DT200/Blaster/KTM250 power comparison
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Thinking about head designs, thought Id share these with you.
These are from my KTM 125 motors.
Left is an enduro motor, jetted rich, about 7 years running with Ipone synthetic 40:1.
Center is a parts motor, 2003 motocross, running conventional oil I'd say (history unknown).
Right is a motocross engine, run heavily on the street at highway speeds and long mileages,
jetted lean on the needle for fuel efficiency. Motorex, Ipone, and Shell Nautilus (sold my Jetski and had GALLONS left over!) at 50:1.
Notice the plug looks rich? Main jet is slightly rich but it runs on needle most of the time.
Notice the enduro head on the left is closest to the DT200 and my modified head?
The later motocross heads went even shallower and even toroid (donut) shaped.
This is a head from a 440 big bore stroker project on KTM Talk forum
Big Dog 440 big bore stroker
The shapes and rough blasting are supposed to promote atomization.
He experienced some knock and ping and later smoothed it, but also decreased compression from 210 to 185.
Good article, even has a bunch on making pipes for those contemplating it:
I tend to do fewer bands, and just slot and wedge the cones 3/4 through to get my curves.
But then, I'm no works racing team!
These are from my KTM 125 motors.
Left is an enduro motor, jetted rich, about 7 years running with Ipone synthetic 40:1.
Center is a parts motor, 2003 motocross, running conventional oil I'd say (history unknown).
Right is a motocross engine, run heavily on the street at highway speeds and long mileages,
jetted lean on the needle for fuel efficiency. Motorex, Ipone, and Shell Nautilus (sold my Jetski and had GALLONS left over!) at 50:1.
Notice the plug looks rich? Main jet is slightly rich but it runs on needle most of the time.
Notice the enduro head on the left is closest to the DT200 and my modified head?
The later motocross heads went even shallower and even toroid (donut) shaped.
This is a head from a 440 big bore stroker project on KTM Talk forum
Big Dog 440 big bore stroker
The shapes and rough blasting are supposed to promote atomization.
He experienced some knock and ping and later smoothed it, but also decreased compression from 210 to 185.
Good article, even has a bunch on making pipes for those contemplating it:
I tend to do fewer bands, and just slot and wedge the cones 3/4 through to get my curves.
But then, I'm no works racing team!
Stop it, you're starting to make my head hurt 
, J/K. Pipe building wouldn't be bad if one could find cones at a reasonable price. Last time I worked on pipes I made replica cones out of posterboard to make templates for final cutsI:I Wouldn't do it except for custom app.
, J/K. Pipe building wouldn't be bad if one could find cones at a reasonable price. Last time I worked on pipes I made replica cones out of posterboard to make templates for final cutsI:I Wouldn't do it except for custom app.
wow...reading all that made my fingers hurt....you are a very good welder/fabricater ...like he pipes
Those last picts are not my work. From an article on a stroker KTM motor.
There is a link to the original article. Thought they showed the process well so included them as well as the head pict.
The cylinder head is a new shallow toroidal design taken to the limit.
The rough finish is supposed to hold a laminar flow boundary insulating layer.
My son and I have another head to cut and will probably weld up the deep cone chamber and
try a shallow toroidal type cut.
I have made pipes, like Larry posted. Figured out my sizes, made cone templates out of cardboard.
Took the templates to the sheetmetal shop and had the metal cut and rolled, then welded up the cones.
Then I cut the cones at an angle and rotate them to get my bends. I had never used as many cuts as this guy did,
but his pictures show the process quite well.
There is a link to the original article. Thought they showed the process well so included them as well as the head pict.
The cylinder head is a new shallow toroidal design taken to the limit.
The rough finish is supposed to hold a laminar flow boundary insulating layer.
My son and I have another head to cut and will probably weld up the deep cone chamber and
try a shallow toroidal type cut.
I have made pipes, like Larry posted. Figured out my sizes, made cone templates out of cardboard.
Took the templates to the sheetmetal shop and had the metal cut and rolled, then welded up the cones.
Then I cut the cones at an angle and rotate them to get my bends. I had never used as many cuts as this guy did,
but his pictures show the process quite well.
I have a feeling we are going to get a trail report on how the DT200 powered Blaster stacks up to Banshees and 450s for power, acceleration and top speed...
Come on Triplecrown, don't hold back on us...
Come on Triplecrown, don't hold back on us...
Blaner
Your Friendly South African Ambassador
Blaner
Your Friendly South African Ambassador
Ok
So i'm trying to understand all the good info here and so made a small picture
of what you are saying:
Is this right ?
