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

[quallman1234]

out of intesst anyone ever dynoed a Stock MB100 or GP125?

Not yet, but Malcolm Nabbs just brought a stock MB100, so hopefully we can get that on there before he modifies it!

We have done a stock AX100! ~6.5hp That was a laugh!
I have a cheap ZXR250C for the road i've just got wof/reg (cost me 800!). So will try put that on there as well. I'll be surpised if its not over 30hp they have some power! They claim 40hp

[cotswold]

out of intesst anyone ever dynoed a Stock MB100 or GP125?

Stock GP125 with a slightly better carb 14 on TZ's Dyno

[F5 Dave]

GP125 needed a washer to restrict it for uk 12 hp rules. 13 I believe.

[F5 Dave]

Somebody add a poll: mx85 in or out. Sort the restrictions (if any) after that.


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

TBH I don't know which way I would vote at the moment.

[CM2005]

If you allow 85's MX engine's you have to allow 150's They make the same power. And both capable of 30hp. Portland rules Jason. But they also run the bikes with slicks. No big deal really. It would also allow kids that want to step up to development class to run at the front on there bucket. Win win. Lets get it done. Move the sport forward and maybe we will see more young ones take it up.

I'm 100% in agreement with this. Should be allowed chassis mods to let you have proper wheel sizes and get rid of the heavy mx USD forks.

The argument about CR gboxes is mostly invalid. FXR's use 2 gears at most kart tracks, so why would six on an 80 be any better if the final drive was similar? They have 5/8 of f all torque so you have to keep them singing.

MX80 or 85cc engines
STANDARD Carb body and slide = no machining
Exhaust open
Chassis open
Rest of the rules as per MNZ rules for F4

Stock GP125 with a slightly better carb 14 on TZ's Dyno

My standard GP125 made 6 on TZ350's dyno! It needed a bit of fiddling and a pipe, some carb mods and a gentle port polish to just make 15

Get it done

http://www.mnz.co.nz/docs/regulation...s.pdf?sfvrsn=2

[husaberg]

I'm 100% in agreement with this. Should be allowed chassis mods to let you have proper wheel sizes and get rid of the heavy mx USD forks.

The argument about CR gboxes is mostly invalid. FXR's use 2 gears at most kart tracks, so why would six on an 80 be any better if the final drive was similar? They have 5/8 of f all torque so you have to keep them singing.

MX80 or 85cc engines
STANDARD Carb body and slide = no machining
Exhaust open
Chassis open
Rest of the rules as per MNZ rules for F4



My standard GP125 made 6 on TZ350's dyno! It needed a bit of fiddling and a pipe, some carb mods and a gentle port polish to just make 15

Get it done

http://www.mnz.co.nz/docs/regulation...s.pdf?sfvrsn=2

The point re the gearboxs alludes to the fact that the rules say
"Engines must be derived from non-competition motorcycles. Motocross, Road
Racing, Enduro and Go Kart motors and transmission parts are not permitted."
irrespective of the silly S
The point i was attempting to make is it is very very easy to slip in a Gearbox from some CR80's into a MB100 or H100.
It is a advantage to do so, as the MB5 6 speed is actually fairly wide ratios ......
But it is illegal to do so. So most people don't.
Yet by the same token if you let in the MX80's or 85's it is legal for them to run these same gearboxs.
Same goes for say conrods and big end bearings.

Those in favor are saying it is all about cost....
Yet, again these same cheap parts are not allowed to be used by the rest of the competitors.......
it seems the logic is faulty.
Not all buckets race on Kart tracks.

Someone mentioned about them being hard to fit to another chassis, their layout actually makes them easier to fit to a RS chassis than most other engines.....

[Henk]

My concern is that to do this properly involves more than just saying "OK MX 80/85 engines are in" husaberg a point regarding the gearboxes is valid and the tip of the iceberg.
If we are going to allow MX engines is there also a case for kart parts or whole engines?
Do we allow aftermarket cylinders to keep rebuild costs down? If so where does that put the race spec malosi etc parts for the aprillia and derbi engines?

[F5 Dave]

My head's hurting. Maybe my mind is changing back to its previous curmudgeon ways

[koba]

We have had our one on the dyno @ ~16hp (cant quite remember will get glen to post the curve tomorrow). Our dyno has a tendancy to run a couple hp below a dynojet.

About the same as mine on the same Dyno wasn't it?



Glen and Chopper wanted to build buckets with MX engines.
Glen did, and had a go on it at the track.

Would allowing these bring hoards of new entries in to buckets? I doubt it very much.

The bike still has to be 'built' so it doesn't have the same 'ready package' attraction of an FXR.
I've heard many tunes on "I would build a bucket if.." violin, none of the 'if's' being fulfilled will have ever resulted in a completed bike.
Glen is is a doer, he has already done it, as illegal as it is.

In reality I think you would end up with:

• Some new people that would have built/purchased a bucket regardless of current or revised rules taking these up.
• Some people with existing buckets may switch to them and start over with development, possibly for a gain in speed, certainly for a loss in money.
• Some people will still claim "I was keen to get in to buckets but now that these MX85's are in there" and still never actually come racing.

Buckets is fundamentally based on non-competition engines, this is a factor that seems to keep it 'grass roots' from going down the Karting or MX paths, as well as allowing massive scope for innovation and keeping many options open.

I for one am a hell of a lot more interested in Glens supercharger project than his cheaterbike.

