Accurate compression testing on 10mm cylinders

[NorthcentralYooper]

I'm trying to get a accurate reading on 10mm plug cylinders. I got a adapter but but readings have to be skewed. I even bored out the adapter end being it was so small. Still the same reading. Tried a diff gauge and it was within 3 psi.
Any ideas ?

 

[Frogfarmer]

My tester came with the adapter and it works just fine. Maybe your readings are actually low.

 

[mdavlee]

Husqvarna makes a tester. It's not cheap though. Surely someone else has one without the adapter.

 

[stihl saws]

Unless the shrader valve is on the bottom of your adapter your results will read low.

 

[NorthcentralYooper]

Unless the shrader valve is on the bottom of your adapter your results will read low.

Ok , I'm checking compression on a WWS 2253 and it's 135psi , I can assure you it's much higher

 

[super3]

This one works,

https://store.snapon.com/Compressio...n-Gauge-Standard-Reach-M10-x-1-0-P644048.aspx

 

[psuiewalsh]

Would be great if someone sells a similar one for $20

 

[mdavlee]

I think the oem ones is about $200. I don't care that much

 

[NorthcentralYooper]

I bought this set and will put my snap on gauge on it. Hope it works


Check out this item I found on eBay: http://pages.ebay.com/motors/link/?nav=item.view&id=261965626793&alt=web

 

[Landmark]

I just got the adaptor for my guage. I hope it works ok but sounds like it might have a problem. I know i wont spend 200 bucks for a set up so the 40.00 option might be more feasible for me.

 

[Basher]

All the compression testers with the long hoses on them will be inaccurate for small cylinder chainsaws, the piston just does not displace enough air to get the long hose filled to capacity. At the very least all the compression testers need the small engine Schrader valves on the very tip of the adapter that threads into the sparkplug hole, if the setup does not have it all of the readings will be very low.

 

[NorthcentralYooper]

All the compression testers with the long hoses on them will be inaccurate for small cylinder chainsaws, the piston just does not displace enough air to get the long hose filled to capacity. At the very least all the compression testers need the small engine Schrader valves on the very tip of the adapter that threads into the sparkplug hole, if the setup does not have it all of the readings will be very low.

Yea I noticed that kit had a longer hose maybe I can swap it out in the future for a shorter one.

 

[Tor R]

As stated over, key is to have the scrader valve as close as possible to the tip, longer hose only need a bit more pull in starter cord to get correct reading
Personally I'll just give a plug + scrader valve to a friend and get him to make an adapter to me.

 

[NorthcentralYooper]

As stated over, key is to have the scrader valve as close as possible to the tip, longer hose only need a bit more pull in starter cord to get correct reading
Personally I'll just give a plug + scrader valve to a friend and get him to make an adapter to me.

I'll post results next week when I get everything .

 

[NorthcentralYooper]

I ag

As stated over, key is to have the scrader valve as close as possible to the tip, longer hose only need a bit more pull in starter cord to get correct reading
Personally I'll just give a plug + scrader valve to a friend and get him to make an adapter to me.

I agree eventually you'll fill the volume of air in the house even for the smaller engines

 

[Landmark]

Here's a pic I took of the adapter installed.

 

[ABarrick]

All the compression testers with the long hoses on them will be inaccurate for small cylinder chainsaws, the piston just does not displace enough air to get the long hose filled to capacity. At the very least all the compression testers need the small engine Schrader valves on the very tip of the adapter that threads into the sparkplug hole, if the setup does not have it all of the readings will be very low.

This has been beat to death but the hose length is irrelevant. As long as the schrader valve is in the tip that is threaded into the plug hole, the reading will be the same with a short hose or a long hose. It will take a few more pulls but the end reading will be the same. If the valve is at the gauge, the hose length will change the readings proportionate to the the change in hose length.

The engine is an air pump. Each stroke displaces a certain volume of air. If the pressure of that volume of air in the combustion chamber is higher than the pressure in the tester hose, the schrader opens and that air moves into the hose until the pressure drops on the chamber side and the valve closes. It acts as a one way check valve. It allows air in but not back out. This repeats with every pull of the rope until the hose has been filled with pressurized air that equals the engines mechanical ability to compress air. It works on pressure differential, not volume. A longer hose just takes more cranks to fill the hose.

 

[NorthcentralYooper]

The set I bought has a designated 10mm hose with installed 10 threaded fitting however there isn't a Schrader valve on the end so it was a waste . I'm going to see if I can have a 14 mm hose with valve on tip machined down and re threaded. Not sure if it will have enough material but I'm going to find out.

 

[psuiewalsh]

Excellent please let us know. Had anyone purchased the snap on hose in the previous link? Just curious if it fits other brand quick connects?

Sent from my XT1585 using Tapatalk

 

[mdavlee]

Excellent please let us know. Had anyone purchased the snap on hose in the previous link? Just curious if it fits other brand quick connects?

Sent from my XT1585 using Tapatalk

I haven't. I thought about getting it. The oem tester only goes to 200 lbs.