Black Streaks On Piston Skirts

[grhonk]

1997 xp: took it in with starting problems .. dealership takes off the raves and points a pin-flashlight down the slot where the raves were and points out black streaks on the sides of the pistons. Does this indicate an engine rebuild, even if the dealership reports good compression?

With such an old craft, does anyone think the oil hoses need replacing, since I pulled the engine anyway? If so, must these hoses come from oem?

 

[Sportster-2001-951C-Stock]

3/32 id tygon tubing, same as used for weedeater type engine fuel line. Good idea to put new on ther if they're old, hopefully yours are broken yet 'cause that can cause oil starvation.

If compression is good, then just using good quality oil should help it clean out. Try XPS-II

I guess this is an rotary valve engine, so you have to get all the air out of rotary valve gear housing you know, the correct way. (I'm not familiar with those details)

"Black streaks" doesn't mean piston skirt scoring although it could, and the ring lands could fill with gum and cause the rings to snag in the cylinder ports due to gum/carbon deposits. Sounds more like gum formation issues you're describing, so I wonder about which oil has been running through it, should not be TCW-3, that would explain it.

The good news is, the XPS-II synthetic will probably clean the gum stains off the skirts and in the ring lands over a season of use, so I'd recommend running that going forward, synthetics clean really well and they don't decompose and leave deposits like cheaper mineral oils tend to. There are other equivalents out there as well, but many of them are more expensive.

Still, an engine that's got high hours on it could go at any time, so you might find yourself yanking it out again.

I'd put new oil lines on it and just run the BPS synthetic, as an experiment to see if it cleans it up(I think it will), unless you're already running good oil, then you just have to hope it doesn't finally snag a ring.

That's my take......

 

[news]

It seems to be water marks or the engine was locked up once! Maybe the motor runs without oil?

 

[AdamXP800]

The motor would not run long without oil. It would cause catastrophic damage within a very short time period

 

[news]

i know!!!! oil failure for a short time is not catastrofic for the engine.! major failure from oil pump locked up engine verry bad! if there some water in the motor for several kind of reason you get black marks on youre pistons. sorry that i replay in this forum if you think i am a idiot!!

 

[AdamXP800]

Ok your post makes no sense to me. Why would you remove the engine for a hard start issue? And the dealership reports "good" compression. Do you know the actual numbers?

 

[news]

i dont know the numbers do you?
i thought this forum was for enthousiast.! i dont know were you up to! if you are so good in this..............! i repair this ski s for 15 years i know the issues . if every one was as good as you this forum never exist. i just want to help.........!

 

[AdamXP800]

Ok, you make 0 sense. I'm not sure what side of the bed you got up on, but no one was talking about your mechanic skills. This forum is for people to help each other out, not to start drama. So if you don't have input to benefit the OP then back off and don't start shi*. All I stated was an engine without oil will not run long at all. If your skis will run without oil ill buy them, how much?

 

[RodInEscondido]

Wow!!! Testy, testy!

I see 97gtxman1687's comments as, like most people on this forum, an attempt to help.

Of course I am out here in California so maybe see things differently.

Rod

 

[grhonk]

Ok. I take all the blame on this one. I should have stated that my daughter swamped this engine twice. I would like to hear from both of you .. I am too new at two-stroke and your opinions are valuable to me.

I will attempt to upload some pix I took today, but this site is hard to navigate around in, at least for me. Does anyone know how to upload pix? Do I have to be a super-duper member to upload? It keeps giving me an error when I try to upload a 800kbyte jpg file. Anyone got any clues? I'm clueless.

Does anyone know what this error message means?

404 [IOErrorEvent type="ioerror" bubbles=false cnacelable=false eventPhase=2 text="Error #2038"]

 

[AdamXP800]

You came to the right forum for help. There are plenty of pros on here with wayyyyy more knowledge than myself. I'm sure they will chum in and get you pointed in the right direction.

When the ski was swamped, were you able to remove the plugs to remove the water and then get it running again?

 

[grhonk]

yes. both times. The first time was the same day .. second time was a day after. I ran my finger over the pistons and they have vertical grooves in them. Engine turns over by hand with ease.

