Top end rattle on cast iron barrel

[rocho68]

my mates 190 barrel nipped up on way back from the white , managed to save everything apart from the rings , had barrel honed at pjme , 3.5 thou clereance before and told they only took a bit out of it , put back to gether but has a rattle that wasnt there before ,any ideas !!!!!!!!!!!!!

[bristolmod]

its probably getting on for 4 thou now, which can cause a touch of piston slap.

Chris

[rocho68]

would this be safe to run ?

[bristolmod]

should be OK dependant on the actual gap.

You may find that as the engine warms up, the "slap" goes away due to heat expansion.

Many, many scooters exhibit this "characteristic"- I had a genuine SR186 a couple of years ago and this rattled from new- due to the taper on the piston being incorrect. It didn't affect running and did get better when hot.

Run it and see

Chris

[soosh]

I had this a few years ago when a well known dealer up the North did a rebore and it rattled like fook after,i sent it back but they said nout was wrong,when checked by someone who actually knew what they were doing,it was found to have 3thou clearence alright....but either side of piston.When it was put right by this proper mechanic,the original lot didnt like it and said it would sieze up.It made it to Milan and back ok.

[eibargum]

my mates 190 barrel nipped up on way back from the white , managed to save everything apart from the rings , had barrel honed at pjme , 3.5 thou clereance before and told they only took a bit out of it , put back to gether but has a rattle that wasnt there before ,any ideas !!!!!!!!!!!!!

Did you Chq it yourself, was it 3.5 top, bottom and middle, i only ask as i got a barral back from lancourts after plateing and it was 3 thou top and bottom and 10 thou in the middle , rattled like a good un, wish i,d check,d it before i put it together, needless to say, they had to replate it.

[jonny snatchsniffer]

4 thou is the norm for a cast iron barrel

[goldeneye]

my work bike with a cast iron barrel rattles like a guddun at tickover, it was like that from the re-bore. its quite a thin walled barrel, and i just put up with it. ive done about 7000-8000 thousand miles on it, with shite oil, in about 14 months, and its been fine. i just chuck any oil in at 3%, and have no qualms about syphoning my petrol out the lammy and putting that in at 4%. i had a T5 malossi 172 that rattled like buggery at tickover, but also went like buggery. its a bit of the old piston slap. some people spend ages, and fortunes trying to eradicate it, some just put up with it, and spend the money on drink.