TOPIC:

A common compression test error is not opening the throttle wide open. If you leave them closed it is like trying to pull air through a straw with your finger over the end of it. You will get low readings. Make sure the throttle is wide open when you test.

Most cars will require the type with a hose nowadays.

I only use this type with the Kz. You can just make out the valve stem in the very tip in this photo. These were called "hold in" compression testers. These are pretty inexpensive, which is nice, but some of them are leaky. Make sure the gauge holds pressure. If not you can sometimes you can re-seal the threads with thread tape etc. I had one that leaked due to a cracked fitting, but I was able to solder it. Tools don't seem to be made like they used to.

I would say you do not have sticky rings as you have been running fine up until now, i assume you done the compression test cold and that will explain lowish readings, engine needs to be up to temperature and spun up on the starter to get the correct readings make sure all plugs are out, but in the interim check valve clearances and that the spark plug is sealing correctly as these can blow by when they have been over tightened, as this also happened suddenly and looks like it's running fine on 3 cylinders check your ignition system paying particular attention to coils as you can drop a cylinder when coils start playing up, also check you have a good 12v at the coils when the ignition is on, can i assume you have a good battery and it's charging fine if not the bike will stop running. these are just a few things to check before you think of pulling the motor apart.

ajsfirehawk:
I had the throttle open all the way. I forgot the first round of testing then remembered and had to redo it.

Loudhvx:
I can't find the receipt for the tester, so I guess I'll be keeping this as well.

Kevski:
the compression test was cold, the plugs were removed and I used the starter. When I took the coils off one of the wires, not spark plug wires the green connecting wire, going to one wasn't attached. I forget if it wasn't attached before or after I messed with it though.

I need to adjust the valves anyway so I'm going to do that, but I also have a bolt that broke off in the head that I need to take care of, and my head gasket looks like it is starting to leak as well. I may just pull the head anyway to get that bolt taken care of and a new head gasket.

loudhvx wrote: Most cars will require the type with a hose nowadays.

I only use this type with the Kz. You can just make out the valve stem in the very tip in this photo. These were called "hold in" compression testers. These are pretty inexpensive, which is nice, but some of them are leaky. Make sure the gauge holds pressure. If not you can sometimes you can re-seal the threads with thread tape etc. I had one that leaked due to a cracked fitting, but I was able to solder it. Tools don't seem to be made like they used to.

This is the same tester I've been using for a while and can be had for only 13 bucks at Farm and Fleet if you have one around. Could do a double check with it.

I think I will adjust the valves, and fix the connection at the coil. Put it together, see if it starts and/or runs. Then do another compression test with the hold in compression tester.

Is this the right tool to remove the valve guide seals?



www.eastwood.com/rockwood-valve-seal-rem...aktvKCRoCpCAQAvD_BwE

Thanks, Matt

Yes, it is.
For removing and installing the new ones

I too have the Harbor Freight compression tester and I question it's accuracy too. Very similar #'s as with Matt ?

I like to purchase another tester and am looking for one like loudhvx. Does anyone have a source where one of these "hold in " testers ?

No eBay APP ID and/or Cert ID defined in Kunena configurationI just did a brief search and it's really getting hard to just buy a simple cheap compression tester. Everyone wants you to buy a whole kit and pay for a bunch of stuff you might never use.

These things were dirt cheap and littered every garage back in the day. As long as you can get good access to the plugs, like on a KZ, these testers are way faster to use so the engine temp is more consistent as you do 4 cylinders. Being smaller means it takes less crank revolutions to fill the test volume. If the tester volume is doubled, it will take twice as many revolutions to pressurize the tester. A smaller tester is easier on the battery and starter. The only real complaint is that it takes effort to hold the tester in place ... probably about 30 to 50 pounds, but with everyone getting heavier, it shouldn't be a problem nowadays .

I searched Actron CP7821 and it seems mostly unavailable at reasonable prices.

I would avoid used ones since they can be leaky and the rubber tips do get worn out. Ebay does have the rubber tip replacements from china cheap. But even the fittings can crack or leak. Usually the gauge, which seems like it would be the most fragile part, is the most reliable part. It's the fittings and tip that leak. You can usually replace the valve with a standard schrader valve from any bicycle shop.

Here's one on ebay for $30, but it's about twice what you should pay.



At least Actron still has them available, but when you buy singles from a manufacturer, you pay a lot.
$49 is way too much.
actron.com/content/stem-compression-kit

Wow I see what you mean Loud...... picked mine up for 13 bucks at F and F but that was in 2013........... Farm and fleet don't list em on the site ..... will check in the store but not till mid next week ..... did find it at tool source .com for 15.95 but gotta add shipping and 22.95 at Jegs....... JB tool sales has a Performance tool stem tester for 12.80 but don't know the reputation of the store or tester.

KZB2 650 wrote: Wow I see what you mean Loud...... picked mine up for 13 bucks at F and F but that was in 2013........... Farm and fleet don't list em on the site ..... will check in the store but not till mid next week ..... did find it at tool source .com for 15.95 but gotta add shipping and 22.95 at Jegs....... JB tool sales has a Performance tool stem tester for 12.80 but don't know the reputation of the store or tester.

Nice job finding those. Looks like about $25 shipped is about the best. That's not actually too bad.
I was assuming a cheap knockoff from China would be easily available, but haven't really found that.