Saturday, October 20, 2012

Aiight then, this is all about my Hi Cam Guzzi Cafe racer build. I’ve been too busy building this thing all summer to blog about it, plus this is my first blog anyway, so this initial dump is everything since I got the bike nearly a year ago.

Basically, I’ve been riding a 1973 Moto Guzzi Eldorado for 15 years or so, incessantly tweaking it, adding the one liter jugs, a B-10 cam, headwork, 40mm pumper Dellorto carbs, RAM low inertia clutch, and tuned the thing to perfection using a wide band oxygen sensor and palm pilot bungeed to the speedometer to acquire and display data.  Took me most a of a summer, but after rejetting the carbs multiple times, the old Eldo runs just about as smoothly and fast as any old Guzzi out there.  The WBO2 sensor and data module was from Not to get off topic, but this technology is the best thing to happen to carburetted engine tuning since the "Used Plugs Tell a Story" poster, and we all know how helpful that was. The wideband oxygen sensor is simply invaluable, no more guesswork as to what's lean and what's rich, at every step of the way from idle to FWOT.  

Anyhoo, I love that bike like a brother, but was hankering for more performance, plus needed something to tweak on.  New bikes (anything made after 1985, and resembling a letter opener) don't appeal to me.  I love vintage bikes, and café racers, and have been following the café racer, shed builder / garage/builder movement, and thought I would give it a bash.  My concept was to take a modern Guzzi and turn it into a retro café racer.  The donor was going to be a Sport 1100 or Centauro, preferably a Centauro, with the 4 valve high cam engine. This bike is nearly identical to the mythical Daytona, Guzzi’s first 4 valve model, very cool looking, rare, and expensive if you can find one.

The Centauros have almost identical engine and running gear, but with lots of swooping plastic all over.  Perfect choice for a café racer, but also hard to find. I searched locally for months, finally put a WTB ad on Craigslist, and got a response. The owner was a well known and respected local bike guy, had a barn full of bikes, but really liked this one, even sold it once and then re-bought it. He made me promise the bike was going to a good home. Technically, that was true, but I didn’t have the heart to tell him I was going to strip it down to the bones and Frankenstein it.

The first day I had it I started unbolting the fairing, chin spoiler, rear cowling, anything that world come off and the bike still function. Replaced the air boxes, which could double as the HVAC system for a small building, with K&N pod filters, and made some other recommended mods (replacing the ceramic temp sensor with a brass one, installing a transil diode to protect the ECU, replacing all the relays which were prone to failure).

Rode it around like this for a while, just to get the feel of the bike.  It's very fast compared to the Eldo, lighter, and excellent braking (compared to drums).  It came with the adjustable swan neck clip ons, which are awesome.

So, I started assembling parts. I knew I wanted a bullet nacelle headlight, and found a 6” bucket on Fleabay, new old stock, off a Guzzi Stornello.  Mounted it using a pair of pliers welded to a wrench.  

Found a front fender  off a Honda 650, and sawed of the rear part. I love the way this looks, all swept back n’ shit. 

Making the mounts was a trick, because the bike has upside down forks, so the fender has to mount to the lowers, not the uppers like most bikes. Finally arrived at the least obtrusive solution by replacing 2 of the Brembo brake bolts with longer ones and making these mounts.

The rear subframe was made out of band iron and steel tubing, relocating all the electronics, ECU, relays and fuse block. This took quite a bit of  trial and error, tack welding and grinding.  I really wanted the subframe, tank, fender, and exhaust to all be parallel to the ground, with no upswept angles, but couldn’t pull it off on the subframe without compromising rear suspension travel (rear tire would have been too close to the subframe) or seat height (too high) and exhaust (would be too close to the ground). I did manage to get the rear stays the same angle as the forks with the help of a surveyor's clinometer (see pics at end).

The pipes are from DanMoto, in China, via eBay. Very cheap, but appear serviceable. I try to avoid this type of product, but couldn’t pass up the price, half that of other exhausts. The metal and carbon tubing is very thin, the welds tiny.  They are light. I just hope the 12 year old girl who made them did so at the beginning of her 14 hour shift, not the end.

