ktm replica (liquid cooled)

Discussion in 'General Questions' started by zippinaround, Dec 30, 2016.

  1. Street Ryderz

    Street Ryderz Well-Known Member

    Dont forget that those are race bikes everything on them is better quality bigger and heavier than a bicycle build would be so even the centrifugal 50cc should be able to hit 50mph!

  2. skyash

    skyash Active Member

    I heard thay come on kids bikes restricted to 4 hp so the kids don't go monos on take off lol ..and make sure it's not broken coz 2 parts can cost a new engine.
  3. KCvale

    KCvale Motorized Bicycle Vendor

    Just curious about the water cooling...
    I live in Phoenix and MB's don't overheat with simple air cooling and the proper spark plug, why add all the weight and complication to accomplish no benefit?
  4. gary55

    gary55 Well-Known Member

    Reliability, greatly increased ride time and life span, Way more potential power.
  5. Steve Best

    Steve Best Well-Known Member

    This statement is true Gary, however a lot of "ifs and buts" come with it.

    For the most part liquid cooling keeps the engine to no more than 220F or the water boils over and you stop.
    An air cooled engine can often be run until the cylinder is over 400F and it seriously cooks.
    There is a lot of your reliability.

    The 50/50 coolant is an enormous heat sink, soaking up lots of heat energy during short full throttle bursts.
    The radiator gets more efficient with temperature, so it works well to keep the engine around 200F.

    Power builds heat, so if you cannot shed the heat produced, you are limited in how much power you can produce. If the cylinder head temperature gets too hot, detonation kicks in and limits power (often by destruction!).

    There is no doubt water cooling adds complication. What about weight?
    I compared various liquid cooled vs air cooled motors, 1974 CR250 vs 1985 Cr250, Blaster 200 vs DT200, etc.
    I found that the weight was surprisingly nearly the same.
    The extra fins and mass of an air cooled cylinder often weighed as much as the water jacket, rad, coolant and waterpump!

    Most liquid cooled engines make more power than air cooled comparables, but these are manufacturer restrictions.
    I was able to make more power with a modified 1974 air cooled CR250 than a stock liquid cooled 1985 CR250.
    I was also able to tweek a 17hp air cooled Blaster 200 to more hp than the very similar 32hp liquid cooled DT200.

    Liquid cooling is not a power adder, but a reliability help, although most liquid cooled engines TYPICALLY have higher power output than their air cooled cousins. Many exceptions to this.

    I like simplicity (well, not in my explanations!) so I favour air cooled and don't feel to be at a huge disadvantage.
    If I were to race or look for endurance I tend to liquid cooling.

    Some pictures of what I am talking about:

    30hp Air cooled Blaster (this one is my bored and stroked 240cc Blaster)
    My son and I have built 35-38hp stock bore/stroke air cooled Blasters too.

    32hp Liquid cooled Blaster with a DT200 cylinder and rad on a 17hp Blaster 200 block. Belongs to my son.

    48hp-50hp KTM 250 powered Blaster with Lazy-Boy Steve taking a sunny nap:
    As fun as this power brute is, I prefer the simplicity of the air cooled Blasters, even if I have 5-10hp less.
    More on top of too much is still too much!

    Air cooled 1974 CR250 (not mine but I owned one just like it back in the day):

    1981 CR250 (web pict) My tweeked 1974 easily outpowered these when they came out.
    Liquid cooling is not essential to make power. It does help to keep things reliable.

    I tend to want my bicycle simple, so I trend to air cooled China Girls.
    I have been to the realm of "too much power" so I have little need to explore it on a bicycle.
    (I own a KTM 380 2 stroke and had a 660 Raptor and that KTM powered Blaster is crazy fast)
    However I cannot help to be awed by the idea of a KTM powered Motoped!

    zippinaround likes this.
  6. Frankenstein

    Frankenstein Well-Known Member

    Does a nikasil coating allow for hotter safe running temps? Does it cause the piston and cylinder to hang onto heat longer than a thin chrome?

    Is there a major expansion difference between the aluminum cylinder and piston and the ceramic coat that you know of, meaning they could expand at different rates and cause the plating to flake off?

    How much longer do you think a happy time motor with a coating like that could survive compared to a normal set up. What about the longevity compared to a liquid cooled motor with normal chromed surfaces.
  7. KCvale

    KCvale Motorized Bicycle Vendor

    That's some feat for water to do, especially the "greatly increased ride time" part of your improvements.
    The only thing that limits my ride time is fuel ;-}
  8. zippinaround

    zippinaround Active Member

    well the main reason i am interested in the engine is its power the aircooled version of this engine would be great , but i found this one for sale nearby at a low low price , anywho i called in to buy it and he had found the front wheel , the seat and the exhaust (from the broken one he replaced but im sure i can weld it) he took the 150 no probs . he was looking for 150 for the 4 stroke 11occ lifans but i dont think i'd have much use for those too heavy and big could be good for a cart or buggy or something tho.
  9. gary55

    gary55 Well-Known Member

    It's not a feat, it's a fact. It is not water creating this fact, but a engine of far superior design.The air cooled version of the 49cc has over 8 hp. 9 on the water pumper. I believe the 65 cc ktm water pumper has 13 hp. If you could manage to get the 66cc china girl to produce such power I am fairly sure you would be shutting it off long before you emptied your tank, or it would shut off for you.
  10. Frankenstein

    Frankenstein Well-Known Member

    I'm still confused as to how water lengthens the ride, I don't think you fixed the dilemma..

