Turbo or supercharged 2Ts?

[TZ350]

Is there room for say 80cc H2O - 100cc air cooled Turbo and/or Supercharged two strokes in F4?

I am interested because I like the development side of buckets, previously we have had MX85's proposed.

So I am just floating the idea to get other peoples opinions about whether there is a place for expanding the rules to allow a broader range of options, particularly options that encourage experimentation.

[F5 Dave]

Only if that 80cc is an MX engine.

I think 65cc is the most I'd be asking for with parity to the 1.5 current rule which in itself - as other turbo classes show is too loose anyway.
example:
Lets get Rich or a Scott FXR engine, destroke it, Turbo cams & compression, whap the boost up to a silly level & 40hp or your money back.

[TZ350]

I think 65cc is the most I'd be asking for with parity to the 1.5 current rule which in itself - as other turbo classes show is too loose anyway.

Yes, I have no idea what is a fair thing myself, would that be 65cc water cooled?


Lets get Rich or a Scott FXR engine, destroke it, Turbo cams & compression, whap the boost up to a silly level & 40hp or your money back.

F4 100cc 4T's are allowed turbo and or Supercharging now and FXR's are good candidates as they are already liquid cooled, supercharging (supercharging for drive out of corners) would be the next logical step for Team GPR.

[F5 Dave]

FXRs are not LC, but CBRs are.

I think the rules is too loose but it was never much threat of someone doing it .

I think turbos get written out of rules in many sports as you can turn the boost up more than you could imagine when rules written.

[TZ350]

FXRs are not LC, but CBRs are.
Yes, not water cooled like a CBR, I thought FXR150's have the "Suzuki Advanced Cooling System (SACS)" making the engine liquid cooled with oil being squirted up under the piston and around the top of the head and then pumped out to a radiator.

FXR150 New Zealand 2002 Specifications

<tbody>
ENGINE
http://www.suzukicycles.org/gifs/3x3_transparent.gif
Type: Four-stroke single, Oil-cooled, DOHC, TSCC
Bore: 62,0 mm (2441 in.)
Stroke: 48,8 mm (1.921 in.)
Displacement: 147 cc (8.99 cu. in.)
Lubrication: Wet sump

</tbody>

[Bert]

F4 100cc 4T's are allowed turbo and or Supercharging now and FXR's are good candidates as they are already liquid cooled, supercharging (supercharging for drive out of corners) would be the next logical step for Team GPR.

It has been discussed in great length. Standard big end likely wouldn't handle it.... Not that a solution couldn't be solved for that issue..
And maybe not a full FXR but maybe it's little brother 125....



Yes, not water cooled like a CBR, I thought FXR150's have the "Suzuki Advanced Cooling System (SACS)" making the engine liquid cooled with oil being squirted up under the piston and around the top of the head and then pumped out to a radiator.

FXR150 New Zealand 2002 Specifications

<tbody>
ENGINE
http://www.suzukicycles.org/gifs/3x3_transparent.gif
Type: Four-stroke single, Oil-cooled, DOHC, TSCC
Bore: 62,0 mm (2441 in.)
Stroke: 48,8 mm (1.921 in.)
Displacement: 147 cc (8.99 cu. in.)
Lubrication: Wet sump

</tbody>



Now, this posed an interesting question, what do the rules actually say.... Sweet FA, in fact the engine specifications have been dumbed down significantly and detailed specs moved to appendix D (as we all already know). But reads a lot loose'er than previously.... No Consideration around turbos in appendix D nor any real specs around water cooling (other than Air cooled requirements for 2t for 125cc)... Hard to say if a 100 turbo would actually be legit for a GP...

[husaberg]

FXRs are not LC, but CBRs are.

I think the rules is too loose but it was never much threat of someone doing it .

I think turbos get written out of rules in many sports as you can turn the boost up more than you could imagine when rules written.



Yes, not water cooled like a CBR, I thought FXR150's have the "Suzuki Advanced Cooling System (SACS)" making the engine liquid cooled with oil being squirted up under the piston and around the top of the head and then pumped out to a radiator.

FXR150 New Zealand 2002 Specifications

<tbody>
ENGINE
http://www.suzukicycles.org/gifs/3x3_transparent.gif
Type: Four-stroke single, Oil-cooled, DOHC, TSCC
Bore: 62,0 mm (2441 in.)
Stroke: 48,8 mm (1.921 in.)
Displacement: 147 cc (8.99 cu. in.)
Lubrication: Wet sump

</tbody>


The wording in the rules is either air cooled or conversely, no restriction to on make type design (of cooling). (as per the class rules)
Fxr150's are not air cooled.........

[TZ350]

No Consideration around turbos in appendix D nor any real specs around water cooling (other than Air cooled requirements for 2t for 125cc)... Hard to say if a 100 turbo would actually be legit for a GP...

I am happy to think supercharging is a generic term covering both turbo and traditional supercharging, but like you say its not exactly the way the rules are written.

Agreed the rules are lagging behind about aftermarket EFI's, and Turbos, but personally I would not have any trouble with someone else running a 100cc Turbo 4T.

But a Turbo or Supercharged 2T is definitely not allowed in the rules at present, but could there be room for them? the only point I guess would be added technical variety for those that enjoy that sort of thing.

I think anyone who could get a Turbo EFI 2T working well enough to race would deserve a medal in their own right but it could be worth allowing for the learning experiences that would come out of it.

[mr bucketracer]

The wording in the rules is either air cooled or conversely, no restriction to on make type design (of cooling). (as per the class rules)
Fxr150's are not air cooled.........hate to know how long it would last if a blanked the top end off from air (-;

[husaberg]

hate to know how long it would last if a blanked the top end off from air (-;

One could say the same about the radiator on a liquid cooled bike:bleh:

[Grumph]

The wording in the rules is either air cooled or conversely, no restriction to on make type design (of cooling). (as per the class rules)
Fxr150's are not air cooled.........

Well.....sorry but another branch of motorsport - speedway - has already set the precedent by accepting the air/oil cooled GSXR's as air cooled motors...And as we all come under the MSA in NZ, I'd see that as a binding precedent.

[husaberg]

Well.....sorry but another branch of motorsport - speedway - has already set the precedent by accepting the air/oil cooled GSXR's as air cooled motors...And as we all come under the MSA in NZ, I'd see that as a binding precedent.

Nah your aguement doesn't hold water you are in over your head.

Ps that's f-ing sweedway.....not even........its a bloody car rule an all..........
So its not a branch is a different tree.........:msn-wink:

[Grumph]

Nah your aguement doesn't hold water you are in over your head.

