Some advice required?

Discussion in 'Some Assembly Required' started by CosentinoEngineering, Oct 19, 2011.

  1. up2L8

    up2L8 n00b

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    Thanks so much for the advice guys,

    It sounds like I really need to go the extra mile and run these in parallel. The problem now is going to be with routing. I'm not sure if it matters which way it's done.

    I may have to draw a diagram, but here's how they're layed out:

    KTM: The cylinder pumps into a T right out of the cylinder, and feeds into the top of each radiator separately. This part I can accomplish with no problem. Then the coolant flows the the bottom of each and the pump pull from the bottom of the right rad only, but there's a connecting line linking the bottom of the left and right rads. THIS is where I have a problem. I have no idea how I'll get a connecting line across the bottom. I can post a pic, but I'd have to either run a line in front of the frame, and somehow make a strong steel shield for it, or I can directly pull from both rads, but I'd have to run a line behind the cylinder, which is a fairly long line.


    KXF: This one in stock form feeds to the top of the right rad, then has a connecting line going to each one at the top, and then the coolant falls and the pump pulls equally from the bottom of both rads. This basically presents me the same problem because I still need to run a line from the bottom of the left rad to the right side somehow.


    Is there any fundamental difference between the way these are plumbed? Can I feed equally into the top of both like the KTM and also have a connecting line at the top, and then pull separately from the bottom of both without a lower connecter? Can the spillover point at the top take care of things?

    If this is too rambling, let me know I'll diagram each method.


    With respect to the fan: your typical 80mm computer fans are pretty thick and only move about 20-45cfm, however, with a little searching I've found some nice 92x92x25mm fans that would cover half my rad perfectly, and pull 100+cfm. I've heard some other people run similar with great success, so I think I'll give it a try. The fans are about $9 each, whereas the KTM kits are like $90. Plus the KTM was an EXC model, so I was going to run the fan right off the headlight power, and put the switch on the bars, since my bike will have no headlight.


    Thanks so much for the advice guys, any other thoughts?
    #21
  2. Luke

    Luke GPoET&P

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    The KTM has a split AC/DC electrical system. It drives the headlight with AC power. The fan will need DC. You can run the fan off the DC side of the regulator output or convert the whole system to DC. If you use the stock system, note that the DC side can supply a hair under 2 amps. The KTM fan draws 2.5 amps so there's a bit of a juggling act going on with regard to the fan, the e-start, and the battery.
    #22
  3. CosentinoEngineering

    CosentinoEngineering Been here awhile

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    >>You can't be a degreed engineer. Your explainations are too concise and too coherent and
    >>too understandable by a layman, and lack any mind-numbing polynomial equations to prove your point.

    That's funny. It's because I started my engineering career at age 5 in my father's 2 bay auto service station. Practical applications of knowledge has always been my forte, although how practical a boutique road-race motorcycle is can be debated.


    Chris
    http://moto2-usa.blogspot.com/
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    #23
  4. CosentinoEngineering

    CosentinoEngineering Been here awhile

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    The KTM or KXF routing would work fine. The KXF version may be more thermally efficient (likely not noticeable) at lower speeds because the inlet tube feeds one rad directly and the 2nd rad is only fed when the first is flowing at capacity. Since water speed is proportional to engine speed at low speeds water is being circulated through one rad and as engine and water speed increase the overflow from the first rad beings the second one into the circuit.

    I'm not sure about the electrical capacities of the KTM setup so will defer to Luke here. Practical experience trumps book knowledge 9 times out of 10.

    As for the fittings and flow restrictions the posted comments are right on the money. Lots of people concentrate on hop-up parts to have their engine make the most power possible (high IMEP- Indicated Mean Effective Pressure or an engine's gross power production) without thinking about the losses the engine makes (PMEP- pumping mean effective pressure which is a power loss, and FMEP- frictional mean effective pressure, another power loss). Restrictive water lines, oil hoses, and crankcase breather lines are all areas where the engine wastes power it's already made to overcome losses that can and should be minimized.


