PGK's beemer with a big update!

[PGK]

flash back to 1981. BMW decides it's time for something completely different, and make this:

The R80GS, and create a new niche within motorcycling. A year gets on, and they decide to create a niche within a niche with this:

The R80ST. it's a GS with a smaller wheel, more tasteful paint, and shorter, narrower bars, a tachometer, and a few other things that make it a more useful streetbike. Back then they called bikes like it 'scramblers' now we would call them 'supermotos'. Either way, no one buys it, less than 6000 are made and 980 are imported to the US. Most of them sit. Then along comes my dad, and buys one, brand new. First vehicle he bought new, only bike he had until he bought his R1100S in 2004. He puts 130,000 miles on it. The first 100,000 are entirely city miles--he trained motorcycle couriers in DC with it. He keeps riding it after he's through with that, and gets almost $15,000 worth of work done to it over its lifetime. He then hands it down to me. I beat the crap out of it and last may I blew it up. Scored the crankshaft, and destroyed the rod bearings.

(old on the right, new on the left)
It got taken down and put into storage at my parents place, with the intention of doing a total restoration, eventually. Eventually gave way to right now, due to impatience, which brings me here. I got a new crank, as you can see in the pic. So this morning I head out to my parents, and load up the car.

Drive to work, and unload, and get started.


The goal for the day was to put together the rolling chassis and ancillaries, bleed the front brake, order seal kit for the motor, and clean/inspect motor parts in preparation for the rebuild.

progress. Installed bars from an R1150R Rockster. kinda a cross between drag and superbike bars, a slight rise and very wide.

headlight/wiring harness/tank etc all on. Really, not much to installing the tank. it's held on with a metal ring that loops around the frame spine. also, i dented it in a crash.

nu shooz!
and now, for the motor:

that's pretty much it. these motors only have 8 or 9 parts.

combustion chamber. Valves, seats, and guides were all in immaculate condition. CC products guides, valves, and seats, along with valve spring shimming was done in '93 or '95. not much to see, but i decided to do a mexican valve job anyways. after:

pretty.

about that time i got tired. and went home. more to come later, as parts arrive/shit gets done.

[CaptainHenreh]

Awesome!

[Ginger]

I never thought I'd see the day! Speaking of the day, I remember the day you put a dent in the tank.

I can't wait to see it going again. Are those the semi-bent bars on it? These are cheap as stink if you don't feel like straightening them:

<!-- m --><a class="postlink" href="http://cyclegear.com/spgm.cfm?L1=&L2=&L3=&L4=&item=CGC_T2-BAR-YZ-GOLD&tier2=65">http://cyclegear.com/spgm.cfm?L1=&L2=&L ... D&tier2=65</a><!-- m -->

[ScottyB]

whoa, cool project! and...progress. not used to seeing that.

[PGK]

Are those the semi-bent bars on it?

No, the bars on it are straight, from a Rockster. the bents ones were from an F650CS.

stayed late today to start on some motor measurements. The rod big-ends are out of round, but we have a machine shop that fixes that. just another bit of trouble. journals on the crank are all a-ok though.

[PGK]

Dropped the rods off at the machine shop yesterday, they are getting machined and having the bearings and bushings installed. once they get back I'm going to balance them at the shop, balance the pistons, install new rings, and have a nicely matched top end.

More bad news today though. One of the exhaust valves is pitted, and closer inspection showed that all of the valves had extremely worn keeper grooves, probably about 5,000 miles from dropping a valve. new valves it is. I might get fancy and do some 5-angle crap or something, maybe polish up the ports.

Rideable and street-legal by early August is not out of the question. that's a very optimistic estimate though. a more realistic estimate would be mid-late September, but if I stay optimistic it might just get done sooner.

[CaptainHenreh]

Time for bigger valves?

[PGK]

Time for bigger valves?

Nah, I'm trying to put it back together stock, but slightly improved. That's why I'm balancing the bottom end, and probably gonna do a 5-angle with some port cleaning. I'm gonna be using aftermarket valves/guides/seats that are allegedly longer-lasting than stock. I'm also going to be machining a groove into the guides so they can accept seals--stock guides are unsealed and adding a seal does wonders for oil consumption. I'll also be replacing the rings.

Probably won't be much progress documented for a few weeks, i'm waiting on these hard parts and sundries to assemble, meanwhile sandblasting a part or two after work every day in preparation.

[PGK]

got the rods back from the machine shop today. put together the jig to balance them, only to find that the small ends were off by .1 grams, and the big ends were off by .3 grams. total weight the rods are .2 grams apart. Basically, I lucked out, this is the most closely matched set that my extremely experienced (35+ years) coworker and partial mentor has ever seen.

Aside from that, this project is getting bigger and bigger. I found out that we have a few 336 cams in stock, so I put one on hold. The 336 cam is a performance cam made by BMW. They started making them in the early seventies, because sidecar racers wanted a cam to raise the powerband without going with a super-radical custom camshaft. The opening and closing ramps are the same as a stock cam, but it has more lift and duration. Another coworker has a pair of 40mm bing carbs that I'm buying off him for cheap, to replace the stock 32mm carbs. This means I'm on the lookout for a pair of cylinder heads from an R100S, R100RT, or R100RS from 77-84, which have intake stubs for 40mm carbs and larger valves.