This from someone who lives where the annual rainfall exceeded 14 METERS !!

[husaberg]

This from someone who lives where the annual rainfall exceeded 14 METERS !!

I didn't come down in the last shower though Noah.......:shifty:
308363

[TZ350]

4T's have a chance to play with forced induction, so in the interests of fairness and a level playing field, what about the 2T's why should they be forced to suffer the humiliation and prejudice of Strokerisim ... :laugh:

<iframe width="560" height="315" src="//www.youtube.com/embed/Y8XM0sl1VT4" frameborder="0" allowfullscreen=""></iframe>

2T's are more and more often coming in for the blower treatment.

<iframe width="420" height="315" src="//www.youtube.com/embed/s4v5OX60e48" frameborder="0" allowfullscreen=""></iframe>

[TZ350]

<iframe width="560" height="315" src="//www.youtube.com/embed/VA0fFhVYNKQ" frameborder="0" allowfullscreen=""></iframe>

I like this one because it has a donkey motor driving the blower.

<iframe width="560" height="315" src="//www.youtube.com/embed/GjD134M1JBU" frameborder="0" allowfullscreen=""></iframe>

Someone explaining why supercharging/turbocharging a crankcase inducted two stroke can not work, even quotes out of a book but I am not sure I agree with him myself.

308379

http://www.theworldofmotorcycles.com/lsr_buddfab_streamliner_50cc.html

50cc 2T turbocharged land speed record breaker.

[speedpro]

It'd be harder to change the rules than to actually build the engine. If it floats your boat just build it.

[jasonu]

Fxr150's are not air cooled.........

The fact that the FXR has cooling fins cast into the cylinder and head would suggest it relies upon the flow of 'air' to 'cool' it. Water cooled engines such as my RGKE do not have 'cooling' fins.
Along with Grumph I thought of the GSXR TQ speedway cars and how that ruling would or could be applied to Buckets.

[FastFred]

308379

http://www.theworldofmotorcycles.com/lsr_buddfab_streamliner_50cc.html

50cc 2T turbocharged land speed record breaker.

http://www.elsberg-tuning.dk/recordbikes.html

50cc speed records over the years.

[Yow Ling]

Oil supply would be a bit of an issue when turbing a 2t

[kel]

The fact that the FXR has cooling fins cast into the cylinder and head would suggest it relies upon the flow of 'air' to 'cool' it. Water cooled engines such as my RGKE do not have 'cooling' fins.

Yep, yet again our rules are exposed as inadequate.
I'd fully agree that an FXR is air cooled; the oils primary role is that of lubricant. Sure the engine oil passes through a heat exchanger but it’s the flow of air over the heat exchanger that cools the oil therefore the FXR is air cooled!
ps. my 2 stroke gearbox oil flows through a heat exchanger, I have no problem with this as the oil is a lubricant and my motor is air cooled.

[avgas]

The fact that the FXR has cooling fins cast into the cylinder and head would suggest it relies upon the flow of 'air' to 'cool' it. Water cooled engines such as my RGKE do not have 'cooling' fins.
Along with Grumph I thought of the GSXR TQ speedway cars and how that ruling would or could be applied to Buckets.
Anything with a "radiator" would beg to differ. FXR came factory standard with them. GSXR did also. XR/GB's did not (the real grey area). Also late British bikes vs modern(ish) British bikes.

But then again if we used your definition of fins for cooling. Doesn't that make the last "air cooled" (as in had fins just for cooling) bikes something like a CZ?

Air cooled means effectively air-to-metal. Liquid cooled means that there is some kind of liquid that is placed near the heat, its absorbed some of the heat and then removed from the heat to somewhere else to "cool", then it repeats.
So really anything that has a "radiator" filled with liquid, really should be called liquid cooled, and anything that is metal onto a metal radiator (like a "heat sink") is air cooled, and stuff that has both (fins on the block + liquid between the walls) is "Air and Oil" cooled.

Sadly we tend to abbreviate this to "air cooled" where the fact of the matter is that is only half the story. As there is a whole heat exchange process with oil. Thankfully most of this was resolved with electric engines.
http://en.wikipedia.org/wiki/Oil_cooling

[kel]

Air cooled means effectively air-to-metal.
Show me in the MNZ competition rules where I can find this definition

[husaberg]

The fact that the FXR has cooling fins cast into the cylinder and head would suggest it relies upon the flow of 'air' to 'cool' it. Water cooled engines such as my RGKE do not have 'cooling' fins.
Along with Grumph I thought of the GSXR TQ speedway cars and how that ruling would or could be applied to Buckets.

A lot of older water cooled bikes had fins Bultaco spring to mind, does that make them any less water cooled?
if you google an FXR150 in the specs it will say oil cooled, The rules say air cooled as a restriction or open type ... surely Suzuki would know.
I remember grumph saying at the time speedway got it wrong in their interpretation.......
Then again there rules way have mentioned liquid cooling or water cooling etc.......

[jasonu]

A lot of older water cooled bikes had fins Bultaco spring to mind, does that make them any less water cooled?
if you google an FXR150 in the specs it will say oil cooled, The rules say air cooled as a restriction or open type ... surely Suzuki would know.
I remember grumph saying at the time speedway got it wrong in their interpretation.......
Then again there rules way have mentioned liquid cooling or water cooling etc.......

Sounds like the rules need to be tweaked. But as Green said that might take a while...

[TALLIS]

I don't really see the problem here with rules, 150 4t air or water cooled. So dose it really mater what type of cooling you dem a fxr150 engine to be? The rules are effective for 2t because it's either air or water cooled... I suppose they are constantly oil cooled if you really wanted to get into it.

[Yow Ling]

Tallis is right, it makes no difference how it is cooled in 4t F4.



But for those who have never been isside a FXR there is an oil jet that cools the bottom of the piston, the oil that feeds the camshaft bearings dribbles down the timing chain tunnel, and the so called radiator is a tiny oil cooler. For sales purposes Suzuki calls it oil cooled . the oil pump is tiny as its only job is to supply oil to the camshaft bearings and a little dribble to the roller bearing in the big end.

[Sketchy_Racer]

Here's one to wet your appetite TZ


https://www.youtube.com/watch?v=gv377_f3cvU


https://www.youtube.com/watch?v=Oxj_OAb5bqk

[Flettner]

one I prepared earlier, nice little turbo.

