Author Topic: auto decomp  (Read 2642 times)

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Offline Ktm181

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auto decomp
« 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.

Offline b490

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Re: auto decomp
« Reply #1 on: September 01, 2013, 11:11:20 AM »
  Got one fitted  to my 500 Husky .




  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   
« Last Edit: September 01, 2013, 11:33:46 AM by b490 »

Offline Ktm181

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Re: auto decomp
« Reply #2 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.

Offline b490

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Re: auto decomp
« Reply #3 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
 

Offline firko

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Re: auto decomp
« Reply #4 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.
                                                                       
                                                                       
« Last Edit: September 01, 2013, 12:37:14 PM by firko »
'68 Yamaha DT1 enduro, '69 Yamaha 'DT1 from Hell' '69 DT1'Dunger from Hell, '69 Cheney Yamaha 360, 70 Maico 350 (2 off), '68 Hindall Ducati 250, Hindall RT2MX, Hindall YZ250a , Cycle Factory RT2MX flat tracker, Yamaha 1T250J, Maico 250 trials, '71, Boyd and Stellings TM400, Shell OW72,750 Yamaha

Offline Ktm181

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Re: auto decomp
« Reply #5 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? 

Offline Mike52

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Re: auto decomp
« Reply #6 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.
85/400WR,86/240WR,72/DKW125,Pe250c,TC90,TS100,XT250,86/SRX250,XR400r
Friend  struggling up a hill on a old bike at MTMee .http://www.youtube.com/watch?v=cjj6E2MP9xU.

Offline firko

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Re: auto decomp
« Reply #7 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.
'68 Yamaha DT1 enduro, '69 Yamaha 'DT1 from Hell' '69 DT1'Dunger from Hell, '69 Cheney Yamaha 360, 70 Maico 350 (2 off), '68 Hindall Ducati 250, Hindall RT2MX, Hindall YZ250a , Cycle Factory RT2MX flat tracker, Yamaha 1T250J, Maico 250 trials, '71, Boyd and Stellings TM400, Shell OW72,750 Yamaha

Offline RD

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Re: auto decomp
« Reply #8 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.
Suck Squeeze Bang Blow

Offline OverTheHill

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Re: auto decomp
« Reply #9 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.

Offline Mike52

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Re: auto decomp
« Reply #10 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.
85/400WR,86/240WR,72/DKW125,Pe250c,TC90,TS100,XT250,86/SRX250,XR400r
Friend  struggling up a hill on a old bike at MTMee .http://www.youtube.com/watch?v=cjj6E2MP9xU.