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500 bullet crankcases apart.

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500 bullet crankcases apart.
Started at 09:01pm on the 30th January, 2018 by stinkwheel
stinkwheel Subject: 500 bullet crankcases apart.
Just dropped the bomb on a 612 kit from our hosts. Scary, now spent more than the cost of a brand new UCE bullet on this project! But anyway. I've just split the donor engine. A 2004 500 bullet. A few questions and observations for interest.

First off, I was wondering if there's anything I should be doing while I'm in here? It's getting new bearings throughout and the crankcase will need to be relieved to fit the new exhaust cam in but anything else?

Secondly, It looks like two of the pairs of stud holes have been machined to take dowels. None are shown on the schematics and this is definately the first time this engine has been split so it's like that from the factory. I'd intended to ask my local machinist to fit dowels when he's fitting the bearings etc. but it looks like I should be able the throw some in there anyway. Is there a reason there aren't any?



Third thing. I'm intending to re-instate the "original" breather system. This engine still has the castings from the original crankcase breather on the upper left side just below the barrel present but not drilled. I've ordered a Redditch style bolt-on breather stub and I'll run it past my machining guy to see if there's enough alloy to face-off the crankcase casting and bolt that on. Failing that, it'll be a case of drilling the cast stub and tidying it up enough to fit a hose to it (maybe cut a thread on it and fit a hose-tail). Also lets me look at the breather hole between the crankcase and oil tank. It's tiny! No bigger than 5mm. I'm going to solder this closed.









On the last one I had apart, the return hole between the crankcase and the timing chest also seemed awfully small for the volume of oil the pumps can chuck out to passively return through. I was considering enlarging the hole (maybe slotting it to maintain the oil level in the timing chest) Someone at the factory must have thought so too, this one has the small hole then another, bigger one above it.

Hope I got my HTML tags right!
Posted: 09:01pm 30th January, 2018
stinkwheel Subject: 500 bullet crankcases apart.
My last paragraph should read "the return hole between the OIL TANK and the timing chest."
Posted: 09:05pm 30th January, 2018
Adrian Subject: 500 bullet crankcases apart.
All the best for your project. Another option for re-instating the breather is to drill and tap a hole 1/4" BSP just behind the existing stub and fit a hose-tail to take a 3/8" or 1/2" hose.

A.
Posted: 10:10pm 30th January, 2018
Barry N Subject: 500 bullet crankcases apart.
Hi Stinkie, I done my 612 a few years ago. A couple of points: 1. you may have to file a little bit off the lip that forms the sump chamber at the bottom of the crankcase – the flywheels are slightly larger diameter and can rub there. 2. Don’t be tempted to run with just the 3mm compression plate! I made that mistake at first and suffered terrible pinking as a result. So use both plates supplied (2mm + 3mm) and I suggest a minimum of 3 base gaskets. I also smoothed off all the sharp edges (including the valve pockets) from the Accralite piston, which I felt would reduce the likelihood of any hot-spots, and would further reduce the compression a little in the process (just my preference). 3. When grinding clearance for the exhaust cam sweep, you will find improved access if you remove the cam spindle. I have a cam spindle that I made slightly undersize (sloppy fit), so that it can be dropped in and out in order to accurately check the clearance of the cam as you grind (thus avoiding removing more material than absolutely necessary). When done, you can then fix the proper spindle back in. 4. My engine breathes via the elbow at the base of the barrel (which was already in use) with the pipe running high over the mudguard and into a plastic bottle in the right toolbox (with a duckbill on the end). Mine breathes into the bottle approximately 100ml of oil per 100 miles (proper miles, not Km’s), which I’m fine with. 5. From memory, I’m pretty sure there were no dowels locating the crankcase halves – I think at least two of the studs are suitably machined to act as such (others may confirm this?). If you want, I will be happy to post you the dummy cam spindle, as long as you return it when you’re done! (Let me know on that). Good luck with the build – I think you’ll enjoy the result! Regards, Barry.
Posted: 12:35am 31st January, 2018
stinkwheel Subject: 500 bullet crankcases apart.
Thanks for that. Plenty to be going on with.

I've actually already ordered a cheap cam spindle from India for that exact purpose but thank's for the kind offer.

I'm quite excited about the whole process. I'm looking forwards to doing some bits of "proper" engineering like measuring cam end-float. I'm also going to borrow a burette from work and physically measure the compression ratio.