[breezy]

308402 maybe this is the way to do it:niceone:

[FastFred]

308402

Hey I think that was TeeZee at Taumarunui, he said his bike farted all the way around the track .... :laugh:

[ken seeber]

The dude in the video explaining how the supercharging of crankcase scavenged 2 strokes is basically correct. However, there can be benefits in that the potential greater throughput of fresh mixture can assist in achieving a greater mass of fresh charge (displacing any combusted gas) at the time of exh closure. However (again) this must be offset by the power loss to drive the supercharger.
The situation is different with a turbocharger. In this case, the exhaust gases drive the turbocharger, incurring an overall pressure rise in the exhaust upstream of the turbo. All thing being equal, this can result in a charge density at the time of exh closure being much greater that what is normally experienced. Lots of factors to consider in this as well though, eg crankcase pumping capacity. So, more mass of mixture to be combusted means more power. Just google turbo 2 strokes, eg snowmobiles and it can be seen that this is the case.
Dunno what this might mean in terms of Bucket rules rewrites, but is a consideration.

Long live 2 strokes though!

[ken seeber]

Further to this though, I suppose that one could artificially increase the back pressure of the exhaust of the supercharged engine (by say a smaller tailpipe) to raise the overall system pressure. This would lead to a higher level of trapped charge mass at the time of exh port closure.
Lots of things to try.

[turbokemi]

I know this is a bit off topic, but I have a turbocharged 2stroke snowmobile, it's a skidoo 2004 800cc twin, works great, I run on 98 octane pumpgas and have 170 hp, original hp is 130 hp, I'm now wating for a new head with a bit lower compression so I can run on higher boost, now I'm running on 0,5 bars on pumpgas and 0,9 on race fuel, it's a rotax 800 engine, stock engine with forged pistons

[FastFred]

I have a turbocharged 2stroke snowmobile, it's a skidoo 2004 800cc twin, works great, I run on 98 octane pumpgas and have 170 hp, original hp is 130 hp, I'm now wating for a new head with a bit lowe compression so I can run on higher boost, now I'm running on 0,5 bars on pumpgas and 0,9 on race fuel, it's a rotax 800 engine, stock engine with forged pistons

That is very interesting, especially some idea of the boost pressures. I cant see your attached image but we would love to know more.

[turbokemi]

https://www.youtube.com/watch?v=_1zKLcGrb7o&feature=youtu.be here is my test video, it was running a bit to rich in this video, but I have re jetted it now, and it runs smooth, more videos are coming

[turbokemi]

and there will come more videos of 2 stroke and 4 stroke projekts on my youtube channel :)

[turbokemi]

D:\bilder\ailo_kemi on Instagram_files\turbo rev.jpg

[turbokemi]

Here's one to wet your appetite TZ


https://www.youtube.com/watch?v=gv377_f3cvU


https://www.youtube.com/watch?v=Oxj_OAb5bqk

I have turbocharged 2 stroke engines, seems to work creat!

[FastFred]

- here is my test video, it was running a bit to rich in this video, but I have re jetted it now, and it runs smooth, more videos are coming

Great to see the video clip complete with turbo pressure blowoff squeek when you close the throttle. :niceone:

Was there much involved in installing the turbo? did you have to modify the exhaust pipe much?

Not much snow here for snow sleds but very interested in two strokes and what can be done with them and I think the technology being developed for snow sleds now may be what revives big capacity 2T road bikes in the future.

[koba]

[QUOTE=turbokemi;1130824142here is my test video, it was running a bit to rich in this video, but I have re jetted it now, and it runs smooth, more videos are coming[/QUOTE]

Did anyone else see this as a scary skull thing before the video plays?
Like a snow version of these guys...

[turbokemi]

Great to see the video clip complete with turbo pressure blowoff squeek when you close the throttle. :niceone:

Was there much involved in installing the turbo? did you have to modify the exhaust pipe much?

Not much snow here for snow sleds but very interested in two strokes and what can be done with them and I think the technology being developed for snow sleds now may be what revives big capacity 2T road bikes in the future.
No mods on exhaust or port timing,I just deleted the silencer and welded turbo french on the pipe and added more springs between the engine and the pipe to hold it in place when the boost hits, I can take some photos when I go for riding, I'm waiting for a new turbo domes for my rktek billet head so I can run on higher boost on pump gas, actually it's quite simple to turbo charge a 2 stroke carburetor engine, I changed the vacuum fuel pump with a walbro electric pump because when you boost a 2 stroke the vacuum disappear in the crank case and you need a fuel pressure regulator that will increase the fuel pressure when the boost hits, and you have to pressurize the fuel float with boost, I can explain with a video or some pictures, and I had to change the reeds to turbo reeds that can handle more flexing, I actually did go down on the main jets from 400 to 360, and added adjustable power jets so I can rich or lean the fuel mix on the run when the temperature changes or the altitude

[turbokemi]

The thing when you turbocharge a 2 stroke is that you need a bigger turbo then in a 4 stroke, like I use a garrett gt2860rs turbo, on a car this turbo is suitable from 1,5 liters to 2,5 liters, have a potential to make 350 hp, on a 2 stroke 800cc this is the smallest turbo you can use and the limit for the turbo is 250hp on 800cc twin 2 stroke, if more power is wanted then gt 2871 or a gt30 turbo is the way to go, and a ballbearing turbo is to recommend, they need less oil pressure and spool twice as fast up then a standard journal bearing, I had a journal bearing turbo at first, but it sucked, I had to use a big oil pump that draws a lot of amps to run, and my stator was working on the limit, so I bought a boondocker turbokit oil pump, small, low amp draw and just enough oil pressure to use on a ballbearing turbo, boondocker developed this pump to use on 2 stroke turbo systems

[TZ350]

Thanks for that, the info is very helpful, there are a few of us here interested in trying a turbo, but our engines are much smaller than yours, the principle is the same I guess, just smaller.

[turbokemi]

Oil supply would be a bit of an issue when turbing a 2t
Boondocker usa makes small oil pump to use on ballbearing turbos, low amp draw an very small

[turbokemi]

Oil supply would be a bit of an issue when turbing a 2t
And weldon makes turbo feed and savage pumps

[Yow Ling]

And weldon makes turbo feed and savage pumps

Yes, there is an engineering solution. A 50 cc two stroke has no provision for a pressure oil system, even one that only has to supply 5 psi to the bearings, an electric pump will use say 25 w from an already small electrical supply. also if you are using the gearbox oil supply which is probably around .5 litres the oil will heat up , so you may need an oil cooler or a seperate oil supply. Its not impossible just comes with a few challenges.

The ecotrons RHB3 copy turbo looks ok as it has ball bearings , but then in some more of their literature they refer to plain bearings, so maybe lucky dip.

