Rule changes for F4

[RMS eng]

Dave makes some good points though I wouldn't be too annoyed about everyone getting to use KT pistons without the cost. I have a few bits I could use to make more engines myself. It isn't the oversize so much as the extra revs using those pistons allow that I'm hesitant about.
Looking back I used to replace the piston in my TS100 every two meetings with another RG400 piston. That added up pretty quickly.
The only reason I'm using the KT piston now is for more revs. The MB pistons, or TKRJ, all last well and the cost spread over 4-5-6 years is neglibible. FYI - the MB pistons are good for a reliable 13,000rpm and the rings will only lose a tip now and then over 14,000rpm.

That does look a bit like I don't want anyone else getting to use the pistons I'm using.

fitting a new piston in your ts100 every 2 meetings,did you run any oil,my RG50 did 13500 rpm and piston would do a years racing ,the rules are ok as they are people just need to build motors that last longer,as none of mega HP two strokes are winning jack.

[Gigglebutton]

I think riding, weight, handling, and HP win races. But torque is good when you don't have some of the other bits.

Horse power may help at the bigger tracks, which is what high hp 2t's need to stretch there legs. Most of big hp 2t's at Mt welly are short shifting gears and don't get into the high hp apart from the front straight. The average rider, like myself, on a short circuit, needs a fat spread of power on a bike that handles. I know of 6 guys at the moment who are working on 2t's with only low to mid 20's power and all want it fat like a 4 stroke.

[ajturbo]

but its carbs are probably illegal so you should vote for options 2 and 2a

they are also std...

[Buddha#81:Me]

they are also std...

......yet illegal Mr Turbo

[koba]

Horse power may help at the bigger tracks, which is what high hp 2t's need to stretch there legs. Most of big hp 2t's at Mt welly are short shifting gears and don't get into the high hp apart from the front straight. The average rider, like myself, on a short circuit, needs a fat spread of power on a bike that handles. I know of 6 guys at the moment who are working on 2t's with only low to mid 20's power and all want it fat like a 4 stroke.

I'm another, low to mid 20's are a long way off yet though.

[ajturbo]

......yet illegal Mr Turbo

by how much..??

[F5 Dave]

So my point is people are already using KT pistons. Do we have to make them go down the offset crankpin (not cheap to get one of those made accurately) &/or re machine crank position? 35hp? Lets be fair, no one much had more than 20hp till recently maybe mid 20s & Nigels bike was a stand out at 27. 2.2cc will make every 100 a 35hp bike?! Yeah right.

[jasonu]

[QUOTE=Gigglebutton;1130034351]Horse power may help at the bigger tracks, which is what high hp 2t's need to stretch there legs. Most of big hp 2t's at Mt welly are short shifting gears and don't get into the high hp apart from the front straight. QUOTE]

That is because most if not all of the recient big HP 2 strokes are really really really peaky, just have a look at the posted dyno curves.

In a similar vein that the recently changed F4 restriction for 150cc 4 strokes was increased to more oversizes (158.09cc) it is suggested that the current 104cc restriction is increased to 106.2cc. [/FONT]

When was this done?
Are you talking about the change from 145cc which was the original rule made to allow GL145's in? If this is what you are referring to then that rule change was mostly to allow FXR150's in which revived (saved) buckets.

[F5 Dave]

No I mean quite recently there was an amendment that gave the 150s a few more oversize CC out to 158 from perhaps 155 (can't remember specific numbers).


[edit] from MNZ site here is what it is now

F4
2 stroke 55-100cc - 104cc
2 stroke 55-125cc air cooled - 130.5cc
4 stroke 55-150cc – 158.09cc

Gives 150s 8cc to do whatever they like with, whereas 100s get 4cc & by percentage doesn't help much, we are talking available oversize pistons.

[jasonu]

No I mean quite recently there was an amendment that gave the 150s a few more oversize CC out to 158 from perhaps 155 (can't remember specific numbers).


[edit] from MNZ site here is what it is now

F4
2 stroke 55-100cc - 104cc
2 stroke 55-125cc air cooled - 130.5cc
4 stroke 55-150cc – 158.09cc

Gives 150s 8cc to do whatever they like with, whereas 100s get 4cc & by percentage doesn't help much, we are talking available oversize pistons.

Thanks for the clarification.

[Skunk]

I'm lov ing the 'only $160' type comments. I wish I had that sort of money to spare. There's a reason I have 5 TF engines sitting on my bench doing nothing.

I still think the KT piston is a fair and reasonable thing. You still have to spend money to get 30hp just like now. But for those without money - they get to keep their bikes running at a reasonable price.

How did the 158cc oversize rule go though? Did anyone here know of it BEFORE it was done?

Seems some can change rules without consultation and others can't even get a reply to an official rule change request.

[Gigglebutton]

I'm another, low to mid 20's are a long way off yet though.

Get speed pro to have a look at your motor. He and Tee Zee have helped me loads

[bucketracer]

Seems some can change rules without consultation and others can't even get a reply to an official rule change request.

TeeZee after prompting on this forum has tried several times to get clarification on his carb modification by writing to MNZ, but has had no reply either.

[kel]

I wish I had that sort of money to spare. There's a reason I have 5 TF engines sitting on my bench doing nothing. .

Thats odd, what I see is "I have 5 TF's sitting on my bench thats why I dont have that sort of money to spare". Sell the TF's

[Buckets4Me]

I'm lov ing the 'only $160' type comments. I wish I had that sort of money to spare.

thats about a standard entry fee for any other type of racing ? f3 f2 f1 postie clasic sidecar motard etc