    Chris
    http://moto2-usa.blogspot.com/
    Chip in and help!
    #24
  5. up2L8

    up2L8 n00b

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    I havn't looked into the electrical system yet, but I'm surprised to hear they might have split AC/DC. Is that with all their bikes? It's a 96 engine and no electric start. It's not a street headlight either, it was just a cheezy trail light. I'd be surprised they would go to that trouble for a tiny light.
    #25
  6. Luke

    Luke GPoET&P

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    My mistake. I read EXC and was thinking of the newer 4 strokes. But according to the microfiche, your bike has a SEM K11 system which is probably set up AC only.
    #26
  7. dhally

    dhally Hammerhead

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    I've been searching for the perfect dualsport - you know, one that weighs under 250 lb, does trails like a trials bike, will run 60 mph down the road, is quiet as a field mouse, and has Honda reliability.

    I happen to have a Gasgas EC300 which pretty much fills the trials handling and reliability, but the motor is loud and has a real narrow range transmission.

    I've been thinking about getting a small engine with a wide ratio transmission, like an XR250L, CRF230L, or maybe DR350, and transplanting it in. The first dimensional problem I can see is that these motors are a little taller than the space available.

    The Gasgas has a steel tubing frame, is it reasonable to consider cutting and welding on it to make room for the bigger motor? I realize that there are probably many other issues to consider, but this one seems pretty basic. I can do some of the cutting and tube fitting myself, and I can get professional friends to do the actual welding.
    #27
  8. sailah

    sailah Lampin' it

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    I had a similar project putting a CR500 motor in a YZ450 chassis. You're correct getting the bigger motors to fit, especially an older air cooled motor is tough. Height above the head and also sprocket alignment are two things I look for in every project I do. For the YZ I remade the engine cradle to accommodate the new motor. Also you'll want to check where the exhaust exits, hopefully its close or you'll need to modify the down tube as well.

    Not to talk you out of it, but I'd seriously consider if you can get it done and what you'd do to a running bike. My YZ was a basket case without a motor anyways so I didn't care.

    I'd get your hands on a real live motor and hold it up next to the frame to visualize where the problems are going to be and decide how much of your gas gas frame you want to modify.

    If it will fit in the envelope you're set. Just get some prefab motor mounts from AA and go to town, just make sure that your alignment is cool with the rear sprocket and that the countershaft sprocket is in the same general area to minimize chain whip.

    I've got an XL500 motor if you want it:deal:lol3
    #28
  9. sailah

    sailah Lampin' it

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    This should give you some ideas as to what I had to modify:

    [​IMG]

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    [​IMG]

    [​IMG]

    Oh and if your swingarm goes through the motor that would be the biggest show stopper. You basically need the width of the motor to be equal or smaller than the GG motor. I got lucky and the CR was slightly narrower than the YZ so the swingarm fit however I had to drill out the CR cases 1mm I think from 17 to 18 or something to get the pivot bolt to go through the motor. Check this first, its probably going to be the most difficult part of the build, everything else is fairly straightforward.
    #29
  10. Lambo

    Lambo Been here awhile

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    What do you guys like to use for steel tubing for frame work. 1018 CR? 4130? DOM? CREW? Diameter and wall thickness favorites? Assume the tubing will be TIG'd

    Thanks,
    #30
  11. sailah

    sailah Lampin' it

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    I use 1" & 1.25" DOM tubing mostly in 0.065" wall. I do have some heavier wall tubing but as I remember back from naval architecture school, the way to decrease weight and maintain strength is to minimize wall thickness (or plating in a boat) and increase the depths of the supporting stringers and frames. I am NOT an engineer so let cosman walk with that one.

    I also use those sizes because they match the bending dies I have for my hydraulic tubing bender., which is important in that most of the tube work I use is not straight.

    DOM welds nice, finishes nice, esp if you are tigging it.

    I have use just regular seamed tubing on the CBR because I needed some heavy stock for the shock brace and I had it on hand.

