Forum

[Alan R]

Hi Ivor--------I actually meant open the oilways WITHIN the rocker blocks......It's a known mod and Paul ( He who whispers to Bullets ) Henshaw can give you the drill size required I hope.....I modded my last 500 but that was pre Bus Pass-- or so it seems and I can't remember the size...........Just a thought but if you are retaining the floating bush big end then I'd keep the standard oil pumps ( to give the pressure required by a plain journal bearing ) but give them a good overhaul...

[scotty]

Replaced a few btm end bushes never had to ream any you and split flywheels with four nuts and bolts cut to fit between wheels with nut screwed down two near pln othersb50mm out pln nut off do your nuts up til they contact wheel then two flats at a time each nut, if you run out of thread back them off and pack with washers once they are nice and tight give pln a tap with hammer they should come apart.
Might be an idea on 535 to get wheels balanced to 63% bit diff in weight between pistons, mine were done with crank completly apart.ndrill size for rocker box holes are in sites tech notes might want to up carby size i run 32mm jap mikuni and pod filter.

[ChrisD]

Ivor. I too went the 535 route on my 1996 500. I too agonised about the OEM conrod. I too eventually went the steel conrod+roller bearing route and alloy barrel.
When the engineer removed the OEM conrod, he discovered it was 20thou longer than it should be, and although there were no nicks there were a couple of dings that must have predated export from India to here in Cape Town. So it was stretching and would soon have snapped!
But I didn’t get the system balanced after installation. That was a DISASTER which cost me a complete rebuild as the vibrations destroyed rotor (and hence stator), drive side crankshaft and bearings. So should you rebalance? YES, and to ~63% as Scotty suggests here (and earlier, too). See my thread about this from mid-last year.
Cheers, ChrisD
PS: just because you have a better-revving engine, make sure the valve retainers are undamaged. One of mine snapped some 6 months ago, barely 2000kms after the above rebuild and the valve made holes in everything it could touch – and I’m still not back on the road. Perhaps this broken retainer was another result of the out-of-balance flywheels etc.

[Bullet Whisperer]

Hi Ivor, First of all, the alloy conrods will break, if exposed to 'high' revs - 6,000 or so should do it, if you want to find out, but they can cope with increased power at 'normal' Bullet engine speeds, say around 5,000 rpm for instance. I have built and tuned quite a number of Bullet engines to date and irrespective of piston or conrod type, have never run into problems regarding vibration due to crank balance factor when a swap has been made. Truing a crank seems far more important than changing the balance factor very slightly, I use a set balance factor for all my lightened cranks, regardless of piston or conrod type and it has worked ok to date.
If you are tuning for more power without increasing the rpms, I would polish the alloy conrod at the very least, or fit one of our host's upgrade British made ones. The plain big end will be fine and only yesterday, I had to hone a new big end eye [which someone else had obtained and fitted to a conrod], in order for the floating bush to fit inside, but usually they are a straight fit on replacement. We broke a forged steel conrod in the 500 racer a few years back and were given a free replacement and the design had been improved slightly compared with the broken one. If you fit the plain big end and high capacity oil pumps, just let the engine warm up properly before revving it too much. I have never drilled any rocker feed oil ways to enlarge them, but have opened out the crankcase oilways a little in just a few engines. Regards, Paul.

[Alan R]

Sorry Paul----perhaps that was what I had in mind ??-----

[Ivor]

Hi and thanks to everyone for the advise. Spoke to Paul Henshaw today and he is going to do the bottom end for me. Splitting and balancing/truing the crank is not something I`ve done before so I`m leaving that to the expert. I will do the rest.

[Alan R]

A wise decision that I'm sure you won't regret.......Keep us posted when you start your re-build please ??