[turbokemi]

A ballbearing turbo needs about 1 bar oil pressure, the minarelli turbo boost busters did build uses a weldon oil pump, and they figured out that the rhb31 is to small and made to much back pressure and made the engine to heat up to much, så they used a k03 turbo with some special specifics, they have a video on YouTube, but he speaks Swedish when he tells about the minarelli turbo

[turbokemi]

Yes, there is an engineering solution. A 50 cc two stroke has no provision for a pressure oil system, even one that only has to supply 5 psi to the bearings, an electric pump will use say 25 w from an already small electrical supply. also if you are using the gearbox oil supply which is probably around .5 litres the oil will heat up , so you may need an oil cooler or a seperate oil supply. Its not impossible just comes with a few challenges.

The ecotrons RHB3 copy turbo looks ok as it has ball bearings , but then in some more of their literature they refer to plain bearings, so maybe lucky dip.
Can't there be fitted a small battery somewhere?

[husaberg]

Something like a crf50 or similar oil pump driven of the autolube drive..........

http://www.dratv.com/oilpu27cotos1.html

[turbokemi]

When you turbocharge a 2 stroke, the best turbo lubrication is synthetic 2 stroke mix oil, that's what we lubricate our turbos on sleds, because a turbo is not totally sealed, and some oil will leak outin to the inlet or exhaust side, so if you use 4 stroke engine oil, and that doesn't burn up like 2 stroke oil, and 4 stroke oil makes a awful smell to the exhaust if it leaks to the intake side, and reduces power to

[turbokemi]

I know some guys here in norway that makes custom turbo oilpumps just for turbo 2T projects, if you have original 2t oil mix pump, they will replace it with a cusom made high volume and pressure pump to feed oil to turbo, or if you are handy, you could make a belt drivven pump thats mounted on the flywheel or something?:niceone:

[TZ350]

.

With two stroke EFI and Turbocharging becoming more common I am thinking about putting forward this proposed amendment to rule 24.2 that gives the 2T tuners the same forced induction options that the 4T tuners enjoy. F4 & F5 is a developers class so its only fair the 2T team have the same options as the 4T crew, the bigger question is an appropriate capacity, constructive input would be welcome.


24.2 Engines must be derived from non-competition motorcycles. Motocross, Road Racing, Enduro and Go Kart motors and transmission parts are not permitted. There shall be no restriction on the make, type or design of carburettor, ignition, exhaust, piston, cam, valve springs or cooling system except for class eligibility. All engines must be normally aspirated except F4 4 stroke engines of less than 100cc capacity, which may be turbo or supercharged. F4 2 stroke engines over 104cc are restricted to carburation equivalent to a single 24mm carburettor, F5 4 stroke engines over 53cc are restricted to carburetion equivalent to a single 20mm carburettor.


Change 24.2 to read as below.


24.2 Engines must be derived from non-competition motorcycles. Motocross, Road Racing, Enduro and Go Kart motors and transmission parts are not permitted. There shall be no restriction on the make, type or design of carburettor, ignition, exhaust, piston, cam, valve springs or cooling system except for class eligibility. All engines must be normally aspirated except F4 4 stroke engines of less than 100cc capacity and F4 2 stroke engines of less than 70cc capacity, which may be turbo or supercharged. F4 2 stroke engines over 104cc are restricted to carburation equivalent to a single 24mm carburettor, F5 4 stroke engines over 53cc are restricted to carburetion equivalent to a single 20mm carburettor.


Reason for Rule Change


There are a lot of people that are attracted to Buckets and two strokes for the shear fun of building something interesting. F4 four strokes have a turbo and/or supercharging option, so to be fair, two strokes should have that option to.

[F5 Dave]

I propose amendment to 4 strokes of 60cc and 2 strokes of 40cc may be super or turbocharged.

Reason. Have a look a F1 and Rally experience.

A further restriction: if it is suspected with or without proof, that boost is increased over 10psi that one wheel will be forfeited.

Just to be fair.:msn-wink:

[husaberg]

I propose amendment to 4 strokes of 60cc and 2 strokes of 40cc may be super or turbocharged.

Reason. Have a look a F1 and Rally experience.

A further restriction: if it is suspected with or without proof, that boost is increased over 10psi that one wheel will be forfeited.

Just to be fair.:msn-wink:

Throw in a the cc eq of 2mm overbore or eq cc increase for all (no stroking up as well though)

[FastFred]

I propose if it is suspected with or without proof, that boost is increased over 10psi that one wheel will be forfeited. Just to be fair.:msn-wink:

seems fair to me ... :laugh:

[Grumph]

Throw in a the cc eq of 2mm overbore or eq cc increase for all (no stroking up as well though)

No way Jose...leave it at 100/70 split for 2 reasons.

1 There are 100cc 4T projects under way now as we all know.
2 In these small sizes that is a huge capacity increase and of course builders would go to the max overbore right from the start...

Looks Ok to me - Now find an MNZ club who will take it further - and quite quickly as remits are closing shortly I believe.

[husaberg]

No way Jose...leave it at 100/70 split for 2 reasons.

1 There are 100cc 4T projects under way now as we all know.
2 In these small sizes that is a huge capacity increase and of course builders would go to the max overbore right from the start...

Looks Ok to me - Now find an MNZ club who will take it further - and quite quickly as remits are closing shortly I believe.

I was meaning for the 100,2s 125,2s and 150's 4s

[Bert]

No way Jose...leave it at 100/70 split for 2 reasons.

1 There are 100cc 4T projects under way now as we all know.
2 In these small sizes that is a huge capacity increase and of course builders would go to the max overbore right from the start...

Looks Ok to me - Now find an MNZ club who will take it further - and quite quickly as remits are closing shortly I believe.

Maybe something AMCC, VMCC or chch...

[TALLIS]

.

With two stroke EFI and Turbocharging becoming more common I am thinking about putting forward this proposed amendment to rule 24.2 that gives the 2T tuners the same forced induction options that the 4T tuners enjoy. F4 & F5 is a developers class so its only fair the 2T team have the same options as the 4T crew, the bigger question is an appropriate capacity, constructive input would be welcome.


24.2 Engines must be derived from non-competition motorcycles. Motocross, Road Racing, Enduro and Go Kart motors and transmission parts are not permitted. There shall be no restriction on the make, type or design of carburettor, ignition, exhaust, piston, cam, valve springs or cooling system except for class eligibility. All engines must be normally aspirated except F4 4 stroke engines of less than 100cc capacity, which may be turbo or supercharged. F4 2 stroke engines over 104cc are restricted to carburation equivalent to a single 24mm carburettor, F5 4 stroke engines over 53cc are restricted to carburetion equivalent to a single 20mm carburettor.


