compression checking

Hi guys been a long time since I've asked anything. When checking compression should you leave the throttle wide open? I did not think that this was necessary but my buddy said this is a must thanks in advance

Yes, wide open. No choke. Engine hot. All plugs out, and make sure the spark has a path from one plug wire to the other on both coils, or disconnect the primary (small) wires on the coils. Might help to pull the lighting fuse or somehow disconnect the headlight, but not necessary if you are only doing the test briefly.

Another issue that has come up very often in the last few years is that there are some compression testers on the market that do not work. The hold-in type seems to be getting harder and harder to find. The screw-in types are usually the ones I see made incorrectly.

I'll see if I can dig up a thread.

This one from October has some tester discussion.
www.kzrider.com/forum/2-engine/606826-lo...-kz1100?limitstart=0

Here's another one from a couple years ago.
www.kzrider.com/forum/2-engine/601036-compression-numbers

Best to check the valve clearances before moving to compression. If the valves are tight you are wasting your time.

Tight valve's will cause fake carb issues also.

thanks guys
Will see if cheap harbor freight gauge works, and checking valves this weekend

I wouldn't bother with the HF compression tester. That is what I used and later found out it isn't very accurate because of the small(er) displacement size of each piston (in comparison to the hose). You need a tester with a valve in the tip of the hose.

I think I linked the tester I bought in the thread that Loudhvx linked to.

Yes, like Matt said, the HF comp tester comes up often. It reads low due to not having a check valve in the tip.

My buddy and I went to look at a Gpz 550 and the seller said the compression was 130 psi. That's incredibly low for that bike, so we brought my two hold-in testers and got 180 to 190 psi. The seller's comp tester looked like the Harbor Freight one.

Hopefully they will someday change the design of the HF tester.

Also keep in mind that regardless of how accurate the tester is what you are actually looking for is the difference between the cylinders. If they are all the same but the tester says it's a bit low you do not have a problem. A better test is a leakdown test.