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The 150 project

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Hey guys:

The 300 and 340 kits are somewhat on hold at the moment. A little disappointing but it will be back on track shortly.

In the mean time, I decided to invest some more time into the yz125 150 package we sell.

Currently it's like a little extra flavor to our 144 package - and adds about 1.5 hp peak with good midrange improvments.

But with the new two stroke class at LL - and an itch I have to qualify/race the class on the 125 - I have decided to build the 150 as best/all out/factory style build as possible.

I mentioned a little earlier on it - but the basic package will be using a longer rod than stock, and a custom ignition box/map and cone pipe to achieve our power goals, which are about 45 to the wheel - shooting for 250 two stroke numbers haha. Obviously to the nitpickers - it's not a torquey, flat, smooth power like a 250 two stroke can be...

I have a few spare cylinders (some are junk) that I started playing with to see just how far a few areas could go and I then started playing heavily with my simulation software to see where it thought I might end up.

After a few tweaks with ignition and pipe, it looks really promising :lol:

HP150.jpg

The software pretty much sims a stock yz 125 right where it is (crank hp shown - expect 10-12 percent loss to the wheel min).

It's no joke to get that - and a lot of tricks are employed that go beyond the ports/window area etc...and the exhaust pipe is trick as heck.

Note: I didn't spend any time optimizing the ignition curve on either motor shown at lower rpms - the low end on both would look much different if I accurately modeled the PV and ignition, as well as pipe temps at lower rpm - but my whole intent was merely to see about what peak will look like...

Now obviously its just initial sim results - but the sim has proven pretty accurate on all previous development projects..so I'm even more excited now knowing its a somewhat realistic goal given the cylinder constraints.

Biggest hurdles at that power level (aside from actually achieving the power) - is keeping the motor together from all the heat production. In performance engines, about 1/3 of the energy combusted is turned into power to the wheel - and the other 2/3 goes out as heat...

This means it will be producing 1.33 times the power, but almost 2 times the amount of total heat (requiring double the cooling capacity)

I have begun looking into improved water pump solutions and a few other coating and heat expulsion techniques..but it's going to be neat if it ever holds up. Of course - the water jacket castings within the cylinder may not be capable - only time will tell.

Of course - if anyone was truly brilliant and could figure out how to convert an additional third of the energy from heat into usable power, changing that ratio to 2/3 power, 1/3 heat loss - we wouldn't need any engine mechanical mods!

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Of course - if anyone was truly brilliant and could figure out how to convert an additional third of the energy from heat into usable power, changing that ratio to 2/3 power, 1/3 heat loss - we wouldn't need any engine mechanical mods!

Turbocharger?

On a serious note, that's impressive. A light weight, skilled rider on a 200 lb YZ with that kind of power would easily give a 450 rider a run for his money.

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Turbocharger?

On a serious note, that's impressive. A light weight, skilled rider on a 200 lb YZ with that kind of power would easily give a 450 rider a run for his money.

Sadly at turbo is brilliant at energy recovery - but doesn't even come close to more than 8 percent improvement in heat recovery - rather just makes more power, and again more heat!

The exhaust pipe on a two stroke (for instance in the picture shown) is very much like a turbocharger - and why two strokes can even make any hp like they do!

One of my friends works at southwest research institute in the engine development department - the big OEM's use them to help along their engine programs - and he says the best motor to date is 40 percent efficient. He then said they are fully expecting in the next 15 years to see that go to 60 percent, but of course no one knows how to get there yet...just 1/4 percent at at time!

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I'm tracking on all that... just kidding you around a bit with the turbo.

You mentioned coatings... it sure seems like ceramic coating of the piston top, cylinder-head and exhaust ports would help a bit with avoiding some of that heat.

If the other ideas don't work, perhaps you could combine that with a larger radiator:

I have been looking at radiators recently. The inlets and outlets on the 250F radiators look very similar to the YZ125. The 250F cores are substantially wider than a two stroke radiator (appears to be about 1" or more). Also they are common and cheap around e-bay, etc.

The only major difference in connections appears to be the hose nipple that goes to the water pump on the right hand radiator lower tank. It looks like it would hit the expansion chamber on the 125. If they'll bolt on without too much fuss, a simple relocation of that nipple would be worth the extra cooling volume and surface area.

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I'm tracking on all that... just kidding you around a bit with the turbo.

You mentioned coatings... it sure seems like ceramic coating of the piston top, cylinder-head and exhaust ports would help a bit with avoiding some of that heat.

If the other ideas don't work, perhaps you could combine that with a larger radiator:

I have been looking at radiators recently. The inlets and outlets on the 250F radiators look very similar to the YZ125. The 250F cores are substantially wider than a two stroke radiator (appears to be about 1" or more). Also they are common and cheap around e-bay, etc.

