Chinese Decomp valve..your thoughts?

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altair

altair

ArboristSite Operative
Joined
May 5, 2012
Messages
280
Location
New Zealand
Finished my mates MS660, on second startup the plastic top flew off the AM decomp valve. Luckily the stem didn't fall into the engine. When I unscrewed it it fell apart into my hands..would have destroyed the top end for sure.
Are the AM decomp valves normally okay? Or am I playing Russian Roulette using one? Bearing in mind from memory a Stihl decomp valve in NZ will be megabucks.
Cheers
 
grack

grack

Addicted to ArboristSite
Joined
Jan 31, 2010
Messages
2,036
Location
wv
I plugged all 4 of my china 372s
The chinese decomps suck.
Button's fell off or they didn't work properly sometimes..
I put d ring handles on mine.
I like them.
 
Ted Jenkins
Joined
Apr 18, 2016
Messages
3,503
Location
Twin Peaks
I had one come loose early this spring. One moment it was running great then would not start. Finally discovered the plunger was about ready to go in to the piston. I machined a small grove near the top of the plunger and put a clip on it and then brazed the clip as a back up so it will not go into the piston. I looked for replacement decomp valve and found that they are hard to come by maybe for a $100, but have not looked lately. Thanks
 
paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
The plastic top also popped off the valve supplied with my 660kit after 2 tanks or so. I was expecting it to happen and was going to just plug the hole but I didn't see no harm in attempting a fix first by making a new top as per this post: http://www.arboristsite.com/community/threads/huztl-ms660.300307/page-131#post-6217621

I'll take a photo at some point but it's very very similar (I'm not creative at all but can copy good ideas) It took all of 20 mins on the lathe (I'm just a beginner machinist). Can't remember the stem diameter off the top of my head but just made the fit as tight as I possibly dare - added some permanent threadlock and pressed it on. 10+ tanks later its still firmly attached with no sign of it coming loose...
 
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