Topic: 1982 CB450T Race Mods

[Rocketman]

My brother has decided he needs more HP to be competitive in Lightweight Vintage Superbike on my 82 CB450T. The motor is stock with a 2 into 1 header. These Hawks are unique with two intake and one exhaust valve per cylinder. Anyone out there who ran one back in the day?  Just starting my research, but thinking hotter cam, porting, close up the squish, maybe bump the compression (pistons?), larger carbs. Any leads, suggestions, and comments appreciated.

[BomberMann650]

Whats allowed under the rules?

You may have to stick with the un-see-able mods like you mentioned.

3 valve heads are good stuff.  Even conservative port polishing can help deliver the goods

[Ramrod_Racing]

Whats allowed under the rules?

You may have to stick with the un-see-able mods like you mentioned.

3 valve heads are good stuff.  Even conservative port polishing can help deliver the goods

Superbike rules, basically if you can do it in a stock head/cases it's fair game. No flatslides for now (there seems to be a rule proposal every year to allow them.)

[Rocketman]

Decided it was time to add some HP to the Hawk. Tired of getting motored!  The head is in Mike Rieck’s hands and a higher performance cam from Webcam has been sourced. Finding better valve springs has us stumped. The 80’s 450 twins use springs that are unique to that model. Anyone out there who is or used to race one and can suggest a source?

[johno]

Your head is in good hands Rocketman.
Id be surprised if Kibblewhite couldn't help you with springs. They used to do conversions for the torsion bar 450 to normal springs and even made beehive springs for them back in the day. Kibblewhite used to hard face the rockers and modify them for better lubrication as well as they were the first thing to fail with bigger cams / spring pressure etc. From what you are saying they are unique to the twin inlet valve model ? so I can't help you as I haven't even worked on that model. I do know anything is possible and likely Mike will come up with a solution.
cheers Johno

[Rocketman]

Mike has made good progress on the head. This is the three valve model from the 80’s. On the intake side using  Kibblewhite springs. Unfortunately on the exhaust side the design of the valve keepers is poor and valves with increased pressure is a gamble. So shimming the springs a small amount is the solution for now. If that is not adequate modifying a valve to take the better keeper design and allow the use of  Kibblewhite springs is an option. The cam is not radical and valve float should not be a problem if we observe the stock rev limit.

[bwaller]

Is that a 6spd model Martin?

[Rocketman]

It is a 6 speed. Tentative schedule includes Mosport. Hope to do the endurance race on it.

[Alan F.]

I remember someone over on the Twins site had built one for flat track racing. He'd removed the counterbalancers, their chain, adjusters and a few other related parts. I understood this freed up some horsepower but at the cost of higher vibration.