T120 top end rattle

[yebbut]

piston slap

[raptorkev]

piston slap
[/quote
ok took head off bores look good pistons marked on tops 70.9488/20 ? there are some other marks but cant make them out theres no small end play no ridge or scores in barrels when pistons on top of stroke in bores i could move them a little bit.the rihgthand piston a bit more than the left.
no broken valve springs and no play in valve guides
the rockers do move from side to side quite easy maybe the springs are a bit weak i have heard of taking them out and just spacing out with washers anyone done this?
would piston slap only be evident when cold ?

[yebbut]

Piston slap is a distinct possibility. . All to often when an engine is rebuilt, the cylinders and pistons are not measured to insure they fit properly. A good clue is to look at the ridge on the top of the cylinder where the top ring stops. If the ridge is very pronounced, that indicates a lot of wear on the cylinder wall and should definitely be measured. If the ridge is there but not very pronounced, then there has been little wear and the old pistons can be reused without a problem. A piston slap noise would tend to be loudest when the engine is cold and disappear.

cut and pasted cos it takes to long to type/
your pistons sem to be original triumph +20
measure everything, it wouldnt be the  first time I seen +20 pistons in a 30 thou bore

[Rex]

Maybe a bit late now the engine is down, but did any experienced mechanic listen to this noise? Sometimes little noises which appear at certain revs can be no more than vibration/resonance and nothing to worry about....

[sparky]

Back in 1966 I got a new  66 bonnie had to go back to meriden, when they stripped the head it was a valve guide going up and down in the head, then it would stop for a while, had a great day out at meriden tho looked after us well..

[triman65]

check piston in each bore and you should have a 4-5 thou gap from front to back. If it is more then piston slap is possible Try each ring in correct bore and you should have between 10-14 thou gap. Remember that the pistons are slightly oval. When putting the rings in the bore use the piston to make the rings level.

I have just done a rebore on my t120



Hope this helps

[raptorkev]

thanks guys it looks like it must be a bit of slap pity because it runs well all back together now will start saving for a morgo kit

[raptorkev]

ok  this is taking over my life had it reboard and new pistons run it in guess what still got it its definatly in th top end  could it be the rockers moving side to side on the shafts there is not a lot of resistance ie could the springs be weak i think ive read somewhere that you can do away with these springs and put in solid spacers does anyone know about this

[Rex]

You're thinking of the Thackeray washers......but just thinking of a cause then paying money for a fix isn't the way to go, unless you like wasting money, that is.

Said it before in this thread...let a Triumph mechanic (or owner, at least) have a listen. It could be nothing to worry about.

[raptorkev]

  hi guys just thought i would update found the cause and fixed my rattle noise turned out to be backlash on the inner clutch drum and clutch hub its caused me some sleepless nights but got there in the end thanks for all your input 

[wetdog]

did you only have this noise when the cluch was pulled in then ? how did you fix this ? rebuild the hub , im just interested

[raptorkev]

only had it when riding about 3000 rpm with no load on the motor fixed with new hub and new inner drum no radial play no noise

[wetdog]

thanks , so where the rollers run was worn , thats the first time ive heard of that one making a noise and one to remember thanks

[raptorkev]

the bit with the splines on goes into the spider