The rules do need to change with the times, the way to change with the times in this case is to keep up with the current crop of engines in the class, which is currently (Road) 150 4 strokes. I can't see where this broken, I still see plenty of $800 FXR's, I purchased one myself a while ago.

Really, if the objective to all this is to make buckets cheaper and more easily available it is simply a case of addressing any supply/demand issues with the desired engines and importing a container load of FXR or CBR's from south east Asia.

One could even make money in the process.

[Pumba]

......issues with the desired engines and importing a container load of FXR or CBR's from south east Asia.

One could even make money in the process.

I have thought about that in the past. Never got past the thinking portion of the equation though.

[kel]

Those in favor are saying it is all about cost....

You are a classic. Do you actually stop to read ? -

"The 2 stroke platforms are pretty much gone (other than those stock piled by ESE), and the old air coolers that make decent power are a major safety hazard. The 85's are a great idea, it will make the sport more attractive and available to new comers, keep the tinkers amused, and make the sport safer. Im all for it, and 4 stroke boys can have their CRF's too!"

Oh wait if you play that quote backwards at half speed you can just make out "its all about cost"

[kel]

In reality I think you would end up with:
Some people with existing buckets may switch to them and start over with development, possibly for a gain in speed, certainly for a loss in money.

Yep I would. I wouldn't expect a gain in speed, but would expect a motor that would hold together and that I can still source parts for.
As far as your four stroke suggestion, its well founded but only worthy of a SHAME ON YOU. And shame on the evil Honda for their brain washing ways.

[speedpro]

If we are going to allow MX engines is there also a case for kart parts or whole engines?

Pistons are already open and I use KT100 pistons legally. I have compared good legal little end bearings to KT100 little end bearings and could not tell the difference looking at them. You would have to use the whole complete engine(s)(just for Husa) or nothing. Using a cylinder on another bottom end or a CR gearbox in a MB should not be allowed. I'm still thinking no mods allowed. "If" somebody decided to police the rules it would be easy to check. Maybe using a later cylinder of the same capacity to allow for replacements. We could take a leaf out of the Aussie rule book and have homologated engines, basically any freely available 80/85MX engine.

[husaberg]

You are a classic. Do you actually stop to read ? -

"The 2 stroke platforms are pretty much gone (other than those stock piled by ESE), and the old air coolers that make decent power are a major safety hazard. The 85's are a great idea, it will make the sport more attractive and available to new comers, keep the tinkers amused, and make the sport safer. Im all for it, and 4 stroke boys can have their CRF's too!"

Oh wait if you play that quote backwards at half speed you can just make out "its all about cost"

Did you stop to consider i was not talking about you.............

But time has moved on. If indeed the power of these things aren’t as high as I’d suspected perhaps it is time to have another look. MX85s haven’t evolved for over a decade. They're just changing decals & pumping out the same thing while they can still sell them to a decreasing market. Heck they still run round slide carbs from the early 80s.

You can buy a complete going less than 10yr old bike for under $2k without really trying & downhill (or uphill) from there. A blown engine is peanuts and can use the carb, rad, ignition & even redo the pipe (Sketchy fit a std one in an RGV frame).

A top end refresh costs less than a hundy & a full engine rebuild can be done for a few hundred. Try that on your popped FXR.

Now that there are very few 30yr ol aircooled 2 stroke engines (ie: me) about we are talking compatibility with FXRs. It appears that there isn’t a big advantage over a std FXR.

So what do they offer & why should we even consider changing the rules that ‘aren’t broken’ ?

I’d offer FXR availability. When were they last sold? The last of the roadbikes are being converted to buckets as they get smashed up & unregistered.

MX85 offer reliable racing on a sensible budget with another stream of motors that are going to be increasingly dumped on the market as 150 4 stroke MX bikes take over.
.

the latest model KX85 (2014 on) and esp the KTM 85 (2013 on) put out more than 24 hp std, the RM/YZ have not been updated for a while but i would be suprised if they are under 20hp std anyway,

although i agree with your theory that they will be way cheaper to run than a FXR150, they will make everything else obsolete pretty quick,

yes all the modern ones are plated cylinders, Barrells are available, but I am not sure what you call cheap,

What about the CRF150 (the air cooled one) and KLX140 (which are 144cc) motors, both these models have been out for a while now, and should be coming up second hand cheap, both are not race bikes, and should be similar performance to a FXR

Seems a bit crazy to force everyone to make a "race bike" and then complain their race bike is too fast because they took an engine out of the standard (MX) frame and made it faster.

I imagine there are truckloads of kids out there with mx85's who want to go racing......but no do trails.
They aren't allowed on the speedways. But with road tyres could they be allowed in buckets?

I mean an MX85 really is just the modern equivalent of half the bikes on the start-line in buckets. Apart from mudbugs, chinese crap and sport bikes......there isn't much in the 50-150 space that is road going these days.

. My thinking is mx85 completely stock including carb but not pipe in any chassis. Completely stock is easy to police. It would actually make buckets more competitive as more people would be able to get their hands on 22hp, and probably at a lower cost/effort. With all the dynos around you could even require them to be dynoed to check peak horsepower.

Right, back from racing (that's right racing, undertaken the sport)..

Does it make any significant difference? Is there a cost benefit?

. 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.

As an aside if there was a class say for up to 2008 KTM50's SX and Pro SNR'S that would open up a lot of cheap engines. They are uncompetitive now and totally unsuitable for play bikes. call it F6 (lil jonies class)

[CHOPPA]

Wonder how a KX85 with a RS125 front end, 17" rim laced on the rear, make some rearsets and may a different rear shock