friend wants to built a CB 450 racer

Exactly ,
- using 20 year old OEM Jap junkyard shock absorbers is a 'race tip' ??
- weak, thinwalled bicycle handlbars , cut and welded ?
- cutting frame tubes from a frame thats 'already too weak for the stock motor' - - - - makes it better ?

Ridiculous.

 

Jim,
Thanks for the reply,I'll be happy to help with your reliability problems,I know the CB350 engine VERY well.I was actually asking about your CB450,I thought you had one?If not,my mistake.I'd like to get back to Putnam,but won't be able to this year,I'm limiting races attended this year to do other things with my wife Tina and our 9 month old daughter.
As for iph,DGs making more midrange?compared to WHAT?some other 1970s pipe?my pipe makes 4-5HP more than DG's EVERYWHERE.Yes,and I have the Dyno charts to prove it.Dunlop 591?what other advice from the ancient past can you give?I thought Rip VanWinkle lived in the Catskill mountains,not California.

 

now lets not be to rough on iph. were all living in the past on something.
what pipes are you using now stan?

 

Exactly ,
- using 20 year old OEM Jap junkyard shock absorbers is a 'race tip' ??

newer UJM comes with decent shocks , some come with fully adjustable Showa pigy backs , and who wants to pay $400 for pair of shocks for that old clunker anyways ?

- weak, thinwalled bicycle handlbars , cut and welded ?

MTB bars are fully tappered chromoly or 7073 alumium sure beats any motorcycle tubes which are heavy weak junk iron

- cutting frame tubes from a frame thats 'already too weak for the stock motor' - - - - makes it better ?

down tubes on those bike is single L shape pipe so it can not offer any torsional strenght , its just there to hold the engine up


Ridiculous.

 

Hey IPH... I hope you understand that this is all lighthearted gab.

I love my old clunker and would pay $400 bucks to make it handle better anyday. I just need to find the money.

If a person can afford a tig rig to weld aluminum or chromoly handlebars I'm sure a brand spanking new set of clubmans aren't out of reach.

If the downtube is cut, will the motor just fall or plop out? After all you say it's just there to hold the motor up. But then if the motor does rely on the downtube for support , why would you suggest cutting it out?

Maybe it really isn't necessary and can indeed be removed as you suggested. Makes me laugh to think all those motorcycle manufacturers and privateer racers who have wasted a great deal of money on unnecessary tubing!

 

check out below link to see how its done :

http://www.tonyfoale.com/gallery/StrFrame/home.htm

you need to put more weight on the front to make it handle thats why you must custom make the drop bars (2-3 inch forward)as comercialy available clubman bars or clip ones do not extend forward far enough , the more weight you out on that front end the better it handles plus it get ride of front end chater plus it moves your whole body forward 3 inch including your feet so you may even get away without a rear set , you may just shorten the stock shifter lever and reposition it , the best tip for old bike is to move the engine forward 1 inch in the frame as done to RDs but making the bar is easier , i raced with triple rate progressive on my FT500 and it did not make much of difference compare to old SW or Koni cheapos , it never be plush like monoshock on a modern bike anyways so $400 better be spent on that rusty tank or a front end with real brakes and alloy rims and tires etc ..

 

CB450 has head mount plus 2 more on the back so engine would not fall out ! just weld a V from neck to bolt on to both sides of block to prevent things from twisting , for tubing metrial i get several streight chromoly MTB bars ( same material motocross frames are made of)

 

Thank you for the links to Tony's work. These pages indicate, as I've suggested, that there is more to using an engine as a stressed member than merely cutting the downtubes.