I've been knocking an idea around now for a while and have decided to implement the plan by the end of this year.
A little background first. I built my F3 dragbike over 25 years ago. I started off with a stock F3 chassis I pulled from the junk yard with a blown engine. The first order of business was to strip the bike down to nothing but a roller to check out the structural integrity of the frame since the upper rails had already been cut for easy engine removal by the previous owner. A close inspection showed all was well so my next step was to install the old engine back in the bike with a sidewinder exhaust. I needed to determine how much clearance was necessary from the front wheel after lowering the bike. We then cut the top backbone at the rear, heated the tubing and raked the neck a few degrees. Raking the neck would also help with high speed stability on the dragstrip.
I knew i wanted the bike as long as practical for the purpose of hard launches off the line. I didn't want it to long because traction on an ill prepped track could become a factor. Some thoght was given to building an arm or retrofitting an aftermarket arm. Instead, We honed in on extending the stock arm 12 inches by adding a piece of mild steel square tubing. Shock mounts were added and i drilled 3 sets of holes so i could choose the correct ride height and suspension dampening. Of course once the rear wheel was moved back 12",
the seat pan was no longer practical for me. My focus was then on what to do about a seat pan that would extend from just behind the rear tank position to over the back tire. My only choice was to fabricate my own seat pan. I also wanted to incorporate the very end of the stock Honda pan so the taillight area would look close to stock. My intention was to use a wide rim and 180 tire so i began by cutting the stock tail piece, adding a wider section in the middle to use a basis for the remainder of the fabricated seat pan. For the seat pan mild, i used a piece of sheet metal and hand formed it in the desired shape. I then hand layed fiberglass matting inside, tied the widened tail piece into the mold and created exactly what i needed to fit the extended chassis. I'm not a body man so i did need to add very thin layers of body filler here and there to make it look good.
Its my opinion that a properly prepared chassis is far more important than building a high performance engine. I took a lot of time thinking through the chassis setup. Once i had everything in order with the roller, my next move was to get a decent engine between the frame rails. The 1030cc was dropped in, and after a bit of tweaking at the dragstrip i made some initial high 10 second passes. Over the years other changes were made to light up the bike by replacing the stock wheels with light weight aftermarket rims and swapping the heavy 630 chain with a 530 to drop reciprocating mass. This change put the bike into the mid 10 second zone and allowed me to begin setting records in Super Eliminator.
Fast forward to the purpose of this post. My curiosity about the ET potential of a stock engine in my proven chassis is taking hold now. I've got several parts engines laying around that can be cobbled together to make a running engine. The only internal work i may perform is rod and main bearing replacement, new riings and a fresh valve job for the head with new heavy duty valve springs. The springs would just be insurance against valve float if its accidentally over-revved.
I intend to use stock, rejetted carbs with no filters and keep my sidewinder exhaust for obvious reasons.
So what ET prediction would all of my performance gurus care to venture with this setup? Lets hear it fellas.
