LCGB Forums

this ...
http://www.scooterrestorations.com/lamb ... d-bearing/

and this...
http://www.scooterrestorations.com/lamb ... shaft-sil/

Now I bought a second hand GP crank off fleabay last yeah and the previous owner said he had it on a muggy engine (he's upgraded to a longer stoke jobby now) I plan to use it in a standard GP150 engine but given the reputation the standard SIL crank has- I'd rather not. I'm working to a uber small budget (as usual) so getting the rod changed etc can't happen. If the crank has been converted to a Jap bearing then it will be idea. Oh yeah its the same picky for both cranks which doesn't help things

I would have thought a standards SIL crank would be fine in a 150 engine. The JAP rods are better but only really a concern in high revving engines.

I put one of the Jap bearing versions in a mate's bike before Euro Ireland and it has been used for regular use since then, including Belgium and Avignon, still running fine. This was fitted to replace a standard SIL crank + bearing in which the big end rollers had turned to a really nasty dull grey and I think would have failed soon after, if not replaced.

Big end bearing failure is so common on SIL cranks that I would bother fitting a standard SIL bearing crank to anything, regardless of cc. I've known too many to fail at low mileages.

Adam

Thanks for the replies,Yes Adam, all the research I've done doesn't paint a good picture of SIL cranks, probably going to use a good condition Li/SX crank instead, yes I know people will say don't but I've been running one in my SX for years without issue, it's a standard 150 engine and not. prone to self destruct like the SIL crank. Thanks again Paul

Make sure that you are buying an appropriate crank for the flywheel/ignition kit that you plan to use as you cannot mix and match LI/SX and GP parts unless you mix like for like.

Best of luck with it.

Adam

Indian cranks (webs) are actually quite good, the webs are tight on the pin, its the bearings and rods that not up to scratch. They can easily be up-rated with better quality rods/bearings to create and excellent crank-shaft.

I think in the ones shown only the bearing is replaced not the rod?

You might be able to tell by looking at the bearing she'll which is which, but SR would be able to tell you for sure.

Your budget maybe tight but I wouldn't risk an unknown SIL crank in a wheelbarrow never mind my scooter. The only experience I've had of a new SIL crank was taking it out of my mates new 200 engine after 500 miles when it melted the big end and locked it up solid.

The SIL standard bearing cage is a blue/ grey colour and I seem to remember the uprated bearings have a silver or copper coloured cage .

Bofs wrote:Your budget maybe tight but I wouldn't risk an unknown SIL crank in a wheelbarrow never mind my scooter. The only experience I've had of a new SIL crank was taking it out of my mates new 200 engine after 500 miles when it melted the big end and locked it up solid.

Totally agree with the above statement.

Yes, many SIL standard cranks really are that bad! Anyone that has managed a decent lifespan from a standard SIL crank is a lottery winner IMO.

How easy is to upgrade the crank by changing the crank rod

I've never suffered any problem with a sil rod.
Standard bearings yes, rods in engines up to 22 bhp have been fine.
I think the last upgraded sil I bought had had the rod tidied up a bit. Might help identify.sip

Wack wrote:The SIL standard bearing cage is a blue/ grey colour and I seem to remember the uprated bearings have a silver or copper coloured cage .

Ah, the bearing in my crank is a dark blue/black colouring- it does sound like a standard SIL bearing

I use a SIL crank with Jap big end bearings.I got the crank from SR in March 2012 and I've done 1000s of trouble free miles on it.As far as I can tell its only the Indian big end bearings that are suspect,providing the crank pin and big end bearing surface of conrod are hardened properly I cant see a problem using the crank,after all most builders say that SIL webs are the best.
Paul

Regarding the crappy SIL bearing cranks- I've been in touch with Martin at Chiselspeed and he can convert the bearing to either a standard steel cage bearing for £35 or a silver plated bearing for £42.95 + £10.20 for P&P, mines off to sunny Leeds next week, hope this is some help to people like me getting by on a micro budget but don't want to scrimp on quality