 

[Sportster-2001-951C-Stock]

Okay, so you're saying the pistons are scored but the compression is still good. That's believable, it tells me the cylinder walls and rings are still in reasonable condition.

 

[grhonk]

So, how do the pistons get scored w/o touching the cylinder walls?

 

[Sportster-2001-951C-Stock]

Just because the soft aluminum pistons are scored doesn't mean the harder iron sleeves necessarily will be. The fact that the compression remains normal means the rings are sealing well to the cylinders, thus they are not worn out, have not lost their tension due to excessive heating, and the ring lands most likely are not worn out or damaged, either.

 

[grhonk]

So, it's back to the original question, "Why does a 97 xp have trouble starting?" And this is after the dealer cleaned the carburetor and replaced all the fuel lines.

 

[RodInEscondido]

Ok. I take all the blame on this one. I should have stated that my daughter swamped this engine twice. I would like to hear from both of you .. I am too new at two-stroke and your opinions are valuable to me.

I will attempt to upload some pix I took today, but this site is hard to navigate around in, at least for me. Does anyone know how to upload pix? Do I have to be a super-duper member to upload? It keeps giving me an error when I try to upload a 800kbyte jpg file. Anyone got any clues? I'm clueless.

Does anyone know what this error message means?

404 [IOErrorEvent type="ioerror" bubbles=false cnacelable=false eventPhase=2 text="Error #2038"]

re uploads
800 kb file should be small enough; I have uploaded up to 1.6mb w/o problems

When creating a response or whatever, click the "go advanced" box, then the "manage attachments" box

It takes a little practice on the site, but the moderators are very patient.

Rod

 

[bigJake]

So, it's back to the original question, "Why does a 97 xp have trouble starting?" And this is after the dealer cleaned the carburetor and replaced all the fuel lines.

loose connection, bad ground wire, weak battery, bad start button, starter going bad, solenoid going bad, mpem post going bad, fouled spark plugs, old gas, , dirty carbs, air leak, The list is endless. Lots of things can cause hard starting. Does it crank but not start? does it not crank at all? have you had the battery load tested? does it crank if you put a screwdriver across the solenoid terminals?

 

[grhonk]

ok .. I have added attachments ...

why doesn't the icon "insert image" work?

 

[grhonk]

yes it cranks for ~2 minutes before it kicks over. If I add fuel to the intake it seems to want to start instantly. Dealer says it is because of a scratched rotary plate.

 

[AdamXP800]

Can you get a compression reading on the motor and report back the numbers?

 

[AdamXP800]

I see signs of rust. If there is rust up top, it's very likely there is rust in the bottom end as well.

 

[Sportster-2001-951C-Stock]

Yep, that's quite a testament to prove how an engine can swallow a great deal of water and keep on running. I'm quite impressed nothing was bent or broken and that it was still running with 150psi in both holes, no less. Makes me wonder how it would've looked if the cylinder walls were nickel plated...

 

[grhonk]

I need to get a real compression tester. My neighbor came over today with a hand held and read 135 psi. He noticed one of the pistons in looser than the other .. might account for the black streaks on the skirt. Wrist pins? Don't know yet.

The manual says you need to get to the counter shaft soon after the flood. It states to drain the 30 weight oil and replenish it with an ounce of fresh 30 wt. Unfortunately, I have not done any of that and the flooding has occurred in 2011 and 2012. Oh well, I am learning a lot.

Ok. I need a new top end and maybe some bottom end work as well. Can anyone comment on what the dealer is saying about hard starting caused by the scarred up rotary plate?

 

[Sportster-2001-951C-Stock]

Considering that those are very reliable skis(when in good condition), and it appears you're facing a decision of whether to rebuild what you have or obtain a remanufactured engine, then if it were me, I would opt for the latter at this point.

You might have been able to overcome a rotary valve issue by obtaining a machined cover to restore clearance and thus reduce the intake cross talk between cylinders but my guess is you probably have corrosion in the lower end likely to cause a rather quick failure once the reciprocating assembly begins rotating.

There can be other reasons for hard starting besides just a worn RV valve, such as a miscalibrated carburetor or less likely, some kind of an ignition problem.

Might take a close look at the condition of the jet pump and see if it's going to need a great deal of work as well, and consider the overall condition of the ski.