    I've never used cromo tubing, mainly because of the cost and the welding sounds complicated. I'm not building bikes to shave the last couple pounds off, I'm building them to ride and have fun. If someone gave me a good reason to use it I would, but so far the DOM tubing has been great and its what most Harley, rockcrawlers, regular racer types use.:ear
    #31
  12. Lambo

    Lambo Been here awhile

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    Sailah,

    Thanks for the reply, is that 1018 DOM? I am always concerned about weight...thecosman would you weigh in re: 4130?
    #32
  13. Bleached

    Bleached Adventurer

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    #33
  14. sailah

    sailah Lampin' it

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    Honestly no idea. Probably. I got out from metals depot online. I bought about 10 sticks sy once.
    #34
  15. sakurama

    sakurama on an endless build

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    Instead of turning it down and adding a shim why not tap it for a bolt instead of a nut?
    #35
  16. ivantheterrible

    ivantheterrible Been here awhile

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    Sorry if this is too rinky dink a question for y'all's awesome knowledge, but I figured I'd ask anyway. I want to change a bike from a 16 rear 18 front (rims) to a 18 front 18 rear. I've been told (inter webz) that this will greatly effect the handling of the bike. The only reason I'm doing this is I think it would look better, and I can't leave well enough alone. What do y'all think? Will the handling be 'different', meaning I'll have to get used to it, or will the handling be 'different' I'm going to kill myself? If it matters, the bike in question is a cb250.

    ( I just re-read what i wrote- seems the kids these days call something 'awesome' if they want to mock it, but i mean 'awesome knowledge' in the 'I'm awed by your knowledge' way! )
    #36
  17. ivantheterrible

    ivantheterrible Been here awhile

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    Thanks! Kinda...........I only have the fuzziest notion as to what trail is, and what changing it will do. Also, what/where exactly would I be measuring? Also also, what does slow my steering down mean? Make it less responsive to inputs?
    #37
  18. ivantheterrible

    ivantheterrible Been here awhile

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    Thanks again! that's just what I'm looking for. you've been very helpful.
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  19. CosentinoEngineering

    CosentinoEngineering Been here awhile

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    Wasn't getting updates form some reason.

    For frame tube material there is not much practical difference between CREW, DOM, or 4130. CREW and DOM are plain low carbon steels. For a given diameter and wall thickness all 3 have the same weight and stiffness which is the primary factor in frame design. The main material difference is that the 4130 has a higher yield strength than the other 2 but no material should be subject to stresses near yield in normal operation. Crashing is a different story but then again if you crash you should expect your frame to get bent. I think it was Kevin Cameron who said that his riders could not crash in a controlled enough manner to stay under the 4130's yield point so it was a wash.

    With that said, I still like to use 4130 material in my frames. I find the higher quality material has better straightness and profile accuracy mainly due to the fact that it is a more expensive product. It does require care to be taken not to use too much heat when welding so has some drawbacks but they are not insurmountable.

    For a beginning welder I would recommend using CREW or DOM. There are much less welding related strength and brittleness issues when compared to 4130 and we all must learn to walk before we can run. Once you've got some fab experience under your belt try some 4130. you may like the better accuracy or may consider the additional price to be a waste and stick to mild steel.


    Chris
    http://moto2-usa.blogspot.com/
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    #39
  20. CosentinoEngineering

    CosentinoEngineering Been here awhile

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    >>Sorry if this is too rinky dink a question for y'all's awesome knowledge, but I figured I'd ask anyway.
    >>I want to change a bike from a 16 rear 18 front (rims) to a 18 front 18 rear.

    Like they said in school the only bad question is the one you don't ask.

    The key to look at here is the overall height of the rim/tire assembly. The 18" tire may have a lower profile than the 16" one so the difference may be less than the rim size.

    Swapping out the rear will have less of an effect than changing the front but with no other changes you will have a higher rear ride height which would result in less steering trail which would tend to make the steering feel faster.

    If it is a twin shock rear bike you could find slightly shorter shocks to compensate and keep the bike in the same front/rear ride height. Mono shocks are more difficult to do this with but some do have built in ride height adjustment which would come in handy here. You could also drop the forks in the triple clamps but then the entire bike will be higher, may be good, may be bad depending on how tall you are!

    Whatever way you go, definitely start slowly and see how differently the bike is behaving so you don't go flying off and hit a car or tree.

    This is also a good reference for bike geometry: http://www.tonyfoale.com/Articles/index.htm


    Chris
    http://moto2-usa.blogspot.com/
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    #40