SR500/705

My street "legal" dirttracker, I bored and stroke a Yamaha SR500 motor to 705cc, + heaps of other internal goodies, my own front perimeter brake just before Buell started making them, viewed from the right there appears to be no front brake, small headlights in the #66 front number plate 6's, outrigger bearing on gearbox mainshaft, list goes on,
http://i1204.photobucket.com/albums/bb4 ... an0011.jpg

What is the bore and stroke? I have a crankshaft that has been stroked 12mm which I plan to use to make a large displacement TT500. Do you know what the largest piston available is? I want to pull out all the stops and just make the largest displacement single I can just for the fun of it. I know it won't be practical but the THUMP will be a blast.

Cheers, Dan.

88 x 101, its not an easy task to fit a piston that big.
if you want to go big, start with a DR750/800 motor, I was planning to take one to 1000cc.

So, with my 96mm stroker crank mine would be a 769cc machine with the 101mm piston. What piston did you use?

The type of piston is fairly insignificant compared to what you have to do to the rest of the engine so the big piston will fit, anyway here are some of the parts I used and some of the mods I did.
2mm offset crank pin, XT600 conrod, Honda XL600 Cylinder liner, Yamaha XT660 4th oversize piston
Bore crankcase opening oversize, machine top and bottom cylinder faces, 6mm cylinder head compression plate (like a thick head gasket). other machining mods I cant remember, unless you have your own machine shop or one at your disposal and you have lots of time ans know exactly what you are doing then I would think twice,
there are many things to take in to consideration ,combustion chamber volume, cam chain length, valve sizes and clearances........

You are one supprising fellow there madass140. Really nice build. I missed the chance to buy an SR500 when I was first stationed in Japan back in '97 (ended up with a Suzuki GS400 4 cylinder that had tons of problems, mostly fuel &electrical) Ended up giving it away so that I could put a Honda NX650 in my name (the base only allowed one bike at a time as I remember) anyway the Honda had a 720 kit in it and it was a FUN ride! Bet your street tracker was even more so! Cj
p.s. The NX had no Kick starter like the XR's did, and I went through a couple of starters before trading it for a 1990 Subaru.

I am prepared to do all of that to the engine. One of my most successful builds was a mild 440 from a Honda XL350 engine by going out to 89mm (XL500 piston, same wrist pin size, shaved 1mm off the flat top.) No stroke increase but did have to bore out the block and install the sleeve. It made a great motor with first kick starting and a gob of torque. Wasn't too bad on top either with a top speed a bit over 140 kph.

On the TT motor I realize that I will have block strength issues. I am sort of planning to go with a Buick piston that is dished out. It is all just for fun to me. I am fully aware that more power can be found in other ways. I just like the thumping feel and walking back over a piece of ground to see the intermittent burn out corresponding to power strokes!

I really like your build by the way. The SR500 is one of the bikes I want to own someday.
Dan.

Here is a Suzuki DR750 Motard I built, the frame was nickle plated, polished Ducati Monster rims, 50mm White Power forks, XT600e bodywork, warmed motor.

here is the crank assembly of the SR500/705 88x101

in the back you can see the left side of the crankcase with extra support bearing for gearbox mainshaft