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

**Skunk** · 14th May 2014, 21:49

Put me on Sketchys cheater MX and see want happens. I'd bet I'm not much better than on my TF125. At the end of all the hp figures and bullshit you still have to ride it. And a good rider will make anything go fast. The fact that Sketchys bike handles better than mine will help a bit.

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

**CM2005** · 14th May 2014, 22:11

Originally Posted by CM2005

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

Originally Posted by Skunk

Maybe the pipe needs to be std as a restriction...

...?

Pretty straight forward, not gonna be a new "be all end all bike" and anyway the rich "little johnnies" will be asking daddy for an FXR RS125/GPR frame

**TZ350** · 14th May 2014, 22:19

Originally Posted by Henk

Just had a look on TM for a laugh, even stuffed 85s ain't cheap. I still have a road legal FXR for sale is anyone wants one

Yea, me to. One "Ported" RM85 engine $500 http://www.trademe.co.nz/motors/moto...-727105457.htm and one buggered KX85 $300 http://www.trademe.co.nz/motors/moto...-728556297.htm

Complete bikes, I saw only one for less than $1K several under $2K and anything that looked half reliable, between $2-$3K, maybe that is a cheap option, not so sure myself.

Hopefully someone else can flick up a few links to show how cheap these 80-85's can be brought for on any day of the week. Or if you have one in the shed and can throw good rubber on it, I guess that would be a cheap RR bike.

I have looked at new AM6 engines from the manufacturer $450 USD each plus shipping and GST the catch is 10 minimum order,

The race winning F4 Derbi I am familiar with has mid 20's hp with a strong spread making it ideal for tight tracks, plenty of cheap parts for those and AM6's, legal too.

**Henk** · 14th May 2014, 22:31

I'm softening on this, from my straight no way stance.

However I'm still in the no camp for the following reasons.
If we let these in the only restriction we can put on is capacity, these are being proposed as a cheap two stroke alternative and last time I looked (admittedly a while ago) an aftermarket Athena barrel was cheaper than replating and significantly cheaper than a new OEM barrel.
As far as other mods go, I don't think I have ever seen a kids mx bike that was stock. In 99 we bought a second hand YZ80 for Michelle, six months old, pipe, porting, rad valve.... Most of these have been played with to some degree and spending more on an old engine to put it back to stock defeats the purpose of the initial proposal, I.e. Cheap.
If we allow these I also can't see how we could be consistent without opening up the gearbox issues and although some seem to think it would make no difference I know others running two strokes who think it would.
As for the if it gets out of control change the rules retrospectively argument that just doesn't work, once the cat is out of the bag it's out. I'm reasonably confident that the folk who wrote the current rules didn't exclude GP frames for the simple reason that they never thought anyone would do such a thing. Anyone think there wouldn't be an outcry now if we tried to ban them at this stage? If I had one I'd be pretty pissed off.

**Skunk** · 14th May 2014, 22:34

I've seen TF125s on trade me for $200 but I got my ones for about $40 each on average. It gives another option. That means waiting until an affordable turns up or spending big on the first one you see.

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

**Skunk** · 14th May 2014, 22:42

Originally Posted by Henk

If we let these in the only restriction we can put on is capacity, .

I'm not sure why you think that. 125 AC are restricted by capacity and carb. No reason the same can't done here. And the gearbox rule for these engines doesn't mean it's free for the others. It all comes down to the wording allowing MX85 with or without their std gearbox and/or carb.

I'd still like to know what sort of power COULD be gained in theory. Then see how to restrict it.

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

**TZ350** · 14th May 2014, 22:51

Originally Posted by Henk

I'm softening on this, from my straight no way stance. However I'm still in the no camp for the following reasons.If we let these in the only restriction we can put on is capacity.

I voted No but if they do come in then I agree the only restriction should be capacity and maybe like pistons, ignitions and camshafts now the gearbox restriction should be lifted too.

**TZ350** · 14th May 2014, 22:54

Originally Posted by Skunk

I'd still like to know what sort of power COULD be gained in theory. Then see how to restrict it.

