Proposal to delete rule 24.2.1 - Alcohol based fuel or fuel additives are prohibited

[ken seeber]

Have been looking at this thread and thought that I’d offer what might be available from STRIKE in terms of pistons for the 2 strokes.

Essentially, we make (in Perth West Oz) two styles of pistons to suit Yamaha kart engines that are commonly used in Australia:

• KT100J. This is a 50 * 50 engine that is allowed up to 51.0 piston size under Australian Karting Association rules. This may soon go up to 51.2/51.3 to allow people to get more life from their cylinder barrels. Unfortunately this piston must use the original style of semi trapezoidal ring design, which has been shown to be troublesome particularly with slightly differing ring thicknesses from different suppliers. This has a 14 mm pin, 100 mm crown radius, with a compression height of a nominal 32.9 mm and we do them in 0.01 increments. So no boring, but just honing to til the bore is of the correct finish and geometry. This is best done with a honing head that is at least as long as the cylinder to ensure straightness. We have made oversize versions of these, 52 mm upwards that utilize the much better 1.0 mm rail rings that are used in KT100S engine. These pistons are available in 0.01 size increments and rings in 0.05mm increments.
• KT100S. This is a 52 * 46.1 engine that is allowed up to 53.0 piston size under Australian Karting Association rules. This may soon go up to 53.2/53.3 to allow people to get more life from their cylinder barrels. These obviously use the 1.0 mm rail rings, available as above. Again a 14 mm pin, 100 mm crown radius, but with a compression height of 23.0 mm. We make these in sizes up to 55 plus, but in these larger oversizes we only have rings in 0.25 increments (bit of extra filing, but seems to work well).

If you go to www.strikeproducts.com.au you can see more info on these plus the pricing, which we consider to be completely reasonable. Not sure if this is of any help, but there you go.

As a comment from an outsider, I would go for E85 anytime, because it contains oxygen, the key ingredient to making power. The more trapped oxygen the better and also allows you raise the compression ratio over that of a (detonation limited) petrol running engine.

Thanks

Ken

[mr bucketracer]

Thanks ken , i'm shore there will be some happy lads to see what you have..!!!

[F5 Dave]

Hi Ken

Thanks for the input & I certainly have had your products recommended. Sadly I haven't been able to use them because

a) the J piston isn't really suitable, the crown height is a bit tall by about a cm, but it suits that particular engine of course so I won't complain that doesn't suit me.

b) My engine is destroked to take a 52mm piston, well actually it can go up to 52.3mm, but I was told by the local kart guy who is keen on your product that Strike starts from 52.5. - perhaps this is incorrect? Not real clear in the price list online.

Either way this requires a destroke in most engines we run, so if you'd be jolly decent & run up a batch of 50.5 to 51mm sizes of KT100S pistons & rings for the few that you'd sell over here & potentially to the Auss bucket racers over there it would be mighty nice of you.. . if potentially not so viable. Heck maybe it isn't so hard these days?

[FastFred]

MB/H100 standard stroke = 49.5mm, with a 52mm piston makes a 105.12cc engine. Using standard MB/H stroke of 49.5mm and a piston of 52.45 makes an engine of 106.95.

http://www.ebay.com/itm/KAWASAKI-KE100-KE-100-WISECO-PISTON-KIT-50MM-50MM-OVER-BORE-ALL-YEARS/151041153433?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222008%26algo%3DSIC.MOTORS%26ao%3D 1%26asc%3D20131003132420%26meid%3D6165395233782219 706%26pid%3D100005%26prg%3D20131003132420%26rk%3D3 %26rkt%3D6%26sd%3D201062420253&rt=nc

Wiseco Kawasaki KE100 50mm plus 0.5mm OS 14mm pin and thin rings. $77.55 USD each (aprox $88 NZD) eight available be quick.

$80USD http://www.ebay.com/itm/New-Wiseco-P...3ce136&vxp=mtr

$34.54 USD http://www.ebay.com/itm/NP-KAWASAKI-...99bd88&vxp=mtr

$85.77 USD 31 avaiable http://www.ebay.com/itm/Wiseco-369M0...673d9a&vxp=mtr

$112.53 NZD 3 available ex Aus http://www.ebay.com/itm/Wiseco-Pisto...728cdf&vxp=mtr

$113.86 NSD 3 available http://www.ebay.com/itm/Wiseco-Pisto...4876b3&vxp=mtr

$76.79 USD aprox $88.42 NZD 4 available http://www.ebay.com/itm/Wiseco-Pisto...ec8ffc&vxp=mtr

And so it goes on.

http://www.ebay.com/itm/SUZUKI-RG400-GAMMA-1-0mm-OVERSIZE-PISTON-SETS-RG400-2/141221592096?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222008%26algo%3DSIC.MOTORS%26ao%3D 1%26asc%3D20131003132420%26meid%3D6166461390313735 400%26pid%3D100005%26prg%3D20131003132420%26rk%3D1 %26rkt%3D6%26sd%3D130787011052&rt=nc

1.0mm OS RG400 piston sets, it looks like $109.38 NZD for a set of four.

