We are located in sunny WHITE ROCK, BC, CANADA

Contact Jim Bush by email

Phone 604-535-5800



project file: MV AGUSTA 1970's CLASSIC MAGNI RACE REPLICA with a modern 2004 MV 750cc F4 engine, fully streetable.

FRAME BUILDING 101: My Frame Blog is in reverse date order - older posts are below, starting July 4, 2011

March 18, 2012 - Final Build and Painting progressing at the same time. It is great to be able to bolt up things to the frame for the last time. Swing arm is final with greased needle bearings, seal and a delrin chain slider. The front forks are tightened down, tail light unit installed, battery box/ignition tray in place and frame fairing support / headlight in place. The Injector manifolds are completed and installed - I have to make a bracket for the throttle cables - this sort of became a huge hurdle, stumper as the final solution did not present itself until after several hours of head scratching.

frame 09


March 11, 2012 - PAINTING underway. The frame, swing arm, triple trees, shocks and head lamp support are now painted in Endura 2 pot polyurethane paint. This is a very hard paint when cured and is the perfect choice for a frame and other hard body parts. I matched the red to my 04 Brutale - which turned out to be a GM colour "Super Red 71U" It has an illuminesence and brightness that is amazing. The Endura paint is hard to apply - it can run in a heart beat. Painting a tubular frame is difficult at best of times and this proved quite a challenge to get coverage in all the nooks and crannies without the runs. So far looks successfull. The only frame I have painted harder than this one was my Banshee ATV frame that I did in passion pearl (purple). This picture shows all the extra bits and bobs welded to the frame - looking at it I can't beleive I actually made this - 9 months of fabrication and here it is.


My paint room underwent a slight reno for this project. I installed proper filters on the exhaust fan so not to annoy the neighbours with clouds of over spray. I added an extra light, so I have a 2 tube floresecent light on all four walls, plus 1 on the ceilings. I also added another 1500W baseboard heater. Becasue Endura likes really hot temps to cure - 30deg C Plus (86deg F), to help things along I brought in a cube heater and left it on full for the first 4-6hours - the room temps acutally got to a toasty 40deg C (104deg F). The paint cures over night at with this arrangement.

February 12, 2012 - Line reamed the swing arm spindle frame hole to 20mm by hand and fitted the stock Brutale swing arm spindle. I used an old set of machinists adjustable hand reamers with the guide taper cone. The only problem was the arbor was too short, so I had to machine up an 6" extension to reach the other side of the swingarm. It did the job perfectly - no CNC here.... The swing arm received the bearing retainer sleeves, 4 x 25mm x 32mm needle roller bearings & races, oil seals, end bushes and end caps. It is all fitted in the bike, with the rear wheel aligned to the front sprocket. The brake stay arm / mount, and shock mounts are the only remaining items.


February 11, 2012 - Swingarm #3 completed. With the help of expert metalworker Maurice, he fabricated, fitted, welded and finished the sheetmetal work to the highest standard. The basic 1x2 HSS swingarm frame has been further enhanced strength wise by adding 14ga (0.080') top & bottom cover, plus the side arms received C section strengthening. A 1/2" x 2" channel was breaked and fitted to the inside of the side arms and bent to fit. This tied into a 0.100" ga circular brace and top covers. It has all be expertly TIG welded and blended. The finished product is outstanding - especially when the eccentric adjusters and SS axle is installed. It weighs in at 14.6lbs right on target. Brake stay and shock mounts still to be fitted. Pivot tube has been machined true for the bearing retainer.


sa3a sa3b

February 8, 2012 SAGA of the SWING ARM CONTINUES.....

Recently made Swingarm #2 went to scrap, Swingarm #3 is underway. The original SA#1 (in the foreground of photo below) weighed in at 17.3lbs, SA#2 (at the back) with light wall tubing would be 10.6lbs, much of that saving from using 0.060" wall 2x1" HSS tube - it ended up just too light and flimsy. SA#3 (in the middle) used 100 wall tube and will weigh in at 14.5lbs, nearly a 3 lbs saving over SA#1. I am using 14ga (0.080") for the sheet metal infill instead of 0.100" sheetmetal on SA#1, as well as the area of sheetmetal is reduced. This time I allowed for heat shrinkage of the cross tube (spaced it out about 200 thou) and the eccentric ends came in on spec width wise after welding, without having to use the oxy torch. It is amazing how proficient one becomes doing the same thing over again.