Change 24.2 to read as below.


24.2 Engines must be derived from non-competition motorcycles. Motocross, Road Racing, Enduro and Go Kart motors and transmission parts are not permitted. There shall be no restriction on the make, type or design of carburettor, ignition, exhaust, piston, cam, valve springs or cooling system except for class eligibility. All engines must be normally aspirated except F4 4 stroke engines of less than 100cc capacity and F4 2 stroke engines of less than 70cc capacity, which may be turbo or supercharged. F4 2 stroke engines over 104cc are restricted to carburation equivalent to a single 24mm carburettor, F5 4 stroke engines over 53cc are restricted to carburetion equivalent to a single 20mm carburettor.


Reason for Rule Change


There are a lot of people that are attracted to Buckets and two strokes for the shear fun of building something interesting. F4 four strokes have a turbo and/or supercharging option, so to be fair, two strokes should have that option to.

How about you build one, find somewhere to run it. See how it goes, if it goes to good forget about it. Oh is this the 85 mx thread? Oh wait, same rules should apply to this, only fair...

[kel]

Oh is this the 85 mx thread? Oh wait, same rules should apply to this, only fair...
Struggling to see the connection. I'm not against the 85 MX per se, but this is completely different. Non competition motors with non competition turbos or blowers, could it be any more true to the spirit of buckets? Just agree on a sensible cc limit and get it done. I won't block this one :shutup:

[F5 Dave]

I wouldn't block it either if I knew what a sensible limit was. But I don't. A 70cc Derbi with a blower wouldn't need much pressure to do the job you'd think.

[husaberg]

I wouldn't block it either if I knew what a sensible limit was. But I don't. A 70cc Derbi with a blower wouldn't need much pressure to do the job you'd think.

Double of original power output with each additional atmosphere of boost is generally considered a good rule of thumb........

[F5 Dave]

So say 19hp at 15psi would double?

[Grumph]

So say 19hp at 15psi would double?

And IMO, life expectancy would halve....

[speedpro]

life expectancy would halve....

:killingme :rofl:

[speedpro]

Double of original power output with each additional atmosphere of boost is generally considered a good rule of thumb........

1 turn on the waste gate screw was worth about 30hp. 3 turns resulted in a noticeable improvement

[husaberg]

So say 19hp at 15psi would double?



And IMO, life expectancy would halve....
AS a general rule if it was 19hp then at 15psi boost it could be expected to produce 28hp without any additional tuning assuming it could be keep in one piece and thermally sound.
Grumph said life expectancy would half ....perhaps.
but it would still expect it to last far longer than a engine of similar size tuned using traditional forms of atmospheric tuning to the same output would.


1 turn on the waste gate screw was worth about 30hp. 3 turns resulted in a noticeable improvement
So what did that add in boost and Hp terms Mike ..........

[Grumph]

1 turn on the waste gate screw was worth about 30hp. 3 turns resulted in a noticeable improvement

Quite agree - but we're not talking a big 4T with a forest of cylinder studs, thick wall gudgeons and forged pistons...
Most small 2T's available for this use will have 4 X 6mm cylinder studs, maybe 12mm gudgeons and pistons which won't stand the heat.
You and i and a few others can do the engineering required to bring the basics of the motor up to scratch, it won't just be buy from a catalogue....
I'm quite prepared to support the proposed remit, but have no intention of going down this track myself.

[F5 Dave]

AS a general rule if it was 19hp then at 15psi boost it could be expected to produce 28hp without any additional tuning assuming it could be keep in one piece and thermally sound.
Grumph said life expectancy would half ....perhaps.
but it would still expect it to last far longer than a engine of similar size tuned using traditional forms of atmospheric tuning to the same output would.


So what did that add in boost and Hp terms Mike ..........
Erm so in what way is double 19hp = 28? Has the rule of thumb changed or did the math get a typo?

[husaberg]

Erm so in what way is double 19hp = 28? Has the rule of thumb changed or did the math get a typo?

Me math got a typo.....mine erngerish is far more betererer.....
it was meant to be 38

Later when you think about it the rule of thumb although it excludes some thermal issues makes perfect sense.
if a NA engine makes Y amount of power (at normal atmospheric pressure) if you double the atmospheric pressure it equals Yx2 hp

[Yow Ling]

Dont forget
21 degrees C inlet
60% compressor effieiency
Compressor pressure 14.7 psig
Compressor Output air temperature 131 degrees C

Very hot engine

[husaberg]

Dont forget
21 degrees C inlet
60% compressor effieiency
Compressor pressure 14.7 psig
Compressor Output air temperature 131 degrees C

Very hot engine

But that's what intercoolers are for though...........
To make the same HP with traditional atmospheric tuning also create a fair bit of additional heat also.......
Any ic engine is at its very essence a pump.

[TZ350]

I wouldn't block it either if I knew what a sensible limit was. But I don't.

I am not sure what a sensible size is either, but the way I figured it, the supercharged 4T limit of 100cc is 2/3rds the normally aspirated 4T. So 2/3rds of 125 is 82.5, but there is talk of MX85's so I chose a 70cc limit for 2T forced induction.

70cc for 2T forced induction? would that seem sensible.... :confused:

[mr bucketracer]

I am not sure what a sensible size is either, but the way I figured it, the supercharged 4T limit of 100cc is 2/3rds the normally aspirated 4T. So 2/3rds of 125 is 82.5, but there is talk of MX85's so I chose a 70cc limit for 2T forced induction.

70cc for 2T forced induction? would that seem sensible.... :confused:the other way to look at it is a 100 4 stroke is a f5 bike , with a turbo its a f4 bike , maybe should be the same been the 2 stroke been 50 cc ?

[Yow Ling]

the other way to look at it is a 100 4 stroke is a f5 bike , with a turbo its a f4 bike , maybe should be the same been the 2 stroke been 50 cc ?

plus that gets rid of the carburetion equivalent part of the 125 stuff 15mm carb would just about kill it

[F5 Dave]

Yhe current 2/3 for a turbo rule isn't adequate if someone made a decent job of it, just no one has. The double cc rule for F5 isn't just either as we've seen carb restrictions are not that effective, its just that someone was thinking shitty old CB100, yeah that'd be right.

[TZ350]

plus that gets rid of the carburetion equivalent part of the 125 stuff

Yes, and the air cooled part confuses it too ... 2/3 of 100cc water cooled ?? and/or 2/3 of 125 aircooled.

[speedpro]

I am not sure what a sensible size is either, but the way I figured it, the supercharged 4T limit of 100cc is 2/3rds the normally aspirated 4T. So 2/3rds of 125 is 82.5, but there is talk of MX85's so I chose a 70cc limit for 2T forced induction.

