The proper way to compression test a 2 stroke?

JW381
Profile picture for user JW381
Posts
10642
Joined
7/21/2009
Location
Harrisburg, OR US
JW381 10/10/2014 3:52pm
10/10/2014 3:52pm
That's how I did it, then just make sure you have a quality tester.
40Plus_922mx
Profile picture for user 40Plus_922mx
Posts
2901
Joined
4/17/2009
Location
High Desert, CA US
40Plus_922mx 10/10/2014 6:45pm
10/10/2014 6:45pm
Thanks guys. I bought a good tester. I think I will try ot cold and warm.

The Shop

See All »
JW381
Profile picture for user JW381
Posts
10642
Joined
7/21/2009
Location
Harrisburg, OR US
JW381 10/10/2014 6:56pm
10/10/2014 6:56pm
Racer_Twentynine wrote:
why on the kill switch? no plug in head no start.....idk just wondering....
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with a compression tester thru the plug hole. That's just my guess, tho.
40Plus_922mx
Profile picture for user 40Plus_922mx
Posts
2901
Joined
4/17/2009
Location
High Desert, CA US
40Plus_922mx 10/10/2014 7:57pm
10/10/2014 7:57pm
Thanks guys. I bought a good tester. I think I will try ot cold and warm.
slipdog
Profile picture for user slipdog
Posts
10044
Joined
7/25/2009
Location
Nor Cal, CA US
slipdog 10/10/2014 8:24pm
10/10/2014 8:24pm
I always do it cold, never thought much about the kill switch though.
harescrambled
Profile picture for user harescrambled
Posts
1889
Joined
4/1/2008
Location
Warren, OH US
Fantasy
1942nd
harescrambled 10/11/2014 8:01am
10/11/2014 8:01am
Kill switch to keep sparkplug lead from arcing, and possibly igniting something, or shocking the mechanic
BobPA
Profile picture for user BobPA
Posts
8025
Joined
10/31/2013
Location
PA US
BobPA 10/11/2014 5:08pm
10/11/2014 5:08pm
JW381 wrote:
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with...
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with a compression tester thru the plug hole. That's just my guess, tho.
Umm no
JW381
Profile picture for user JW381
Posts
10642
Joined
7/21/2009
Location
Harrisburg, OR US
JW381 10/12/2014 6:35pm
10/12/2014 6:35pm
JW381 wrote:
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with...
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with a compression tester thru the plug hole. That's just my guess, tho.
BobPA wrote:
Umm no
Okay fine lol like I said, it was a guess.
JW381
Profile picture for user JW381
Posts
10642
Joined
7/21/2009
Location
Harrisburg, OR US
JW381 10/12/2014 6:36pm
10/12/2014 6:36pm
40Plus_922mx wrote:
Coulda done without that.... [IMG]http://i77.photobucket.com/albums/j77/factorydad/20141011_153844_zps4e87bafc.jpg[/IMG]
Coulda done without that....


Time to order some fresh goods!
40Plus_922mx
Profile picture for user 40Plus_922mx
Posts
2901
Joined
4/17/2009
Location
High Desert, CA US
40Plus_922mx 10/12/2014 7:04pm
10/12/2014 7:04pm
40Plus_922mx wrote:
Coulda done without that.... [IMG]http://i77.photobucket.com/albums/j77/factorydad/20141011_153844_zps4e87bafc.jpg[/IMG]
Coulda done without that....


JW381 wrote:
Time to order some fresh goods!
Definitely. Was hoping for more compression. Oh well now I have another reason to go shopping.
ToolMaker
Profile picture for user ToolMaker
Posts
6088
Joined
11/19/2011
Location
Escondido, CA US
Fantasy
762nd
ToolMaker 10/13/2014 5:35am
10/13/2014 5:35am
JW381 wrote:
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with...
I think it's just a safety thing. All it'd take was a weird occurance to have the bike start deiseling while you've got it WFO with a compression tester thru the plug hole. That's just my guess, tho.
BobPA wrote:
Umm no
I believe it's to keep the electrical system form overloading as it can't discharge otherwise. Causing damage to the system. Whether or not it can retain the charge for any length of time and shock you later I don't know. But it can and will damage the system if it can't discharge. If you have the plug (or plug wire) grounded that will also work.
TM
40Plus_922mx
Profile picture for user 40Plus_922mx
Posts
2901
Joined
4/17/2009
Location
High Desert, CA US
40Plus_922mx 10/20/2014 12:19am
10/20/2014 12:19am
Jakes Dad wrote:
Now get a set of snap gauges to help measure the bore, Keeping her tight will mean more long term satisfaction.Wink

http://www.youtube.com/watch?v=SmXfGan_NXQ
What about a micrometer? I am getting 66mm both cylinder and piston.

The cylinder still has circular hone marks, and the cylinder wall feels like a mirror with my finger nail. There are zero signs of virticle wear or marks on the cyllinder walls. There is zero up and down play in the rod bearing. I checked it in all positions as I rotated it around checking for play. I am told this had a rebuild 3 years ago and the dude only rode it a few times a year when he went camping. I am wondering since he obviously ran a very rich mixture , and to looks like he lugged it everywhere if that is why it still looks good inside.

Can just needing a piston and rings cause such a low compresion test? I am also at 4000 feet.

Post a reply to: The proper way to compression test a 2 stroke?