Hitchcocks Forum

Hello people,
I've just got a '73 Indian 350 bullet that already had been modified to 500 and supposed to be in a good shape after rebuilding, but the more I check and starting to understand the bike I just find more and more defects.
I'm trying to figure out what are the limitation of the 350cc engine (lower engine?) that prevent
from modifying it to the 612cc kit (in case of staring complete new rebuild).

Thanks, Mark.

First one is the condition of the threads for the relocated barrel studs...


Next, and probably more important, the condition of Fit & Finish of the Bearing seats.


Does your engine number end in an X?


If the crankshaft bearing outer races are anything other than A PERFECT fit in the crankcase, you WILL have serious problems!!!
No Loctite, No Sleeves, No Knurling, No Staking, AND most important of all that the bearings seats are confirmed to be in alignment!!!


If the crank cases are not a matched pair with line-bored bearing seats, you will be pushing runny poo up a very steep hill with a short pointy stick.

Are you sure an old indian 350 bottom lump is a good candidate for the 612 conversion? What compression are you running now? I don't know the compression of the 612 but expect 8.5 or even 9:1. Plus the extra thump. Stuff has to be done up tighter. I've seen alloy crankcases stripped out. Will your crankcase take that?

as with anything, if you want it to end in smiles and joy.



preparation and follow up is the most important part of the build.



check your engine casing on any problems, alignment, stript treads, damaged surfaces,…..



check and recheck every part you receive, alignment crank, piston to bore size, straightens of pushrods, ……..



i had one new crank wich was so badly alignt, that the person who recheck it for me ask me if a had dropt it!.

same example goes for the cam followers and guides 90150, these are listed since quite a long time as “ currently unavailable”.

the hard chrome came of those after a while, the replacement did the same.



the 612 kit can maybe mistakenly seen as a furniture kit from ikea.

a kit you bolt together and its done.



reality is, unless you are a decant mechanic who can make an analysis of a problem and subsequently figure out a solution.

it will cost you more money than just the initial price of the kit.

and end in a lot of how’s, what’s ,dam’s, bugger’s, bloody’s……….

The 350 and 500 share a common crankcase, just machined differently for the cyclinder studs and spigot. If its a 'backstreet' conversion I would look carefully at how its been done and get a reputable engineer to check it.

I've heard it said more than a few times, that the three-fifty is a much nicer bike to ride than the five hundred. Makes me wonder why anyone would want to go even bigger.

Indian bullets crankcases were only paired and in-line bored (whilst bolted together) from 1982. If yours is 1977, then might be a problem with alignment.

I would not spend anything more what is required to correct the known bodgery anything else is a recipe for financial damage and real tears.
If indeed it is your desire to seriously modify a 500 lump then by all means do so but, get hold of known good one that has not been molested by suncontinental hammer & chisel operatives

Markus, I'd love to do a 612 also. I think personally though, if I was to go for it I'd use a good, tried and tested, British export market genuine 500 as a doner

You could try one as a doner, with plenty of chili sauce and not too much salad, though it would never fit in the pitta bread and would probably break your teeth when you tried to eat it. Alternatively, you could use that 500 Bullet as a DONOR bike for the 612 kit.



https://en.wikipedia.org/wiki/Doner_kebab br>
Mmmm - hungry?

A.