Cylinder compression bad?

[Redshirt]

79 Special.
I just bought it and took it straight to a mechanic. He did a compression test and found 2nd cyl. compression is "less than half" what it should be.

He suggested soaking it in transmission fluid for a month (I have no idea how or where... or anything). What exactly is the problem? Rings frozen from sitting?

Option 2: Rebuild.

Since I'm not a mechanic, I would need to pay the shop to get it all done. Is it worth it?

So whats a guy to do? I just sunk some cash to buy it and immediately faced with sinking more cash into it.

Does anyone have a suggestion or wisdom for this situation?

[tinman905]

Stay away from any mechanic, most don't know how to fix our bikes in a reasonable amount of time where it won't cost more than you payed for the bike.
If you can't fix these bikes for yourself you are going to spend lots of money at the shop.
If you are anything closed to handy you can usually get any help here you need to fix your problem.

[James England]

If you have no mechanical ability whatsoever, I can't help thinking that a 30 year old bike is not a wise choice for you. Unless you have a lot of money to pay other people to do things for you (as per previous response posting), every time you need it, I think you will find it a steep learning curve. I think you've probably gathered that many users of the forum have at least some mechanical experience or are willing to give it a go and learn.

The thing is, you've mentioned having to spend more money on the bike. Even if you do the repairs yourself, you will have to pay out for spare parts and, although many of these are available used, many aren't. If cash really is tight for you, I'd say you're in a no-win situation.

But.... if you can at least afford spare parts, you could always use the bike as a learning platform and get stuck in. Based on my own experience of other forum users here, everyone would be only too glad to give you all the help and advice you'd need.....

If the above is too daunting for you (and you did ask for advice/wisdom), I would sell the bike immediately and not spend any money at all on it.

PS You haven't mentioned... does the bike actually run reasonably well? Did you take it to the mechanic for a checkup rather than repairs or to get it going? If it actually runs reasonably well, why not just run it and forget the compression? I've used my bike for a year now and have every confidence in it. I've never once checked the compression. Why did you get yours checked??

[Redshirt]

Runs very rough at the low end. Keep some throttle on and things are improved.
Once you get beyond a certain rpm range it picks up power and sounds better, except for intermittent backfiring.
From things Ive read I figured it was dirty carbs after sitting for a year (my estimation) and the addition of pods (airbox removed, I dont think it was rejetted either).
I took it to the mechanic so the carbs could get taken care of. That was the day after I bought it.
The compression test was done as the mechanic thought it was warranted, after a quick evaluation.

[DAVINCI]

Geez, did the guy at least go one more step and verify if it was rings or valves that were leaking? or maybe he was just trying to get you to bite on a rebuild? sounds like he did half a compression test.

[Redshirt]

I didnt have time to ask about the details, and he isnt pressuring me to rebuild. I got the impression he thinks its more expensive than its worth, but is leaving the decission up to me.

So I should ask is he thinks its a ring or valve? Again, my impression is that he suggested soaking it and see if its a ring "stuck" (is that right terminology?).

I know the carb boots are shot (they only looked cracked to me an thought I could seal them and search for new/better ones).

Im not affraid of attempting any maintenance, however Im wary that my inexperience may cause more problems than solve. I have a service manual (Clymer) for the bike, given to me by the PO... but its suspiciously clean.

Is this nature of work excessively time consuming or so difficult that a novice shouldnt attempt it? I will read the service manual until Im blue in the face if that is what is required. Oh and bug you good folks

[Rickrod3]

79 Special.
I just bought it and took it straight to a mechanic. He did a compression test and found 2nd cyl. compression is "less than half" what it should be.

He suggested soaking it in transmission fluid for a month (I have no idea how or where... or anything). What exactly is the problem? Rings frozen from sitting?

Option 2: Rebuild.

Since I'm not a mechanic, I would need to pay the shop to get it all done. Is it worth it?

So whats a guy to do? I just sunk some cash to buy it and immediately faced with sinking more cash into it.

Does anyone have a suggestion or wisdom for this situation?

Was there a specific reason why you brought the bike to a mechanic?

Do you know more about the bikes history?

It has been my experience that when these bikes sit long enough' the rings stick to the cylinder and get stuck in the piston.
This could be your problem.
It could also be a bent valve or valve out of adjustment.
You need to make a decision weather you want to tackle this.
I would down load a manual and read through it.

The top end on these bikes can be done with the engine in the bike.
If you have the patience and persistence; the members here collectively know more about these bikes than any mechanic any where.

