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[Onedayrestoration]

Hi,
First post here for a long time.
For an iron barrel 2000 Bullet.
Q:Will the 350 crankshaft and rod fit the 500 engine?
I know the barrel/piston/head and crankcases are different, but was wondering about the little end/piston pin size.
If the answer is no, there'll be a Bullet, with a fully rebuilt 350 engine, going spare.

Cheers

[Bullet Whisperer]

The components will physically fit, but the balance factor of the 350 crank is a bit different, although the Bullets seem fairly insensitive to changes in piston and conrod weights, so you might get away with it without suffering excessive vibes. Also, the small end eye of the 350 conrod is narrower, but the 500 piston 'will fit'. Regards, Paul.

[ChrisD]

Hi BW and OneDayRestoration. As a slight digression from here back to the discussion on the new steel conrod on my 535cc Bullet (1996) because I think it may be pertinent. I fitted it without re-balancing because several of the authors here suggested it wouldn’t be necessary as the flywheels etc are so heavy anyway that a few grammes make little difference. Wrong.

I’ve just done a 4-day, near 1000km ride post-rebuild, and the vibrations over 4000rpm, i.e. when accelerating through the gears, were something awful to feel. In fact the vibs at 4500rpm are large enough to make the tachometer shake a centimeter or so up-and-down and it is now destroyed. The vibs also cost me the loctited and spring locked nyloc nut holding the main engine stud and silencer to the frame whislt the loctited and spring-locked rotor nut which unwound itself and destroyed the rotor.

So, YES, my experience is that you neglect the balance factor at your own risk, especially if you change the OEM aluminium conrod for a steel one, as a difference of a couple of hundred grammes (in this case the new conrod is 240gms heavier) is very destructive at higher revs. On the plus side the bike went very well (for a while).
Cheers, ChrisD

[Dennis C]

240 GM's, plus a heavier piston?, good grief no wonder it shakes.

[Bullet Whisperer]

Hi Chris, I can only speak from my own experiences, where I have changed from alloy to forged steel conrods and to the Accralite pistons from standard in some 500cc Bullet engines, without altering the balance factor of the flywheels. I lightened a set of 350 flywheels to use in a 500 and rebalanced them, because they would have been way out of balance otherwise. Personally, I would be more worried about getting the truing of the flywheels and mainshafts as good as possible, as even a fairly small runout on the mainshafts and / or flywheels will really cause the shakes! Regards, Paul.

[Adrian]

With nearly 8½oz. extra whizzing up and down for the rod (in old money) I would insist on a re-balanced crank, which is what I had Bullet Whisperer do when I got him to sort out a (former 350) crank for my current 500 project bike:



https://www.youtube.com/watch?v=huIKRPrfRaM







Onerestoration, I'm not sure where you're heading with your original question, but if you're thinking of using the original 350 alloy rod in a 500 conversion, please don't! The "correct" 500 alloy con-rod is itself a known weak spot in the 500 engine, even with the beefed-up section around the little-end eye. There was a thread about this a little while ago on here. How much less should you trust the weaker 350 rod when it has to cope with a heavier piston than intended? In some engines even steel con-rods have been known to let go when the weight of the piston is too much for it, think BSA B50 and the after-market in CCM and Carillo con-rods... Our hosts sell 500 cranks complete, either the factory model or their own performance version, if you don't fancy changing con-rods and rebalancing the 350 crank.



A.

[Adrian]

Sorry Paul, you beat me to it again! A.

[mauri]

lining a crank out directly on the original axels is something i don’t do, especially on enfield’s.

the axels can be so non-round lining out on them will give a correct measurement but a incorrect result, hence the crank is not actually aliningd.



neither do i pin them between centers.

the slightest of tension between the centers by itself gives a wrong measurement.



but to each there own way of doing things .

[Bullet Whisperer]

Actually, Maun, I also have a rig to spin the cranks supported by the mainshafts while running in their bearings, to make doubly sure all is well. Then, for a third check, I place the crank into the crankcases and bearings, without bolting them up and spin the crank to check if the crankcases 'walk' against each other and for any actual runout on the mainshaft ends. Fourth, I clamp the cases up tightly together and check the crank spins freely, as can be seen here ... https://www.youtube.com/watch?v=qKd_gVrhxsE - if a crank does not meet my requirements at any of these stages, I work to put it right. Each to their own, as you say. Regards, Paul.

[Tim NZ]

Yes they will fit, I have worked on several such motors from out of India and all were total disasters. I would not contemplate doing such.




Truing a crank?


Crank fitted with bearings to be installed in cases, bearings sitting on Knife edge v blocks, dial indicator of each end of the shaft. Any and every discrepancy in assembly is immediately discernible: pinched, eccentric, offset, mismatched halves or bent.


Balance? In my experience a change in excess of 1 oz of reciprocating weight is discernible, more so on the 500 than the 350.