MM Low Compression during break-in?

sagerider

sagerider

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Feb 7, 2009
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Two mountain max's, an 00 and 01. 00 new rings, 01 complete new top end - done, both done by a sled mech. Compression on 00 (stock) after 50 miles breakin is around 100 each cyl. Compression on 01 (piped) after 136 miles breakin is around 105 each.

Warmed sleds up, then pulled all plugs and tested each cyl with WOT and three good pulls.

Is this normal? I know guages can vary... shouldn't the rings have seated by now?
 

I'd compare it with another gauge before jumping to conclusions. I usually pull until the compression stops raising.
 
suva57 said:
I'd compare it with another gauge before jumping to conclusions. I usually pull until the compression stops raising.
Click to expand...

I usually pull until it stops raising too... just usually seems to be the second or third. I'll go back and do it again, and maybe run down to a shop tomorrow and borrow someone else's guage as well.

Thing is, just used it yesterday on a 600 twin and it was showing like 115 on his and the engine is ??? old.
 
possibly not seated yet, are you useing synthetic oil? how did you break it in like a granny or drive it like you stole it?
 
no1chevyboy said:
possibly not seated yet, are you useing synthetic oil? how did you break it in like a granny or drive it like you stole it?
Click to expand...

OIL: Yamalube.

Breakin: Well I was preplexed. I searched all over here and snowest for breakin procedures. Seemed to be as many opinions as dudes writing them. If there was any concensus it seemed to be on the easier side. Same with the manual. Same advice from the mechanic. He heat cycled them both, in the shop, a few times. The piped 01 several times. I trail rode pretty mellow, a lot of throttle/rev/speed changes. First 5 or 10 miles stopped a lot, checking plugs, coolant, oil reservoir etc... all looked fine. I started riding more normal (still lots of rev changes throughout) minus big hard pulls in deep snow. Around a hundred miles I went up top, snow was pretty set up, so no real hard pulls, still a lot of throttle control. Did a little playing, nothing too excessive. Some short bursts of WFO, but only a second or two, or three.

The OO with 50 miles, trails only except the 11 year old kid rode it the last 10 or 15 miles and was playing some in some pretty set up snow.

I wouldn't call it granny... but far from WFO.
 
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So what? Time to start hammering them? Ride 'em like I stole 'em?

With 130 miles plus on the 01, I'm about to pull my hair out if I can't let them pipes breathe!
 
I would out that thing to the bar!!! That'll seat those rings. The longer you go without seating the more likely your going to have to re-ring it and start over. Besides, it's no fun just puttin around!
 
drive it like your going to drive, giver in my opinion thats the way you should break them in.the heat cycles thing i dont think does much good on seasoned parts, but on all fresh brand new everything bearings,cylinders,pistons,rings,crank,rods,block, then its ok, the baby it way, like the manufacture tells you is an *** cover, you would see it if you tore down a motor that was babyed from day one, terrible blow bye,on a two stroke motor its all needle and ball bearings they dont breakin if there bad they fail,(if you change a bearing be it a wheel bearing on a car or a bearing in a machine do you break that in? LOL) the only real thing you are breaking in are the pistons thrust faces and rings, on a cast cylinder, once you have worn the high points down from honing you are pretty much done, so if you babyed it the hole time and then give it, the stress and pressures are not the same, and areas that were held apart many now touch, and will slide instead of size together like they should, and rings that were running with low pressure now can no longer wear to size, now on nikisil cylinders, the cylinder doesnt wear any were near as much, and the rings they must wear to the cylinder if you dont put pressure on them they will not. i agree with rpm vary pin it, off blip,blip down then throttle exc. this is my opinion from what i have seen and learned in school
 
Thanks. So what exactly will seat the rings... running for longer periods, harder or what? I know I don't want to overheat, its never happened anyway (not enough for the idiot light anyway... no AM guages here). So go for it, full blown long heavy pulls and all?

Taken your opinions fully into account. The 01 (130 miles) had complete top end, cyls, pistons, bearings etc... the 00 (50 mi) just rings. I'm doing my first overhaul on sons 01MM600 (morphed to 700). Just got the jugs today. I would be out hammering mine right now, buts its raining. And these jugs finally showed up. :o|
 
well heat cycleing takes away ring seat time, im not saying put it together take to lake and hold it pinned, no, but take it out and run it like you are going to run it, check jetting right away, if all is good giver, you can pin it, just dont pin it and then close throttle right away blip it on way down from wot. heres a read www.mototuneusa.com/break_in_secrets.htm it has some good info
 
Head gaskets

Thanks no1chevyboy, yeah I read that article last year and could not find it again these past couple weeks when I was looking. Hmmm Well, I will try it with the boy's sled when I'm done and see what kind of difference it makes.

Also- Got the winderosa gasket kit, there's no stamp on the head gaskets for "up" is there another way to tell?
 
Getting Better

Okay, took both sleds from previous posts out for a 10-15 mile ride today. Did several big, long, heavy hill pulls starting at 5,500 ft and turning around at 6,400 feet at mostly 3/4 to WFO, blipping. By the end, things started "feeling" different (better) in both sleds. I was hoping it wasn't wishful thinking.

Havn't checked the wife's 00 yet, but mine read 114, 114, 114 on same gauge. And 123, 120, 118 on a borrowed guage. This was warm. I only trailered 2.5 miles, drove off trailer, pulled plugs and tested.

Hmmmmmm
 
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