Power Junkies Rejoice

[Boo]

Kawasaki did a huge amount of testing engine displacement for the 500 class of engines ranging in size from 380-500cc 70hp was obtainable from the displacement sizes but ride ability suffered on the smaller engines as they were to peaky and lacked torque. The 420-450 cc range offered the best compromise in this regard over the race duration.
If you could build a 380-420 top end on 250/300 cases with DCI, 3 stage ignition etc the ideal off road bike.
Maico are still made in Holland and they produce models ranging from 400-750cc single cylinder 2 strokes.

Yes , but there were two reasons that happened. One, the ability to port an engine to the required application, in any instance where an increase in hp on a motor is done, a compromise has to be taken into consideration. If you increase hp usally all you are doing is moving it into a power band, by narrowing it you can provide improvements to that situation. ie good top end, very little on the bottom end. A carb passes a measued amount of fuel into the cylinder, it is based on how much you wind the throatle. What revs it is doing or what happens to the fuel once inside the cylinder cannot be changed, other factors are temp and humidty.If an EFI system was to be used and we assume it offers the same adjustments as the 4t then it puts the user in control.
My motor in my 07 was ported to produce a linear power delivery, the exhaust ports were raised to increase revs and produce torque, compression was raised to off set the loss in the bottom end, reliabilty was a major consideration as I still wanted it to be . The work was done by red, the motor had done 15hrs on it and had been ported for a smoother power delivery before. The bike was run after, the motor was good and did exactly what it was suppose to do. All and all a 7% increase in preformance.
But what it did to the handling was amazing, the bike settle well, flex was controlable by throatle response,there was no sudden hit of power which tended to unsettle the bike, Choose a gear to high to low into a corner it didnt matter change up or down before, after or at the apex it didnt matter. Suspenion worked 30% better, overall a 50% incease.
I sum it up as a there needs to be a compromise as the frame is built to handle a linear delivery a 2t needs to find the middle ground to work well mine still has the character its just more civilised now. I love the way its turned out, I don't know if it would be competitive I doudt it would with my lard ass on it, but good gains and alot nicer ride.

[Shorty_925]

As seen in Dirtrider Downunder, now can listen to it as well : http://www.youtube.com/watch?feature...&v=Y91Jms6MyCY

[Shorty_925]

Another clip of the bike : http://www.youtube.com/watch?feature...&v=TE5ENcMH1ZI

[Crasherfromwayback]

.

Yes , but there were two reasons that happened. One, the ability to port an engine to the required application, in any instance where an increase in hp on a motor is done, a compromise has to be taken into consideration. If you increase hp usally all you are doing is moving it into a power band, by narrowing it you can provide improvements to that situation. ie good top end, very little on the bottom end. A carb passes a measued amount of fuel into the cylinder, it is based on how much you wind the throatle. What revs it is doing or what happens to the fuel once inside the cylinder cannot be changed, other factors are temp and humidty.If an EFI system was to be used and we assume it offers the same adjustments as the 4t then it puts the user in control.
My motor in my 07 was ported to produce a linear power delivery, the exhaust ports were raised to increase revs and produce torque, compression was raised to off set the loss in the bottom end, reliabilty was a major consideration as I still wanted it to be . The work was done by red, the motor had done 15hrs on it and had been ported for a smoother power delivery before. The bike was run after, the motor was good and did exactly what it was suppose to do. All and all a 7% increase in preformance.
.

Yeah but that's where power valves are great. A KX500 from '06' onwards was KIPS equipped, and in my opinion way nicer to ride than a CR500, which was certainly faster. You can have great low end and top end with power valves. No need to compromise.

[Boo]

I agrree but it still reilies on a valve to make the adjustments in certain circumstances. But still the point is what ever appliction you choose the possibilties are endless.
For the instance where the perfect dirt bike was to be said, it is inself a number of different requirements based on the indiviual, ie what maybe good for one may not be for some one else. A 2t EFI does that, porting changes, ignition compression all variables that with time make a bike that was not considered to be possible.

[yokel]

So how come this new old engine that is almost 30 years old be more powerful, lighter and reliable than the old new engine?? WTF is up with that

How much longer do we have to put up with this 4 stroke nonsense for?

[scott411]

Yeah but that's where power valves are great. A KX500 from '06' onwards was KIPS equipped, and in my opinion way nicer to ride than a CR500, which was certainly faster. You can have great low end and top end with power valves. No need to compromise.

thats from 86 onwards they had the power valve,

[Stylo]

Good thread and I want one too...... far out

Question, why did they use an old, differently ported '85 CR powerplant and not a more recent up to 2001 CR500 motor on that Blue Rooster ?

[Boo]

I don't what your talking about Yokel.
READ A BIT ABOUT HOW A 2T ENGINE WORKS, THE POST IS ABOUT IMPLICATIONS FOR 2T. GO AND JUMP ON ANOTHER TREAD, MAKE SURE READ ALL THE POST BEGfORE YOU MAKE COMMENTS OR OTHERWISE YOU MIGHT MAKE ANOTHER STUPID ONE AGAIN.

[del-solider]

See http://www.kiwibiker.co.nz/forums/sh...unkies-Rejoice

[scott411]

So how come this new old engine that is almost 30 years old be more powerful, lighter and reliable than the old new engine?? WTF is up with that

How much longer do we have to put up with this 4 stroke nonsense for?

because people never brought them when they were made,

infact so little were sold in NZ they stopped having a racing class for them in the late 80's, aussie and america in the early 90's and the last poeple stopped racing them in europe in the mid 90's, the last person to win the 500 class on a 2 stroke was in 1996, and that was a 360, the minimum allowable cc for that class,

the fact is anything over about 55 horsepower is to much for a mx bike, even the full factory 450's are not made for more power, but more useable power, the world champ doesn't even use a full 450 cause he does not feel he needs it, quite often in both US and European series a little 250F sets the fastest lap times,

I know a couple of people that have over 60hp on their motard 450's, they now do not bother converting them back to dirt bikes anymore as they are no fun on the dirt anymore, and they have a 250 for dirt riding,

I love riding 500's in a straight line, and in a flat straight line, they are faster than a 450 MXer, but round a mx track, they are not,

infact, i think any decent rider will be faster on a stock standard YZ450F would be faster than on this machine on any real life mx track,

(notice they tested the bike at the Pirini ATV track, the perfect place for a 500, open, fast and flat)

[Shorty_925]

See http://www.kiwibiker.co.nz/forums/sh...unkies-Rejoice

Yea I know...was like whole heck gota post this and then saw the other thread..

[Crasherfromwayback]

thats from 86 onwards they had the power valve,

Yep sorry. That's what I meant. I had a KX500B2, loved it. Kicked arse on it everywhere.

[Boo]

I agree with what your saying in the now, they were saying that when the EFI came out on 4t. But still not relavent for this thread, the thread is about EFI for a 2t not the 2t 4t thing

[CRF119]

I know when my CRF450 engine blows up ill be doing a CR500 conversion. For some of us its not about how usable the power is its about being scared to twist the throttle and my 450 just doesn't do that anymore and the cost of rebuilds is to much.