Sleds won't start. Now the engine is down on compression!

[Skydog]

also, ifwere cranking it over and it never started, whats saying it wasnt washed with fuel? that would bring compression down

Yes sir!

 

[welterracer]

If there was THAT much water in the gas, it never would have run before it was shut down. Also, if the valves get stuck open, the pistons will actually HIT them, which would do one of two things;

a) eventually work the valves loose,
b) cause damage to the valves and pistons - this would be a HUGE major rebuild and would cost thousands.

My money says it had nothing to do with the valves.

For once i agree with you 100%... Im sure the valves are stainless steel and the guides are probobly brass... No way they are sticking unless you over heated the crap out of them...

 

[snowbeast]

Sorry to hear this,but my dealer stated to me less than two weeks ago,that he was getting down in the dumps lately,just because of this same problem,i asked what that was,and he stated that this year he has had way to many 4-stroke motors fail,i asked which ones,and he said both 3 cy. and 4 cyl. i was shocked by his comment,and now i am not feeling so great about my foolproof 4-stroke,now he did not go into details about the motors failure,but it sounded like they were all catastrofic failures,and that is not good news for yammi.

Snobeast where is your dealer?

Caribou Maine

 

[danq]

Thanks for the suggestions. I appreciate all of them. I'll have to check some of the details with the dealer. I'm not sure how the compression test was done. but he was giving me the before and after numbers so I assume the same method was used on different sleds.

I'm not sure yet what exactly was done to free them up. And I'm worried if they were stuck open they could be damaged.

some more background. Sleds weren't overheated. no warning lights of any kind. The only thing wrong with the sleads at the end of the trip were the hyfax were completely shot. (I just bought some fix powersport wheels for the bend in the rails before this whole thing started).

I'll keep you all posted on what we hear from yamaha. but it might be a few days before I get back.

Again thanks for the comments.

 

[danq]

Another thought on the low compression from gas washing the cyls. From the initial turn of the key you could hear there was no compression load on the starter. Its not like it had compression for a few rotations and then lost it after it didn't start. I also am in the habit of listening for the fuel pump relay before I finish the key turn. the relays were working. We even took off the gas cap and listened to fuel cycle in the tank after a few failed starting attempts.

 

[danq]

I've been happy with the dealer in the past, so I'm not really thinking it is anything intentional. I don't think they have much experience taking motors apart.. they haven't had to I guess.

 

[schmeg]

Usually valve guides are bronze inserts, hard to corrode anything that is contacting bronze. I would believe deposits left from funky gas could be a possibility. If it happened to 2 motors on the same trip using the same fuel, I would think it may not be the motors fault. The other sleds in the group if they were 2 smokers may not have suffered ill effects as long as jets weren't plugged. If it were 1 motor, I'd chaulk it up to a bad engine.

 

[bluemissile]

i never trust trail gas always put dry gas in and i carry octane boost for the places that dont sell 91 octane. do a little math and add approx the right amount of boost to get the fuel you just bought up to 91 .

 

[Philscbx]

Re: Sleds won't start. Now the engine is down on compressio

Background. We just put about 1500 miles on our sleds in the UP and wisconsin over a period of 11 days. Engines ran fine, started great, 15 mpg, used no oil.|

Parked them on the trailer.
after >>> sitting for 12 days, <<< won't start.

Something other than normal in those 12 days has something to do with it, and nothing else. If the time line is fairly accurate.

Here is the past weather for a random city I picked in Michigan showing the dates around the time this occurred.
http://wwwa.accuweather.com/forecast-cl ... 1&metric=0

In the first 2 columns for the last 2 weeks, you had extreme temperature swings.

If the Machines were covered, they were possibly subjected to a very high moisture condition, then sub freezing temps. If Humidity is 100% under the canvas, it then entered the engine as well at 100%, right up the exhaust pipe.

Including the electronics.

I still extremely dought this ---
This usually is not an issue, but you just happen to pick the perfect hour ice was present, and very likely caused this rare occurrence.

The valve only needed to be off the seat a few thousands, and not in striking distance of the piston.

But again, not 2 machines at once - something about this story is missing. Were there by chance women involved? In the bigger scheme of things?

If you retraced the hour of the day this happened,
I'd be wiling to bet a heathy sum, if the sleds were uncovered in a warm dry garage, we would not be here.

This is of course is if the valve was truly stuck open, and maybe it was before you brought them to the shop, but not when they tested compression. Flat out impossible.

They say the >>> valves were stuck open.<<<
You can't develop enough rust in this short of time for them to stick - Period. This is too far a stretch of imagination.

I'd be willing to bet once they were brought in the shop and sat till at room temp, that they fired right up. You'd have to have a photo session to prove otherwise.

With hundreds of engines apart in all ages of storage, the rings would be frozen to the cylinders first. From this same moisture intrusion. 18 months later. Not in 2 weeks.
That's that wrong colored crack used.

******* For the record **********
If the engine never rotates in the next 3 years in the condition stored, no amount of hitting piston with sledge hammer will it break loose.

