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Bearings Big end
Posted: Fri Sep 11, 2009 12:40 pm
by the-elf
I can remember this topic in the past but I can't find the actual answer. Is there a better, bearing that'll fit the big end?
Got a crank to get done this winter, but due to the latest engine making a lot more RPM and power I'm looking at improving the rest of the engine to cope.
Posted: Fri Sep 11, 2009 4:58 pm
by mj43
What are you planning Kev?
Posted: Fri Sep 11, 2009 7:18 pm
by kwackman12
Spoke to Graham file in the week & he mentioned this to me, think he said he can get replacement con rods that come with a "bigger "main bearing, might be worth giving him a ring?
Posted: Sat Sep 12, 2009 7:08 am
by TwoStroke Institute
You will need to swap a pistons aswell as rods with a smaller 28mm big end eye can take a bearing with 18 rollers, more rollers = more rpm.Problem is there is no 106mm rod with 20mm small end eye and 28mm big end eye. Only a 110mm rod thus the piston swap.
Posted: Sat Sep 12, 2009 10:35 am
by the-elf
mj43 wrote:What are you planning Kev?
Depends on how this engine performs when I've got it back together in the next fortnite.
Waiting for the pistons and cylinder to come back from BDK. In the mean time I've got a bit of crank case work to do.
The first part of the plan is:
I need to confirm the datalogger info again, (should be at Brands at end of month with PB) and if it's correct then I'll need a day on the dyno to get things set up.
The datalogged measured the maximum RPM as 12380 with the rev limiter set to retard the ignition 200 RPM before it kills it totally at 12500. The trouble was there was no over rev at all, so I'm guessing there might be more to come if I can be sure that the engine could cope with 2K+ extra revs

My main worry ATM are the big ends bearings and I was wondering if there are any better alternatives on the market to the 20 year old originals.
2nd part of the Plan is;
To explore some single ring (TZ style) pistons & different rods, but I'm guessing you will be ahead of me in this bit.

again this might help improve big end bearing life.
Does it ever end?
