High Compression piston noisey?

[UglyMotha™]

just got done doin some breakin runs on my new revamped*sp motor and was wondering if a higher compression piston goin to make more noise than the stock compression piston there seems to be more racket coming from my head than it did stock it's still the stock cam and i've check the lifters and there good and it's not pre-detonation so that just leaves me to believe it's the piston anybody got the answer for me

[honda250xrider]

i had the same problem i thought it was the vavles adjusted them and it wasnt i just assumed it was normal and went on with it, but that is a good question it very well may be the higher compression making more of a sound inside your engine

[RAPTORAZ]

Forged pistons take longer to heat up than cast pistons and tend to rattle when cold. If the noise goes away after its warm than it's normal.

[remlapr]

so are all aftermarket pistons forged and the stocker is cast? Is this is what is referred to as "piston slap"

[BigThumper33]

Piston slap is the back and forth rocking motion of the piston skirt against the cylinder.

As far as the noise goes....I don't have a clue...

[Glamis400ex]

ask someone with a late model Chevy Silverado what piston slap is...they'll be able to tell ya....:eek2:

Glamis

[jchevy]

If it sounds like it might be noisy valves check for an exhaust leak where the header mounts to the cylinder head. Might need a new gasket for it. Just a thought.

[RAPTORAZ]

Originally posted by BigThumper33
Piston slap is the back and forth rocking motion of the piston skirt against the cylinder.

As far as the noise goes....I don't have a clue...


Yes, piston slap is the noise that you're hearing. Very normal for forged pistons.

[RAPTORAZ]

Originally posted by remlapr
so are all aftermarket pistons forged and the stocker is cast? Is this is what is referred to as "piston slap"


Most aftermarket pistons in ATV and motorcycle applications are forged. However in automotive applications , most pistons nowadays are hyperutectic (meaning a high silicon content casting) piston. Hyperutectic make more power than forged pistons because they expand more and have a tighter ring seal. However they are not as strong as forged pistons.

[RAPTORAZ]

Originally posted by Glamis400ex
ask someone with a late model Chevy Silverado what piston slap is...they'll be able to tell ya....:eek2:

Glamis


G.M. (God's Mistake) fixed this problem with the LS1 based engines. The older 350's (98 and older) were the only ones that had a lot of piston slap. Their piston slap was due to loose factory tolerances however, not the piston type.

[UglyMotha™]

well the sound doesn't go away after it's warmed up so i don't know piston rattling i gapped the rings before i installed it and they were mint it's not an exhaust like it's almost like the mechanical noise that it made before only louder, is it goin to make a racket until the rings seat i'm also wondering if the decompressor ain't goofed up i dunno

[swamprider7]

I see that you have a hotcams stage 2 in your sig. Did you remove all of the decompressor parts? I think that you are supposed to with that cam.

[UglyMotha™]

the hot cams is on my desk right now i have the stock cam in it right now cause it took me 3 months to get the hotcam and i didn't want to wait any longer so i assembled the motor with the stocker for now i'm wondering if the high compression piston isn't goofing with the decompressor cause i have no clue how that thing even works i guess i'll just have to switch cams and see what happens

[TORO1968]

Originally posted by Glamis400ex
ask someone with a late model Chevy Silverado what piston slap is...they'll be able to tell ya....:eek2:

Glamis

Yeah, I hear you on that one, my dad's 6.0L has some nice piston slap when its cold...same goes for F-bodies with the LS1.

[400ex99]

is the piston in right? arrow pointing to the exhaust? mine was in backwards, made a little slap noise, opened it back up and turned it the right way, didnt do no damage, been running fine...

[Smoker]

Check your chain tensioner, it could be the cam chain, sometimes the adjuster doesn't do it's thing right away, my guess.:p

[UglyMotha™]

ya i put the piston in right arrow pointing forward the sound more or less sound like it's coming from the top and seems to be louder on the right side of the bike i talked to colby yesterday and he said it might be the decompressor goofin but he didn't know for sure cause he's never used a H.C. piston with a decompressor unit but the sound is really getting to me so i ripped it back apart and i'm goin to put the hot cam in it and see if it's still making the noise hadn't planned doin it until next week but i'm not running it making this racket i've done many motors but this is a new one on me:huh

[UglyMotha™]

ya and the chain was tight i made sure of it before i put the valve cover back on

[400exRacerX]

Check your valve adjustment, mine made noise when it was cold and that was the valve clearance being too much when cold but when it warmed up the clearnace was perfect. I adjusted the valve clearance and it runs fine now. BTW I sure hope your 400ex doesnt have lifters!:macho

[skemp]

Ugly, did you use a new head gasket? Even if you did, it could already be blown, or perhaps you just didn't torque it down good enough. A blown/leaky head gasket will make a ticking sound that can be quite annoying, and if you leave it, will erode the aluminum of the mating surfaces on the cylinder and head, not to mention you won't have the power you should. You could also make sure that your cam chain has no broken links. They will also slap around and make a racket. Needless to say, the sound you are hearing isn't normal. :)

[UglyMotha™]

well i changed cams over the weekend and the noise is gone i'm guessing it had somthing to do with the decompressor but now that the noise is gone i can now here another noise, i guess i should've changed the head gaskets when i changed my header:rolleyes: