Spec 400-450cc roadrace class

The guy to answer this kind of questions is Dr.C. He races a Honda(?!)/ Berg in the Nordic supermono cup.
Plain stock the 450s lack some power (at least my FE450) but with minor mods they put out great power. Don't forget you will have a six speed box which is great on a RR track.

What are the road race chassis options are available for this?

Are they all custom fabricated chassis or are there some off the shelf options?

ok crew cheif, let's have a look at this then!

we have examples of two road racers i believe, there is a bloke from the UK who used to race a 650 and of course DrC. he knows far more than he lets on and would be a very good man to stick close too.

the husaberg is VERY oversquare which could mean that it theoretically can rev higher than any other bike out there. as i see it there is only one restriction on the power and that is the weight of the valve and rocker assembly. officially, a DOHC bike should beat your SOHC husey due to better valve control at peak revs.

you can get over a great deal of this by making sure that you buy one from the two years of MX bikes that husaberg made with the 450. so you need a ,04 or '05 FC450. they will give you the Ti valves and and the springs and cam etc to go with it. i'm not sure but i think it was 4-speed.

before i go on i'll say that as i read the rules you can tune the phuq out of any original part! or you may be allowed to fit another OEM part from another bike so for instance getting the Ti valves and springs into an FE or putting a 6-speed box in a FC?

there is a theoretical RPM ceiling that the 57mm stroke offers. it's this that you need to be aiming for and without the valve bounce.

regarding thew husabergs suitability, i would say that the engine is VERY light and on small courses any lack of power will be more than made up for by as much as a 30LB weight advantage. on the longer courses the WR might disappear!

there is tons you can do to a standard engine legally. you need a blue printer to tune it.

interestingly, two things may slow you down: the camshaft which will be breathless well before any RR redline and the ignition curve. lineweaver could modify the kokusan for you. regaing the cam, well you could look at a 'base' grind. despite 20,000 members on TT nobody had ever heard of it before..........

you take the cam and you grind say 1mm off the base not the peak of the cam profiles. you then tighten the tappets by 1mm. now when the cam goes from base to peak you have gained 1mm. and it's legal.

there's lots more you can do including cutting back the valve seats which dale ahem! didn't do to the race team bike he was with at daytona! you can skim the head, skim the rim of the piston for higher comp, lighten the rocker arms - all under the guise of standard parts!

because you need a steep head angle you'll have to jack the rear right up necessatating that you do something with the subframe (like cut it off!).

regards

Taffy

In a Spec class like you're talking about, HP makes a big difference. As much as I hate to admit it, the stock DOHC Japanese 450's are very hard to beat in the HP department. Over the last few years, the engines have been refined and HP has increased. A friend who has a new '08 YZF 450 and I did an impromptu roll on drag for about 100 yards from 2nd gear, and the YZ was right there the whole time against my 550.

The oversquare Husaberg 450 makes a great off road engine,where out right HP is not so critical, but it wouldn't be my choice in a 450 class road racer, sad to say. Wait until 2009 and Husaberg may have something for the Japanese 450's in the power department.

Johnf3 said:

The oversquare Husaberg 450 makes a great off road engine,where out right HP is not so critical, but it wouldn't be my choice in a 450 class road racer, sad to say. Wait until 2009 and Husaberg may have something for the Japanese 450's in the power department.

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can't agree at all john. this is the most oversquare engine in the class and is therefore - all things being equal and capable likely to produce the highest revs and maybe the highest horsepower. it's therefore the best engine - maybe! for road racing! let's forget the 4 v 5 valves for a minute as i think most agree after 20 years that there is nowt in it.

if the bike can rev to 12k, has a good cam profile and tappets that can cope without floating: if those are right then you have the core. if the ports are the wrong shape, combustion shape, etc etc are all wrong then you have a marginal problem.

finally, the weight gain is worth about 1-2hp.

regards

Taffy

I think that the weight advantage and the extra gear will make enough difference that the engine will be competitve.Thr ti valves from the 04-05 fc will give a little safequard in peak rpm as well.
I really never could understand why the makers seem to be happy to go to the trouble to make a supermoto bike and not just go a little further and make a production roadracer as well.Its been a long time since a TZ250 was a viable option and as good as the 600 sport bikes are they are just not and never will be the same as a purpose built roadrace bike.

