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Noisy KX65 normal?

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Hey all. I just finished my first top end redo on my son's aforementioned KX65. After starting the bike to begin the break-in process, it seemed awfully noisy. Like a string of tin cans being drug behind a car. Basically excessive motor noise. I don't know if I'm being hyper-sensitive to it, since I never paid attention before. Maybe I'm just now noticing?

I did fire up my KX100 with a well worn top end (my next project) but it still runs very strong. It sounds only slightly less noisy.

So would it be normal for the 65 to run a little noisier than the 100? Everything went together well, but I did NOT measure the pistons and cylinder. I now feel I should have.

If I need to, i post a vid this weekend. I did see on only one other site that Kawis are notoriously noisy. Would that be correct?

Thanks all in advance.

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Check the squish. Pull the head and look for damage on the piston dome. It could be hitting the head especially if the big end bearing has grown some slop. Also my KX 60 pitbike pinged horribly at lower speeds with my weight until i tuned the carb a bit richer. Not sure if thats an issue with the 65.

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Check the squish. Pull the head and look for damage on the piston dome. It could be hitting the head especially if the big end bearing has grown some slop. Also my KX 60 pitbike pinged horribly at lower speeds with my weight until i tuned the carb a bit richer. Not sure if thats an issue with the 65.

Ok will do. Thanks. If I find no damage, then I'm good, right? I felt absolutely no vertical play in the bottom end bearing. The cylinder looked fantastic, so all i did was a light sanding of the wall with 240 grit paper to dull the shine. The old plug looked great, a dark chocolate brown. Maybe a little rich, but that's better than white.

It's been rather confusing for me with all the research I've been doing. I hear of guys doing a top end in an hour or even less, and I can't wrap my brain around that. Seems to do it right, with mic-ing parts, sanding/honing the cylinder and cleaning, an entire Saturday afternoon seems more appropriate, I just can't figure out how much or little to do. Then my neighbors telling me I have to hone it and check to make sure the bore is round (but I believe it would take a diamond hone to work on these cylinders, right?). Ugh, I just wanna get rid of the bike, but want to make sure the next kid has a REALLY good running bike with no major maintenance next season.

Thanks for the help, and I'm definitely open to other points of view.

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This is my cylinder head. It's still perfect, as is the top of the piston. I hate to say it, but I think it's just my OCD (I do have it, unfortunately) I think I just never noticed it before, since it was only my boy's bike.

I'm still wondering if I should have pulled the cylinder and measured the piston etc. image.jpg

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Since that cylinder is plated, sanding with 240 grit sandpaper sounds excessive.

Usualy a green Scotchbrite pad is used, at most a 400 grit wet sandpaper to clean up light debris imbeded on the surface.

 

One thing for sure after sanding it, it has to be spotless for re-assembly, simply spraying it down with parts cleaner isn't enough.

Wash the cylinder with dishsoap and warn water, after it's dry wipe it down with a white rag dampened with WD-40.

You'll be surprised to see dirt/metallic particles still appear on the rag even after all the washing.

Continue wiping down the cylinder until the rag remains clean.

 

A few questions since it was your first top end:

-did you check the ring end gap

-install the right size piston for the bore

-replace (not re-use) the circlips and install them oriented as indicated in the manual

-check the condition or replace the wristpin bearing

-install a forged (Wiseco) replacement piston rather than a cast piston

Edited by mlatour

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Our 02 65 isn't loud at all, in fact, it sounds like a nice little 2 stroke.

"like a string of tin cans being pulled behind a car" sounds would be enough to get me to take it back apart.

Good on you for caring about the next kid that owns that bike!!

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Since that cylinder is plated, sanding with 240 grit sandpaper sounds excessive.

Usualy a green Scotchbrite pad is used, at most a 400 grit wet sandpaper to clean up light debris imbeded on the surface.

One thing for sure after sanding it, it has to be spotless for re-assembly, simply spraying it down with parts cleaner isn't enough.

Wash the cylinder with dishsoap and warn water, after it's dry wipe it down with a white rag dampened with WD-40.

You'll be surprised to see dirt/metallic particles still appear on the rag even after all the washing.

Continue wiping down the cylinder until the rag remains clean.

A few questions since it was your first top end:

-did you check the ring end gap

-install the right size piston for the bore

-replace (not re-use) the circlips and install them oriented as indicated in the manual

-check the condition or replace the wristpin bearing

-install a forged (Wiseco) replacement piston rather than a cast piston

Thanks so much for the reply. As I've mentioned in other posts, 2-strokes are very new to me, so it's been a somewhat overwhelming task of learning them with all the varying opinions and advice from all the sites I've toured. So I hope you guys continue to be patient with me, especially when I answer the following questions :)

1) yes, the gaps are within the specs of the manual. Maybe even slightly large at about .30 (can't remember if it's .30 mm or .030". Either way, they came in under the recommended upper limit of .35/.035)

2) I don't know. I did order the piston for a stock bore. And when I test fit it, it slid in almost snug, with VERY little play.

3) yes, I used the new clips, with the gap orientated in line with the rod, either up or down.

4) it came with a new wrist pin bearing. I dipped it in a cap full of 2 stroke oil before installing.

5) uh oh, well, I used cast. But only after doing much research. I saw many riders of even 250's who love them. They just warned that you can't take chances with long maintenance schedules. They need to be replaced more often than forged. I hope I didn't mess up there. Again, I can only go by a consensus on what I've read. And I have every intention if informing g the next potential buyer so they know what they're getting.