The head chamber OD is what is what i don't get
is that the full diameter including the quench ring?
If the piston is the same size should it not be the same?
Nuno
Here is a screen shot of the CAD design I used to mod my head.
Bear in mind I made a base plate space to adjust port timing...
i got to take the dtblaster out for an all day ripe yesterday with the boys. other bikes included a sx125, kx250f, banshee, 400ex and a trx450r all stock. i had my extended mint race modded aircooled blaster out first but it decided to lose spark at the beginniing of the day. thats way i built my secondary blaster which im happy i got to take out instead cuz shes a WOT machine making for a better day with my buddies. the liquid cooled blaster worked flawless. it really shocked the boys of the amount of power that could be unleashed with the little quad. altho we dident line the bikes up to compaire i got a good idea where i stood in the crawd. the only bike that would line with me was the sx125 (smallest bike of crowd) most of been the only one willing to see if the old blaster would keep up. maybe the bigger bikes dident wanna find out for sure. the blaster stuck with the sx125 neck an neck till about 80 kph where wind resictence started to hold the atv back and the dirbike would just keep excelerating. this is awsome cinsidering the sx125 is a very quiick dirtbike (deffinitly quickest of 125 motocross bikes). as for the bigger quads i got a second beside the banshee and quickly left him altho this was a new quad to the owner and he wasent comin on to it much. the blaster had no porblem keepin with the big boys. a quick snap of the cluch and flick of the gas and the blaster would "Expload" into its powerband litarilly launching it up at any speed. kinda scarry. the bikes set for Peak rpm hp, as long as you wanna hold it it will keep makin power. pulls the figures from the bars at limmiter but not mych for mid range torque.
the ride really saprised me as to how much you can build one of the blasters to smoke larger bikes. its nott hard my bike is a simple stock dt top end on blaster bottem. nothen special not even a powervalve. no porting carbs squish adjs nothen just bone stock. as for the other bikes on dry pavvment with 100% traction i think the blaster would stick nose to nose with most of the bikes maybe not the banshee or 450r but id be confadent with the other bikes
there was a thread resently about askin if a modded blaster could beat a stock 400ex and my answer right now altho not proved yet would be yes a heavly modded blaster could smoke a stock 400ex
the ride really saprised me as to how much you can build one of the blasters to smoke larger bikes. its nott hard my bike is a simple stock dt top end on blaster bottem. nothen special not even a powervalve. no porting carbs squish adjs nothen just bone stock. as for the other bikes on dry pavvment with 100% traction i think the blaster would stick nose to nose with most of the bikes maybe not the banshee or 450r but id be confadent with the other bikes
there was a thread resently about askin if a modded blaster could beat a stock 400ex and my answer right now altho not proved yet would be yes a heavly modded blaster could smoke a stock 400ex
Blaner
Your Friendly South African Ambassador
nice. PS I should email you are your dad my varsity notes and let you write my essays!
Ha! While spelling is not his forte, he is much more eloquent and knowledgeable in person.
He knows his stuff and does good work, and can ride better than I ever could.
He has that DT200 engine tuned up pretty good, even without the powervalve.
I don't know if your quib is about his spelling or my verbosity, but I hear you.
Hopefully we are returning enough to be worth putting up with.
This was a real nice read.
I wish there were more photos and info. any updates and pictures ?
Sporty
I wish there were more photos and info. any updates and pictures ?
Sporty
hello best im new to forums so dont kill me if i dont post correctly i read your specs on the dt200 ports vs the blaster ports and maybe i missed it but it seems you took all you measurements from the top down. i wondered about the hight from piston to ports at bdc. the blaster piston covers the ports slightly at bdc and i wondered about the dt200. the port difference on the exhaust is about 5mm i have seen porting vids on blasters and they only raise the port about 1-1.5 mm. i was reading about raising the blaster cylinder up 1mm and milling off the top of the cylinder and not changing the ports as well so imtring to decide what route to take.
thanks
thanks
All roads lead to Rome. All will work.
Cylinder heads, especially damaged ones, can be bought cheap and easily machined to any height and chamber spec you want, so milling the cylinder top off is not needed, although Vitos cylinders take this approach. With this in mind, raising the cylinder is a more economical move (considering possible failure) than altering a cylinder. The 1-1.5mm exhaust height is a good balance of increased rpm without a dead mid-range. The DT200 cylinder with the exhaust valve wide open is a screaming demon but falls flat as the rpm drop. It needs the exhaust valve to be operational. The largest thing of all these mods is that the pipe has to match the ports.
Steve
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