I am not sure but I know not to bother thinking about the carb ....

... maybe no expansion chamber ...

**Sketchy_Racer** · 15th May 2014, 08:29

Originally Posted by Henk

I'm softening on this, from my straight no way stance.

However I'm still in the no camp for the following reasons.
If we let these in the only restriction we can put on is capacity, these are being proposed as a cheap two stroke alternative and last time I looked (admittedly a while ago) an aftermarket Athena barrel was cheaper than replating and significantly cheaper than a new OEM barrel.
As far as other mods go, I don't think I have ever seen a kids mx bike that was stock. In 99 we bought a second hand YZ80 for Michelle, six months old, pipe, porting, rad valve.... Most of these have been played with to some degree and spending more on an old engine to put it back to stock defeats the purpose of the initial proposal, I.e. Cheap.
If we allow these I also can't see how we could be consistent without opening up the gearbox issues and although some seem to think it would make no difference I know others running two strokes who think it would.
As for the if it gets out of control change the rules retrospectively argument that just doesn't work, once the cat is out of the bag it's out. I'm reasonably confident that the folk who wrote the current rules didn't exclude GP frames for the simple reason that they never thought anyone would do such a thing. Anyone think there wouldn't be an outcry now if we tried to ban them at this stage? If I had one I'd be pretty pissed off.

The term cheap needs a little definition. An 85 is expensive compared to a old GP125, TF (but probably pretty close to the price of a MB100 to be honest) But it is however a bolt in semi competitive motor which is where the word goes from cheap to value.

My enthusiasm towards them is based almost completely on the availability of parts and cheap parts. Also reliability, a 85 will handle getting the revved to the moon and back all year long and then a freshen up

http://www.motocrossparts.co.nz/moto...=2&fitsbrand=5

If I order that it'll be here the next working day generally.

Your right about once the cat is out of the bag in terms of rules, if 85s were let in, we certainly couldn't just ban them, however I'm sure we could easily restrict them to stop them killing the other bikes. In some ways I think it would be better to have the rules say stock motors only as that means that while they will be competitive for the likes of people that just want to stuff a motor in and go, it wont deter or interfer with those who are mid way building bikes. Again, maybe start conservative with the rules and then open them up if needed?

It would be interesting to get my hands on a CRF150R and put it on the dyno. Again maybe a ruling allowing 150s and 85s MX engines but motors must be internally stock?

**kel** · 15th May 2014, 08:44

Originally Posted by Sketchy_Racer

Again maybe a ruling allowing 150s and 85s MX engines but motors must be internally stock?

This would create an entry level bike/class.
If this is the type of thinking then I want to change my vote to no as its all just a waste of time. A stock (read restricted) MX85 against an open CBR, FXR etc

**kel** · 15th May 2014, 08:56

Now that we have killed the chance of a new bread of two stroke buckets how about we sort out the rules for the current.

Forget the spirit of racing, intent of rules and all the nonesense that gets thrown up and deal with the written rule
Engines must be derived from non-competition motorcycles. Motocross, Road Racing, Enduro and Go Kart motors and transmission parts are not permitted.
If I can buy a bolt up aftermarket part specifically designed for my non-competition motorcycle but the manufacturer chooses to market the part as “Racing Cylinder kit” would it still be legal?
Anyone who can read must answer yes. So how do we ammend the rules to stop buckets becoming the Derbi cup?

**F5 Dave** · 15th May 2014, 09:15

Originally Posted by steamroller

Do you ride your bike i only ever see you working on it

Well it is a 36yr old air cooled 2 stroke modified within an inch of its life. Maybe I should be trawling the TM pages for a cheater engine. But I'm a sucker for punishment. Actually I want a TZR. . .

**F5 Dave** · 15th May 2014, 09:24

Originally Posted by chrisc

. . .I would vote yes on whether 85cc MX engines are allowed in with the normal % bore allowance.

Shouldn't be required. Nikasil bore means long lasting & no oversizes. If one gets rooted you replate it so it will always be under 85cc. Think the 80s may have had steel liners (I don't know) so maybe they can be bored up to 85.