The tank is off a 80’s Suzuki GS 1000.  I chopped off the front mounts, made and welded in new ones to get the position right, and shimmed out the stock rubber donuts on the frame. 

I welded NPT bungs on both sides, 3/8" on the left (to the fuel pump) and 1/4" on the right (to the pressure regulator).  Adapting the stock, tank-mounted pressure regulator and "electric cock" as the Guzzi manual calls it (insert your own rude double entendre here) took some kerfuffling, too.  Both needed adapters from the very obscure stock M16x1 (an almost unobtanium thread size) double-ended, left and right handed threaded adapters to good old NPT.  For the regulator, I found a stainless adapter (metric to NPT) from some HVAC place on the web after an exhaustive search, and remotely mounted the whole unit behind the air filter pod. For the petcock, I made an adapter by tig welding a spare M16x1 fitting off a Guzzi petcock secured on eBay (AFTER I sprung $80 on the stainless adapters) to some 1/4" NPT, and mounted it on the tank.  Much shorter and pleasing than the store bought'n adapter.

I cut out the side panels and welded in sheet metal for the knee cutouts.  I considered the hammering method, but don’t like the way those look.  This took dozens of hours, tig welding at 20 amps, barely enough to trip the sensor on the welding helmet, but plenty to burn through occasionally. Also spent nearly a day pressure testing and fixing pinholes.  The tank (another eBay gem) was very rusty, even came to me with a locked cap and no key.  Had it boiled out and coated at a local radiator shop. 

Here's some fun at the bike junkyard before finding the right tank.

The seat is from Dime City  They have a very cool, well organized, and entertaining  website, and lots of nice bits.  The seat was light as a feather and was very cheap. That’s the good news. It's a little asymmetrical, probably a very hasty job making the pan, so it took quite a bit of jiggering to get it on straight.  The stuffing is urethane foam, I’m guessing out of a can, the kind you get at the hardware store. Its hard as a rock. If it becomes too uncomfortable or breaks down over time, I can always get it restuffed at Richs or an upholstery place, or put in the layered closed cell foam myself. I made front mounting prongs, a rear releasable latch using the stock release mechanism, and four adjustable T shaped seat supports (threaded into nuts welded onto the subframe). 

The best part of this seat is that the stock Centauro tail light, turned upside down, is  a near perfect fit under the rear part, the bum stop. I had to put the seat under a heat lamp and bend it a bit, but the effect is awesome - totally tucked away under there like it was meant to be.  

Note the little curved gusset welded on to the back of the tank to fit around the seat - a nice touch I thought, albeit messed up by all the guts, battery and wiring visible underneath.

Turn signals are the old bar end kind, from Emgo. Kind of vintage looking, so on they went.  Had to cut them down a bit to make the hollow (for the wire to go through) mounting bolt reach through the rear subframe and headlight up front.

The instrument is an Acewell computer, with speedo, tach, clock, and all kind of indicator lights and modes, in a 2.5” diameter gauge. It even has a fuel level gauge, which connects to an Acewell sender I welded on the Suzuki sender mounting plate. 

I've never had or ridden a bike with an actual fuel level gauge - I'm going to miss unscrewing the tank bung every few miles and peering in there to see what's left.  I never really took to the whole concept of “reserve”  on the petcock, which is basically a system that lets you know when to find a gas station by stalling out the engine right as you try to merge into freeway traffic.

The battery went under the tank, although sadly is somewhat visible once all the bits fell into place. I couldn’t figure out where else to put it. Here's the battery box (upside down).

Also under the tank is the compressor for the Nautilus air horns. I sawed of the horn part and affixed it to the front of the bike.  I have had Fiamm or Nautilus (after they came out) air horns on every bike I’ve owned for years; these are invaluable and have saved my life more than once.  Here's the trumpets on the Eldo, affectionately known as the "death ray" for their ability to burst the eardrums of anyone in their path. 

