Monday, August 9, 2010

July update

I raced in Portland in July at the Vintage Days put on by the local organization OMRRA. Much to my shame I didn't take pictures as I had a new on board camera to try but unfortunately I was having technical difficulties with it.

Quick report. The Guzzi ran great. I installed a new gear set 8/35 as the 7/33 I used at the previous race was too short for Portland's long front straight. I was topping out at 8,000 rpm well before the end of the straight. The 8/35 made a huge difference. I have a wonderful gearing chart from Click here for the link. Scroll down to table of contents and the gearing Excel spreadsheet application will be there. Using the chart I was able to calculate that with the 7/33 and tyre combo I was doing 135mph at 8,000rpm. Using the 8/35 I would be at 142mph. In the race I was hitting about 7700rpm at the end of the straight. Not necessarily any faster but it meant I wasn't flogging the engine unnecessarily. My shift points remained the same so acceleration didn't suffer. Thank you Charley Cole of Zydeco Racing for the 2 week turnaround time on the gear set.

I have finally found a jetting combo that works too. In the past I was way too lean and I think this may have been the cause of my failed rod bearings due to pre-ignition....

Without my usual long-windedness here's my jetting at the moment: 41mm Dellortos. 165 mains, 265 needle jet, 2nd clip position. K4 needle. VP110 red race gas. 30 degrees of timing.

I think there's some tweaking to be done with timing, plugs etc but I'm definitely in the ball park. The Guzzi is pretty quick (for an old tractor).

Had 3 races. Got a second and 2 thirds. Battled with a Honda 750 the whole weekend. He beat me twice (:
Steve Arnett's Duc was still broken but we will be racing this coming weekend in Seattle, his home track. I've been prepping the bike to make it somewhat eligible for the Seattle Vintage Days. Technically they have a 750cc, 1972 cut off year but the Guzzi kind of looks the part. Nobody really cares and are just happy to have bikes on the grid. I did have to take off the lovely Astralites and source some Borrani wheels to make the bike more 'period correct'.

Seattle 'tweaks': Borrani wheels with new Avon Vintage race rubber for skinny rims, jetting, fork brace to handle the crazy downhill full braking hairpin. See a vintage bike go around Pacific Raceways here .

Hopefully I'll have some footage up too in a couple of weeks.

Below is the bike almost ready for Seattle.


  1. where did you source the 'period correct' air from, for your new/old vintage skinny tyres? I did have a supplier in the Scottish outer Hebrides, but his oak caskets were a little leaky, & to be honest the saline saturation was a little high. Now what?!

  2. It's special light weight air to save reciprocating weight. I get it on ebay from Italy. Some ex factory mechanic by the name of Bruno sells it.