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Message started by DanClarke on 04/13/09 at 01:19:06

Title: Interference engine?
Post by DanClarke on 04/13/09 at 01:19:06

Hi,

New guy here. Bought a 24000 mile '98 Savage not running. I'm in central CA on the coast.

I'm intending to make a trike out of it, a local run about for riding to the store, etc.

I've got an exploded view but no manual and will pull the right cover to answer my questions, but can't get to it for several weeks so I thought I'd ask here for now.

By pushing it in gear, the motor turns free part revolution, then comes hard against something.

Feels so solid I'm thinking maybe the counterbalance drive broke and the crank is hitting it.

Just trying to rule things out by asking if the timing chain came off would the piston hit valves?

I tried searching the older posts but didn't come up with anything.

Thanks,
Dan

Title: Re: Interference engine?
Post by DanClarke on 04/13/09 at 01:39:02

Correction: This is an '89 not a '98, if it matters.

Dan

Title: Re: Interference engine?
Post by marshall13 on 04/13/09 at 02:00:07

if you check through the cam-chain tensioner threads, you will find a pic that answers your question... really 2, the valve head shaped crater on the edge of the piston crown, with a sizable crack radiating from it down the skirt, and the combustion chamber side of the head, with the broken off valve head imbedded..... i'd say this motor is the poster child for "interference engines".....

Title: Re: Interference engine?
Post by Oldfeller on 04/13/09 at 02:02:49

Piston won't ever hit the valves, something else is hitting.

You are going to have to tear it down to find out what is going on.

Get a Clymers manual (you need a basic how to manual) and read the applicable posts here on the list for tearing down the top end -- the tips will save you some broken/stripped fasteners and some wasted time "doing it over".

Title: Re: Interference engine?
Post by DanClarke on 04/13/09 at 10:52:10

I'll get a manual before I tear very far into it.

From the exploded view I have, it looks like if I pull the right cover off I can see the cam chain and tensioner etc. to tell if it's got something broken.

It looks like the end of the counterbalance shaft can be observed too which can confirm if the counterbalance gears are working right.

As I said, it'll be weeks before I can be able to have a clear place to do much work on it. Just trying to eliminats possibilities beforehand.

I guess it might be the rod broken, but it feels like when pushing it in gear that the piston is doing something.

Title: Re: Interference engine?
Post by srinath on 04/13/09 at 10:57:01

Its hitting the compression cycle.
A single has a compression release for a reason.
You should be able to struggle with it and get it to roll with the spark plug removed. If that dont work, its prolly dead from a broken something.
Cool.
Srinath.

Title: Re: Interference engine?
Post by verslagen1 on 04/13/09 at 11:21:42

Srinath has the right question... did you remove the sparkplug?

The tech section has a cam chain adjuster check that should help you thru removing the clutch cover and seeing what's up with that side.

At 24k, it likely a cam chain problem, but not only thing.

can be counter balencer as you've said and it can be the starter too. Prior to '95 when the engine shuts down it can run backwards. This engages the 1way clutch of the starter. If it jams it can break teeth or the starter mounts.

I've only heard of the counter balencer breaking a couple of times.

If it is a cam chain problem, the piston will strike the valves.

Title: Re: Interference engine?
Post by cscootd on 04/13/09 at 15:58:27

I guess it is my turn to jump in. Been watching here for a few months now.
With the wealth of info on here I did not think I would have anything to add anywhere. I might have an answer to this question
Bought a 95 with a blowed motor. It had Dropped a valve and ruined the head. I think I can still save the cylinder.
I had the same problem with this motor. It would do about 340 degree turn and stop solid either direction.
Had to split the cases anyway to do a good cleaning and found the reason.
The balancer has a key in it to locate the timing gears. from looking at it, it appeared to look good. This key had sheared. Took it apart and made a new key. Put the balancer in an now it turns free without hitting. The total movement of the gear was ?? about 1/32 shift ??
So what I think happened is the motor was at full speed when the valve broke and the sudden stop (lock-up) is what made the key fail
From what I can see there is no other damage internally other than where the the balance shaft an crank had hit. Slight dent in both.
Glad I was not the one riding when this happened
Now that I have started. Hope I can still help out now and then.

Love this site
Cscootd
Dave L
Columbus, Ohio
a couple of Cushman scooters - couple of HDs
Had a savage - sold it to a freind. Got to thinking (Bad Thing)
Missed haveing it. Found this 95. Not going to sell this one.

Title: Re: Interference engine?
Post by DanClarke on 04/13/09 at 20:11:01

Couldn't stand the suspense.

I removed the pipe and peg and the right cover.

The case, behind the chain just in the neighborhood of the tensioner, shows wear from a timing chain flailing quite a bit.

The chain that's in there looks new, even on the side that faces the case as viewed with an inspection mirror. Blue sealer on the gasket gives away the fact that someone has been inside, probably replacing the chain and tensioner.

The crank turns about 340 degrees between definite mechanical limits. A clunk.

There's also a ratcheting sound, when turning the crank backwards, coming from the starter area.

As heard through a mechanics stethoscope, the clunk is most audible coming from the crank itself. Less at the counterbalance shaft, and hardly at the cylinder top.

Bottom line, I'll need to get a manual, and it'll be some weeks till I can make room on the bench for it to come apart.

I'll report back.

Thanks,
Dan

Title: Re: Interference engine?
Post by verslagen1 on 04/13/09 at 20:29:20

Look at the front shaft, does it turn with the crank? (thank scoot for your input)

you can take the head cover off with it still in the frame. takes some doing, but possible (most of the time). then check to see if they timed the cam to the crank right. put the crank on TDC of the compression stroke it you can before you take the cover off. The bolts aren't preloaded then. There's a pic of the head cover that shows all the bolts to be removed, some are hard to find. If it don't come off, come back and ask.

Title: Re: Interference engine?
Post by DanClarke on 04/13/09 at 22:18:51

Front shaft does turn with crank. Tried with a wrench on each to see if there were any play or relative movement between the two but not sure.

Since someones already been messing with it, I think I'll wait till I can get it out of the frame and take it all apart on the bench to be sure.

Dan

Title: Re: Interference engine?
Post by verslagen1 on 04/13/09 at 22:39:08

certainly easier on the bench.
I found the lay down method for getting the engine out of the frame the easiest.
lay a pad down on the lawn. lay the bike on the pad. wiggle the engine until it's loose. tip it up, pick it up and set it on the bench. Take as much crap off as you can.

Title: Re: Interference engine?
Post by cscootd on 04/14/09 at 02:29:13

When mine was still together the Gear timing marks were still in time

The shaft had sheared the key and the shaft moved not the gear. Had to take it in to work and use a press to seperate the two

CscootD