Rule changes for F4

**Skunk** · 9th April 2011, 11:50

We at the Vic Club had a member propose a rule change for F4 100cc two strokes. It was submitted to MNZ in October 2010 and (even though we have followed it up) we haven't heard anything.

So: I'm proposing two 'unofficial' rule changes:

1. F4 100cc two stoke to be a maximum of 107cc (to allow the use of KT100 pistons in MB100 engines - cheaper to get than quality MB100 pistons)
2a. Maximum effective carb size for 125cc two stroke to be 30mm or
2b. Maximum effective carb size for 125cc two stroke to be 28mm

Vote now if you are an MNZ member - quote your licence number and I'll tally up the results. Voting closes 1 June 2011.

Vote for or against on each proposal. I plan to see if we can't 'even' the playing field for 125's and keep the running costs of MB100's down.

Disclaimer: I have a TF125 (std except for the chamber).

**RDjase** · 9th April 2011, 13:02

Originally Posted by Skunk

We at the Vic Club had a member propose a rule change for F4 100cc two strokes. It was submitted to MNZ in October 2010 and (even though we have followed it up) we haven't heard anything.

So: I'm proposing two 'unofficial' rule changes:

1. F4 100cc two stoke to be a maximum of 107cc (to allow the use of KT100 pistons in MB100 engines - cheaper to get than quality MB100 pistons)
2a. Maximum effective carb size for 125cc two stroke to be 30mm or
2b. Maximum effective carb size for 125cc two stroke to be 28mm

Vote now if you are an MNZ member - quote your licence number and I'll tally up the results. Voting closes 1 June 2011.

Vote for or against on each proposal. I plan to see if we can't 'even' the playing field for 125's and keep the running costs of MB100's down.

Disclaimer: I have a TF125 (std except for the chamber).

Great ideas !

Rule 1, Yes
Rule 2a, Yes

Rule 3? , water cooled 125 2 Stroke

MNZ# 19813

**Ivan** · 9th April 2011, 13:46

I think it should be fair considering we can now use 150 cbrs etc so

both i tick yes to

Ivan Juggins 13660

**saxet** · 9th April 2011, 14:44

Sorry- don't agree.

Rule 1 doesn't help anyone except those using MB100 motors- what about other engines.

Rule 2 the 24 mm carb isn't a hinderence to gaining power, same with no water cooling.

As far asI can see the 2 strokes have an advantge when tuned well.

MNZ 8522

**Trudes** · 9th April 2011, 15:21

1. For
2a. For

19887

**Slingshot** · 9th April 2011, 16:07

Increasing the carb size for 125 smokers would suck for 100cc smokers.

**jasonu** · 9th April 2011, 17:31

TZ350 and one or two others have proved good HP (near 30 rwhp) can be made from aircooled 125 2T motors with the presant 24mm carb rule. IMO that particular rule is OK and doesn't need to be changed.
If you make it easier for the AC 125's then the 100's will want something, then the 4t 150's will want something then...

**speedpro** · 9th April 2011, 17:42

Originally Posted by Skunk

1. F4 100cc two stoke to be a maximum of 107cc (to allow the use of KT100 pistons in MB100 engines - cheaper to get than quality MB100 pistons)
2a. Maximum effective carb size for 125cc two stroke to be 30mm or
2b. Maximum effective carb size for 125cc two stroke to be 28mm

1. definite NO, it would make getting 30ish hp from an MB not too hard - unfair
2a. no point, 24mm carb is not actually a restriction, see ESE
2b. no point, 24mm carb is not actually a restriction, see ESE

Wobbly has said a number of times that the 24mm carb rule doesn't restrict the performance of a well built 125.

Proposed change 1 would help with costs but would also allow mega revs and horsepower. MB motors I have built have done over 5 years with lots of racing on the same piston. If you look at the cost of a piston spread over 4-6 years racing it isn't much. If you are going through pistons then you need to find out why rather than finding a cheaper piston.

MNZ4597

**Dom** · 9th April 2011, 20:16

Current rules are fine. A well built 2 stroke in a 125GP chassis will definitely smoke any 4 stroke offering. It might look like the CBR/FXR have the upper hand but it's because recently national champion/lap record holders like Al Hoogie ('10 125GP champ), Kenneth Jones (Levels 125GP lap record) are riding them.

**k14** · 9th April 2011, 20:23

Originally Posted by speedpro

1. definite NO, it would make getting 30ish hp from an MB not too hard - unfair
2a. no point, 24mm carb is not actually a restriction, see ESE
2b. no point, 24mm carb is not actually a restriction, see ESE

Wobbly has said a number of times that the 24mm carb rule doesn't restrict the performance of a well built 125.

Proposed change 1 would help with costs but would also allow mega revs and horsepower. MB motors I have built have done over 5 years with lots of racing on the same piston. If you look at the cost of a piston spread over 4-6 years racing it isn't much. If you are going through pistons then you need to find out why rather than finding a cheaper piston.

MNZ4597

Agreed, nothing is broken so nothing needs to be changed. Leave the rules alone.

MNZ 15930

**Bert** · 9th April 2011, 20:33

Originally Posted by speedpro

1. definite NO, it would make getting 30ish hp from an MB not too hard - unfair
2a. no point, 24mm carb is not actually a restriction, see ESE
2b. no point, 24mm carb is not actually a restriction, see ESE

... If you are going through pistons then you need to find out why rather than finding a cheaper piston.

MNZ4597

Originally Posted by k14

Agreed, nothing is broken so nothing needs to be changed. Leave the rules alone.

MNZ 15930

I don't really see the benefit on changing rule 1.; we are already allowed to run them within the current rules (but you need to do some work first).

2&3. well maybe at a club level for newbies??? but no way at national/gp level. otherwise we should just park up the 100cc 2T (which would make me cry).

MNZ 975 (last time I looked)