So it looks like there are plenty of suitable pistons for the different 100cc engines.

Attachment 296133

Looks like the myth of needing a 107cc oversize allowance and 52mm + pistons because there was nothing else suitable for a 100 in the 50mm bore size is well and truly busted.

Have been looking at this thread and thought that I’d offer what might be available from STRIKE in terms of pistons for the 2 strokes.

Essentially, we make (in Perth West Oz) two styles of pistons to suit Yamaha kart engines that are commonly used in Australia:

• KT100J. This is a 50 * 50 engine that is allowed up to 51.0 piston size under Australian Karting Association rules. This may soon go up to 51.2/51.3 to allow people to get more life from their cylinder barrels. This has a 14 mm pin, 100 mm crown radius, with a compression height of a nominal 32.9 mm and we do them in 0.01 increments. If you go to www.strikeproducts.com.au you can see more info on these plus the pricing, which we consider to be completely reasonable. Not sure if this is of any help, but there you go. Ken

Hi Ken My engine is destroked to take a 52mm piston, well actually it can go up to 52.3mm,

Looks like a de-stroke or plenty of pistons for for the current capacity limit if you look around.

[husaberg]

Looks like a de-stroke or plenty of pistons for for the current capacity limit if you look around.

Fred as i pointed out the Kawa pistons do no go big enough, they don't go past .5os for an MB. even with the largest Wiesco do......
In fact none of the ones posted with fit an std MB......
as dave and mike pointed out, the others are not suitable for high revs.
The strike piston that suits without destroking from ken has a unsuitable crown height for our use.
Ask Yow (the other mIke)
Strike pistons are quality and great price available locally, totally suited to the application other than size. (This is not Kens fault.)
I blame Yamaha....

[F5 Dave]

Looks like a de-stroke or plenty of pistons for for the current capacity limit if you look around.

C'mon Freob, all it pointed out is we have to destroke the engines to run KT or similar pistons. And to get much further you have to destroke beyond reasonable limits of the crank. It isn't a simple offset bore a bigger pin type job. Its a compromise & not particularly cheap. Every rodkit means machining a pin.

I have one std bore MB barrel, that I might be able to run a 50.5, but it is a bit worn. We're also talking vintage old school pistons.

[ken seeber]

Hi Ken

Thanks for the input & I certainly have had your products recommended. Sadly I haven't been able to use them because

a) the J piston isn't really suitable, the crown height is a bit tall by about a cm, but it suits that particular engine of course so I won't complain that doesn't suit me.

b) My engine is destroked to take a 52mm piston, well actually it can go up to 52.3mm, but I was told by the local kart guy who is keen on your product that Strike starts from 52.5. - perhaps this is incorrect? Not real clear in the price list online.

Either way this requires a destroke in most engines we run, so if you'd be jolly decent & run up a batch of 50.5 to 51mm sizes of KT100S pistons & rings for the few that you'd sell over here & potentially to the Auss bucket racers over there it would be mighty nice of you.. . if potentially not so viable. Heck maybe it isn't so hard these days?

Dave,

As with all these things, there is bad news, medium news and good news.

The STRIKE KT100S pistons, that have the lower crown height, only come in sizes from 52.00 upwards with the 1.00 mm rail style rings. We could try to do them at 50.5, but all we would be left with would be the crown & pin bosses and no skirt. We are not aware of 1.00mm rail rings being available in very fine size increments. This is the bad news.

The good news is that we are also the Oz importer of Meteor kart pistons. They do all sorts of KZ, KF etc etc pistons, but also the 50 mm sizes as used in the earlier reeds & rotaries. These have a 14 mm pin witha compression height of 26 mm. Currently we have these up to 50.16 (to suit a bore size of around 50.27). Meteor are looking to make these in sizes up to 51 and beyond and in very fine size increments. This is so people can keep their vintage motors running. The medium news is that these pistons are basically designed for a 3 transfer port engine so the ring anti rotation pin is indexed around by 45 degrees. Depending on the motor this might cause the ring gap (or ring end) to become exposed in a 4 transfer port engine. However, if the ring gap is in the centre of the port, then this might be ok as this is often done. One example being the Rotax Max kart engine, although in this case the gap (and the C port) is directly opposite the exhaust so there would be no real possible effect of the piston rocking causing the A/R pin to maybe force a ring end outwards.

