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Engine noise has me a bit worried, maybe I'm just paranoid?

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Hello group,

I just bought my first used 02 250f that was in good shape. Just to be safe I decided to go through the engine. I was totally impressed with how good everything looked (master certified auto mechanic ), I can see why you guys love these things. My only concern was some slight scoring on the wrist pin, but the connecting rod felt pretty good. I decided to go with the slighlty larger than stock bore kit. Sent cylinder down to LA sleave, and went with new Wisco Piston kit.

Installed new t-chain while I was at it.

Took my time putting it back together, and used this AWSOME FORUM for assemble tips. BTW it already has the 03 cam.

Went to fire it up, and it fired right up, no leaks, but It sounds like it has more mechanical noise than I remember when I first bought it 6 weeks ago (I told you I took my time putting it back together). I shut her down after just getting the engine warm and drained the oil, all looked okay. I then thought maybe the steel sleeve is just noiser than the stock coated one, and if I remember right Wisco pistons are a bit louder than stock?

It runs awsome, power is fantastic, just concerned with what sounds like a Deep rythmatic "piston" slap?

I did have trouble at firt getting the rings all compressed, but with some light "finessing" finally got it.

I used engine oil and coated the cylinder, and cycled the piston up and down a couple times. I felt like a "new" setup, tight, but not binding.

I'm giving as much information to help you guys see if I boned something up, or if I'm just being being paranoid?

Does anyone else have any idea's that I might be overlooking?

Is there anyway to inspect further with out tearing it down again? It was not fun the first time!

Thanks for your help and advice!

RR

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my 450 never ceases to amaze on the noises it makes,sounds kinda like a yanmar single sometimes the sounds change under different conditions so far it seems like thats just the way they sound! it could be with the tight new cylinder that its changed the sound,and will lessen as it breaks in. did you put a new skid plate on or leave it off while starting it? that will change the sound also :cry:

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I did the wiesco kit also, and my first several hours the thing sounded like a rattle can, but runs like a scolded ape. The noise lessened until recently, got to looking and my valves are quite loose. Remember, fourstrokes are noisy. My buddys crf450 is way louder than my ride. Have fun with that thing. :cry:

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I was curious why you had the cylinder sleeved? Wiseco offers up to 2mm over, which still doesn't require sleeving. You can just punch it out and have it re-plated. If you sleeved it, I wonder what piston-to-bore clearance your piston went in at? Since the sleeve is cast iron and doesn't expand as quickly as the stock aluminum bore, I wonder if it was honed big and left you with excess clearance. That piston was designed to run in an aluminum bore at a specific clearance (says on the piston box).

With all that being said, I agree with the rest of the guys. Don't worry too much about the noise. Check your valves, but let the seat of your pants be the final judge!

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The piston will push some chage backwards before the valves shut and it causes the slide to slap. Make sure that isnt it before you tear it apart.

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Thanks for the info on the engine noise!

The reason I bought this YZF was because of this site, and man you can do some things to this bike.

Great question CB Daddy:

Why did I have it re-sleeved with Steel.

The honest answer, I went off what my local motorcycle mechanic said and reccomended "God forbid if anything where to happen, I could always rebore it"

Now that I have more experience I would take my changes with a coated cylinder "like I mentioned before the stock setup was 2 years old and it looked AWSOME"!

Let me ask the group some questions:

My reciept says 79mm piston? What size overbore kit is this?

Could I have this cylinder recoated, and the clearances rechecked, and who would you guys reccomend I have do it?

I do think that the clearances are to tight, especially when the piston is going to expand faster than the steel sleeve.

I'm going to be racing this thing in the "A" class NMA offroad series next year as a backup to my YZ and I like to rev it up, and man do these things rev up!

I can't wait to get this thing in the slimmy, rock and root infested woods of the pacific northwest to see how it really shines.

Also any way to get that high center of gravity feeling toned down a little?

Also what is a good oversized tank to go with.

Thanks for the info!

RR :cry:

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I just hung a couple of acerbis 3.2 gallon tanks on our 250's. I'll let you know how they work out after the race today. One thing I do need to do is make a heat shield for the right shut off valve. It's close enough to the pipe to get hot, and hot gas is not a good thing. Hopefully it works out for today making changes at the race always sucks.

the 79mm is the 262 cc kit. It's the only overbore allowed by the ama. 2mm overbore max. You'll like it, just run 92 or 93 for sure as the compression ratio is higher with it.

Actually they say the steel sleeve is better for heat conduction which means cooler temps for the piston. It should do fine as long as you had enough clearance to start with.

saddle time will make that high center of gravity feel normal to you.

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Yes - the 79mm is a 2mm overbore. Stock bore is 77mm. Yes on the 92-93 octane pump gas.

I would ask to see what clearance your mechanic honed your liner to. That piston was probably supposed to drop in a plated aluminum bore at .0015-.002" clearance, so as long as you aren't much over .0025-.003 with the cast iron liner, you should be fine. If you have more than .003" clearance, it is probably more than you need. I have to disagree with the last post regarding heat conductivity of a cast iron liner. The thermal transfer rate of aluminum is higher than cast iron, so a cast iron liner would NOT conduct more heat and keep the engine cooler. I think the difference in this application is negligable, unless your first name is Bubba, in which case you might notice slight difference.

RRussel, back to your question about replating - if your cylinder is already sleeved, you can't get it back to an aluminum bore. You could have someone like Millennium plate your cast iron bore if you felt the need to close up the clearance a bit, but that will cost you another $125-$150 probably. Besides, that is a lot of hassel for no reason unless you have way more than .003" clearance. I would just ask your mechanic how much clearance he honed it to, and go from there. :cry:

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Did I understand someone saying that a skid plate would cause a different sounding motor?

Mark

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yes a skid plate will cause the motor to sound different as there are diferent vibations and echos coming from betweeen the skid plat and the cases, dont worry bout the noisy engine, mine sounds similar and it is just because it is tight

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