The only major difference in connections appears to be the hose nipple that goes to the water pump on the right hand radiator lower tank. It looks like it would hit the expansion chamber on the 125. If they'll bolt on without too much fuss, a simple relocation of that nipple would be worth the extra cooling volume and surface area.

Well what's interesting is the 4 stroke ones are thinner without a doubt..

It sounds stupid - but radiated heat from a black radiator would help considerably - I may look into a black coating that helps heat transfer there..

The head design is very trick - and should also help radiate more heat.

I wont share all my secrets on piston dome coatings - but I have found that it creates detonation on motors that are pushing the limits if it's coated. A little research farther into it revealed why - but with any insulator - although heat transfer into the piston may be considerably less - one side still remains/retains heat - and this is a negative for the piston crown.

But I DO intend to coat the exhaust port and probably the UNDERSIDE of the piston.

But from research I've done on cooling systems - I will also need to boost the shear volume of fluid being pumped at once...faster impeller speed/better impeller being one aspect to that.

The bike will probably be servo controlled for the PV - so I will get rid of the stock ball and ramp system...and just plug it.

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Just a thought.

Ceramic flow coat (inside and out) the expansion chamber. Better heat dissipation

(Will be a future upgrade of a OE 05+ pipe on my 144 with an ally ceramic coat)

Oversize radiators (The ASI's on my bike have 10 or 12 cores (Stock has 8 per side) and larger end tanks.

I'm lead to believe the Boyesen waterpumps are more efficient too, unless that's a marketing ploy. But I don't thing it would be too hard to change the impeller shaft gear ratio to get it spinning/pumping faster.

But even if the pump wasn't upgraded, wouldn't the added shear volume help cooling efficiency?

Could even get more old school and get a CNC machine cylinder head with cooling fins!

Keep up the work! Can't wait to see the progress!

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Harrperf,

I did not look closely at the thickness of the radiators. That's good to know.

A little research farther into it revealed why - but with any insulator - although heat transfer into the piston may be considerably less - one side still remains/retains heat -

Although I never thought about it before, it makes sense. You insulate that crown from heat, but you also insulate it from the cooling effect of the intake air charge.

Coating the underside is interesting... It seems like you would put a heat conductive coating on the underside to allow intake air charge to cool the dome/crown.

I've heard that some of the Athena kits have bronze head inserts. I'm under the impression that it's done for heat conductivity on the big bore.

The bike will probably be servo controlled for the PV - so I will get rid of the stock ball and ramp system...and just plug it.

It would be cool to precisely tune the main and secondary valves to their optimum RPM. The stepper motor or servo and the controler would probably weigh less than the governor and linkage. Plus you reduce the rotating mass and mechanical friction a tiny bit in the process.

This stuff is really interesting. I can't wait to see this project come together.

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Harrperf,

I did not look closely at the thickness of the radiators. That's good to know.

Although I never thought about it before, it makes sense. You insulate that crown from heat, but you also insulate it from the cooling effect of the intake air charge.

Coating the underside is interesting... It seems like you would put a heat conductive coating on the underside to allow intake air charge to cool the dome/crown.

I've heard that some of the Athena kits have bronze head inserts. I'm under the impression that it's done for heat conductivity on the big bore.

It would be cool to precisely tune the main and secondary valves to their optimum RPM. The stepper motor or servo and the controler would probably weigh less than the governor and linkage. Plus you reduce the rotating mass and mechanical friction a tiny bit in the process.

This stuff is really interesting. I can't wait to see this project come together.

This bike has the single stage gate PV - but yes - accurately controlling it would be nice.

Basically the underside coating is to keep intake charge still cool/less heat soak while it waits, and we are attempting to keep as much heat as possible in the combustion process for extra energy for the pipe to use. Once the transfers open - and it exits into the combustion chamber it will draw heat away from the piston crown (if the transfers and designed well)- and vaporize - also drawing heat away from the piston. Fuel vaporization qualities are really important for high performance two strokes.

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This bike has the single stage gate PV

Addmittedly, I haven't been inside a YZ125 engine since the 2000 model. I own a 2008 model, but I haven't even seen the bike in person yet (I'm currently working overseas).

I was thinking more of the current YZ 250 with the two stage PV comment. I've been rolling that idea around for a while. I have played around with programming Microcontrollers and a little work with stepper motors and servos in unrelated projects. Those electronic parts are perfect for this application.

The discussion of heat transfer and fuel vaporization makes me think of the direct shot injection on some racing four strokes (F1, etc). They figured out that atomizing the fuel at the injector nozzle wasn't as efficient as shooting a stream at the valve. The cold fuel hits the hot valve and evaporates while sapping the latent heat from the combustion chamber. As the fuel evaporates, it cools the chamber causing a pressure drop thus drawing in a larger intake air charge. Obviously this requires a precisely timed injection event, but it's a neat concept, and a neat way to take advantage of thermal transfer.