Taffy said:

Johnf3 said:

The oversquare Husaberg 450 makes a great off road engine,where out right HP is not so critical, but it wouldn't be my choice in a 450 class road racer, sad to say. Wait until 2009 and Husaberg may have something for the Japanese 450's in the power department.

Click to expand...

can't agree at all john. this is the most oversquare engine in the class and is therefore - all things being equal and capable likely to produce the highest revs and maybe the highest horsepower. it's therefore the best engine - maybe! for road racing! let's forget the 4 v 5 valves for a minute as i think most agree after 20 years that there is nowt in it.

if the bike can rev to 12k, has a good cam profile and tappets that can cope without floating: if those are right then you have the core. if the ports are the wrong shape, combustion shape, etc etc are all wrong then you have a marginal problem.

finally, the weight gain is worth about 1-2hp.

regards

Taffy

Click to expand...

Theory looks great on paper and on line. Look at the dyno and tell me where the advantage is. This is a spec 450 class, with few modifications allowed. So, talking about potential is not relevant in this case.

Tell me why Husaberg got out of the 450 supermoto business? Do you think it may of had anything to do with a non-competitive engine, in a class where raw power does atually matter?

will it make any difference that the ti vlaves are prone to stretch? or is it just max performance your after.

i say this as when i was sorting out my new bike i asked why the shop was throwing perfectly good valves in the bin. ansa "ti **** stretches bad, we run stainless in all the engines" this was on a supermoto

just a thought, but it was what i was told.

The ti valves will give a bit of safe quard in the overrev condition.Oft times roadraces are not so much about peak power but having a bike that can be geared best to the race track.Winning races is not all about power,you need enough to get up to the lead pack,when you are there it all comes down to who has the best bike,chassis ,tires,brakes ,rider position etc .Dont forget the guy on the bike is not just a weight.

Dear Mr Crew Chief,
I´m racing the Nordic Supermono Series with a Honda RS250 1999, propelled by a 2003 Husaberg 650 (Check out my gallery named "Dr_C" sorted under S for all the good logic reasons). This is what we call a full-size Supermono. A couple of years ago, Tigcraft started to fabricate chassies in the 125-size. These little jewels are referred to as Minimonos. There has been a lot of chassie-builders fitting Yamahas and KTM 450-engines in chassies with components from Honda RS125, since then. As far as my experience goes these bikes are very well handling, if the "blob on the seat" dares to use the high cornering speed that is possible with a 125. The 450´s can very well do without the higher resistance 250 fairings and wheels give. You can also have the scale stopping at 90kg with a Minimono. So, in short, if using the 450´s - settle with the 125-dimensions and you´ll have a killer regardless of engine make!

in truth john, i know why they aren't out there. it's the camshaft(s).

i've profiled all the cams i've run mate including the WR400 cams and unfortunately the weight of the husaberg valves, the very poor cam profiles mean that they aren't producing. even dale's cams are MX and not roadrace with relatively short duration and overlap.

go see popups gallery to see a WR rod v a husey, to see a WR valve against a husey? the husey valve was double the weight of the WR.

that's why i specifically said that it must be able to reach it's theoretical redline without valve bounce and a cam that will let it rev at such giddy heights. don't get me wrong, i want the husaberg to do well but short of stealing a cam i can't think who can afford to have one made?

that Ti valve stretch thing? i don't totally think you have the whole story on that. Ti valves are trouble free at the original redline therefore beating their SS rivals but the trouble is that the cam profiles and the valve spring strength aren't changed to account for the new lighter weight! i hope you catch my drift.

when excelsior, sunbeam and norton all went to double knocker in the late thirties only nortons finished the races. the other two makes broke down. turned out that the 'wicked' cam that had been usd with flexi push rods was now viollent when added directly onto the valve stem.

here endeth the lesson!

regards

Taffy