Compression Test

[OldNTired]

Originally Posted by Way

I just wasn't sure what you were addressing as far as the compression test was concerned and just wanted to know your opinion. Thanks!

I was thinking to try one last time using mrlmd1's suggestion but I'm wondering if it's worth the mess versus just taking the head off and knowing what I'm dealing with for sure.

Regarding this:

Do you mean to take out all the other bolts first and then tilt the cover so I can remove the top bolt? Or do you mean that all the other bolts come out all the way but the top bolt can only be unscrewed so far but never comes completely out while on the bike? In other words, I can remove all the bolts except the top one, but can loosen it enough to slide the cover off sideways..

Sorry for the questions, it may be that you're not the one who's dumb.. :tongue:

No need for apologies, I should have explained why.
Your first guess was the right one. You can loosen that bolt all the way, but there is just not enough room between the head cover and the frame to pull the bolt out. I removed all bolts except that one, then lifted it just enough to lift it out of the head, then tilted the head cover while I removed the bolt. I also, when removing the head cover, used a couple plastic ties to keep the wiring harness out of the way as much as possible.

[Way]

You know it's funny... I've been a collector of tools all my life and I had to look around for my compression tester. I totally forgot that I have an oil suction gun I bought a long time ago - never used it. :roll: Looks like this, except in chrome:



If this doesn't work, nothing will.

Don't know about the scope though it would be nice.

On a side note, I compared the threads on my tester to those on the spark plug but it seems the tester is very slightly thicker diameter. I used it in a Geo Metro engine last so I know it's a metric thread. I suppose I have to buy an adapter but I guess it's cheaper than a head gasket at this point.

[jonathan180iq]

Ahhhhh, Geo Metros...... Probably the best car ever made. I'm totally not joking. I've owned two of them.

[Way]

Haha, I know exactly what you mean... I've got 4 of them. :2tup:

One is my daily driver, 1 is a maybe fixer-upper to sell, one is on its last legs as a winter beater and the last is a parts car with 25K miles on the odometer. Hopefully I'll be driving my Geo for a long, long time.

Well the oil trick turned up nothing. I'm not sure whether I should bother with the compression test as I don't have the proper adapters anyway. What I have only fits 2 sizes and neither is the correct one for the bike. I suppose I could take the old plug, hollow it out and clamp a piece of tubing between it and the tester fitting. I don't know whether it can hold up to 145+/- psi though. It would give me a little bit of an idea as to the condition of the motor before I take the head off though.

Do you all think it would do much damage if I were to do a compression test if there was still a piece from the eraser in there? I almost don't think anything is left in there but without scoping it, I can't be 100 % sure.

[Water Warrior 2]

If you only have a small piece of pencil lead and not any other stuff in there you might get away with a compression test and suffer little or likely no damage. The lead is soft enough to turn to powder in time etc. That is just my opinion of course so don't say I told you to do it. You should have a proper tool for the test though. A rigged up old plug would be real iffy at best. Try your local auto parts store for adapters. Take in the plug so they can compare the threads.

[Way]

These dang computers .. :skeptical:

I had tried to post yesterday and lost my original post due to timeout. In the original post, I explained that I had gone to 3 different parts places and no one had any adapters that would fit. They did have compression testers though with all the necessary adapters but then that's $40 on top of the tester I already have. Sorry about that, I thought I had explained it already. Well I did, but no one read it... :lol:

Anyway to make a long story short, If anyone is considering it, buy a compression test kit that has multiple adapters so that you can test any size engine. In the long run it will save money.

[Water Warrior 2]

Suggestion for you. Take a plug down to a tool rental place and see if they have a compression tester that will fit /match the plug threads. Asking is free.

[mrlmd1]

Don't they have a big rubber plug that jams into the spark plug opening, for sort of a universal fitting?

[alantf]

Originally Posted by mrlmd1

Don't they have a big rubber plug that jams into the spark plug opening, for sort of a universal fitting?

That's what the last one I used (a few years ago) had.

[Way]

WW, thanks. Nearest rental is 20 miles (32 km) away. By the time all's said and done, I'd probably be better off just buying another tester...

Mrlmd1, yep some of them do. I bought the thread-in kind because I usually work by myself and it's easier to just thread a tester in and keep my hands free. Can't remember where I bought it, but I know now I should have bought one with plenty of adapters instead of just thinking of the job at hand.
I tried to use a cone washer that is usually used in faucet repairs with the same principle in mind but between trying to hold the tester in with one hand and reaching over to press the starter button, I could not hold it on long enough- kept blowing off at about 85 psi which I hope means I have plenty of compression.

I believe I have rigged up an adequate solution, but will have to wait till tomorrow if it's not raining. I bought a nylon hose connector with a barbed section on one side and a threaded section on the other, an M12 die and a small bit of high pressure 3/8 (9.5mm) fuel line and 2 hose clamps. I threaded the fuel line onto the connector, tapped the end so I can screw it into the spark plug hole and threaded the other end onto the compressor fitting. Seems to be pretty tight, hopefully will hold up. I really am anxious to get the test done so I can see what I'm dealing with.