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Message started by FLDoug on 02/09/15 at 15:17:44

Title: No spark and low compression
Post by FLDoug on 02/09/15 at 15:17:44

My daughter has a 1987 Savage with 11,888 miles on it. We bought it with 6,700 miles on it and to my knowledge there have been no modifications to it. We live in Ocala, FL (north central). I raced motocross in the 70s & early 80s and have a lot of experience with 2 stroke engines. I work on cars, have a lot of tools, including a multimeter, but electrical stuff is my weak area. My daughter and I replaced the plug under the head cap about 1800 miles ago and have seen no indication of leaking. The oil and filter were changed about 1500 miles ago. A different daughter needed transportation at college and took it to school. Several times she left the key in the wrong position and it killed the battery. I took and put a new battery in it about 2 weeks ago. While I was there I check the oil and it was almost 2 quarts low. There are no signs of leaking from the engine and no oil on the ground where she parks it. I put oil in it, started it and it ran fine. Last week she rode it about 70 miles and she said that a car turned short in front of her, she down shifted and then it was hard to shift up. When she did shift up, she said it made a crunching noise and quit. The battery is charged and it turns over without making any bad noises. I pulled the tank and watched the decompression solenoid and it appears to be operating correctly. I pulled the plug, it is black instead of the typical brown and it doesn't have any spark. I am looking for some guidance as to what I should be looking at next, Thanks.

Title: Re: No spark and low compression
Post by verslagen1 on 02/09/15 at 15:50:16

Quote:

she said it made a crunching noise and quit.

Doesn't sound like good news to me. Check the compression to see if you have any.

Quote:

While I was there I check the oil and it was almost 2 quarts low.

Burning oil, time for rings. leaving the choke on for too long can wash the walls causing the rings to wear out.

Quote:

I pulled the plug, it is black instead of the typical brown and it doesn't have any spark.

Probably black cause it's not sparking.
or if it is sparking, loaded with oil.

Title: Re: No spark and low compression
Post by FLDoug on 02/09/15 at 16:03:16

There's no compression - none of this sounded like good news to me either.

Title: Re: No spark and low compression
Post by Serowbot on 02/09/15 at 16:42:33

Try a squirt of oil in the plug-hole... to reestablish the ring seal... if that don't work, you're probably in trouble...

Title: Re: No spark and low compression
Post by Gary_in_NJ on 02/09/15 at 18:20:56

When she down shifted to avoid the car she may have over-revved the engine. This can result in all sorts of issues with the valve train. I would start with a proper leak-down test to determine if there is a compression problem and where it is coming from, ie air from the breather is a ring problem and air from the carb or exhaust is a valve issue.

Title: Re: No spark and low compression
Post by FLDoug on 02/09/15 at 18:56:29

I will try a shot of oil and if that doesn't get give me some compression I will try the leak down test.

Thanks fellows - I will let you know how it goes.

Title: Re: No spark and low compression
Post by verslagen1 on 02/09/15 at 19:08:24

3B282D3A2C2C5F0 wrote:

There's no compression - none of this sounded like good news to me either.

I'm afraid she's probably dropped a valve.
you can take off the header and the carb to see the valves.
one missing or bent is bad news.

Title: Re: No spark and low compression
Post by FLDoug on 02/09/15 at 19:22:06

I will try to pull them tomorrow to see what it looks like. I will let you know what I find out.

Thanks for responding.

Title: Re: No spark and low compression
Post by justin_o_guy2 on 02/09/15 at 21:45:27

Hmmmm, 2 quarts low, crunching noises.. Sounds fatal,But,

Before you pull the plug,clean out the cavity it is in.
Then you can see if it's gonna live.
If you have to buy a can of air or Berrymans you can blast around the plug, pull it, add oil, pull the oil fill plug, blast into the cylinder, and if you feel it come out of the oil fill hole,the piston is not okay.

2quarts, that's pretty much all there is... just good she was not running highway speeds and sieze up. Could have been a lot worse than messing up a motor. Congratulations, you can hug your undamaged daughter and laugh about it.
SERIOUS learning moment. She got away with it. Anyone who has really run 2 stroke dirt bikes Knows about keeping a finger on the clutch, just in case it locks up, rarely do the daughters know that. Oil levels are critical, not just because of the small amount of lost oil that will ruin an engine, but also because a locked up engine equals a locked up rear wheel if it is in gear and the rider doesn't know to grab the clutch,, ugliness ensues.