70cc for 2T forced induction? would that seem sensible.... :confused:

The forced induction limit of 100cc was created when the capacity limit for F4 was 125cc(4T)

[F5 Dave]

Yeah it was pretty silly then, but I guess they were thinking Victor motor driven onto a C90.

[jasonu]

The forced induction limit of 100cc was created when the capacity limit for F4 was 125cc(4T)

Good point that man

[Flettner]

Back in the day the rule was 100cc fourstroke, open, no restrictions. Don't change that rule, as has been said earlier there are a few 100cc supercharge projects under way, would be a pitty to see these projects die before they raced.
Dave before you answer, remember, you will be riding this SC twin bucket to fame and glory. Got your vote then?

[Grumph]

Back in the day the rule was 100cc fourstroke, open, no restrictions. Don't change that rule, as has been said earlier there are a few 100cc supercharge projects under way, would be a pitty to see these projects die before they raced.
Dave before you answer, remember, you will be riding this SC twin bucket to fame and glory. Got your vote then?

I suspect that if you can guarantee it will last longer than 15min on Ruapuna B track, the answer is yes...

Back in the day it was also open fuel for the blown 100's - which helped a LOT.

[jasonu]

Back in the day it was also open fuel for the blown 100's - which helped a LOT.

In the Buckets class?????

[F5 Dave]

Meh I'm getting too old to go any good these days

[Flettner]

Meh I'm getting too old to go any good these days

Maybe I'll ride it, after all I'm getting a new hip shortly. Told my wife I'll be 17 again, with a mature 53 year olds brain. She says more likely 53, with a 17 year olds brain. Probably closer to the truth.

Yes open, methanol fuel with a hint of nitro, (say 50%), 14lbs boost, approx 18,000 rpm. Weigh a ton and have a short fuse I would imagine. More parts turning up on saturday for this project.

Who am I kidding, I can't ride a bucket any more.

[husaberg]

Maybe I'll ride it, after all I'm getting a new hip shortly. Told my wife I'll be 17 again, with a mature 53 year olds brain. She says more likely 53, with a 17 year olds brain. Probably closer to the truth.

Yes open, methanol fuel with a hint of nitro, (say 50%), 14lbs boost, approx 18,000 rpm. Weigh a ton and have a short fuse I would imagine. More parts turning up on saturday for this project.

Who am I kidding, I can't ride a bucket any more.

Potentially Less fraught than telling her that you'd like to ride a 17 year old.

[mr bucketracer]

Potentially Less fraught than telling her that you'd like to ride a 17 year old.i saw you on the chaser today , good win ;-)

[husaberg]

i saw you on the chaser today , good win ;-)

I just finally got that......ya bugger.... hopefully I get my braces off in a few weeks.........:lol:
The girl was a bit dim......I still would (of course),but id feel a little guilty afterwards though.

[mr bucketracer]

I just finally got that......ya bugger.... hopefully I get my braces off in a few weeks.........:lol:
The girl was a bit dim......I still would (of course),but id feel a little guilty afterwards though.lol kind of had your look (-: nasty me

[husaberg]

lol kind of had your look (-: nasty me

Yeah yeah I am black and smart.........

[TZ350]

The proposed change to allow super/turbo charged 2T's

Write to MNZ to have your say.

http://www.mnz.co.nz/docs/default-source/regulations/2015-summary-of-all-proposed-rule-changes-for-websitea97dfb456e51694ab575ff0000938921.pdf?sfvrsn =2 (http://www.mnz.co.nz/docs/default-source/regulations/2015-summary-of-all-proposed-rule-changes-for-websitea97dfb456e51694ab575ff0000938921.pdf?sfvrsn =2)

The proposed change is on Page 5

[F5 Dave]

So 70cc? That still feels like 38hp minus some losses is still quite a lot.

[koba]

I haven't got past giggling about this bit yet:

22.3.1a – When the riders have lined up on the grid they are deemed to be under the starters control at the instant the RED FAG reaches the side of the track. Any motorcycle that moves in a forward motion whilst under the starters control shall be deemed a jump start. Starters control ends once the event commences as per Rules 6.6.1 and 6.6.2.

[koba]

So 70cc? That still feels like 38hp minus some losses is still quite a lot.

Yeah, 70 sounds quite large.
I'm guessing the logic is giving N/A Engines 1.5 times the capacity, same as the 4 strokes, plus a wee bit of rounding...?

[TZ350]

So 70cc? That still feels like 38hp minus some losses is still quite a lot.

I am not sure what is possible or even if someone would bother or could make it mechanically reliable enough but I thought 2T's deserved the option as 4T's have it and it is also an interesting area and some of the attraction of buckets is the chance to be innovative.

And if you think about it, from a commercial point of view, a forced induction 2T with direct fuel injection could be a very handy sort of engine. Cheap to make, light weight, clean burning, fuel efficient, very good performance, lots of sporting, commuting and small vehicle applications for an engine like that.


Yeah, 70 sounds quite large. I'm guessing the logic is giving N/A Engines 1.5 times the capacity, same as the 4 strokes, plus a wee bit of rounding...?

Yes NA 1.5 X Supercharged 70's

There is some question on the net about whether forced induction on a crankcase scavenged 2T will work anyway. And if it did, the thinking seems to be that there will be natural limitations on usable boost and power increases that are possible, and for sure, because of blow through the pressure power relationship will not behave like it does with a 4T.

I don't know about any of that but Buckets is a great place for the mechanically adventurous to find out.


I am not sure what a sensible size is either, but the way I figured it, the supercharged 4T limit of 100cc is 2/3rds the normally aspirated 4T. So 2/3rds of 125 is 82.5, but there is talk of MX85's so I chose a 70cc limit for 2T forced induction.

My thinking on capacity was 70cc because that allowed room for the possibility of NA 85cc MX engines to fit in between the forced induction 70's and the water cooled 100's and air cooled 125's.

And from a practical point of view, 70cc is a common big bore kit size for a lot of 50cc bikes and scooters.

I think allowing a forced induction option for 2T's is fair enough, its just the capacity that is the question.

[F5 Dave]

What about 50cc. 50cc is a common size for fifties. If it ends up not being enough then try the big bore, but it's hard to go back. Look what happened to F3 with SV650s.

[speedpro]

There is some question on the net about whether forced induction on a crankcase scavenged 2T will work anyway.

You only have to look at the turbo snowmobiles in Canada - turbo, direct injected, and LOTS of horsepower.