3sas tube

January 28, 2012

Back to making a new swingarm #2. This time I machined, welded, machined the eccentric adjusters, BEFORE completing the rest of the swing arm. I have also modified the retainer cap to include perimeter ribs for strength. After welding up the rings to the swingarm stock, they were cut and threaded, then machined to true up the distortion from welding. The billet eccentric adjusters were machined to fit the caps, drilled in the rotary table for the axle and lightening holes. I included drill indents around the perimeter for indexing the adjusters when in the frame. This is much superior construction than what I had fabricated back in August. I will also be shortening the swingarm by 35mm in the process.

sw1 sw2

This week I also ordered up a set of custom shocks from WORKS PERFORMANCE. They have been very accommodating and helpful. I have a set of black trackers, with black springs, billet eyes and retainers and I can run them the conventional way with the spring up. I will repaint the body MV red - they will look really sharp.

December 27, 2011

Completed the fairing and headlight mounting, also final fit of the front fork bearings and forks. Check out the BODYWORK BLOG for more details and for the gas tank reconstruction.,

cockpit2 fairing3

October 31, 2011

Completed measurement and design drawing of the rear hub. In the following 2 weeks, completed machining sprocket adapter, axles, bearing spacers. Test fit with Chain Nov 20. Check out the WHEELS, HUB & BRAKE blog here (click photos for larger image)

hub hub9

October 30, 2011

Tail light mounted - using a classic period BREVETTATO casting and CEV light unit found on many MV's and other Italian bikes from the 60's & 70's. Direction indicators will be mounted just behind the light (to keep Transport Canada happy). To gain proper wheel clearance, I had to recess the tail piece about 20mm for the light. The battery tray / electronics compartment is fitted with final tabs and cross braces. Seat brackets and tank rubber tie down fabricated. I will be moving on to machining the rear wheel hub components including axle, nuts, sprocket carrier spacer, eccentric adjusters etc.

tail3 tray

October 24, 2011

Completed the frame welding adding gussets to the side plates and mounting tabs for the radiator. Checked the rear frame for clearance to the rear wheel - this involved bending the end of the frame upward about 20mm for added clearance. It will make the rear seat hump look better. Did a test fit and check over of the wiring harness, looks like I have all the required components. The ECU will be relocated to under the seat along with the battery and the rather large fuse box. I will make a sheetmetal base & sides to keep the water out - will still need a few more tabs welded. The foot rest mounts are finished and welded in position. I envisage a wheel hugger on the swing arm to close the gap between the wheel and frame. I slipped the faring on for a quick check - there is just the right amount of clearance all around - the rad fits in nicely. Now all the fiddly work begins.

wiring rear4

October 17, 2011 - We have a FRAME!

I was able to borrow a frame welding rotisserie fixture to start on the final weld up. Interesting was removing the frame from the engine jig and feeling that is was not as heavy as I expected. Once out of the jig after the weld up, I did a "struth test", checking the alignment of the steering stem (fingers crossed) - I am happy to say that it lines up perfect to the center line and the inclined angle is still 25 deg. I am now welding various tabs mount brackets, footpeg mounts, which is the slow part. The frame is now attached to the engine for final set up, no longer stuck in the rigid jig. Lots to get on with - rear wheel comes to mind, layout the electrics, finish the seat etc...... stay tuned.

rotisserie STRUTH TEST struth2

October 9, 2011

Big Thanksgiving push was on. Saturday I hosted an "open shed" for the BMOC members to come check out the project - really great turnout of 20plus interested parties. The back part of the frame is in final stages. The top tubes and seat support are in place. Down braces and the muffler support completed, except for final fit of the footpeg lug. Had a test fit of the MAGNI swan neck mufflers - I can see it all coming together now. Seat is next on list - have to fabricate the flat portion of the fiberglass base, lengthen and fit to shape of frame. Plus I have to redo the upholstery pan at the same time. I have not done much fiberglass work - should be interesting making a plug and doing the glass. Coming up is also fitting the radiator and finding a home for the ECU and other electrical items.


pipes1 mufflermt

MAGNI muffler set sure look that part!!!!

