Author Topic: What did you do to your RE Continental GT today?  (Read 176247 times)

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Joe_535i

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Reply #1050 on: August 01, 2020, 11:17:58 am
The flying around chips could have sized the piston too from the bottom end. That is up to speculation, I am rather sure though that the big end bearing was not the fittest. Maybe the bearing itself might be ok, but who may know which indian high tech company machined the race in the conrod. Anyway I couldn't care less, there is no warranty on the bike anyway.

But it was more important to put a silly ABS on it instead.  ;)
« Last Edit: August 01, 2020, 11:21:32 am by Joe_535i »


ace.cafe

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Reply #1051 on: August 01, 2020, 02:11:53 pm
The piston failure. Why it should size i don't know. Gap was pretty big, about 0,1mm...don't have the exact material specs though.

I know why.
The piston/cylinder clearance was not big enough for a forged piston.
Forged pistons are denser material which causes more thermal expansion than cast pistons. Also, some cast pistons have silicon content in the alloy which reduces thermal expansion.

Bottom line:
You need more piston/cylinder clearance than 0.1mm.
Without actually measuring the piston, it is hard to say exactly how much, but my experiences with forged pistons in the 535 show need for at least .005", and maybe even .0055".
But if you go too much, it will have some piston slap on cold starting, which isn't really harmful, but sounds bad.
Most of the time, .006" clearance is too much and might slap.
« Last Edit: August 01, 2020, 02:18:18 pm by ace.cafe »
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Joe_535i

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Reply #1052 on: August 01, 2020, 02:19:18 pm
It's extremely difficult to get good data for aftermarket pistons, I took the risk without doing any further investigations to it and I would not recommend it to anyone unless it's from a reputable source and verified to work in the engine it is intended for. The flat top was good for only about 0,5 horses. And the higher compression reduced the idle stability.

Almost certainly ACE is correct on the gap.
« Last Edit: August 01, 2020, 02:40:48 pm by Joe_535i »