The cheater MX85 argument. I might be changing my mind.

[seymour14]

Sorry buddy but that just does not stack up.

Why do you say more expense. If someone finds a cheap MX engine and whacks it in a frame. What is the difference between that and an FXR engine. Except that the FXR engine will cost 800 bucks. Oh and be just as fucked.

As far as I can see F3 is still working fine. The numbers go up and down over the years and what do you know still a 400 or 450 ZXR is running at the front at the Nats.

Buckets will still be what you are prepared to invest. Thats the beauty of the class. Allowing MX engines will not change much at all. I will still run my heavy 27hp FXR. And still get smoked by better riders with less power. If someone wants to drop all there coin on a flash bike and engine then so fucken what! They still have to ride the bloody thing.

If people want to play with engines then ummmmmmm. Guess what, they still can.

People need to just step back and think about the sport not about themselves. Its not a big deal.

I just mentioned the above because it did ruin F3 for a lot of people, and by using these MX motors we are opening that horrible debate on competition parts, which may end up in open slather if we're not careful.

[Bert]

I just mentioned the above because it did ruin F3 for a lot of people, and by using these MX motors we are opening that horrible debate on competition parts, which may end up in open slather if we're not careful.

Right, back from racing (that's right racing, undertaken the sport)..
Great event at taupo, in which we had a ball of a time mixing it up with the 250...

Not sure why we a paralleling F3 in this debate. When the 650 we let in, many didn't want them. The same group we also slowly stepping away. Numbers were down and the opportunity was taken to provide a step up class to address the significant hole to 600s. Many new riders didn't want a 10+ Year old 400/250 nor had the skill to work them up for racing, the demographic has changed; a shame maybe but that's life. Not everyone are engineers or can afford the work. The 650 offered an solution for the long term.

85cc in F4; I agree with Speedpro & Rich.
Are we ready for change? Is it needed?
Does it make any significant difference? Is there a cost benefit?
What effect To our current culture will this change? It's a great class with a great group of people will this change it?
Can the rules be controlled enough to limit potential foul play across current motors and current rules?
Buckets for junior development? Or old men having fun? Which one?

[Skunk]

Who polices the current rules?
When was the last time a 100 was checked to see if it was 104 or less?
We don't police the current rules so do the same with this.


If it ain't smokin' - it's broken.

[Pumba]

Buckets for junior development? Or old men having fun? Which one?

Only comment I have felt worth replying to. My answer is neither. It is a class to race in and it is whatever one wishes to make it, not to be defined by others. Personally I hate it when classes get pigeon holed, like you are meant to be continuously moving forward through a predefined class structure and everyone in NZ should be aiming to ride a super bike. Personally I know I don't have big enough balls to do so.

As I have made that comment I may as well through my $0.02 n the ring on the engine. I still cant make up my mind, was dead against now not so much but still not feeling positive as I feel the negatives will out way the benefits at this time. I don't think it is a sure thing that Buckets will head in this direction but it is a high possibility, only question is around timing.

My gut tells me now is not the time.

[Bert]

Only comment I have felt worth replying to. My answer is neither. It is a class to race in and it is whatever one wishes to make it, not to be defined by others. Personally I hate it when classes get pigeon holed..........

My gut tells me now is not the time.

I hoped someone would answer that in that way.


While I've held a view on this for a long time, F4 is in great shape and can sustain under the current structure. F5 is on the comeback and sidecars are making headway.

But is there an opportunity being missed, and a chance to expose more people to the sport?

On the side, we had a number of people popping over and asking what the F these bikes were and that they looked like a heap of fun. Mostly car guys (and a few drifters: I do separate them)... Actually had questions around, can I uses little johnnies 85cc engine and come racing, a slightly different twist on the question. Dads thinking about using their kids out grown bike for something else.

[sonic_v]

If you allow 85's MX engine's you have to allow 150's They make the same power.

Standard they do not make the same power. None of the 85's make more than 20 hp standard, with some coming in at about 18hp. The 150's come with 22 hp standard and a linear power curve from 5000 rpm. Their advantage is such that the AMA in the states have banned them from AMA sanctioned 85cc events. See second paragraph here. http://www.motorcycle-usa.com/123/11...rt-Review.aspx

The 150's have a bore and stroke of 66 x 43.7. I suspect that none of your present 150's in buckets have a bore size as large as that and as power is directly proportional to bore area in a four stroke, you would make all your 4 strokes redundant if the honda crf150 were allowed to be used.

I do however think it would be an excellent idea to allow the 85cc moto engines in. They all give 21/22 hp with a good pipe before any tuning. With tuning they all give about 24hp with a decent powerband. The good thing is that there is no standout engine. They all have almost identical port timings durations of 186 exhaust and 126 transfers.

An other point in favour of the 85cc engines is that there has been no development in the past 25 years. As an example suzuki introduced the first crankcase reed rm80 in 1989. That engine did not change until it got an 85cc cylinder in about 2002. The bottom end has not changed in 25 years.

Yamaha introduced the first crankcase reed yz80 in 1993. Again, apart from a small capacity increase this engine has not changed in 21 years.

Hence there is absolutely no need to have a recent engine as it will offer no advantage.

As an example of how reliable the engines are, the recommended service time for the crank in a TM 85 is 120 hrs. I help a young lad on one of these and he is presently on 70 hrs from new with no bottom end work done to date.

