Crank noises are now PISTON noises

[bare]

My pore engine '87 1UA . Fresh everything is making what seems to me as wierd clanking Crank noises.
Crank is rebuilt by Scott Clough Racing ( google he's reputable)
Using New Yama parts ..only ..Trued and welded.
Engine runs "fine" up to my 10,5 k rev limiter setting.
Sounds like rod big end clacking ..not overly loud but audible over the exhaust noises . Dismantling / Rechecking the clearances/play revealed ALL are spot on..with No.. palpable or measurable crank problems. Pistons are Prox with just now fresh oem Yama rings and wrist pin bearings (this after 3500kms since their first install)
But the thing makes this disconcerting metalic sound,
Dunno IF this is normal to these engines or what?
Any body know?

[Norbo]

well sounds like all the crank and top end should be ok so may be its something coming from clutch basket or kick start meconisum. could any of the gear cogs be worn or selector forks .

Its a hard one if you know for sure that the crank and barrels are all fine .

[midlifecrisisrd]

Apr 27, 2010 3:26:52 GMT 1 bare said:

My pore engine '87 1UA . Fresh everything is making what seems to me as wierd clanking Crank noises.
Crank is rebuilt by Scott Clough Racing ( google he's reputable)
Using New Yama parts ..only ..Trued and welded.
Engine runs "fine" up to my 10,5 k rev limiter setting.
Sounds like rod big end clacking ..not overly loud but audible over the exhaust noises . Dismantling / Rechecking the clearances/play revealed ALL are spot on..with No.. palpable or measurable crank problems. Pistons are Prox with just now fresh oem Yama rings and wrist pin bearings (this after 3500kms since their first install)
But the thing makes this disconcerting metalic sound,
Dunno IF this is normal to these engines or what?
Any body know?

Have you checked the primary gears have right backlash. Mine has the same kind of problem and has done less than 300 miles on new crank and bores. I am presuming it is just slop in the clutch basket/transmission, still got to balance the carbs properly so will see if that helps.

Steve.

[dredge3]

Me too. Taken heads off all ok. No play on conrods (31k) crank was suppost to be new when I got her. 1 thing what people miss is if the case is worn. Where the end bearings sit in the case. Not sure how tight they sit in the case. I am going to strip the rest and check

[bare]

Thanks for the input people..Any.. info is useful.
The noise is constant varying only with rpms.
No differences in N, in gear, or clutch in ,or out, or bike moving .
Although when moving the ex noise drowns out the crank clatter.
Initially I thought the flywheel was touching the stator.. But It is free turning when hand turned.
On the other end the Primary gears are a matched set (checked on install). Maybe wear or a chipped tooth ? .. will have to examine. Clutch basket is in v good condition.
Case /bearing mounts are (were ?) in Pristine condition. No marking on the bearing seats. Trans box: ALL parts are in beautifull condition. Shifts better than Son's brand new 600RR (his claim) Nothing obvious there/anywhere.. unfortunately
The noises seems equal on both sides of the engine A 'guess' is the rod big ends clacking..??
But these have no axial play whatsoever, not overly surprising, being new.

This is what makes it all so frustrating: there is nothing obviously wrong ..which would make 'fixing it' easy/easier.
Seeing as this has done 3500kms since initial build (the noise was there first fire up) AND the noise has neither lessened nor increased ?? Is it harmless?
Usually wierd / problem mech noises turn ugly very quickly.. If ..there is a genuine problem.. this one hasn't... yet.
Then these noises are definitely Not Normal ??
Guess.. I'll have to do another strip down ....I just got it back together again on Sunday. and have only managed 3 heat cycles since .. sigh.

[dredge3]

That makes 4 of us. Only time it was silent was when it was - 4 outside. I assume its exspansion/compress of some kind.
Anyone got vid of the noise?

