I was playing with some numbers in MOTA last weekend on a piston ported motor. I was trying to get more than 100 at the crank at less than 6500 with a huge fat torque curve. Hey - A guy can dream can't he?
Well I initially guessed a small number for crankcase volume and it was really not helping the results, so I arbitrarily increased it to a larger volume (lower CR) and it helped with what I was doing.
Until I work out the real primary CR I'm just guessing, but it looks like the pressure and volume animations are way too high with the numbers I plugged in.
Would have to check my notes from twenty years ago and those are a ways away from here for the time being.
Hate working in the field...like a jail sentence.
We did not want to go the way of stuffers on the 500 twin but did end up with a crank lighter than the cut down ones.
Kris Bernstein wrote:Would have to check my notes from twenty years ago and those are a ways away from here for the time being.
Hate working in the field...like a jail sentence.
We did not want to go the way of stuffers on the 500 twin but did end up with a crank lighter than the cut down ones.
Kris
Hey Kris,
Feel free to post as much as you like about race tuning a T500 here!!!!
Nice to hear from you again!
Actually got out of vintage road racing for a decade or so when I got burned out. AHRMA hated the big smokers and would not let us any ware near the track. I started up the Seeley 750 in the pits when I raced the T500 at Daytona back in the early ninties and they rudely rushed over and asked me to put that nasty thing back in the hauler. Just did it to piss them off.
Seems a 750 with stinger exhausts does not get any respect at the four-stroke club. They have come around since they went bankrupt in the pissing contest with Rob Inaucchi. Never get in a legal battle with a lawyer...his fees are f.....g free!
Anyway restored or still restoring four Ducati's and still have a few strange two stroke racers that survived divorce #2...
Sadly the TZ750 went to France...will miss that thing...
Just getting back into the game as funds allow now...
Kris , i see your TZ is gone but still this is a nice place to hang out with the TZ guys http://www.getphpbb.com/phpbb/viewforum ... m=2stroker also it was great to see the mighty TZ's at the Vintage Races at Daytona this yr .
tz375 wrote:
So the best way to get there IMHO is to build a reed valve motor with additional boost ports. Of course that really needs pistons with ring pegs in a different place, but that's not too hard. The reed conversion gives you scope to change the transfer porting and add intake port area without the bad effect of too much intake timing. You really want to add a modern squish head to that package and the exhaust ports will end up very wide, so the shape is important and so are the rings you choose to use. Add in custom designed pipes and another $1000 or so to change to Fuel Injection and you should have a nice package.
Come on now Teaser , who would be crazy enough to drop all that on a lump like the Gt750 engine
Dave,
Believe it or not, I heard that there are people two deep in GT750 projects for absolutely no good reason. There are tales of people buying up Snowmobile motors and cutting reed boxes off the crankcases and measuring snowmobile and motocross barrels and ports and heads, and stripping cranks, just to work out WTF makes these things tick. Then they supposedly spend ridiculous hours working computer numbers till 3 in the morning and leaving huge piles of shavings on the workshop floor.
I even heard of people buying 34mm carbs and then 38mm flatslides and sets of EFI and ECUs. I even heard that someone cast their own barrels up.
Personally I don't believe any of those urban myths. No one would be that demented.
BTW, you never did send me the name of your therapist..........
There are at least two people on this board that have done it or are in the process.
Shannon built his own GT 1000cc cylinder with reeds. There is a thread on this board regarding his engine with pictures and of course, Dave is in process with his GT750 EFI shown above.
Harpowa built several reed conversion cylinders back in the early 70's in the UK, hoping to market the conversion. Never caught on as six and eight petal assemblies didn't exist back then and the effect, most likely was not worth the expense.
I've seen pictures (a few) and I know Keven Fletcher has one on his TR750 motor in Canada.
Same welded up reed box's after intakes milled off, I guess.
I'd thought they used RD reed cages. Info lost in the smoke of time, me thinks.
I'll email Kev and see if I can get pictures. He's always about the world with his work. He just stopped into Nova Racing in the UK to have a look at the TR750 six speed gear box Paul Smart sent to Graham Dyson to possibly replicate....although Graham dismissed it as a bum design....
Better to start with a fresh sheet of paper me thinks
Kris