[avgas]

No a MX85 is not a modern eq of a bucket, it a fully fledged production MX bike build from the ground up in a factory to be a competition bike.
It is exactly the kind of engine deliberately excluded in the rules.
Letting them in the class becomes cheque book racer class for lil johnies...........
plus it begs the question, if they become legal, does that also follow other competition parts are then ok for the other bikes say Sleeved NX4 b kit cylinders
TZ125 crankshafts.......CR125 Gearboxs

a) fully fledged for what medium? I don't see any MX85 motards out there......
What is the top speed of a 85 vs a CBR125? How successful would a KX85 be in stock trim against the current bucket race-spec bike?

b) Wait is that not happening now? Last time I checked the bucket line up, there were more whispers and secrets than the popes choir boys.
Hell it had to reach boiling point until someone actually pointed out that MX engines are illegal!
Imagine how many other "part skeletons" exist in the pits.....

Who polices the current rules?
When was the last time a 100 was checked to see if it was 104 or less?
We don't police the current rules so do the same with this.

But with proper policing - middle aged men can't get their knickers in a twist about a little bike class.
"He's cheating" they will say about the next person who thought outside the box of the rules (which state you can't have competition engines......just parts of a competition bike).
Rather than riding what they brought and having a bit of fun.

Without policing we are left the Kangaroo court which is currently in session.

[Kickaha]

The 150's have a bore and stroke of 66 x 43.7. I suspect that none of your present 150's in buckets have a bore size as large as that

Mine does

"He's cheating" they will say about the next person who thought outside the box of the rules

Yes but they wont have the balls to put a proper protest in and sort it out

[scott411]

Standard they do not make the same power. None of the 85's make more than 20 hp standard, with some coming in at about 18hp. The 150's come with 22 hp standard and a linear power curve from 5000 rpm. Their advantage is such that the AMA in the states have banned them from AMA sanctioned 85cc events. See second paragraph here. http://www.motorcycle-usa.com/123/11...rt-Review.aspx

The 150's have a bore and stroke of 66 x 43.7. I suspect that none of your present 150's in buckets have a bore size as large as that and as power is directly proportional to bore area in a four stroke, you would make all your 4 strokes redundant if the honda crf150 were allowed to be used.

I do however think it would be an excellent idea to allow the 85cc moto engines in. They all give 21/22 hp with a good pipe before any tuning. With tuning they all give about 24hp with a decent powerband. The good thing is that there is no standout engine. They all have almost identical port timings durations of 186 exhaust and 126 transfers.

An other point in favour of the 85cc engines is that there has been no development in the past 25 years. As an example suzuki introduced the first crankcase reed rm80 in 1989. That engine did not change until it got an 85cc cylinder in about 2002. The bottom end has not changed in 25 years.

Yamaha introduced the first crankcase reed yz80 in 1993. Again, apart from a small capacity increase this engine has not changed in 21 years.

Hence there is absolutely no need to have a recent engine as it will offer no advantage.

As an example of how reliable the engines are, the recommended service time for the crank in a TM 85 is 120 hrs. I help a young lad on one of these and he is presently on 70 hrs from new with no bottom end work done to date.

your information is wrong, the 150 is back in the 85 class as of last year in the USA amateur nationals,

also the YZ85 is the oldest engine around now, and the only one without a exhaust power valve, (the CR85 has not been made since 2007) it still has very good top end power but no where near the midrange of the KTM or Kawasaki 85 which were new in 2013 and 2014 respectively,

[F5 Dave]

Well Husi's dyno curve post by itself make me think - No. - Too good straight of the bat.


Sonic's is more in line with what I was lead to believe.



Don't suppose an 85 has ever been dyno'd o the GPR dyno?

[kel]

Well Husi's dyno curve post by itself make me think

Oh come on, its a classic Husabender.
What a shame I've missed all the fun of this thread while away racing. To think I could have been sitting at my computer debating this instead of ripping around Taupo and having a great weekend away with like minded people. SLACKERS!

[F5 Dave]

My kids 5th Birthday, no way was I going to get away with missing that, and I went riding on Mothers day so its not all bad.

Besides my 100 is still where I left it after the GP, presumably with considerably less gearbox oil as it was smoking for last 1/2 of GP apparently (I was too busy trying to stay on).

[richban]

The 150's have a bore and stroke of 66 x 43.7. I suspect that none of your present 150's in buckets have a bore size as large as that and as power is directly proportional to bore area in a four stroke, you would make all your 4 strokes redundant if the honda crf150 were allowed to be used.

Ummmm. You are talking bullshit. Its hard to get any idea of what is on the track and what power the bikes are making from the EU.

[husaberg]

Well Husi's dyno curve post by itself make me think - No. - Too good straight of the bat.


Sonic's is more in line with what I was lead to believe.

Don't suppose an 85 has ever been dyno'd o the GPR dyno?

I just posted what was on the net (no filtering) all measured on the same dyno no less.
If this is stock standard, with a decent pipe a bit of squish and some gentle massaging who knows?
I just struggle to get past the fact they are designed as a competition engine and have factory close ratios.

[F5 Dave]

And I have always struggled with that. I don't want to see a competition engine that would make my bike obsolete.

The running costs make them attractive, much more attractive than they were 10 years ago.

But there are dynos & dynos. If your from the net curves are truly indicative (and thanks for posting) then I'm a bit worried. If they are spiced by a optimistic dyno then there needs to be some control.

The problem with dirtbikes is they have bumpy tyres so just running them up on the dyno isn't that easy. The other factor is MX is surrounded by huge swaths of bullshot marketing to get Dad to part with his spare money so Junior can achieve Minibike glory and make up for his own inadequacies. Heck if my kids start MX I'll probably be as pulled in to tuning them as I am with buckets. Maybe that's a reason to keep them away from bikes as I don't have time enough & it would cut deeply into my riding. My Dad didn't stop playing golf to buy me a YZ80 & take me to meetings.

Anyhoo, there isn't a heap of dyno curve out there, or maybe there are some more. Just would love to see where they were at on a industry std old school dynojet.