[bare]

I've been having email consults with my 350 Guru
home.earthlink.net/~scloughn/
Once a customer ..he happily advises forever, it seems.
Apparently the noises that are annoying me are most likely piston rock/slap. These occur on over sized / clearanced bores AND 0.003" is right at the point that piston slap becomes an issue..with CAST pistons. All made worse by the lack of 'Expander' rings, which do help the problem, but invariably are unreliable as they often break in use.. not good either.
So my Crap Machinist apparently Did Not set my barrels to my 'demanded' .002": clearances, despite all assurances that he could/would ..Bloody Fool!
Allegedly, Cranks don't make noises, at least not for very long as they fail dramatically, soon after noises first appear.
So people I'd be checking your Bores and pistons for clearances that MUST be between 002" and 003" as the cause of unknown persistent engine noises.
Apparently: noises Should Not be there.. if there are.. there is Something wrong. But we all knew that deep down.. we just choose to ignore it.. more or less... then something breaks spectacularily and we are dumbfounded by it
.I'm wondering just how many of us have been screwed thusly by incompetents to whom we paid good money for an expected good job

[midlifecrisisrd]

Apr 28, 2010 4:12:40 GMT 1 bare said:

I've been having email consults with my 350 Guru
home.earthlink.net/~scloughn/
Once a customer ..he happily advises forever, it seems.
Apparently the noises that are annoying me are most likely piston rock/slap. These occur on over sized / clearanced bores AND 0.003" is right at the point that piston slap becomes an issue..with CAST pistons. All made worse by the lack of 'Expander' rings, which do help the problem, but invariably are unreliable as they often break in use.. not good either.
So my Crap Machinist apparently Did Not set my barrels to my 'demanded' .002": clearances, despite all assurances that he could/would ..Bloody Fool!
Allegedly, Cranks don't make noises, at least not for very long as they fail dramatically, soon after noises first appear.
So people I'd be checking your Bores and pistons for clearances that MUST be between 002" and 003" as the cause of unknown persistent engine noises.
Apparently: noises Should Not be there.. if there are.. there is Something wrong. But we all knew that deep down.. we just choose to ignore it.. more or less... then something breaks spectacularily and we are dumbfounded by it
.I'm wondering just how many of us have been screwed thusly by incompetents to whom we paid good money for an expected good job

This would make sense, explains why noise is hard to pinpoint. Mine was done by Stan Stephens so doubt dodgy workmanship although don't know if they are deliberately built "loose"

Bought it already done but receipt shows piston part numbers ending 15 which would suggest 1.5 oversize which may be contributing to mine being a bit noisy.

Not too worried about stripping it to find out, tuned barrels and 1.5 oversize aint going to last long and no real point boring again so will just thrash it till it pops then get new barrells. As long as it lasts till I finish the second one.

Steve.

[bare]

More discussion/information:
Apparently a bore clearance of .0035" is the onset point of Piston Slap .. using Pro X pistons.
Allegedly these have a 'different' Taper than OEM yama ones.
So much for "they are the same as oem" nonsense.
.0035" is Beyond the Yama spec for a fresh bore.
Clearly mine's the result of a BUNGLED rebore , no if's and's or buts.
I clearly specified/demanded a .002" clearance, the Machinist Ass didn't deliver it, is my issue.
Overspec clearances significantly increase the likely hood of siezures as well as dropping a few HP .. a Double win.
How do these people manage to be so incompetent?
NO pride at all in their work?

I have been "riding it like I stole it" :-) Miraculously without misshap/siezure.. so far.
I built it specifically to beat on it.. why else own it ?.
I do not like the fact that it's not 'right' tho.
I can't trust it...period. Until it's right.
Mo' Money, Mo' time.

[dredge3]

Haynes lists piston/bore clearance 0.060mm.....0.0024"

[billbott]

We generally work on 0.001" per inch (on diameter) clearance as a running fit. Standard bore of 64mm equates to appx 2.1/2" diameter, so ideal clearance would be, as said, 0.0025" (two and a half thou').