#6

[richban]

To keep the change fair , maybe some compassion could be shown to the diesel brigade by allowing then 160 cc , then everyone benifits .

I think that if the rules change it should be thought through proper like. Trade experts together from either camp talking it through. Otherwise its just people trying to make up rules for there own gain. Its gotta be fare and all.

[F5 Dave]

The 4 bangers just got a capacity increase a few years back. From 140 to 150 (155 for rebores) & then later 158.09 for rebores. 100s have been the same for eons.

[Grumph]

I think that if the rules change it should be thought through proper like. Trade experts together from either camp talking it through. Otherwise its just people trying to make up rules for there own gain. Its gotta be fare and all.

My god man, has no one ever explained to you how MNZ rules are established ? Go to a conference as an observer...warning - you'll need a strong stomach. the "workshops" which put the agreed versions through to the main conference are late night boozy arguments where every possible axe is ground and the strongest prevail - the weak go to the wall. Months of training in drunken arguments are required to qualify as a delegate...

That said - the current rules aren't too bad. I know you'd like to have more overbores available but let's face it, most would go straight to the max bore allowable anyway. Kev's "big" MB used a venturi shaped restrictor downstream of the slide and with development would have been up with the Hoogie's bikes based on Greymouth. Wasn't that much slower as it stood.

[TZ350]

We now know 28rwhp can be sucked through a legal but cleverly modified 24mm carb, and the plenum idea might help push it past 30. Mikes ideas fit within the rules as they are and he suggests a way of making a cheapish MB100 that could touch 30rwhp using a 52mm KT100 piston and no expensive crank pin or special parts. With a bit of copper to aid air cooling its all pretty much something anyone can do. But the FXR's have shown that Hp is not everything.

I think the rules work pretty well as they are.

[jasonu]

You are slow but with a quick bike...
Why not increase the 100cc overbore limit to 106cc from 104cc and stop all the expense and stuffing about. Might see a few more 2 smokes at the track instead of FXRs.

And then the H20 100cc crowd will say 'increase the max capacity to 110cc as it saves me a cylinder'. Then the aircooled 125cc mob will want 135cc and the coal burner crowd will want 160cc.
Bag of worms I say.

[husaberg]

We now know 28rwhp can be sucked through a legal but cleverly modified 24mm carb, and the plenum idea might help push it past 30. Mikes ideas fit within the rules as they are and he suggests a way of making a cheapish MB100 that could touch 30rwhp using a 52mm KT100 piston and no expensive crank pin or special parts. With a bit of copper to aid air cooling its all pretty much something anyone can do. But the FXR's have shown that Hp is not everything.

I think the rules work pretty well as they are.

Yeah can of worms but i should add. We know that 28rwhp can be sucked through a 24mm venturi carb with 125cc
he would still be handicapped quite a few cc's if you catch my drift.
Dave made a point above re the rules with cc increase only for the 4 strokes plus the tweeking for the 125cc ac's.
but forgot they also got a hike from 130.5cc as well. Food for thought, or fought fodder?or aimless talk that never goes nowhere. It will cost me plenty to debore and destroke Vanessa, but shit happens (Unless i am doing it then stuff all happens- till the last minute then panic stations.)
but 50mm or so are not that cheap or easy to find kart ones are cheap plentiful and a couple of cc to big, Life sucks. Murphy drafted the rules.

[speedpro]

The rules don't need to be changed. Look at the GP this weekend. Who is going to win on what bike? Every combination allowed by the rules is in with a chance
except those pesky 4-stroke things

[bucketracer]

... plus the tweeking for the 125cc ac's....

What was the rule tweeking for 125cc ac's?

[husaberg]

What was the rule tweeking for 125cc ac's?

The 125cc 24mm carb 2t rule never used to exist. It used to be 2 stroke to 103.5 or so, four strokes to 130.5cc with 100cc or there abouts prob 103,5cccc supercharged/turbo charged for F4, tweak may not be the correct term.But i like it(Thoughts and opinions discussed by Husaberg may differ from the opinions expressed by Mrs Husaberg)

[speedpro]

Luckily I made the 4-stroke comment in really small letters. Have dismantled the motor and it isn't looking good. It could easily have been a LOT worse as the following pictures show. The piston had smeared itself up the bore but not too badly, more of a good rub for a lot of its circumference. There is an obvious crack in the crown which extends down to the gudgeon pin hole. When I inspected it more closely there is 8 or so other cracks including in the other gudgeon pin area. There are cracks above and below the pin boss. To me it doesn't look to be a tuning problem. Basicaly Dave did a plig chop and it doesn't look too lean though the pipe is pretty light in colour just down the header. The other thing of concern is the little end bearing. It was all there when dismantled but in a few more pieces than when I put it in. The crank will definitely be coming apart to check the big end.

[husaberg]

Luckily I made the 4-stroke comment in really small letters. Have dismantled the motor and it isn't looking good. It could easily have been a LOT worse as the following pictures show. The piston had smeared itself up the bore but not too badly, more of a good rub for a lot of its circumference. There is an obvious crack in the crown which extends down to the gudgeon pin hole. When I inspected it more closely there is 8 or so other cracks including in the other gudgeon pin area. There are cracks above and below the pin boss. To me it doesn't look to be a tuning problem. Basicaly Dave did a plig chop and it doesn't look too lean though the pipe is pretty light in colour just down the header. The other thing of concern is the little end bearing. It was all there when dismantled but in a few more pieces than when I put it in. The crank will definitely be coming apart to check the big end.

Prolite or MB100 little end Mike?

[speedpro]

The bearing is out of the ProX catalogue. It was a while ago but I seem to recall it was a slightly odd one to fit the rod and pin and also the KT100 piston, I'll have a note of it somewhere though it's easy to measure and order a new one. Might try for a better one next time. There are some good marks on the inside of the gudgeon pin bosses where the cage has rubbed. It would be good if somebody could shine a bit of light on possible causes. There is the same amount of wear on both sides. I've used Draino to take all the alloy off the bore so it's just a matter of dropping it at the kart shop now. It has a 52.15mm piston so will probably end up with a 52.2mm bore next.

[F5 Dave]

more rollers might be nice.

Lucky to catch that before it spat the pins out.

[bucketracer]

The rules don't need to be changed. Look at the GP this weekend. Who is going to win on what bike? Every combination allowed by the rules is in with a chance
except those pesky 4-stroke things

"those pesky 4-stroke things" .... at least it was in small print.

[husaberg]

The bearing is out of the TKRJ catalogue. It was a while ago but I seem to recall it was a slightly odd one to fit the rod and pin and also the KT100 piston, I'll have a note of it somewhere though it's easy to measure and order a new one. Might try for a better one next time. There are some good marks on the inside of the gudgeon pin bosses where the cage has rubbed. It would be good if somebody could shine a bit of light on possible causes. There is the same amount of wear on both sides. I've used Draino to take all the alloy off the bore so it's just a matter of dropping it at the kart shop now. It has a 52.15mm piston so will probably end up with a 52.2mm bore next.

I am guess by slightly odd it would correspond to the std Honda OD and ID?

My gut tells me the limit of the std style generic bearing has been reached (assuming there is no sign of localized overheating from lack of lubrication which is a reason as well for wrist pin failure.) A solid cadge would of course be better. but is it available in a size to suit if it is an odd one.? Kind of like these but the right size.
or
What sort of Hours or miles on the piston and wrist pin?