Re: scotch brite. Which color were you referring to? Because different colors are different grits. Both green and red scotch brite are more aggressive than 240 grit. White is around 400 I believe. I did see another site that recommended 200 grit paper, so I felt 240 would be fine. He said because of the hard plating, it would take a LOT of sanding to hurt the finish. Mind you, I'm not arguing the point, just explaining how I came to these decisions.

Edit: oops! Just saw you wrote green scotch brite.

And no, I did not do the extensive cleaning that you recommended. I emptied about half a can of carb cleaner in it, wiped and blew it out. Shoot, I wish I'd have talked to you earlier. I have no problem cleaning things like a madman. I just never read that in my research. But it definitely makes sense and will be redone. Do you think I've done damage to the motor?

Our 02 65 isn't loud at all, in fact, it sounds like a nice little 2 stroke.

"like a string of tin cans being pulled behind a car" sounds would be enough to get me to take it back apart.

Good on you for caring about the next kid that owns that bike!!

Thanks for the reply. Remember, I did say it's only slightly louder than my 100, which also has noticeable engine racket. But quiet enough that I never noticed it until this project, then I started paying attention to it. My analogy only refers to the tone, but not necessarily the volume of the tin cans :D

Well, I've got no problem taking the top end back apart. I want to verify things, and I've already become rather proficient at it. 15 minutes last night and I was looking at the top of the piston.

Thanks again all. Please continue with the great advice.

Edited by Bron-Yr-Aur

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Cast piston is fine,

a forged Wiseco could have produced a bit more noise at startup than before due to expansion characteristics when cold.

Edited by mlatour

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Your welcome, I don't pretend to know it all (there are some far more mechanicaly experienced members on this forum)

but to the best of my knowledge I like to explain things in detail.

 

Perhaps post a video of the KX65 running so we can hear the engine / noises.

Edited by mlatour

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I'd get nervous if you felt play with the new piston in the old cylinder.  I don't think you can get away with any play there, but maybe I'm wrong.

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I'll definitely get a video posted as soon as I can. I pulled it apart and measured the parts. The cylinder measures 44.45 mm. The piston 44.25. Although I thought those numbers seemed sloppy, I believe they're on the outer limit of what's acceptable. I can't understand why they made the piston so small for the "stock bore". Oh well.

I also cleaned the cylinder as recommended. Everything looks really good inside. It's time to I beat my OCD into submission and finish this thing!

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No, I didn't notice anything. But then again, I wasn't looking for it, so I didn't even inspect the exhaust side. Anything I should have been looking for? Does .2 mm play sound like too much?

Edited by Bron-Yr-Aur

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Alright kiddos, got the motor back together, but not the whole bike. I did the fourth heat cycle afterwards, taking it up to about 3/4 throttle and just into the powerband. This little thing screams and hits the band hard.

Here's a vid that I shot as it was warming up. I now feel kinda foolish, since most of what I'm hearing is coming from the left cover. Meaning it was there all along and my work has nothing to do with it. But I'm really glad I got the help of you all because it forced me to go back into the motor, measure everything and clean it appropriately. Now I feel really good about it and won't be putting these projects off like I have up to this point. I can also refer the next owner to this thread so he can feel a little better about trusting the work that I did and that I'm being up front. I wish my stepson weren't growing so fast, since he just graduated to my KX100. I'm so impressed with this little thing.

One thing I can't understand: this is my third Kawi 2 stroke, and I've never had a single bit of trouble from any of them. I often read posts of people who say KX's are junk. Some of the kids that I take out with my son make quiet remarks about what junk Kawi's are, yet both of their YZ's are broken down right now. None of my KXs have even fouled a plug, much less left me stranded. And I'd put my 100 up against my YZ125 for speed any day. The KX100 stands straight up in 4th gear and goes up any hill I have the guts to climb. But at 130 lbs and 5'3" I definitely tax the suspension. And bigger wheels of the 125 have been a great upgrade for me, not to mention the additional torque. Now all I have to do is look for rocks to stand on the start the thing!

Edited by Bron-Yr-Aur
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Bike sounds fine. I wouldn't worry about it just ride. Sounds just like the 65 we did this summer. We did top and bottom, sounds exactly the same.

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your a awesome dad Man!!!! :thumbsup:

Haha thanks. Although, from your signature, you're doing pretty good yourself! Some of the best memories of my life were in the mid 70's riding my '74 Honda Elsinore MR50 with my dad. I'm a new step-dad and feel lost sometimes in how to be one, so I just go by what worked for me as a kid. So far it's worked. He loves not only riding them with me, but working on them too.

Bike sounds fine. I wouldn't worry about it just ride. Sounds just like the 65 we did this summer. We did top and bottom, sounds exactly the same.

Thanks. That's good to hear. I was hoping someone would chime in. I've been wondering from some other threads, what part of PA are you from? I'm near Johnstown, in Windber. There's some great riding up here. Although I'm from here, I spent most of my life in FL. So it's been great to be back on 2-strokes. I was away from PA and dirt bikes for 33 years.

By the way, as an update, the little KX is a madman! I didn't realize how wore out the other rings were. But now, it'll stand up in 3rd gear when it hits the power. It is hilarious...

Edited by Bron-Yr-Aur

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I'm from southeast pa. Bucks county. We race hare scrambles in the Ecea and d6. We are heading to Florida for the first gncc in March in believe.

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