I'm not sure if I'll be able to bring myself to modify that piston.
Posted: 09:32am 31st January, 2018
ric Subject: 500 bullet crankcases apart.
The upper hole was originally there to equalise pressure between the timing chest and the oil tank not as an additional return route for oil exiting the timing chest. The oil level sits a lot lower than the bottom of the smaller hole. If you could (temporarily) fit an old style filler cap with a built in dipstick into the threaded crankcase orifice you'd be able to see where the upper and lower oil levels sit in relation to the lower hole.
Reinstalling the old breather system and blocking the airway between the crank and oil tank will result in a dramatic reduction of air movement (and oil loss) from the spigot hole currently used for all engine breathing. Probably wouldn't do any harm to retain this rather than revert back to the original breathable filler cap required to relieve air pressure in the timing chest built up from scavenged air from the sump.
Posted: 10:09am 31st January, 2018
mauri Subject: 500 bullet crankcases apart.

kudos for doing this
i mounted my 612 kit long before there was speak of the efi's.

today i wouldend bother to pour this amount of money the old type of engine.
its not only about putting the kit in, because in time you'll find you'll have to upgrade everthing around it.

these days i would get a second hand conti, put a high bar on it and have a way beter bike for in the end less money.

Posted: 12:14pm 31st January, 2018
stinkwheel Subject: 500 bullet crankcases apart.
"The oil level sits a lot lower than the bottom of the smaller hole. If you could (temporarily) fit an old style filler cap with a built in dipstick into the threaded crankcase orifice you'd be able to see where the upper and lower oil levels sit in relation to the lower hole. "

It actually has the threaded type filler cap with dipstick. I was going to do this anyway tonight to see where the oil normally sits, I'll post a picture.

"Probably wouldn't do any harm to retain this rather than revert back to the original breathable filler cap required to relieve air pressure in the timing chest built up from scavenged air from the sump. "

Good one. I've done this on my 350 on the basis that it probably doesn't want a vacuum in the oil tank to fight the feed pump. I fitted a small filter element designed for a car crankcase to the oil tank spigot.
Posted: 12:17pm 31st January, 2018
Barry N Subject: 500 bullet crankcases apart.
Some more thoughts on the 612 build! With the 5mm stack of compression plates (if retaining the original cylinder studs) you will of course lose 5mm of thread length to engage with the cylinder head nuts. To go some way to counter this, I trimmed off the tapered “lead-in” of the thread at the end of the nuts to maximise the thread available (using a lathe to ensure squareness and removing just enough from the length, and no more). It may have not been necessary - the gain being not much more than 1mm - but I felt happier doing it! Another thing you will find, is that because the engine will be 5mm taller, fitting and removing the rear rocker cover is almost, if not impossible (because the frame tube is in the way) without removing one of the studs. I use an ordinary nut, with a saw cut through one of the flats, used with molegrips, to whip the stud in and out whenever I need to remove/refit the rocker cover. B.
Posted: 01:40pm 31st January, 2018
stinkwheel Subject: 500 bullet crankcases apart.
Good tips.
I'm planning on making some new studs anyway. The cylinder head studs on my engine are bent from it being stored with no top end on and having stuff stacked on top of it. The plan is to make a set of new ones slightly longer than standard and with a square on the top (inspired by our hosts ones I have fitted to my 350) to allow for their removal with the head in-situ. Makes stuck cylinder heads a thing of the past because they can be twisted off.

Good tip on the rocker cover studs. Thinking about it, the simplest way may be to file a flat on the stud just abover the bottom thread. Then the cover can be lifted up slightly and a spanner inserted in the gap to loosen the stud. I'll have a look at that nearer the time.

I also think this would be a good time to make some marginally longer gearbox studs, again with a flat/square filed on the end, so the gearbox can be fitted or removed with the engine in the frame.
Posted: 02:08pm 31st January, 2018
Alan R Subject: 500 bullet crankcases apart.
Good stuff, Stinkwheel...........Don't forget that EVERYTHING relating to the barrel ( and therefore head as well ) will now be 5mm different..eg The exhaust pipe and its' mountings will need re-aligning.....The carb will that much higher as will the inlet air trunking..and also your head steady bar....As 'er indoors said to me recently}----"You're doing a good job, keep it up" !!
Posted: 03:18pm 31st January, 2018
stinkwheel Subject: 500 bullet crankcases apart.
Well. Oil tank level sits higher than I'd expected according to this dipstick, which is the one it came with.



