So, Kramers have shown up in LRRS and are quickly making their presence known. With the standard CCS single cylinder blind spot in the rules they're eligible for and competitive in a metric boatload of classes. 80hp, 280lbs... So, if one doesn't want to go down the exact same path, what would one build to counter them? I'm thinking chassis from the last of the 250GP era, BRC 500 smoker? (It's a full conversion based on a KTM 250 / 300 motor, retaining the transmission / clutch / waterpump.) Counter balanced, 67hp / 52ft/lbs with a 38mm carb, first attempt at a pipe design. It looks like the XR650 mill is too heavy and can't make the needed numbers without becoming a grenade. Raptor / MZ 660 I suspect suffers a similar fate? The Maaco / Zabel 700 is supposedly 83hp but only has a four speed transmission and I don't believe they're counterbalanced so they'd be like a CR500 build and libel to vibrate to pieces? What combos am I missing?
Hah, already trying. My personal best on my FZR is a 1:20, the Kramers are dropping 1:17s without any development work. Dunno if my machine can match them or not, but thinking about the concept behind them got my gears going, hence the thread.
I think a TZ Chassis with the BRC500 would be awesome! I think there is a lot more power than 67hp in them. That is a 500 breathing through the same carb as my 250. A good pipe for road racing, good combustion chamber, and get the ignition timing map right. I could definitely see mid to high 70hp. I'm wanting to build something based on a 250 motor (think 125gp for a big guy). I will get on it when ever the funds become available.
Just take that same motor they are using, lc690??, and stuff it into a tz250 chassis. Or build your own trellis frame chassis around that engine. Use top o' line olhins, brembo, etc. Send engine to some builder to get hp and beat them at their own game???
My thoughts exactly. I'm sure the Kramer is a nice piece, but I doubt it works a ton better than a standard 690 with good suspension and the same motor build.
The husky/ktm 450 mx engines make 64 hrose power at the crank and are reliable and light. Maybe an option?
From eavesdropping conversations when suspension guys were around, it seems the Kramer got the geo pretty damn close to spot on, not sure how the 690 in Duke / Sumo trim would compare. We had one rider make a go of it on the FS701 last year, switched to the Kramer this year with the same mill and instantly dropped time. (Same mill isn't fare, Kramer has had the ecu heavily monkey'd with, dunno what actual build changes they make, internal touch ups, etc.)
I think with any of the dirt based motors a big limitation is the need for the swingarm to mount through the engine cases, this really limits the orientation of the engine/swingarm since the relationship between sprocket and swingarm pivot is essentially fixed, which pre-defines many other parameters. My TZ250/MZ660 hybrid has been stalled for some years because of life stuff, but as it sits I'm not really happy with the geometry related to the above. Also I wanted to retain the starter for ease of use and that really compromises the frame. Also any dirt bike based cylinder head really isn't made for high rpm, and without rpm you're not going to make power. My 660 mill I'm counting on riding it on the torque curve, and I don't really expect it to be a weapon on the straights, regardless of bore/stroke or how much I can get the 3 intake valves to flow. I had a CR500 powered NSR250 but that really wasn't a good combination because the vibration (without a dedicated crank balanced for the usage) was too much and it was finicky to start. Unless you like building for the sake of building, I think a Kramer isn't worth trying to out-build, it's a pretty nice piece as it sits. Although for the money...
I'd need to look at the KTM smoker cases, but my first thought would be to just cut the swingarm boss off the cases, grab the engine elsewhere? And re building for the sake of building... have you seen my stable?
Turn a 998 Ducati into a single. Built one for a customer of mine and he won a bunch of races on it, including a WERA GNF championship. It's not cheap...but...
Oooooh, it's crossed my mind before. Prior to going down the long path with the FZR I was fantasizing about a poor man's supermono. I'm curious if it could be done to a Panni twin... That said, with the debut of the Kramer I'd be curious how it'd stack up. Last one I read about was still in the 340lb range, 80hp IIRC?
So, they've gotten the Kramers down to 16 flat at NHMS. I managed to find a high 19 on the FZR... damn moving bar. Doesn't seem like they crash particularly well, clamps/etc prone to getting tweaked and no one has spares to steal, not much of a surprise when there are two of them at the track. On the flip side, my FZR is a literal unicorn so despite crashing 'better' when something does break...
Larry at MotoCorse helped a customer who built one from a 1098. It blew up multiple times. I'm no engineer but I know the crank counterweight adds up to the weight of the pistons and rods- so taking one piston away means it's going to shake itself to death? One cylinder doesn't seem like that much of a weight savings. I haven't ridden the Kramer, but last year those guys at the Vintage fest were flying on them.
You have to rebalance the crank, IIRC Ben Fox? has the formula figured out? Like any big single you still have a lot of primary vibration to deal with after as well but the crank itself should survive once adapted to the job. I agree that the weight savings isn't going to be that big, and I don't know if you can even do it on the newer Pani style V2?
You need one of these, a Bare Bones Machine, 1988 TZ250 reverse cylinder chassis, 1992 TZ front end, Honda XR500R motor (will work with the newer XR650L motors as well) :
I don't know as the 500/650 can hang with the 690, I thought they were heavier and topped out around 60hp without becoming grenades?
