Head Gasket Replacement

Valve clearances first.
The low compression on the ring end of things may be from stuck rings from siting over the winter.
They can be freed up with a soak of Seafoam. The can has directions.
You can also use a 50/50 mix of ATF and acetone, Diesel, or Kerosine. A tablespoon down each plug hole and let it sit for a few days.
Whatever you use be sure to start the bike up outside, and let the fire department know what you're doing so they don't roll out when the neighbors call.

Also make sure that your compression gauge is reading accurately. Test the compression on your daily-driver before messing with soaking the rings.

 

Did you do your compression test with the throttle fully open?

 

I just tested it on my car and it looks like it's reading just fine. Do I just try to run it normally with the tablespoon in each hole? How long would you run it like this before doing another compression test?

 

I did a test with it closed, waited a bit then did a test with it wide open.

 

I let the mixture soak for a few days (at least overnight), then let it idle until the smoke cloud clears. After that go for a short ride and retest compression the next day.

 

How about we start here before we go dumping Sea Foam or whatever down the cylinders? Get the valves in spec first. Then, I'd use a good healthy shot of engine fogging spray, or maybe Kroil if stuck rings are suspected.

Was the motor slightly warmed up prior to the compression test? All plugs out (TCI disconnected) and throttles wide open? Did all four cylinders give you the same reading within a couple pounds of each other?

A couple things to think about (don't start pulling things apart just yet) the reason for the compression test is a suspected head gasket leak which could be the issue but we should see uneven compression test results.

"Replacing the rings" involves a lot more than you might think, and if all the cylinders are equally soggy it is probably not the solution here;

and a bunch of tight valves will give you low compression test results.

 

Agreed. The only reason for mentioning rings was the increase in compression with oil in the cylinders.

On thing at a time though, otherwise we'll never know exactly what the culprit is.

 

Nice, might have to consider trying this next.

 

I tried a cold test and a warm test and got almost the exact same reading for each cylinder. Each between 60-65. Are there any other things that I could be missing in doing the compression test? I'm curious if I'm doing something wrong that could be giving me an inaccurate reading. I'm also starting to see why it would be odd that each of the four cylinders have a low reading.

 

I just love how the most important thing here keeps getting glossed over or flat ignored, or did I miss something? GET THE VALVE CLEARANCES IN SPEC or you are simply wasting effort. You may not have an actual problem other than some long-neglected critical maintenance. You're talking about replacing rings, which is one heck of a lot more wrench work and expen$e and you still haven't done the basics.

 

My engine valves were tight reshimmed it and motor ran great.

 

That's why valve adjustment is the very first item in the "maintenance" section of the manual. It is critically important, and a lot of other things depend on it.

 

Exactly my clearances were tight opening the valves too early.

 

I have just noticed that 750 years ago in my post lol. No wonder you had the ??????.

 

Two interpretations.

 

I understand. I was just thinking of taking a step further back to determine whether or not I did the compression test incorrectly. Someone mentioned that it was odd that each reading for every cylinder was around 60-65, so I'm wondering if there was something else that could have caused an incorrect reading. My manual wasn't super descriptive in the testing procedure. I'm not planning on tearing into the pistons right away, just a theory if that what was going on. Getting the valve clearances in check is going to be my first remedy.

 

Good plan. There are many things that can cause odd compression test results, especially if the motor has not been regularly run. Valve clearances are the most obvious. The fact that all of the cylinders are testing within 10% of each other is a good sign, and the fact that the motor runs or was running tends to lend credence to faulty testing; at 60psi it likely wouldn't have run at all. If you were getting say, 100, 100, 60, 100 then yeah, big problem. The fact that they closely match is a good sign.

My suggested course of action would be to get the valves in spec, then re-test compression and see what you get. Get ahold of a second gauge and do another test, regardless of results. Replace the valve cover gasket and the donuts on the bolts; and clean off the outside of the motor thoroughly (use mineral spirits) so you can ascertain the source of your seepage. And go from there. Get a factory service manual if you don't already have one, and leave it in the bathroom. STUDY it every day, read up on what's involved with removing/replacing the head; the intricacies of fitting new rings; etc. Learn what makes your bike tick.

If you plan to keep and actually ride this motorcycle, go through the "maintenance" section, IN ORDER, STEP BY STEP, and don't leave anything out. Don't skip a procedure because it seems daunting. If it's in the "maintenance" section, DO IT. Clean, inspect, refurbish, repair or replace anything you come across that isn't 100% serviceable. (Plan to spend some money in the process.) Once you've done that, you will have a reasonably reliable 35 year old bike. I say reasonably because, due to the age, it's gonna send you a surprise every so often to keep you on your toes no matter how thorough the recommissioning. The secret is to "pre-eliminate" as many of those surprises as possible. Here's the real key: anything you skipped over or weren't thorough enough with IS going to come back and bite you; so those shouldn't be considered surprises.

 

Makes a lot of sense, thanks for the insight. I wondered that too, it sounds like if compression is that low across the board, it should hardly run at all like you mentioned. It still definitely runs, it just doesn't run well. It bogs and has been having issues with acceleration. At first I thought it was a carb-related problem, but I've been noticing the somewhat leaky gaskets on the engine, which is where this all started.

I 100% see where you're coming from with up-keeping maintenance. I've owned it for about 4ish years now and it has about 35,000 miles. I've had to do a decent amount of repairs here and there so far. It definitely gives me it's fair share of surprises, this obviously being one of them. I actually enjoy doing maintenance and working on it, it's the troubleshooting that I struggle with sometimes.

The manual also states to have a fully charged battery and to have the headlight unplugged for the test. I guess a weak battery on an electric start can cause it to crank slower giving an inaccurate reading? Either way I'm going to read through the manual about getting the valves in check too.

 

Bogging and lack of performance are likely not directly related to gasket weepage. TIGHT VALVES ARE. Start there. There's a reason valve clearances are the very first item in the maintenance section.

 

The more maintenance you do the better you become at troubleshooting, well that's my experience anyway. Yes do the valve clearances first.