Mach 1 Replica Lives!

[Lonestar]

Hello all,

I finished most of the work on my Mach 1 replica (born as a '67 Monza) on Friday, and today put some gas in it. This promptly began dripping out the carb - the float valve wasn't closing. The carb is an SSI27D, with a long float needle seating at the top of the chamber. It turns out there should be a clip to hold the needle in position as it passes through the float - but mine had none. Somewhat the fault of the bonehead who assembled it in 2006 (that would be me), but on the other hand I checked the parts book and it's not listed there. Happily a throttle needle clip from an old Amal Concentric fit nicely.

The next challenge was getting it running. It's not so easy to kick, with a 10:1 piston and a short lever on the left side. But after a while it roared into life. Sounds good, very loud, but would die below 2500 rpm. I guessed this was a blocked idle jet, and that was correct, so now it runs through the range. I couldn't take it on the road, though, since the clutch has a severe dragging problem that won't adjust out. Very likely warped plates, so I've ordered a new set.

Anyway, it looks beautiful and with some fettling should be a good ride. The only other snafu is with the toolboxes. These need to be repainted, but it also turns out the brackets on my Monza frame don't match the Mach 1 toolboxes. I'm still pondering how to get past this problem. Ideas welcome.

I posted a bunch of pictures of the project from 2004 to now, take a look: http://www.vincent-hrd.co.uk/Galleries/

Cheers,

Dave

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[Rick]

Really nice, the Comet and Gran Sport too. It's gonna be hard to hide any sort of clamp on tool box tabs.
Rick

[Bevel bob]

New clutch plates did not cure my draggy clutch but shimming the springs to get the clutch to lift square did.

[ajleone]

Dave - Great pics, really nice bike ! Thanks for sharing.

Here is a pic of my 250 Mark 3 frame that shows what the side box mounts look like.
Tony

[Lonestar]

Bob,

Thanks for the tip; I'll inspect for even lifting while installing the new plates. It probably it would have been wise to pull it apart and investigate first, but at this point I want to ride the little beast and new plates can't do any harm.

Tony,

Excellent picture, just what I need! I've been trying to locate a pic of a proper frame to see those brackets, but they're not to be found. Strangely, people seem to prefer posting shots of their completed bikes, with the toolboxes getting in the way of the brackets. I'm still mulling over strategy, but am leaning towards making up the rear brackets (with the two slots each) and having them welded on, since they attach to the inside of the frame where the weld won't be very visible. For the top brackets I may bolt a bracket to the regulator attachment points, and avoid more welding.

One question - how do your frame's top brackets fit to the toolboxes? Mine have slots in the back for a bracket to bolt to, but from the photo the bracket looks to be at the outer plane of the frame tube - too far out to reach the slots in the box. Is there additional hardware involved?

Cheers,

Dave

[dav]

Wow Dave, your bike looks great mate, top top job.

[ajleone]

Dave,
I will post a pic of the top bracket. It is positioned so that the box bolts directly to it.
Tony

[Lonestar]

Hello all,

Just an update on the saga of my Mach 1 replica. The new clutch arrived and was duly installed, so I set out on a test ride Sunday - being careful to stay within walking distance of home. No point being overconfident.

Anyhow, the clutch now works and the bike is great fun. It's the lightest bike I've ridden in many years, maybe ever, and very agile. I'm pleased at the braking power; if anything the rear is too strong and easily locks the wheel. Riding position is more comfortable than I expected, given the clip-ons, although I wouldn't want to go touring. The seat has the same springs and stiff leather construction as the originals, and was hard to distinguish from a rock at first. I think it's breaking in a bit, though, as I now detect a bit of deformation while sitting on it.

Initial issues:

Speedo is quite inaccurate - this probably proves it's genuine.

Veglia tach is original, and I think it's reading high. This may be due to my using a Smiths tachometer drive with it, as that's what I bought and besides it's brass and polishes up beautifully. I need to investigate this further.

Misfire in evidence, sort of a stuttering at most throttle openings.

Idle needs adjusting, and due to SSI slide stop design I need to raise the tank at the rear, to apply a wrench to the locknut. In due course I'll install a stiff spring there instead.

The first ride ended three blocks from home when the engine died. It would restart, run a few seconds and die again. This led me to suspect fuel starvation, but removing the plug beneath the jet produced a steady stream of gas. The jet itself was clear. So I walked the bike back; happily it was downhill slightly.

As it turned out, the problem was oil on the points. Some overzealous type (me) had added too much oil to the advance cam wick, and it had fouled the points. I cleaned them and tested spark by manually opening the points with the ignition on. This was interesting since doing this 10 times produced around 9 sparks, and they were none too robust despite an iridium plug. Time for new points, after which a big improvement. The old ones looked OK and were clean, but I noticed the spring was much stronger on the new set, which probably improved contact.

One curiousity - I found the timing was only marginally correct with the points plate rotated as far CCW as possible. I elongated the slots a bit to get past this; anyone else have this issue?

Another ride Monday brought total mileage on the rebuilt engine to 37. The bike feels fast because it's light, low, quick-steering and firmly-suspended. Power is good for a 250, but I think if I could get into the powerband, it would be excellent. Ducati says in the owner's manual not to exceed 40mph in top gear for 300 miles, and 56mph for 600. I've stretched these limits already, but stayed well below redline (guessing, due to tach uncertainty). Anyone have tips on successful break-in strategy?

Thanks to the forum for helpful info during the project, and special thanks to Tony (ajleone) for creating an engineering drawing to help me fabricate toolbox brackets.

Cheers,

Dave

[Bevel bob]

IF you have Mach1 gearing 40mph in top will do the big end no favours ,don't want to do anything much below 3000 revs .Keep it spinning.