More progress, with some pics this time!
Roebling is fast approaching and I have a ton of small things still in progress. The majority of the engine parts are at my place, save for some primary/cam chains and a cam chain tensioner. I also realized that I am out of middle shift forks for the trans, and need to source one before buttoning everything up. The trans is an all new pro-cut set from Kenny at Cycle X, so fingers crossed that with my more gentle use of the transmission through becoming a better racer, I won't have issues like I did before. The cases had the main bearings lapped, and will be fitted with new shells for the crank, along with new shells for the rods as well. More or less, the entire bottom end will be new or have been serviced and checked out since the boo-boo at Barber in October.
I started installing the primary chain tensioner system from Mirko as well. I am not sure if I am the only one racing with it or not, but certainly among the first few. The machining needed was simple enough, with my mill JUST big enough to handle the job. The upper tensioner needed minor trimming to fit into the upper case as the foot was touching one of the bosses for the cylinder stud, but was easily fixed. Taking the belt and suspenders approach, I safety wired the bolts as well as using some loctite, along with a light smear of Hondabond where it sits against the case.
The lower tensioner went in, again with slight trimming as the metal foot that has the bolt hole and pin was wide enough to touch a part of the casting in the lower case half, but went in quite easily.
New oil lines with stainless crimps are all done with new hoses. I should have done this item a long time ago, after splitting an aluminum collar 2 different times. The last one I noticed right before Barber as I was sitting in a chair just staring into the distance. The collar pulled off with my fingers so with 80psi of oil pressure, it could have been very bad. The stainless collars are far stronger, so that should be a done deal.
I also had a cracked front brake rotor after Barber. There were 6 or so cracks between the holes and it was time for a replacement. The cracked on was an RPE cast iron that had been drilled by them. I found that the cross drill pattern was lacking because the holes did not cover the entire swept area of the brake pad, leading to some pretty noticeable peaks and valleys in the rotor. My solution is interesting to say the least. I sourced another RPE rotor through George Schuld (thanks George!) as he was ordering some as well. I chose the non-drilled variety and after doing some reading online about the reasons rotors are drilled and decided to dimple the rotor instead. The dimple pattern covers the entire swept area of the brake pad and with smooth bottoms (round end mill) there wont be any places for cracks to propagate from. Its a bit of an experiment, but the vast majority of things I found online stated that drilled rotors today are more for looks than performance and that dimpled and slotted rotors perform to the same degree, without risk of crack formation. I likely wouldnt have had issues if I had 2 discs up front, but the stress that is put into that single rotor on a 360lb bike with a 220lb rider likely overdid it a bit. Time will tell. The rotor is out getting clear zinc plated now so it doesnt look so awful after a damp night in the paddock.
An observation from staring at this engine in pieces was that the main bearing bosses that hold the bolts (or in my case, studs and nuts) were really not flat at all, and in some cases had noticeable concavity to them. The simple solution was to index off of each hole and touch off with an end mill to get a nice flat, true surface for the nuts to rest on. In most cases, I only took about 0.007" or so off each boss to get a nice flat surface.
The last little thing is one that I have been thinking about all season, which serves no real practical purpose, but is really cool and will make people who know cb750's do a double take. I have no need for the tach drive on the valve cover any longer, so decided to get rid of it. I cut the left side out of one valve cover and grafted into the right of the one I am using. After some careful laser welding and nice fitment, I will even be able to keep the OHC logo and most of the small fins in the cover. When done, it will look like it was never there to begin with.
That's all for now, but plenty more to do as I get closer.
36 days...