[TZ350]

What about 50cc. 50cc is a common size for fifties. If it ends up not being enough then try the big bore, but it's hard to go back. Look what happened to F3 with SV650s.

I thought 70cc, but good point, please put 50cc capacity forward in a submission to MNZ on the proposal, better to have 50cc or maybe 60-65cc than nothing.

[TZ350]

You only have to look at the turbo snowmobiles in Canada - turbo, direct injected, and LOTS of horsepower.

Does anyone have actual numbers and or back to back dyno graphs, I am sure it works, but how well????

[F5 Dave]

I'd rather progress 107cc so I didn't have to do crazy destroking, but I got over it.

[Yow Ling]

Does anyone have actual numbers and or back to back dyno graphs, I am sure it works, but how well????
Post 28 has a 50cc AM6 making 19hp

[TZ350]

Post 28 has a 50cc AM6 making 19hp

Thanks

Ok so 50cc + Turbo = 19hp then 70cc might be 70/50*19 = 26.6hp much the same as other developed 2T's.

So in this example at least, 70cc looks about right for the capacity.


Here's one to wet your appetite TZ


https://www.youtube.com/watch?v=gv377_f3cvU

[TZ350]

A 50cc 2t turbocharged engine based on an AM6 as used in the aprilia RS50, running methanol and close to 20 psig boost. (1.4 bar)

<iframe width="420" height="315" src="https://www.youtube.com/embed/mYINrhTNiyM" frameborder="0" allowfullscreen=""></iframe>

http://www.motorcycle-usa.com/287/1518/Motorcycle-Article/Salt-Addiction-Buddfab-Streamliner.aspx

50cc and 24hp on Nitrus Oxide but mechanically unreliable. Turbo worked better from a reliability point of view.

You can pretty much bet that this motor is as developed as your likely to get.

So 70/50*24 = 33.6hp for 70cc (assuming the Turbo didn't make more power than the Nitrus)

Looks like for 70cc 33.6hp is going to be pretty much the upper limit, now thats not to frightening.

310379

Been close to that already with the air cooled Suzuki GP125.

From what I can see, 70cc for turbo 2T's still looks about right.

[F5 Dave]

That's probably 6hp more than any bucket has hit the track with. You should have seen how Kels 29hp, read 26 by lap 3, pulled away from everything at the GP. Oh wait. You did.

[TZ350]

That's probably 6hp more than any bucket has hit the track with.

310381310383

30 hp has been out there.

310382310385

And ended when the ring jumped the peg and turned into the exhaust port.

And the 31hp version expired at Kaitoki, thats when we learned that if you run a 2T in the power band on part throttle you need to retard the ignition timing to avoid detonation. Who would have thought you needed to do that! another lesson learned.

310387 copper cooling fins on what is hoped to be a mid 30's hp engine, or maybe even the first to touch 40.

The 30 and 31hp engines didn't seem to suffer the same power fade as Kels does at 29hp. Kel has some very effective looking air scoops and I expect his bike will run stronger for longer when he incorporates a bit of copper into the air cooling system.

[sonic_v]

310379[/ATTACH]

Been close to that already with the air cooled Suzuki GP125.

From what I can see, 70cc for turbo 2T's still looks about right.

TZ, Hp is not directly proportional to cylinder capacity in two-stroke engines. It actually follows a 2/3 rds power law.

Hence for a 70cc v's a 50cc you have 24 * (70/50)^0.6667 =24 * 1.251 = 30.0 hp

Basically hp is directly proportional to cylinder bore surface area - hence the reason over square 2 strokes are so poor.

[TZ350]

TZ, Hp is not directly proportional to cylinder capacity in two-stroke engines. It actually follows a 2/3 rds power law.

24 * 1.251 = 30.0 hp


(Using the Buddfab turbo 50 that makes 24hp as an example Sonic_V suggests a turbo 70 might achieve 30hp)

Thanks, so 70cc is still looking good, maybe even a bit on the small side because some F4 2T motors have made over 30hp now and it would take a lot of work to develop ones 70 to anything like the Buddfab motor.

[lodgernz]

Interesting thread, but if I might be permitted to add a note of caution:

4-stroke + supercharging = blowups = oil on kart tracks = end of bucket racing.

Just sayin'...

[TZ350]

Interesting thread, but if I might be permitted to add a note of caution:4-stroke + supercharging = blowups = oil on kart tracks = end of bucket racing. Just sayin'...

Plenty of NA 4T's have dumped a shit load of oil on the track and then some 4T riders have had the audacity to point the finger at the blowback from 2T carbs.

In fairness I guess 2T's blow back all the time and 4T oil dumps are mostly spectacular localised events or in some cases long snail trails as they slowly bleed to death.

A broken rod from a forced induction 2T probably won't dump as much oil as a similar 4T blow up but I can see what you mean.

[TZ350]

The proposed change to allow super/turbo charged 2T's

Write to MNZ to have your say.

http://www.mnz.co.nz/docs/default-source/regulations/2015-summary-of-all-proposed-rule-changes-for-websitea97dfb456e51694ab575ff0000938921.pdf?sfvrsn =2 (http://www.mnz.co.nz/docs/default-source/regulations/2015-summary-of-all-proposed-rule-changes-for-websitea97dfb456e51694ab575ff0000938921.pdf?sfvrsn =2)

The proposed change is on Page 5

4T's have a forced induction option now and its proposed that 2T's have the same opportunity. MNZ would welcome sensible input that would help them to judge the merits of the submission.

[speedpro]

A broken rod from a turbo 2T probably won't dump as much oil as a similar 4T blow up but I can see what you mean.

Speaking from experience, breaking a rod and poking a hole in the cases "may" cause a few drops of oil to fall out of a 2T, unless you manage to poke a hole through to the gearbox. Done it on the track, don't actually recall any oil but I did wake up strapped in a stretcher. Done it on the dyno where it poked a hole in the gearbox as well. It still only leaked a couple of spoonfulls

[speedpro]

It does seem to me to be another option for Rob to explore with regard to destroying 2-stroke engines :innocent:

[jasonu]

(Using the Buddfab turbo 50 that makes 24hp as an example Sonic_V suggests a turbo 70 might achieve 30hp)

Thanks, so 70cc is still looking good, maybe even a bit on the small side because some F4 2T motors have made over 30hp now and it would take a lot of work to develop ones 70 to anything like the Buddfab motor.

How many of the 30 and 30+hp Bucket motors have proven rideable or reliable and have won championships and or GP's? The winning bikes (at the present time) make 24-27hp. Using the above calculations a forced induction 2T f4 motor capacity limit should be around 60cc.