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This bike has the single stage gate PV - but yes - accurately controlling it would be nice.

Basically the underside coating is to keep intake charge still cool/less heat soak while it waits, and we are attempting to keep as much heat as possible in the combustion process for extra energy for the pipe to use. Once the transfers open - and it exits into the combustion chamber it will draw heat away from the piston crown (if the transfers and designed well)- and vaporize - also drawing heat away from the piston. Fuel vaporization qualities are really important for high performance two strokes.

You need to write some technical articles with all of your knowledge.

Did you by chance go to engineering school? It seems you have a great understanding of the laws of thermodynamics.

One question, does the Nikasil coating provide any sort of thermal resistance, or is it only designed for it's wear properties.

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Addmittedly, I haven't been inside a YZ125 engine since the 2000 model. I own a 2008 model, but I haven't even seen the bike in person yet (I'm currently working overseas).

I was thinking more of the current YZ 250 with the two stage PV comment. I've been rolling that idea around for a while. I have played around with programming Microcontrollers and a little work with stepper motors and servos in unrelated projects. Those electronic parts are perfect for this application.

The discussion of heat transfer and fuel vaporization makes me think of the direct shot injection on some racing four strokes (F1, etc). They figured out that atomizing the fuel at the injector nozzle wasn't as efficient as shooting a stream at the valve. The cold fuel hits the hot valve and evaporates while sapping the latent heat from the combustion chamber. As the fuel evaporates, it cools the chamber causing a pressure drop thus drawing in a larger intake air charge. Obviously this requires a precisely timed injection event, but it's a neat concept, and a neat way to take advantage of thermal transfer.

This I did not - but it makes perfect sense.

I do know that there is TONS of room for power improvement via correct fuel atomization and distibution into chamber. Of course wet flow testing is one avenue builders are using to help this - but with direct injection it will be neat to see how port design changes when purely air charge and qty is the goal - and how chamber shape/piston shape changes to atomize the injected charge.

Diesel piston shapes are pretty cool! Of course their direct injection process is also really high tech these days!

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You need to write some technical articles with all of your knowledge.

Did you by chance go to engineering school? It seems you have a great understanding of the laws of thermodynamics.

One question, does the Nikasil coating provide any sort of thermal resistance, or is it only designed for it's wear properties.

I have a few years in engineering under grad (which anyone can tell you these days is worth jack shit - except in teaching you how to learn and become self sufficient)

My parents are both phd's in engineering, one being ME (with specialization in resonance) and the other a chemE.

My uncle is a phd in Chem E, and is/was the dean of engineering (I think now he is a VP or something) at a premier technical university in canada.

Basically all that means for me is Im constantly the dumbass in the family...

Most of what I learn (and many top builders in better racing avenues than mx) is via failures. You take a step forwards with one aspect (say you make more hp) but two steps back (it blows up)

Some of this heat discussion stems from some yz85 projects I do - and once I got them running really hard - I started caving in piston crowns from heat.

Nikasil transfers MORE heat away from chamber into cooling system - which sounds bad. BUT - in reality is prevents what some call thermal runaway - where chamber temps would rise/stay at unsustainable levels.

AKA we NEED to cool the system via the water cooling - but if you didn't transfer ANY heat into it - it couldn't...and surface temps would be too high.

Tis is the same problem that I found on piston crowns and heads with coatings. Sure the less heat is transferred - but it creates another ball of worms.

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same thing as the other ones

Thanks for the great comments - we are all aware your 144 is the fastest bike on the planet! Until I reach the meca that is known as BRM's 144 output levels - my life is not complete!

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The long rod stroker crank - you are staring at about 750 bucks - for a crank - I know.

IMAG0611.jpg

Next to a stock crank

IMAG0612.jpg

IMAG0613.jpg

Checking clearances and case fitment - this is actually a different crank than shown above.

IMAG0602.jpg

Test Cylinder 1 (on right, test cylinder 2 is on left)

IMAG0614.jpg

Test Cylinder 2

IMAG0615.jpg

That's where it sits at moment - sorting out the ignition (requires a DC 12v output) and getting a the CAD on the head finalized.

The head I was initially going to produce looks like this:

headassem.jpg

headassembottom.jpg

But I've switched it up to look like this:

Fullscreencapture1217201172637PM.jpg

Fullscreencapture1217201172653PM.jpg

This head compared to the old design will help minimize cylinder distortion under load - something I never thought about until I learned more about the aprilia head design on their gp winning engine.

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Thanks for the great comments - we are all aware your 144 is the fastest bike on the planet! Until I reach the meca that is known as BRM's 144 output levels - my life is not complete!

OUCH! Bitch:smirk:

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