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post #1 of (permalink) Old 03-29-2003, 10:21 PM
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2-stroke break in

Hi, over this cold winter I took the engine out of my YZ250 and into the basement to rebuild it. I bought a wiesco pro-lite piston and put it in. I just had some questions about breaking it in. The clymer book for it says to mix up some 14:1 and basically puts around, then tear it all back apart and inspect. I have read many different break-in procedures, and am kind of confused now. It's still in the basement, so no damage yet. I rented a hone from autozone and used that just to break the glaze, they only had one kind, with the three spring loaded arms, is that ok? I had a quart of amsoil 2-stroke synthetic, is that a bad idea for break in? I know that you can't break 4 strokes in on synthetic. On the powervalve, the clymer book says to use "molybdenum disulfide grease", the guy at the hardware had no idea what it is, i just used some ball joint grease that I had, it said it's a high temp lithium complex grease, is that going to cause any problems? I have also been having problems with the clutch, so I bought a EBC race clutch kit, but when I tore it apart the disks arent the problem. The basket had badly worn grooves, and the lever, the thing that the cable goes to that moves the pushrod, also has a big worn spot on it thats causing trouble. Not gonna be cheap for new a one, it seems if I were to smooth out the teeth on the basket that it would have more slop and just wear back fast. I havent gone the the dealership yet to price it. What do all of ya think? [img]images/graemlins/RockOn.gif[/img]
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post #2 of (permalink) Old 03-30-2003, 01:21 AM
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Re: 2-stroke break in

Mix your gas normally. more oil makes your bike run leaner.

DO NOT tear it down again after awhile to check things.

Those hones are not what you are supposed to use, but you may get away with it

Did you check your clearance and roundness and measure your new piston t make sure you did not need to go 10 over? Do you have a Nic bore or a Cast bore? If its cast, you probably should have went 10 over if the bike has alot of miles on it.

Because Wisecos do not have as much silica in them as stock pistons, they need to be set up looser and require MUCH longer warm up times. they also should be replaced more often.

any oil is fine for break in, synth will just take longer to get a good ring seal.

be aware that your new base gastket may be a different height. ie if it is thinner and your squish is already close. you may end up with detonation.

hope this helps
post #3 of (permalink) Old 03-30-2003, 09:53 AM
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Re: 2-stroke break in

Okee, I'm gonna sound like I know what I'm talkin' about here but....not really. I've seen that molybdenum disulfide grease in a hundred different shop manuals. And I know the look you get when you go to the store and ask for it. So I does a search for it.....

Molybdenum Disulfide is a powder added to grease. Molybdenum-disulfide and tungsten-disulfide based lubricants can withstand temperature ranges of up to -300 F through +950 F, and pressures of up to 400,000 psi. From what I've seen, grease with "Moly" in front was what we're looking for. [img]images/graemlins/burnout.gif[/img]
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post #4 of (permalink) Old 03-30-2003, 04:21 PM
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Re: 2-stroke break in

File your basket. The fingers of the clutch basket on my WR 400 take a beating. I heard a funny sound one day and got a little extra play at the clutch lever. Turns out I broke a couple of plates. I popped her open to replace them and saw the notches. I felt the same way about not wanting to file the basket which would give the plates more room to beat up the fingers. I took the edge off them a little and put in the new plates. They broke the first day. Some of them must've been hanging up in the notches while the others moved and made 'em shatter. I was going to order a new and expensive billet basket from Dennis Kirk but didn't want the bike to be down for a couple of months waiting for the mail to get here. Since I was ordering a new basket anyway I experimented with the old one. I filed all of the fingers 'till they were almost perfectly smooth, you could just see little shadows where the notches were. It would've taken a lot more hogging to get them shiny and I could hardly feel the ripples so I put it back together like that. The clutch worked perfectly so I held off ordering the new basket and I have never had a problem. The next season I opened it up to pop in new plates and the fingers were notched a little again so I filed them again and been riding since last year with no trouble.
If you don't file the fingers you may shatter plates like I did. You could lay out the long green for a new bullet proof basket or you could get another season or two out of yours with a little elbow grease, which is much more readily available than molybdenum disulfide grease.
As for your cylinder, the spring loaded 3 stone job can put a little uneven taper in your cylinder and you can hook the ends of the stones in the ports if you're not careful and run it in too far. In the old days before Nicasil coated cylinders, we used parallel stone hones that had 2 stones and 2 brushes that all stayed parallel and you could set your diameter. You ran the hone a bit and when it loosened up you re-adjusted it and ran it until you cleaned up the scratches got the cross hatch you were looking for. Then we took a ball hone and ran it through to chamfer the edges of the ports so you wouldn't hook a ring. If no ball hone was available we used little round files like chainsaw files and did all the edges of the ports by hand. The ball hone is a lot less work.
The coated cylinders we have now are very different. I'm not up on the latest tech stuff but they used to recommend not honing coated cylinders at all, just replace them. Of course us privateers aren't going to spend that kind of cash so we gingerly scuff them up enough so the new rings will seat. The cylinder of my WR is coated and I popped in 1 set of rings so far and scuffed the barrel to break the glaze and have had no problems, but I don't have any port openings in mine. Check (maybe too late now) around the edges of your ports. Sometimes honing will chip or flake off the coating. If it is chipped you can get it re-coated, buy a new barrel, or do what I do and drive it 'till it blows up, it may not.
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post #5 of (permalink) Old 03-30-2003, 06:31 PM
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Re: 2-stroke break in

It's an old bike, 1989 and it's a cast iron bore. I only honed it for like 10-15 seconds, really didnt do anything but scratch it up. I didnt check the roundness or piston-wall clearence but the ring end gap was at the lowest tolerance, so I assumed it must not be bigger. Does that make sence? [img]images/graemlins/smile.gif[/img] The bike had great compression before i tore it apart, 230psi, I alwase run 110 gas with it. I will try takin the basket and filing it down smooth, and see how much the lever thing is.
Thats what never made sence is mixing tons of oil in will just have less gas, why does it say to break it in that way. So I should just mix up normal, 40:1 is how it's jetted but I'm gonna try to jet it to 32:1.
Anyway, THANKS for the help guys. [img]images/graemlins/grin.gif[/img]
post #6 of (permalink) Old 03-30-2003, 06:42 PM
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Re: 2-stroke break in

do your normal.
post #7 of (permalink) Old 03-30-2003, 07:47 PM
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Re: 2-stroke break in

I like that Mr_T, "drive it 'till it blows up". Sounds like a plan [img]images/graemlins/smile.gif[/img]
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