October 2, 2011

An hour or so was spent "struthing" the swingarm after all the welding. I set the spindles up on vee blocks and applied oxy-acetylene flame to specific locations, heated red hot and allowed to cool. It is amazing how much I could adjust the side rails. The swingarm is now installed in frame for first time. Layout and measurement check for shock mounting and the top rails completed. I installed a 2x4 HSS tube stanchion on centre that fixes the swing arm and top shock mount in alignment for the top rails. I am using Marzocchi AG Strada shocks for now - common for the era - they will be rebuilt and painted in the frame colour. The top mount was milled for the frame tube. It looks like the top tubes will require 4 minor bends each - off to Maurice's this week to use the tube bender for maybe the final time.


Good view of the frame jig and the mounting supports.

swingarm4 mill

September 25, 2011

After a week away riding the glorious back roads in Oregon & Washington with my buddies on my R1200GSA, I have finally been able to get back into the shop. Progress on the swingarm has gone well. The sheet metal strengthening has been added along with the shock mounts. The result is a well braced unit - I used 12ga plate (0.100") - due to the lenght of the swingarm, the cover is a little longer and now heavier than the Magni version. The inside shock mount plate is longer so that it can provide some strength to the weld joint in the side arms.The sheetmetal work required a lot of welding and I am proud to say that my TIG welding skills are improving. The welds will be cleaned up prior to painting: I need a welding inspection to register the frame, so I am leaving the welds virgin for now. The truing and sizing the pivot tube on the milling machine for the bearing housing has been done, using my rotary table in an unconventional manner as an angle plate! The strengthening of the wheel adjusters with a shaped support is next - awaiting waterjet cut brackets.

swingarm2 mill

On the right is the swingarm mounted in the milling machine to true the pivot tube for bearing holder.

September 5, 2011

Work on the swing arm progressed well with the main arms ready for the sheet metal work, bearings and wheel adjusters. I transferred the design layout plan on to a piece of sheet metal and constructed the side arms from 1"x 2" HSS tube 100 thou wall. I am using 2 1/2" dia eccentric wheel adjusters, which makes the end of the arm a little complicated. Once welded up, I used two machined blanks with a 1 1/2" solid round bar to keep things in line. The side arms were clamped in place to a large piece of 1/2" metal plate with 3" x 1/2" metal flat bar. The pivot tube was fitted in place so that is was parallel to the spindle at the adjuster end. Once all checked the welding began. The final result is true and still in line, I lost about 100 thou width at the adjusters due to welding the cross member and I was able to correct that with an application of oxy-acetylene torch to opposite side of the weld. I am planning to add the sheet metal cover with the curve matching the wheel - I figured the 2"x 2" cross brace would ensure structural integrity, plus the sheet metal covers will also help with the physical connection of the arms to the pivot tube..The red one below in the picture is the MAGNI version I am using as a guide.

swingarm2 magni-arm

swingarm3 fit1 fit2

The bearings for the pivot tube are housed in an steel insert that will be machined to an interference fit, once the pivot tube is trued up in the milling machine where the welding distorted things. I cannot proceed to the rear frame section without locating the rear shocks width properly.

August 28, 2011

Very little actual physical progress this week - it was time to prepare SHOP DRAWINGS of the swing arm construction and the rear half of the frame. This involved an inordinate amount of measuring, drawing to full size and trying to think of all the eventualities. I did get the rear frame mounts welded into position.

Some basic things came to light - my special will have a 90mm longer wheel base at 1500mm than the stock brutale 1410mm - my initial plan was only a 50mm increase. The rear hub requires a 32mm spacer to use the Grimeca hub. It looks like I can adapt the new spacer to use the stock 41T 525 MV F4 rear sprocket. To finish off the weekend with some flair - I decided the MV 750 America gas tank needed some more attention from my zip cut and hammer - nicely opening up the front to clear the frame bracing - looks like it will work - not much left of my $1000 investment except 2 sides and a top.

Click here or on thumbnail plan below for larger view

plan2 tank4

August 21, 2011

After a 2 week break from "the project" visiting with my mum, I finally got 2 productive shop days in this weekend. Progress saw the front of the frame nearing the final stages. Added the triangular and spine braces, fitted the side plates and am working on the rear engine mounts. Don't ask to look in the scrap bin - lots of "shorts"

frame trig1 frame trig2

The side plates will require some gussetting on the underside to the cross braces to keep the engine solid in position. NOTE TO SELF: (AUGUST 2012) Do away with the side plates, bring a tube from the steeering head to the rear top engine mount. Also relocate the side brace tubes to the rear of the steering head - by being in the front it makes the tank opening extremely wid.

frame mt1 frame mt2

Rear engine mount - fabricated two mount boxes, The mount required a compound angle hole milled 1.2" dia for the lug. This was quite a brain teaser setting up the milling machine..