Posted: 07:18pm 31st January, 2018
stinkwheel Subject: 500 bullet crankcases apart.
Try those again:



Posted: 07:19pm 31st January, 2018
Wayne Subject: 500 bullet crankcases apart.
Stinkwheel - the design of these long stroke cranks have changed over the years and now the 5 mm spacers are no longer required, of course as with all tuned engines - these must have a dry build to check clearences etc and the previous comments made were made in good faith but I thought I had better mention before you built an engine with 8 : 1 compression !
Posted: 02:11pm 5th February, 2018
stinkwheel Subject: 500 bullet crankcases apart.
Thanks for that. I'm going to physically measure the compression ratio anyway. Got a burette on order. I'm quite looking forwards to doing some of the more enigmatic aspects of engineering like plastiguaging end float on cams and calculating compression ratios.
Posted: 03:59pm 5th February, 2018
Alan R Subject: 500 bullet crankcases apart.
Good stuff O wheel that doth stink !!.........At this rate you'll be up for an HNC (Mech.E).....Keep going, we are all behind you !!
Posted: 04:15pm 5th February, 2018
stinkwheel Subject: 500 bullet crankcases apart.
Just dropped the cases in with the engineers today.

As you'll know, the exhaust cam comes VERY close to the crank seal and the standard advice is to burr away the alloy until the cam fits.



That leaves almost nothing supporting one edge of the seal (picture from our hosts fitting instructions).



Local engineer loves doing stuff like this up and he says he can press out the cam spindle, measure up the cam rotating diameter then centre the crankcase on his boring bar over the cam spindle hole. He reckons he can then tool it with a longish cutter to undercut the seal seat to the exact diameter and depth required for clearance on the cam while leaving the seal seat unmolested. In much the same way as it is now, only deeper.

Glad I asked before diving in myself with the pneumatic burr.

He also questioned why they bothered knocking a recess out of the crankcase casting for the two topmost "blind" crankcase studs other than to as a vehicle for trapping dirt and corrosion when they could have run through the alloy all the way through. I said you stop asking questions like that after working on Enfields for a bit. It's what they do, there may once have been a good reason that's lost in the mists of time and now they just do it because that's what they do.
Posted: 11:10pm 6th February, 2018
Chris Tindal Subject: 500 bullet crankcases apart.
There must be more room on Indian casings than Redditch ones. A previous owner modded my 59 500 cases to take a timing side oil seal rather than just the bronze bush. In doing so he cut right through into the cam area so that the seal penetrates through and will therefore allow oil in behind it. Be aware there's very little alloy between the cam and the crankshaft.
Posted: 07:39am 7th February, 2018
Alan R Subject: 500 bullet crankcases apart.
Hi matey !!-------- If I'm reading your chap's idea correctly he wants to machine a cavity below the seal housing without cutting down through the seal housing itself ??.........Is that the case ??...OK, if you do it that way how will you assemble the gearwheel/cam unit onto the shaft ??........You'll have to place the cam/gearwheel unit in position first ( ie ---with the cam inside the newly-formed cavity ) then push the shaft through the gearwheel and into the inner casing.....Then later on, how will you remove the camwheel ???

Personally I'd stick to our hosts method as the amount of "Almost unsupported" seal is very minimal........More important is the point raised by Chris Tindal}--- Be VERY CAREFUL not to break through behind the seal and thus effectively by-pass it...........I hope your man is a skilled machinist and can handle a vertical miller proficiently ??...........PS}--- has anyone tried actually reducing the cams' lift ( In order to make it fit more easily ) and relying more on the overlap for power increase ??
Posted: 02:54pm 7th February, 2018
stinkwheel Subject: 500 bullet crankcases apart.
The cam slides straight onto the shaft providing the lobe is pointing roughly away from the crank. There's a roughly 270 degree arc of rotation where the cam doesn't interfere with the casting at all.

To assemble it correctly timed, I can fit exhaust cam first, then the timing pinnion then the inlet cam.

Yes he's a very skilled machinist. The stated clearance is 0.02" round the highest point of the cam so that's exactly what I'll get. In a perfect circle. He'll be using the boring bar normally used for reboring cast iron liners to a WAY finer tolerance than that. It's a proper piece of 1950's british machinery he bought when tru grinds in Carlisle shut down. Also huge, they built the workshop extension around it. I should take some pictures of this guys workshop some time. He has over 20 lathes.
Posted: 04:40pm 7th February, 2018

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