Does this look and sound right? Video - Snowmobile Forum: Your #1 Snowmobile Forum

g1teg · 01-23-2013, 04:17 PM

Hi guys,

In a couple of threads so far, Ive had help putting new pistons oversized in my 97 Formula Z 583.

I had some issues with the oring, and now ive replaced both. Before putting it together, I made sure to pull and that nothing was binding, or catching, but now it sounds like something is tinging, or rattling... This morning I started it after putting it back together, and the engine was cold. Its -38 Celsius today (-36F) with windchill.

The engine is smoking a lot. I feel like too much but Im not sure after a rebuild. I know that since I had the Oring I may have some coolant leaked in, though it doesnt smell like coolant.

I have only let it run for less than a minute, and this is my first sled, so not sure if this is normal or not?

maddad · 01-23-2013, 06:17 PM

Cold will produce smoke, but thats way too much! Didn't see your other threads...did you hone the cylinder, and if so, did you get all the debirs cleaned/flushed out good? If not, youcould have scored things up inside and might have to start over.

g1teg · 01-23-2013, 11:11 PM

Yeah, this is too much I agree.

I had the cylinders bored and honed by an engine shop. I chamfered the ports myself.

As for the smoke, as long as the tinging is normal, I will let it run for a while. Im confident that the cylinders are ok, but worry that im pouring oil or coolant in while running.

How could the bad cylinders cause more smoke?

ridegreen · 01-24-2013, 05:15 AM

Did you do a 50/50 premix? You should have the oil pump wide open as well to make sure it is feeding. Did lube up the cylinders as well? It's possible coolant got into the cylinders to produce that amount of smoke. If the motor was done rite it should be sound with on kind of noise. I built a motor once and it had a knock or ting and ended up the rod broke.

IRONDOG · 01-24-2013, 07:18 AM

That knocking noise is terrible- sounds like WAY to much piston clearance. That engine has to come apart and have the clearance checked. RAVE valves could be hitting the pistons also.

g1teg · 01-24-2013, 08:46 AM

So the shop that did the engine work honed it to. 0045". I shaved the rave valves myself and checked the clearance once it was together.

Can I take the raves out and run it without them.?

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IRONDOG · 01-24-2013, 01:17 PM

You can remove the plastic caps and hold the RAVEs open manually while the engine runs to see if the noise goes away.

g1teg · 01-27-2013, 11:22 AM

OK,

So yesterday I finally got to work on this, and here is what I found. I had you guys telling me it sounded bad, but other local guys saying it sounded normal for a very cold engine.

I pulled the raves out, and it didn't make any difference. The sound seemed to be coming from the exhaust can almost like it was rattling. I added coolant mix to bring the level up, and I let it warm up.

Once warm, that sound was way more reduced. I let it cool down, added coolant to the right level and then tested the compression. I am getting 140 on the mag side and 138 on the brake side. This is with four pulls, 90 120 130 140. I repeated the test on both and got the same results.

I adjusted the idle screws, so Im idling at 1750 bang on once warm (was at 2100) and made sure that my air screws are at the nominal in the book. (2.25 turns). Plugs look brown after just a few km of riding.

Starts nice and easy when warm, a bit of a pig when cold. My start up procedure maybe needs to get sorted out better... New video.

ridegreen · 01-27-2013, 11:56 AM

So you rode it? How's the power

g1teg · 01-27-2013, 12:49 PM

well, Im no veteran when it comes to sleds, so I cant base its power against anything else, but I am surprised for a 580cc!

Im 220lbs and from a stop I can have it lift the skis for a while... Seems powerful!

I did 50/50 mix of coolant btw.

ridegreen · 01-27-2013, 01:37 PM

I know but I mean since you rebuilt it how does it feel? You think you did a good job? Is the noise still there under load? You feel it will be reliable? So on and so forth...

g1teg · 01-27-2013, 07:45 PM

Well, I didnt ride it enough before the rebuild to suggest that its any different than before, but I assume it is. the mag cylinder had only 30 psi when I bought it...

with that said, the engine shop i went to was fantastic. Measured cylinders at .0045 over pistons. which is nominal. Rings I gapped at .018" which is basically nominal. Everything was sliding well when I put it together, and aside from an Oring being pinched, I think it went back together perfectly.

I think it feels great now. since many here felt like there may be too much clearance based on the sound, is there any way to check other than by taking it apart? Does the compression test being that high rule out this issue?

360 xrt · 01-27-2013, 09:19 PM

i cant speak of 2 strokes,but with my knowlege of stock car engines and a little common sense i come up with this. i believe your problem to be piston slap. is that a bad thing on 2 strokes,i dont know. you say your premixing your fuel right now for break-in purposes i assume. i would think non-synthetic oil is being used.i can only assume once your rings seat and you switch back to injected,that your cylinder temps will rise and your piston slap should go away.goodluck.

ridegreen · 01-27-2013, 09:22 PM

There isn't any way to check other then to go back into it. High psi won't rule out anything other then good compression. Like I mention before I built a motor once before and it had a noise to it and it ended blowing a rod and wasted the whole motor.

ridegreen · 01-27-2013, 09:27 PM

Negative on that one, there would be no noise what's so ever. If there is noise on start up with a fresh rebuild then something is not right

Josh Kidner · 01-28-2013, 09:44 AM

If i didnt know any better, id say it sounds like sheet metal knocking together. Check to see if the exaust is vibrating on something? Sometimes recoils make that noise. It doesnt sound internal to me.

g1teg · 01-28-2013, 10:51 AM

I thought exhaust rattle at first as well. I have checked all of the springs, everything is tight. It does sound like maybe from inside the "can" which is under the exhaust pipe. Not sure what that is called.

Ive put pressure on a lot of different places on the exhaust trying to get of the noise, but no avail. Again, it is far reduced once it was warmed up.

I tried removing the pipe and just having the exhaust manifold, but the noise is obviously much louder overall, so its impossible to tell if that solves the noise that was the problem in the first place...

ridegreen · 01-28-2013, 11:26 AM

I personally don't hear anything out of the norm in your videos. I even put on head phones so I can really listen to it and the only thing I hear is your can had cracking sound to it witch I don't see as being abnormal. Is this your first time building a motor? If so maybe your over analyzing it cuz you want it to be so perfect.

Josh Kidner · 01-28-2013, 11:39 AM

Um dont ever run it without the pipe. You need that haha. The silencer could have a piece broke or rusted in the inside. Try it with the pipe and without the silencer (can)

g1teg · 01-28-2013, 11:55 AM

I have never rebuilt an engine, and have NO experience with 2 stroke at all. Thats why I posted the vid so people could hear and help me decide if its normal for a sled.

As for running without the pipe, I didnt go anywhere, just ran it for a minute with it off at idle.

i think i was over analyzing since i have no experience. After running saturday im confident its ok!

thanks again for all the help!