frame mods?

[turtlemann14]

I have two bikes and one needs a motor and the other needs a wheel. one is a klx250 1979 and the other is a xr200r 1985 the 200's head cracked so i want to put the 250's motor in the frame, but the motor is about 2 inches to big how hard would it be to cut the frame and put spacers or something like that back in to make it big enough for the 250? any suggestions?

[wr250f95]

if your crafty you can do anything.
perhaps make mounts that move the engine back?

[turtlemann14]

i think it is to big for the space... to tall and to long I'll get some pics soon enough

i try to be crafty but it doesn't always turn out for the best lol

[tigmaster]

idk, cutting your frame in half is a real bad idea. you were saying you basically wanted to extend your frame to fit the motor correct? this is a bad idea in every way if this is what you meant. first off, your entire geometry of the bike is changed in ways that the designers had not counted on. and the other problem you run into is strength, you will never be able to have the same strength you had with a single frame member. if you want to do it, i would suggest trying to just cut away a bit and add a bunch of gussets.

[turtlemann14]

yes that is the basic idea, i need to get some better measurements its been a long time since i thought about it. i think that most it is out is 2 inches on the head of the motor
maybe like 1/2 - 1 inch on the case and the rest could be done with a new set of brackets right now i have a machine shop at my hands so i want to get this done or make everything i would need
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looking at it again the only this that would have to change is the front most bottom point (closest to the wheel) and the top "gusset"(the bar that makes a triangle to the main frame bar under the tank)

here is a pic clicky

[tigmaster]

so from the looks of the pic, you just need to cut that cross brace out? if so that would be fine as long as you put one in above where the engine cleared. throw in a few gussets too.

[turtlemann14]

what do you think about the bottom of the frame do you think you could cut into more of a corner shape instead of being rounded like it is? on my klx it is cornered like this

[tigmaster]

if you want to do this frame mod you can do it but be careful because there is a lot of stress on the frame. if you want to corner it like you were saying, use a tube that will slip inside the original frame. now with this tube, you should use math to determine the wall thickness to match the strength of the frame since the tubing will be smaller or if you dont like math, just get like 3/16 inch wall. slip the tubing in the frame about an inch. make sure to tig this seem with filler rod. lay down a real nice bead. and since you will be making a cornered frame, try to put the engine mounts right where the corner is to use them as gussets. i would really suggest all the seems be tiged because of the high stress applied to everything with a dirt bike.

[turtlemann14]

thanks for the conformation can you tig it for me¿ lol

[tigmaster]

funny story about all that. never used a tig welder in my life. if ihad the cash i would buy one but instead i just have a real nice mig and a stick. my welds are ridiculous tough and look like tig welds but unfortunately i dont have a tig. the name comes from this one day a long time ago when i was at my buddies house and i clamped up a screwdriver in the stick welder as the electrode and had some grid wire in the other, trying to strike an arc. so there ya go.