Went a little subtler with the Hi Cam, barely visible over the fuel pump.

So, here it is, flat black and ready for paint. Still deciding on colors, but leaning toward black and red, maybe black and off white, a vintage look.  Overall, I like how it came out, but it only looks vintage on the top, with sport bike looks on the bottom – kind of  a mullet bike.  The lines aren't as clean as I'd hoped, especially the tank to seat transition - I couldn't figure out which lines to carry back. There are no straight lines on the seat, and the subframe was problematic due to rear wheel clearance and seat height.  Also I had a hard time hiding all the wiring, hoses, and intestinals, but that gives it kind of  a machine-y Borg look.

Future winter projects are to make a new exhaust crossover that will allow horizontal placement of the exhaust cans – I think they will fit in front of the rear wheel. That might help with the looks, provided I can get the same or more ground clearance. Also wondering about the carbon fiber - not very retro. Options are limited - stainless would be heavier, so maybe I could find some aluminum tubing.  If I had a few thousand bucks kicking around, spoke wheels would be nice, but that’s a bit out there. Also ruminating about switching to carbs, like some flat slide Mikunis.  That would be an effort, plus require a new ignition system  With the wide band oxygen sensor, I’m pretty sure I could get the same performance as the fuel injection, at least within a narrow range of conditions like during the summer around here which is where I will be riding this.  Anyway, now I need to ride the thing, see what else need tweaking. 

short videos  
before paint
and after

Nice writeup at the Bike Shed here

More photos here
Note to purists and those from the SPCM (society for prevention of cruelty to motorcycles) there was no cutting or grinding on any stock part of the bike – all the stock bits are safely put away in boxes, swaddled in old underwear, in case someone ever wants to restore this to its stock condition.


  1. I love what you've done - A good trick I've been using on my DOHC Honda Sandcast tribute bike project, is to soften the lines of the engine covers - I'd suggest grabbing a spare pair of cam covers for those heads, a bastard file, and a detail sander - You could probably take those square corners right off of those heads, get more of the rounded dome look on the Ambassador etc, and all without thinning the metal down at all - they're probably a lot thicker in those parts, I'm sure they could be mike'd easily enough - they'd probably round down a huge amount before they matched the thickness of the flat surfaces. Oh, and another one - I know your forks are stock and all, but it really gets me when people put USD forks on old classics, going for a cool café look & everything, but they neglect to include the USD in the paint & bodywork of the whole design - Look at the forks on old Guzzis again, or Hondas or some Brit bikes for that matter - they use painted shrouds over a lot of old forks - Well USD forks are just BEGGING to be painted up in gloss, maybe with a nice chrome ring detail over the clamps etc. If you're bothered at the thought of painting a tube that won't pull out of the triples, they would lend themselves very nicely to a simple shroud or even a sticky mack-tack sheet of shiny vinyl etc. I'd do it with an alloy or fiberglass tube if nothing else - a one piece tube that uses a cut-out for the triples in the same vein as was done on Guzzi Nuevo Falcone military bikes - IIRC - For sure, painting tubes that need to slide out of clamps afterwards, sliding clamps over newly painted surfaces etc - that's all a huge pain in the ass - but if you compare how much more difficult it is to make shrouds to cover a non-USD standard fork, it's far far easier to work with the USD stuff. When they're un-painted, the colours don't match yet it looks like they should, and the bike looks incomplete. Just a brain-fart. Great bike by the way! - SoyBoySigh


    1. Silas, Thanks for the comments. It’s true, it’s a bit of a mash up, all vintage on the top and all modern on the bottom. Taking the valve covers off and at least polishing them was on the list, but I got sidetracked with other bikes and, uh, life. Fork covers or paint is a great idea, never occurred to me. It would look even more like the Eldorado. Good luck with the CB. Cheers.

  2. Hello Arnie,

    thank you for the story. Good job! I will strip my Centauro next winter and I`m still struggling with the fuel tank. I`m wondering what Kawasaki tank is it on the picture above. It looks very good to me.
    Cheers, Mario