604.photobucket.com/albums/tt127/scm00/DSCF8198_zps2b14b181.jpg) (http://s604.photobucket.com/user/scm00/media/DSCF8198_zps2b14b181.jpg.html)

(http://i604.photobucket.com/albums/tt127/scm00/DSCF8143_zps0375c4fe.jpg) (http://s604.photobucket.com/user/scm00/media/DSCF8143_zps0375c4fe.jpg.html)

  I used  Vulcan Engineering brand    (as recommended by the Husky Guru s)  ;)
 http://vulcanworks.net/store_4/product.php?productid=231&cat=1&page=1
   Well made , no problems .
  Feels more like a 250 to start when decomp used .
  A worthwhile investment for a big bore 2 stroke

  Regards ,
                  Steve   
Title: Re: auto decomp
Post by: Ktm181 on September 01, 2013, 11:22:02 am

Thanks for the reply mate, nice job by looks of it, love the Husky too, i had one back then, bit of a weapon in the bush (430 & 390).  Vulcan Engineering on google exists in several countries, which one did you use?  The comp release looks like the Stil one i saw, small and simple.  MIne is relatively easy to kick, i mainly would like to lessen the wear/damage to the kickstart mechanism by making it easier, and of course my skinny long legs are not getting any stronger!

Kt.
Title: Re: auto decomp
Post by: b490 on September 01, 2013, 11:28:38 am

 Vulcan Engineering on google exists in several countries, which one did you use?  !
Kt.

   I used 14mm type , from this place ;
 
   http://vulcanworks.net/store_4/product.php?productid=231&cat=1&page=1

     Regards ,
                   Steve
 
Title: Re: auto decomp
Post by: firko on September 01, 2013, 12:22:57 pm
I use those Vulcan Eng. decomps on nearly all of my vintage bikes. With my rooted knees I need all the help I can get ::). Here's a couple on my new Ratbike Racer DT1 and 360 Yam flat tracker.
                                                                       (http://i1112.photobucket.com/albums/k495/firko2/DT1fromHell2010_zps15424519.jpg) (http://s1112.photobucket.com/user/firko2/media/DT1fromHell2010_zps15424519.jpg.html)
                                                                       (http://i1112.photobucket.com/albums/k495/firko2/flattracker008_zps1db4155d.jpg) (http://s1112.photobucket.com/user/firko2/media/flattracker008_zps1db4155d.jpg.html)
Title: Re: auto decomp
Post by: Ktm181 on September 01, 2013, 12:48:36 pm

   I used 14mm type , from this place ;
    http://vulcanworks.net/store_4/product.php?productid=231&cat=1&page=1
     Regards ,
                   Steve
 [/quote]

excellent bit of gear by the looks of it, so yours is just a bolt in or machining work too? 
Title: Re: auto decomp
Post by: Mike52 on September 01, 2013, 01:10:48 pm
I have this type of deco fitted to my big bore huskys and they work well BUT they are not AUTO.
They have to be manually reset each time you want them to decompress.
If you want an auto one then look towards the one fitted to a Victa as they are auto.
Before anyone snickers about the Victa deco there is a guy in NZ who swears by them.
Title: Re: auto decomp
Post by: firko on September 01, 2013, 02:03:24 pm
Quote
excellent bit of gear by the looks of it, so yours is just a bolt in or machining work too? 
Mine just screwed into the spare plug hole on the early Yamahas......as simple as changing a spark plug ;D.
Title: Re: auto decomp
Post by: RD on September 01, 2013, 04:34:34 pm
As a mower mechanic of nearly 30 years i would be really carefull using a victa deco,the end breaks off the valve,ok in a mower as they have a casting to catch it but without that it would drop straight into harms way and you can imagine the end result of that.
Title: Re: auto decomp
Post by: OverTheHill on September 01, 2013, 06:01:04 pm
i'm learning all the time as would have thought any decomp in the head would take too much 'bounce' out of the compression to actually make it harder to start as opposed to the genuine yamaha in front of the cylinder type which once the piston/rings are past that point then it's compressing what's left positively--but i'm learning!!, never too old.
Title: Re: auto decomp
Post by: Mike52 on September 02, 2013, 07:24:13 am
As a mower mechanic of nearly 30 years i would be really carefull using a victa deco,the end breaks off the valve,ok in a mower as they have a casting to catch it but without that it would drop straight into harms way and you can imagine the end result of that.
I worked at Victa in the 70's as an outside service man and saw that happen.
I told  the Kiwi guy and he got upset but he had made the hole smaller at the cylinder end to stop any problems so it worked ok.