The only true way to protect vitals from moisture is fill the engine with oil up to the vent cap of the valve cover. This is done for archival storage, with poor storage conditions.

It's a fact, if there's visible frost conditions outside, you will also have frost inside. Even on top of the oil level surface.
If I had a digital camera at the time, then you would see every square inch of the inside covered in frost.
It's just a normal day in the life of any motor.

It's history in 10 minutes as it warms up

.. Proof of oil additives do cause problems ..

I've only seen it happen once where a oil modifier actually did create a stuck open valve.
The modifier separated out and during the cool down and a valve open, it formed a hard coating on the stem, and could not reenter the valve guide the next time after sitting. I had to remove the coating. Gaining access from exhaust ports.

Not saying this happened to you, just saying it can.
The engine was flushed out hot, and never happened again.

This person was taking to the nearest whipping post, and That's how we found him your Honor.

****************************************

Must be bad gas or something. Since when is a 4 stroke affected by >>> "bad gas"? <<<

As stated by others as well - You never would of been able to ride them in the first place.

There's no physical way water in the fuel caused any problem with the valves - Impossible.

***********************************
>>> This is where My Money Is <<<

You would of had to hit the engines exposed with a pressure washer or steam cleaner and let them be exposed to sub weather conditions.
Including the electronics.

This is the only way one could kill 2 machines at once. Even if one drop never entered the engines.

Did You by chance do this?

************************************

>>> A quick Note on Compression Values. <<<

You could have 15 engines built the same day, and tested 6 months later and have 15 different readings. I'd be shocked if If saw much more than 165 psi. In any engine.
You could see all kinds of readings right here if we all went out and tested.

But you do need a minimum of 90 to fire.
This is the next mystery stated.
Compression is (0) ? Not in the hour tested.

If compression is 90 or above -
1. the engine will run.
2. This disproves a stuck valve, a stuck valve is (0).
And Lasybastard is on the same page.
3. You need only 3 things, Fire, Fuel, Compression.
4. This story is missing something more than Fire, or Fuel, and 2 Machines? WTH?

Testing aircraft engines, we don't use compression as a value. The prop leaves a mark.
The true test for inspection is a leak down test. It proves the problem.

99% of the problem is usually improper break in.
Piston rings never were fully seated.

>>> The oil was fine. <<<
Hopefully, and I assume no additives were ever added to the oil.

Now a recorded conference call to the shop, This I have to hear before getting out the post hole digger.

I see a new whipping post coming.

Especially if the engines had improper antifreeze, and at those sub temps were damaged.

 

[danq]

Let me try to answer some of Philscbx questions. The weather situation is interesting in my case. When we parked the sleds I'd say it was high 20's and clear. When we went to start them 12 days later it was 50's and raining. Very Humid. The sleds were stored in a covered trailer outside during that time. Probably ranged 15-40 degrees most days. No condensation in the trailer, but snow from suspension had melted off while they were stored in the trailer.

We had just finished washing the sleds, but no water got on the engines or the intake. The sponge under the panels was dry. The suspension was hosed down. A day later at the dealer it was still in the high 40's low 50's and the sleds were dry.

So if I understand your point they were never wet and below freezing..

I agree with your point on a leak down being the only measure of ring and valve performance. A low compression will still run just fine.

 

[Philscbx]

I had mine in the exact conditions and ice & snow melting while in my trailer.
I do keep the side door open a little the last few days.

I meant to go out today and warm him up a little to add to the drying process. I may just throw a small heater plugged in for the night. If it gets too late, I hate to run it. It really seems to make it's sound more obvious running in the trailer than out of it. The trailer skin acts like a $3000 boom box in a $200 car.

Thanks for those details.
I have to admit, this case is a mind blower.
Hopefully I didn't offend in translating 30+ years of chaos
into 2 minutes of realistic turmoil.

Above all, Hang in there,
We're pulling for Ya.

 

[jkenosh]

Danq, i see you live close to me What dealer did you take them to? i take mine to recreation plus in twin lakes wisc and he seems to take good care of me,

 

[gsxr]

THESE ENGINES ARE BULLETT PROOF , unless overheated or run out of oil !
Call the Yamaha rep , get him involved , your dealer is WRONG !
If there is really a problen Yamaha will take care of it because of minimum failures !

 

[SledFreak]

I think it is a gas issue and/or humidity/condesation issue. I think if it wold have been in a warm garage, they would have fired up no problem. The compression test was probably don wrong.

 

[kviper]

Juat a note, I like to take my sled out of the enclosed trailer during the winter when not gone riding. The condensation frome extreme temp swing frome night to sunney day's is extreme inside these trailer's and if nothing else it will cause a lot of water in the gas tank not to mention all other places where water is not welcome as stated above. I would think any gas engine with 180 LB of compression would not live long on the regular gas that we run in these motor's. I would get a nother opinion and have them get Yamaha involved. A good dealer will know how to get Yamaha to step up to the plate. kviper