[TZ350]

How many of the 30 and 30+hp Bucket motors have proven rideable or reliable and have won championships and or GP's? The winning bikes (at the present time) make 24-27hp. Using the above calculations a forced induction 2T f4 motor capacity limit should be around 60cc.

Personally I wouldn't expect a 70cc 30+hp turbo 2T to be any more reliable and a winning combination than the 30+ NA 125 air cooled 2T's, but the turbos would be great learning experiences if you're into that sort of thing.

[Henk]

Personally I wouldn't expect a 70cc 30+hp turbo 2T to be any more reliable and a winning combination than the 30+ NA 125 air cooled 2T's, but the turbos would be great learning experiences if you're into that sort of thing.

Could you dial in some reliability by backing off the boost? If full noise 60cc gets the required HP in a pull pin stand back engine, then maybe 70cc but not quite so on the edge is the right number.

[F5 Dave]

Sweet can I have a bigger engine? Those mito and Apr 125 do about 25, 26 std road bike and touching 30 with carb and pipe. That'd be enough for me.

[bucketracer]

Sweet can I have a bigger engine?

Sure you can have more power, no one is stopping you, instead of looking for the easy options and bigger capacity with stealthy rule submissions, its Buckets, you just have to apply yourself and build a better motor.

Maybe fitting a 70cc big bore road kit and turbocharging your Derbi could put you at the very sharp end of F4, it is something to think about.

[F5 Dave]

The bigger CC request was above, I was just echoing it to show it's absurdity.

And my Derbi is an F5 bike. Not everything rotates around F4.

[husaberg]

Im all for 2t turbo but for f4 it has to mirror the commonly accepted 1/2 displacement. ie 50cc only.

[speedpro]

Not actually the case in F4.
The forced induction option is 2/3 capacity of the NA, 100cc versus 150cc.
For the watercooled 2T capacity limit of 100cc applying the same ratio would make 66cc, rounded up to 70cc.
In reality what's the likelihood of one being built, and raced, and winning or even getting close. Stop yakking about it, support the amendment and see what comes out of it.

[TZ350]

I see the new rule changes are out.

F4 2T 55-110cc

and

Supercharged/Turbocharged 70cc 2T's

http://www.mnz.co.nz/docs/default-source/rules/2015-summary-of-ratified-rules-for-website78e3fb456e51694ab575ff0000938921.pdf?sfvrsn =2

[F5 Dave]

Ahh fuck
So the 22.1.3 is quite specific on crashing. The F4 rule is out to 110 not 107, for some reason but no dickhead changed the 24mm carb rule so it is pointless. Glad its not my concern anymore.

[husaberg]

Ahh fuck
So the 22.1.3 is quite specific on crashing. The F4 rule is out to 110 not 107, for some reason but no dickhead changed the 24mm carb rule so it is pointless. Glad its not my concern anymore.

Appendix H – 125 Grand Prix/250 Mono
1.1 - All machines must be fitted with an integral lower fairing dam (belly pan) or separate catch tray which must be constructed and fitted to trap and hold engine oil and coolant with a capacity of not less than, four strokes = 3.5 litres or two strokes = 2.5 litres.

Why are they worried about the 2T 125 getting oil everywhere?

I see they have not removed the S

I see they never fixed the Carb wording for over 104 either.
A 70cc supercharged unlimited fuel system is interesting.

[F5 Dave]

Appendix H – 125 Grand Prix/250 Mono
1.1 - All machines must be fitted with an integral lower fairing dam (belly pan) or separate catch tray which must be constructed and fitted to trap and hold engine oil and coolant with a capacity of not less than, four strokes = 3.5 litres or two strokes = 2.5 litres.

Why are they worried about the 2T 125 getting oil everywhere?

I see they have not removed the S

I see they never fixed the Carb wording for over 104 either.
A 70cc supercharged unlimited fuel system is interesting.
Yeah, forgot to Menton the s but i did during feedback through two different channels

[husaberg]

Yeah, forgot to Menton the s but i did during feedback through two different channels

It should save a few people some money on crankpins and or pistons anyway so its a good move with the 110cc.
You might be able to move that pin around a bit to stroke it now Dave.
looks like a 54.5 doesn't need to be de-stroked with a os 85mx piston.
Plus conversely a 53mm Kt100 and a bit piston can be used with a MB100 49.5mm crank.
52.5 and a bit KT100 piston can be used with the others that have a 50.6mm stroke.

[jasonu]

I see the new rule changes are out.

F4 2T 55-110cc

and

Supercharged/Turbocharged 70cc 2T's

http://www.mnz.co.nz/docs/default-source/rules/2015-summary-of-ratified-rules-for-website78e3fb456e51694ab575ff0000938921.pdf?sfvrsn =2


Ahh fuck
So the 22.1.3 is quite specific on crashing. The F4 rule is out to 110 not 107, for some reason but no dickhead changed the 24mm carb rule so it is pointless. Glad its not my concern anymore.


Appendix H – 125 Grand Prix/250 Mono
1.1 - All machines must be fitted with an integral lower fairing dam (belly pan) or separate catch tray which must be constructed and fitted to trap and hold engine oil and coolant with a capacity of not less than, four strokes = 3.5 litres or two strokes = 2.5 litres.

Why are they worried about the 2T 125 getting oil everywhere?

I see they have not removed the S

I see they never fixed the Carb wording for over 104 either.
A 70cc supercharged unlimited fuel system is interesting.


Yeah, forgot to Menton the s but i did during feedback through two different channels


It should save a few people some money on crankpins and or pistons anyway so its a good move with the 110cc.
You might be able to move that pin around a bit to stroke it now Dave.
looks like a 54.5 doesn't need to be de-stroked with a os 85mx piston.
Plus conversely a 53mm Kt100 and a bit piston can be used with a MB100 49.5mm crank.
52.5 and a bit KT100 piston can be used with the others that have a 50.6mm stroke.

None of that matters as Buckets is a self regulating class.

[seymour14]

Ahh fuck
So the 22.1.3 is quite specific on crashing. The F4 rule is out to 110 not 107, for some reason but no dickhead changed the 24mm carb rule so it is pointless. Glad its not my concern anymore.

I would ignore the crashing part, the precedent has been set now.:rolleyes:

Don't see any rule disallowing rocket launchers or rotary cannons either...:shifty:

[TZ350]

313716

Worlds Smallest Turbo.

http://www.ecotrons.com/products/small_engine_rhb31_vz21_turbocharger/

[chrisc]

313716

Worlds Smallest Turbo.

http://www.ecotrons.com/products/small_engine_rhb31_vz21_turbocharger/

Do it!

10chars