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Post by wallcraft on Apr 3, 2024 23:07:22 GMT 1
Gents. Can anyone recommend an engine compression tester that has the scharder valve in the end off the flexible tube that screws in the plug hole.
Many thanks
Mark.
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Post by stusco on Apr 4, 2024 7:40:12 GMT 1
Gents. Can anyone recommend an engine compression tester that has the scharder valve in the end off the flexible tube that screws in the plug hole. Many thanks Mark. Can i ask why? Out of interest |
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Post by wallcraft on Apr 4, 2024 8:19:22 GMT 1
Doing a test on my engine and the testing kit I’ve got is a general automotive one with a long hose and no valve at the tip so is giving me a false reading of 70psi each side. The ones with a shorter hose and a scharder valve at the end give a more true reading apparently.
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Post by stusco on Apr 4, 2024 15:46:45 GMT 1
I have this one from performance fabrications ill look it out as he probably got it from someone else  It doesn’t have a schrader valve but is a good tool |
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Post by jessy03 on Apr 4, 2024 20:21:45 GMT 1
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Post by wallcraft on Apr 4, 2024 22:18:34 GMT 1
Cheers jessy, have you used it yet? Has it got scharders in the ends of the fittings. |
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Post by JonW on Apr 5, 2024 1:01:15 GMT 1
FWIW Personally Ive never found a compression tester that useful on a 2 stroke. If it starts easily then its got enough compression, if it doesnt then its needing a rebuild etc.
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Post by wallcraft on Apr 5, 2024 8:41:38 GMT 1
Cheers Jon, that’s pretty much my thoughts. My motor has plenty of compression by feel on the kicker, just wanted to know where I was with a reliable reading as a bench mark. There seems to be a lot of unreliable compression testers on the market so just try to make sure I can get my hands on one that’s up to the job for a two stroke.
Mark.
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Post by jessy03 on Apr 5, 2024 12:11:09 GMT 1
I’ve got 2, the one on the right is the one you want, the one on the left is shite. Both had 5-6 kicks    |
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Post by JonW on Apr 5, 2024 12:58:02 GMT 1
Your pic reminded me that I have the Gunson... somewhere in my toolboxes. hmm... I should find it, last used on a Rover V8 i think in the late 90s.
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Post by JonW on Apr 5, 2024 12:59:11 GMT 1
Cheers Jon, that’s pretty much my thoughts. My motor has plenty of compression by feel on the kicker, just wanted to know where I was with a reliable reading as a bench mark. There seems to be a lot of unreliable compression testers on the market so just try to make sure I can get my hands on one that’s up to the job for a two stroke. Mark. Fair point Mark. Always good to have reliable test equipment. |
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Post by wallcraft on Apr 5, 2024 20:34:09 GMT 1
Hi Jessy, that’s a coincidence. The one on left is pretty much identical to my Clarke one i bought from machine mart, also registering 70psi.
Bought another one today, again pretty much the same as the gunson with the scharder valve on the end. Bingo proper readings now. 135psi on both sides. Oh this is a 421 motor.
Happy now I’ve got a bench mark to work with.
Next question… any opinions on 135psi for a 421? Or am I opening a can of worms😜
Thanks gents for your input.👍
Mark.
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Post by jessy03 on Apr 5, 2024 21:07:18 GMT 1
I reckon you’ll be ok at 135 psi, my 421 is running a bit more.
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Post by davecroucher57v on Apr 5, 2024 22:34:23 GMT 1
mines at 150 psi.421 2200 miles all good.
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Post by davecroucher57v on Apr 5, 2024 22:37:33 GMT 1
blew up at 170 psi big time.
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Post by wallcraft on Apr 5, 2024 22:41:16 GMT 1
blew up at 170 psi big time. Whoops, to much of a good thing then 😠 Did you squeez the squish down to much? |
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Post by muttsnuts on Apr 5, 2024 22:59:14 GMT 1
150psi is fine so long as you use super unleaded, pushing your luck a little with normal unleaded at 150psi, 135psi you'll be fine with either fuel, once you start venturing beyond the 150/155psi you run the risk of detonation unless you start getting clever with your squish band and ignition timing etc
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