I'm going to stick with the stock 800cc displacement though, going to reuse the stock pistons (lightened and balanced, of course).

All of this means that the bike will take longer to complete, but man alive will it be a runner. I'll upload pics next week of the assembled/cleaned bottom end, possibly even installed in the chassis.

[Ginger]

w00 w00 - go Phil! I'll have a more substantial response later when I have more time.

[PGK]

Made progress today, just not as much as I had hoped. I need new crank main bearings, but the good news about that is that i need them in the stock size, not oversize. i'll take care of that sometime this week, i would have done it today but if you do that you also have to check crankshaft endplay and replace the thrust bearings, which i did not feel like doing. that's something that you do only when you are ready to completely assemble the motor.

The flywheel forms an integral part of the crankshaft assembly. if it is not attached, the crank can slide forward, and the thrust bearings can come out of location, taking with them their locating dowel pins. this sucks 'cuz then you have to tear the motor down again.

what i did do today was measure the crank, clean some stuff, and balance the top end.


Pistons and wrist pins.


remember sig figs!


see the little numbers? and the tabs a little inside from the base of the skirt? yeah, those are on their way out.


spot the difference!

when all was said and done, each piston/wrist pin assembly weighed 503.7 grams.


that's aluminy. you can't stick a magnet to it, nor is it in any way poignantly funny.

i mentioned in my last post about adding 40mm carbs....

stock 32 on the left, new 40 on the right.


stud pulling. to sandblast the case, i had to tape over every oil passageway, and put a bolt into every threaded hole. even with all that, the oil filter compartment was full of sand.

here's an after picture:


and here is the block with crank:


cylinders:


my dog in the sink:

[/img]

[Dave]

this is an awesome build and I really like your attention to detail. I have no idea what you're building and I'm too lazy to look it up, but I'm enjoying the updates and documentation.

[ScottyB]

this is an awesome build and I really like your attention to detail. I have no idea what you're building and I'm too lazy to look it up, but I'm enjoying the updates and documentation.

ditto....i don't really know what's going on but it looks awesome. :thumbup:

[PGK]

Sneak peek update! not too much to comment on. Every time I work on this bike my estimated time of completion grows further and further distant......maybe in 6 months it'll be done. I had to wait for pistons, then I had to find some heads, then I had to find cylinders.....now I'm waiting on custom prototype lifters, which aughta be stronger and lighter than stock. Which is important, because the cam I put in the block is a Crane Cams 336 regrind...they take the BMW 336 cam and regrind it. stock cam valve lift is a puny .225", lift with this cam is .485". that's right. double.

So, I've basically eaten my words with the 'stock but slightly improved'.

That's the new one on the right. I'm not keeping the stock 800cc displacement after all, instead, it'd going to be 1050cc. It's also lighter than stock.


Black diamond coated valves, heavy-duty concentric valve springs, and titanium valve spring retainers. Believe it or not, all of these are less expensive than the same BMW parts.

I'm working on grinding the valve seats whenever I have a spare moment at work. I'm starting to really get antsy about this thing....

[Ginger]

Looking good, of course.

:thumbup:

[PGK]

Put it together yesterday and today. Crank turns freely, nothing hits anything else. Used a pair of custom re-usable copper head gaskets, I'm testing them for possible production and sale. They just need to be annealed prior to each installation. You can't see them, but they are tres cool.

Headers mocked up. You can see in this picture just how offset the cylinders are, which is the source of the only discernible vibration in the otherwise perfectly balanced horizontally opposed twin.

Engine covers painted, with highlights added by Black&Decker and a roll of 100 grit.


A couple close-ups of the new valvetrain parts.

A few days ago I cut open the exhaust collector and removed the baffles. I didn't have my camera with me, but the way the baffles were arranged was baffling to me. Very restrictive. So, I removed them. Today, I re-assembled the collector with an Oxygen-Acetylene torch and some wire coat hanger.

This is the first time I have welded anything, ever. So naturally, I screwed it up, and my first experience welding led directly to my first experience brazing.

I actually went a little overboard. there were a few pinholes that i wanted to plug, and i wanted to patch up some holes that had rusted through. Once I painted it it didn't look so ugly.

Then, once all the exhaust paint had cured in the oven, i mocked the whole system up.

The can is a Leo Vince, for an '07 R6, courtesy of Andrew. It's just hanging on the end there, I need to weld and elbow to it so I can neck the inlet down enough to fit on the collector, and I need to angle it down enough to clear the subframe on the bike, but as it hangs there is basically as it is going to be.


BRAAAAAAAAP

[CaptainHenreh]

OMFG THAT'S BEAUTIFUL

[ScottyB]

you don't mess around, do you?

[Ginger]

Yay BMW! I like progress.

Do you think you'll be finished in time to come to the show? I might make an effort to get the F4 90% to come down if I have some company.

[D_Eclipse9916]

Beautiful build!