Suggest that if the excites you, you might want to go to a kart engine builder and grab an old 50 * 50 reed/rotary piston (as these were all generically very similar) and see how it might fit.

As an aside, instead of stroking by modifying the crank, there is the offset crankpin alternative. These come in 20 mm with, I think, 1 & 2 mm offsets. A simple press operation.

Ken

[speedpro]

. . . . . As an aside, instead of stroking by modifying the crank, there is the offset crankpin alternative. These come in 20 mm with, I think, 1 & 2 mm offsets. A simple press operation.

Ken

This would be of interest to a lot of us bucket racers. Dave had a 22mm pin offset ground on the ends but there was a problem though not sure if related to the pin and modification. I myself have had a pin with a 22mm centre and 20mm ends made from scratch. the centres are offset .75mm for a 1.5mm stroke reduction. All up with the dummy pin I had made to test balance and then the good pin ground to precise dimensions and heat treating and the rod kit my crank was over $1000 more than 10 years ago. The crank wheels had to be machined back on the big end thrust washer faces to make allowances for the wider rod.

With the offset is there much trouble getting the big end bearing and rod fitted or can you wriggle them on? The rod won't be a problem but the bearing might be if the rollers are trapped type. What is the width of the various sections of each diameter? The centre part needs to be the correct width for the rod + washers + clearance and the outer parts need to be long enough to fully engage with the crank wheels.

[F5 Dave]

Thanks Ken

Option one would obviously be a lightweight piston, but piston slap may be unacceptable & as you say, no rings

I've been looking at IAME stuff some while back (for those non karties, I think it stands for Italian American something engines). I think Meteor covered stuff in that stable. I am talking from a position o ignorance (as usual, but it doesn't stop me).

I run the KT piston with the ring over the open boost port. But indeed it is at the back opposing the symmetrical exhaust. Twisting & unsupported in an open port, well it might work but I'd give it evens.

I see Mike has put some questions as I'm typing this. My pin failure I think was unrelated, but it did crack at the interface which raises a question even though we were very concerned & did what could be achieved to reduce stress raiser from sharp corners (machinist sees this stuff all the time). We believe my issue was rotation in the crank as the scribe lines no longer lined up & vibration went up. spot of the dreaded weld seems to have cured that.

Either way destroking is a pain for several reasons & can be quite pricey,

[ken seeber]

This would be of interest to a lot of us bucket racers. Dave had a 22mm pin offset ground on the ends but there was a problem though not sure if related to the pin and modification. I myself have had a pin with a 22mm centre and 20mm ends made from scratch. the centres are offset .75mm for a 1.5mm stroke reduction. All up with the dummy pin I had made to test balance and then the good pin ground to precise dimensions and heat treating and the rod kit my crank was over $1000 more than 10 years ago. The crank wheels had to be machined back on the big end thrust washer faces to make allowances for the wider rod.

With the offset is there much trouble getting the big end bearing and rod fitted or can you wriggle them on? The rod won't be a problem but the bearing might be if the rollers are trapped type. What is the width of the various sections of each diameter? The centre part needs to be the correct width for the rod + washers + clearance and the outer parts need to be long enough to fully engage with the crank wheels.

Have a look at the following:
http://www.sip-scootershop.com/main/...ot)&a=1&sort=0

Couple of guys over here have used these in KT100S engines. You are right in that the relief for the big end in the crank webs would have to be checked and possibly machined out.

Ken

[husaberg]

Have a look at the following:
http://www.sip-scootershop.com/main/...ot)&a=1&sort=0

Couple of guys over here have used these in KT100S engines. You are right in that the relief for the big end in the crank webs would have to be checked and possibly machined out.

Ken

Ken do the 50-51mm kart piston that could work for us (you mentioned above meteor) have dykes or plain ring...?

[speedpro]

Have a look at the following:
http://www.sip-scootershop.com/main/...ot)&a=1&sort=0
Ken

No good. We need shorter stroke, not longer.

[husaberg]

No good. We need shorter stroke, not longer.

That's funny Mike......

[Pumba]

Covered elsewhere but MNZ rule changes are out.

http://www.mnz.co.nz/docs/default-so...d.pdf?sfvrsn=2

Bit surprised that there has been a change to rule 24.6. Dont remember any changes to that one being proposed. Does anyone know what has been changed?

[Bert]

Covered elsewhere but MNZ rule changes are out.

http://www.mnz.co.nz/docs/default-so...d.pdf?sfvrsn=2

Bit surprised that there has been a change to rule 24.6. Dont remember any changes to that one being proposed. Does anyone know what has been changed?

Points one?

It's been put up a number of times now: to fall in line with all other classes. Not sure whom put it up this year though...


And one more change - for the better, NZGP recognised within (all be it after) the championship classes in appendix D