Title: Re: No spark and low compression
Post by FLDoug on 02/10/15 at 14:20:15

At lunch time today I put some oil down the spark plug hole and then put my finger over the hole as I turned it over. I didn't feel any compression. I pulled the header off and watched the exhaust valves as I turned it over - they seemed to work properly, and there was a big puff of air that came out on every rotation. I checked the plug hole again, and nothing. I will try to pull the carb tonight and look at the intake valves.

Title: Re: No spark and low compression
Post by Dave on 02/10/15 at 14:30:31

544742554343300 wrote:

What is the compression release doing while you are turning the engine over? If you have not disabled the automatic compression release before you hit the starter button (remove the small cable).....you most likely will not feel any compression at the spark plug hole.

Title: Re: No spark and low compression
Post by Gary_in_NJ on 02/10/15 at 18:27:41

Good point Dave. Also, if you do use a compression tester make sure the throttle is at WOT. Like I mentioned above, a leak down test (aka differential compression test) is the proper diagnostic tool.

Title: Re: No spark and low compression
Post by FLDoug on 02/10/15 at 18:51:10

Fellows I really appreciate all of your input. I disconnected the decompression cable and I still didn't have any compression at the spark plug hole. It did still push a lot of air out the exhaust. I removed the carb and looked at the intake valves. They are there (which is a start) and they appear to function ok when I turn the motor over.

I will try to get some air tomorrow and try both Justin's air test for the piston and Gary's leak down test.

Thanks again guys - I will keep you posted.

Title: Re: No spark and low compression
Post by verslagen1 on 02/10/15 at 19:09:42

if you have a borescope, might help to look down there.

Title: Re: No spark and low compression
Post by Dave on 02/11/15 at 05:34:05

The ball and roller bearings on this bike are pretty durable, and do survive the low oil issues better than a few other parts. The piston/cylinder being one area - the cam/rockers are the other.

Since the engine made a crunch and stopped....and now apparently has no compression, I would suspect the piston/cylinder may have become damaged. It does seem a bit weird that this would have become terminal a while after the low oil issue, and the bike did run after you installed the oil.....I can't explain that one.....or why downshifting might have broken something (unless she just overevved the engine and floated the valves and bent them...which doesn't seem likely).

This one is just going to take some investigation to see what is wrong.

Title: Re: No spark and low compression
Post by FLDoug on 02/11/15 at 10:46:48

Yikes! Dave you are correct. At lunch time I put the spark plug back in to try a test - something hit the plug and completely closed the gap on the plug. I will start to pull it apart tonight. Does anyone know if you can pull the head on an 87 in frame? Or is it easier to pull the engine and then work on it?

Thanks

Title: Re: No spark and low compression
Post by Gary_in_NJ on 02/11/15 at 12:06:49

Yeah, that sounds expensive.

You're gonna have to pull the engine for the removal of the head and cylinder. If you remove the engine mount bolts you might be able to move the engine around enough...but at that point you might as well remove it.

Start looking around for a used engine. Not that you have to, but based on the damage it might be more economical to just do an engine swap.

Title: Re: No spark and low compression
Post by FLDoug on 02/12/15 at 10:52:42

I pulled the head cap today - it sucked an exhaust valve and the cam and cam bearing on one side are scored plus whatever the valve did to the piston.

Not the news I was hoping to report.

Title: Re: No spark and low compression
Post by Dave on 02/12/15 at 11:41:18

No, that is not good. Used cylinder heads go for $ 250 - $ 300, used cylinders and piston sets that are serviceable are in the $ 100 range for low mileage ones, gasket sets and seals and miscellaneous parts another $ 100. Good used engines are in the $ 500 - $ 800 range....depends on how good of a deal you can find.

Man.....what a bummer. :'(

Title: Re: No spark and low compression
Post by FLDoug on 02/12/15 at 13:36:25

Thanks Dave for giving me an idea on prices. Not knowing what other damage is done, I think I will go engine shopping.

Title: Re: No spark and low compression
Post by Gary_in_NJ on 02/12/15 at 13:50:53

322124332525560 wrote:

Thanks Dave for giving me an idea on prices. Not knowing what other damage is done, I think I will go engine shopping.

It might actually be more cost effective to go bike shopping. Ratty bikes that have been parked outside can be had for $500. A little clean up and you have yourself a nice parts bike.

Title: Re: No spark and low compression
Post by Dave on 02/12/15 at 14:16:35

Gary is correct...watch Craigslist for ratty bikes, salvage bikes, crash bikes, etc. You might even put a "wanted" add for a project bike and see what comes your way. A parts bike might even get you a good rectifier, ignition module, turn signals, etc. to keep as spares.

Title: Re: No spark and low compression
Post by FLDoug on 02/12/15 at 14:40:09

Thanks Gary and Dave.

That's a great idea to shop for a "project" bike.