    Boats should run forever with that ocean or lake worth of engine cooling... Yet we still have to drag the damn things out of the water to refuel all the time... Maybe it's the yamalube...
  11. gary55

    gary55 Well-Known Member

    Take the 66cc china girl and mod. it to it's max potential, which still will not be as strong as the 49 cc water pumper. then run the two under high heat and loads continuously. Which one do you think will fail first? If your talking about having to stop for fuel look at my tank. How long do you think my engine would last running it hard till this tank was empty. It wouldn't bother the water cooled engine.
  12. Street Ryderz

    Street Ryderz Well-Known Member

    And they do!My modded 25 merc outboard produces over 30 hp and can run all day at w.o.t and never over heats!My sons rm 65 lc can run 40 min mains screaming high rpm's no problem!The quality of the components and design of these engine allow for much greater power output and still maintain reliability far greater than a china girl!And no matter how well you have modded and set up your china girl if you run it at over 9000 for 40 min your taking that engine home in a box!Trust me I have tried it and didn't get 40 min the temp went above 400 f lost power then spit two roller bearings from wrist pin bearing!
    gary55 likes this.
  13. Frankenstein

    Frankenstein Well-Known Member

    I tried running my bike underwater to simulate water cooling but I think I broke it.
    gary55 likes this.
  14. gary55

    gary55 Well-Known Member

    What would Lloyd bridges do?
  15. Frankenstein

    Frankenstein Well-Known Member

    Build a bridge and not destroy his electrical system? Or edit the shot...
  16. Steve Best

    Steve Best Well-Known Member

    Nikasil is very tough, I've never had a problem with flaking on KTM, Husaberg and Yamaha motors.
    There are no expansion issues with Nikasil and the aluminum cylinder.
    It is not a ceramic and I don't know of ceramic cylinder coating. Ceramic paint for on the outside exists.
    The aftermarket nikasil replating is usually much thicker and tougher than the original manufacturer's plating.

    My only previous experience with chrome plating was with 1970s air cooled snowmobiles.
    They had some big advantages over iron cylinders, cooled better and less detonation prone and less friction.
    The chrome was much thicker but was prone to blistering and separating from the aluminum.

    A nikasil coating on these cylinders would substantially improve their life and heat tolerance and allow 50:1 oil.
    Liquid cooling does not necessarily increase the life of an engine, it limits temperature fluctuations that can improve reliability and life. Sounds like a lawyers answer and it is. There are no absolutes.

    Marine outboards can run all day in part because of the unlimited cooling, but largely because of light cylinder loading. My 7.5hp was about 200cc IIRC, whereas a 200cc Yamaha Blaster makes 17hp in its detuned state, 25-35hp with light mods . My 18hp Evinrude was about 360cc. My 300KTM makes about 55hp, a considerable difference in power output per cc.

    I did run my modded 48cc China Girl full tilt 9000rpm for many 20-100 kms trips. It withstood it quite well, but did fatigue a piston wristpin circlip at about 1600 kms and wristpin and bearing were pretty much worn by then.

    If I were building an engine for maximum power and durability, I'd choose liquid cooled nikasil as all the MX bikes have done. No question about it.

    As for water extending the ride, I found that to be true back in the day of waterbeds, mainly due to 4 stroking.
    One power stroke and 3 riding the waves...
  17. Frankenstein

    Frankenstein Well-Known Member

    Interesting. Very interesting you say that nikasil isn't ceramic. I forgot some of my chemistry, but Chem was never really my strong suit. How could I forget my favorite Latin phrase's most important element.. Carborundum! For some reason I was reading silicon carbide but brain was telling me silicon nitride...

    Cool none the less. I could see that stuff lasting a long long time.

    You must have had a damn good frame to handle a 4 stroke on a waterbed mattress. Back when bed frames were built to handle extra chain and leather accessories, they just don't make them like they used to...
  18. gary55

    gary55 Well-Known Member

    The only time I experienced this particular 4 stroking issue was back when I was running with a rich girl.
  19. Steve Best

    Steve Best Well-Known Member

    Nikasil is a nickle electro-plating process in a silicon carbide suspension where the silicon carbide gets trapped in a matrix of nickledeposited on the aluminum cylinder bore.
  20. Frankenstein

    Frankenstein Well-Known Member

    Yes I know that, I was reading carbide but my brain told me I was seeing nitride, which is ceramic, carbide of silicon is what nikasil is.

    Basically I thought it was a ceramic coating because I was thinking something else.

    That's not called having an issue, that's called an experience.