Good luck
Rick

[mack]

Do It Yourself

There is nothing scary or tricky about these bikes other than the torque off the line. Do all the work yourself. Take lots of pictures as you take it apart for future reference. They are extremely well designed and very simple to tear down and put back together. Even the carbs. No question is stupid, all you need to do is ask. PS Don't go near that mechanic again, especially if he makes you an offer to buy.

[Redshirt]

Bikes history as I understand it:
PO purchased bike from a short female. She informed him "it only runs good on Premium fuel". Dent in right side of tank may have been an indication it was dropped (but maybe in a garage since no other damage is apparent). PO "tried regular" one time but performance was poor so went back to premium.
Dent was pulled out and painted tank by PO.
PO bought it 3 years ago. He seemed like a casual rider, so my assessment is: year 1 ride alot. year 2 ride infrequently, year 3 let it sit in the garage.
It seems he intended on doing some of his own work, but apparently didnt find the time (clean service manual). He had his "mechanic" brother help him with some sort of work, but never specified. I dont think the guy was a bike mech.
Oil/Brake indicator is on. Brake light works.
New plug wires. Looks like new plugs, but I didnt confirm.
Gears had no problem shifting smooth even under load up to 3rd. didnt have running room to check higher gears/speed/performance.

I must look like an idiot for buying this now, but it all seemed fixable.

Thats all I know.

[slow mo]

hi red shirt

dont give up this might be an easy fix!!! and if you ask nice a local xs11 member may be able to help you out!! read all you can on the tech tips on this site first you may find they answer some of your question,s ride safe and good luck ,.,slow mo!

[tcoop]

It sound like the first thing you need to do is check and adjust the valve shim clearance (the process is in the manual). If that is good retest the compression. If one or more of the cylinders are low turn the engine over by hand until that cylinder is in the compression stroke (both valves closed) then pressurize the cylinder and listen to where the air is coming out.

1. Out the exhaust - bent or burnt Exhaust valve
2. Out the carb - bent intake valve
3. Into the crank - stuck rings or hole in the piston

Then decide if you want to tackle the problem. I'm not a mechanic and I was able to rebuild the top end (new valves at least) on my bike.

Good luck.

[foreda]

Half of what

Did he give you the actual readings? Does he even know what the readings are supposed to be?

[CatatonicBug]

I must look like an idiot for buying this now, but it all seemed fixable.

Not at all! Most of us got our bikes in similar or worse condition. The XS was my first attempt at opening a transmission on anything, and I learned a lot by doing it. As was said, these bikes are simple, and basically bulletproof. The things you've mentioned will need to be fixed, but are not impossible for the average joe. If you have a few basic tools, you can fix just about anything on your new bike. Trust yourself, take pictures, and get greasy! paying a mechanic will quickly drain your wallet, since it may not take a lot of fancy tools, but it takes a lot of time to tinker with a 30-y/o machine.

The engines were designed to run on Regular. Premium is nothing but a waste of money, unless you have a big-bore kit installed. The carb boots are double-walled, so unless they are cracked all the way through, you can re-seal them. If they ARE cracked all the way through, they WILL affect performance quite a bit with a vacuum leak.

BTW, we like pictures, so let us see your new ride!

[Redshirt]

foreda,
his words to me (paraphrased) were:
#2's compression is less than half what it's supposed to be.

I would guess he knows what it should have been, but "never assume", right?

Still disconcerting if one cylinder is woefully less than all the others.

He then went on to tell me to take the bike back and soak it in something (I thought trans fluid, but I may have remembered wrong) for about a MONTH!

I assume he was telling me to soak the cylinder somehow. I read MMO and saw on here something about Seafoam. Not sure I am armed with knowledge enough to consider those as options.

Im leary about running it at all right now. If it is a problem in the cylinder, the last thing I want to do is make it worse by riding it. I will likely borrow a trailer and drag it home. This is all based on my meager understanding of possible problems.

He did tell me that at least one boot is cracked through completely. He pointed out the boot on the second from the right carb (as you sit on the bike) as having a hole that was obvious when engine was running. I couldnt see it since I was holding the clutch on the other side. What cylinder is THAT boot to? Where did I put that manual again?

This guy is supposed to be an honest, knoweldgable mechanic, but Im struck by his lack of enthusiasm to tackle anything.

[DAVINCI]

A compression test, done correctly, will tell you all you need to know. You already know that #2 is low. Now pour a teaspoon of oil in #2 and re-test. if the compression gets better, it's a ring problem. If it does not, it's a valve problem.

A simple, basic, age-old test that any 'mechanic' that can fog a mirror should know how to do right.