July 31, 2011

Some major progress this last week - I was able to enlist the help of Master Metalworker Maurice to help bend the main frame tubes. He has a mandrel bender with 6" dia (3" radius) dies. Two hours shop time we had the tubes bent to my profiles. I cut and fit them to the frame, TIG tack welding into position. He also supplied the two waterjet side engine mount brackets, which will be bent in to meet the frame tubes and welded & braced. THANKS. I welded up the lower engine mount, swing arm unit on the bench, adding a corner gusset. The top engine mount ended up in a different place than I planned, I will have to re-machine the spacers and fabricate a gusseted mount on an angle. NOTE TO SELF -(August 2012): Think about chain clearance NOW - interferance with the vertical frame member became and issue, as with the lower engine mount, both required "adjusting" later on. Vertical frame tube should have extended vertical for at least 4", then neck back in. Also relooking at the frame design, next time do away with the side plate brackets and bring a tube from the steeering head around the engine to the rear engine mount, my current design relies too much on the integrity of the engine as part of the frame, something I am sure isn't really designed into the engine.

frame31 frame31-2

I also test fit the injectors and found out how tight it all is there. My plan to turn the injector pack upside down to allow the injectors a clean shot down the inlet does not work, back to "indirect injection" where the fuel flow will be around the elbow. I was also surprised to see how much the injector sticks out beyond the side of the tank, right at the point where the tank necks in. Considering several options for this - machined velocity stacks, adapt K&N pod filters, or fabricate an air box.


The big issue became the tank - this resulted in the me zip cutting the bottom out of the tank! (rendering a $1000 MV America tank worthless). Looking that the tunnel configuration and the front corners, I figured that significant modification would be needed under the tank, including fitting the fuel pump (6" dia round flanged opening), making up a new bottom plate seemed the logical answer - it will mean some serious sheetmetal work down the road.

tank311 frame-314

July 23, 2011

All the machined spacers and lug mounts are completed and mounted with the engine in the frame jig. The engine has a 15mm offset which might make the top engine mount interesting. Having the MV America tank means the tube bending can begin. First attempt (see photo below) was a fail - the broad curves do not look good - will have to look at a different bending process.

frtube1 fr3 fr2

JULY 4, 2011

The frame fixture (jig) is now a reality. The main post is fixed in place and trued. The steering head stem set to 25 deg, tack welded in place and the engine being positioned in the jig. The dimensioning and positioning of the engine is a critical step and is very time consuming. Laying out, measuring, marking, checking again, adjusting all takes time. Once the engine is in the correct location, it will be tack welded to the jig and the side plates made up to locate the swinging arm.

frame 1 Frame 2

The frame jig is a piece of C12 - 12" C section structural steel channel 60" long with 1/2" steel plate closures at the each end. I had the sides machined true - the top was adjusted in a few spots to level out. The post is 3 1/2" square HSS tube with 1/4" wall. The cross pin is 1 3/4" dia solid bar, drilled and tapped for the 3/4" UNC threaded pin anchor. The jig is mounted on a rolling base for ease of moving around.

The two critical elements of the frame construction are the struth of the steering head and its relationship to the swinging arm. The engine is secondary.The MV engine has a 15mm offset. First pencil concept sketch of my frame design below.

Frame 3 frame1

The steering head neck tube has been machined from 2" Schedule 80 tube - heavy wall (2.375" OD, 1.939" ID). This has been machined to accept a pair of tapered roller bearings 32006. Since I am using A Triumph Daytona 955 forks and triple tree the selection of bearing was pre-determined. Two solid machined slugs are temporarily in place of the bearings during the frame fabrication process. The vertical pin is 3/4" UNC ready rod - seems very sturdy.

As stated before, my frame JIG follows concepts from Michael Moore of Euro Spares in California. On his web site he shares his vast experience and wealth of knowledge with motorcycle frame design and making specials (Thanks Mike if you ever read this) Here is the link to his page Tony Foale's book "Motorcycle Handling and Chassis Design - the Art & Science" has also been a useful resource.