Forum

[Terry]

Hi all a short while ago I added a topic on the big end I stripped my bullet 500 down and the big end shell had broken up to a fine dust. however the CRANK PIN appears to be OK nice and shiny with no marks or scores in what so ever I'm temped to re-use it but the QUESTION IS DO I ruff up the shiny contact area and hone the new bush or just hone the new bush Thank you.

[Dennis C]

The first thing to do is measure the pin accurately with a micrometer to ensure it is perfectly round and not worn, if it is OK don't rough it at all leave it well alone just fit the new bush to it.

[Terry]

Many thanks for your quick and helpful reply I will get that checked

[Bullet Whisperer]

Hi Terry,
Make sure the crankpin oilway to the big end is not clogged with debris if you plan to reuse it!
Regards,
Paul.

[MadMike]

Terry the pin may or may not be damaged. Indded it may be damaged and it might not be obvious to the uninitiated and/or the naked eye (is there any other kind of eye I wonder?)

Whilst it may seem to be perfectly feasible to reuse the old pin with new shells, I would not recommand this course of action.

You should only ever fit new bearing surfaces to new bearing surfaces. If it is a ball or roller big end then simply change the bearing. In doing so you actually fir new bearing surface to new bearing surface, if you see what I mean. So with shells and a crankpin change them both so that during running in they can become perfectly matched. Despite what others might suggest anything else is false economy.

[John L]

+ 1 to what Madmike said.
You'd be kicking yourself if you spent all that time and money and the big-end failed again shortly after.......

[Alan R]

---- +1 more to that !! If you have access to a skilled and competent engineering person or company then have it changed and checked for true running etc. You then start off after re-build with a known quantity, an "even playing field" if you like. You've come this far so why not ?? Please do wash, blow-dry and prove ALL oilways clear( including the feed to the rockers PLUS the rockers themselves.) And, predictably here we go again }-------- whilst the engine is fully dismantled be hard with yourself and consider --- a) replacing the Indian mains bearings for European spec. ones.--- b) A complete set of new seals and a full gasket set---naturally. ---c) Then there's the cyl. head for a visual check and double-check the state of the exhaust valve recession if any. It's worth it in the long run for peace of mind and a job well done. Best wishes for the project.

[MadMike]

Terry what Alan says about very careful and thorough cleaning of cases, engine parts etc etc is absolutely correct. New bearings and seals are cheap enough and you should take to opportunity to upgrade as well while the engine is down.

Now then there is also another area that you MUST thoroughly clean before re-assemling and filling with lovely new oil. Any and all external oil pipes, in line gaze filters and cartridge oil filters (if not already fitted now is a good opportunity) and most importantly.......the OIL TANK, if the Enfield has one. Remember I am not a Royal Enfield owner.

Metal "dust" in the oil will be both visible to the naked eye, and not visible. Both types will have been deposited upon any surface with which they have come into contact.

Sorry to labour the point(s) but I do have a thing about cleanliness and clean oil in engines. Once an engineer always an engineer I guess. Hope this helps.

[Mark M]

Terry, while I agree with what everyone else has said about cleaning and close inspection, you CAN re-use the crankpin if it is undamaged and measures up ok. I have done many thousand miles on a Redditch 500 which was rebuilt this way. The floating bush (which on yours has disappeared!) is designed to wear faster than the other components and is termed "sacrificial" in this context, ie, it wears out before the other parts. Remember, this includes the outer track which is in the conrod eye so check that too. This type of big end was designed in the 30s and is very reliable BUT must have a good flow of clean good quality oil. This does not necessarily mean you should fit high capacity oilpumps by the way, they can cause problems too! While you're at it, check the small end in the rod, I've seen cracks and ovality in Indian rods at this point. With a Redditch forging the small end can be bushed but I wouldn't risk it on an Indian one, I don't think the metallurgy is good enough. If in doubt, do the whole thing, it's your peace of mind!
REgards, Mark

[PeteF]

I would agree with our Mad friend if the engine had shells but I think with the floating bush you will be fine IF it measures accuratly.