| Author | Message | ||
     Tom_b |
Found and H/D sporty shovel head powered flat track bike that could possibly be for sale. How can i tell if this is one of the genuine XR750 bikes or a 1000 or 1200 powered bike bike built just to race by someone. Price is cheap, but has been sitting for about 20 yrs. the current owner really doesn't now a thing about it or forgot most of what he did know. has orange and black h/d paint scheme with what appears to be the correct seat and tail section.. What i'm concerned with is where to find frame and engine numbers for verification. For the price it would be a resale item if i knew what it was. Any help would be appreciated. | ||
| Ulynut |
Post some pics if you can. Lots of people on here with tons of knowledge on these things. | ||
| Spiderman |
this is what an XR750 looks like  and a XR1000  The easiest spy for a vintage XR is the primary. A production 1k will be big an bulky like a stocker and the limited 750 will look like tin. | ||
| Moxnix |
There may not be a chassis number if it's old. If it has a cast in part number ending in -52 or -57, it's in a K model or Sportster frame. If it's an iron barrel XR750, look for a model and serial number on the left side of the crankcase below the bottom of the V of the cylinders. The exhaust originally exited on the right side with a single Sportster style carb. Some were greatly modified and all kinds of set-ups can be there, dual carb, etc. Cases will have serial numbers on the bottom, stamped. If they don't match, it may be mismatched from a rebuild. It it's an alloy XR, the number will be stamped on top of the right side case. If the frame is from a factory racer up to 1980, look for old style cast iron "tomahawks" below the swingarm mount on the frame. A factory racing chrome moly frame likely has no serial number, unless it's a stamped two or three number matching the pro license number of the original owner or factory rider. 19 inch wheels front and back, no front brake unless it's a TT bike, Gremeca rear, quick change hubs, yadda, yadda. It might be a KR or KHRM if the heads are flat and made of aluminum. Good find it it's genuine. Let us know what you want for it . . . . . | ||
| Spiderman |
The exhaust originally exited on the right side with a single Sportster style carb. So an original race xr750 had only one carb? | ||
| Crusty |
Yes; it was, for all intents and purposes, a de-stroked Iron Head engine. It was a fill in measure between the Flat Head KR and the alloy XR. It didn't work too well. (Message edited by Crusty on August 17, 2010) | ||
| Tom_b |
It is definately a flat track racer set up very similar to the one spiderman posted except the pipes are on the other side. I didn't get to take pic's. It was in a customers garage, i saw and started asking about it. Said he bought it in 1981 from a cousin who had raced i and intended to race it himself, but changed his mind and parked it. it has sat since the end of 82. Has 19 inch wheels, no front brake, wide flat track style tires, no lights, single car, flat track seat and tank. It needs a good solid cleaning, tires, tank cleaned out at the minimum. The engine kicked over and seemed to have good compression. The guy also has two big boxes full spare carbs, plugs, cables, sprockets and various stuff. I will try to get back and get a closer look and look for numbers. I just don't want it to turnout to be some odball conglomeration that i really can't do much with or even tag if i wanted to make it streetable.. Thanks for the help on what to look for maxnix.. | ||
| Moxnix |
Called the "waffle iron" for the heat it made. Before it seized. | ||
| Just_ziptab |
It's either a Sportster engined flat tracker or the 1970/1971 XR-750. 1972 was the first year for the alloy XR-750........ and the most beautiful one. 1970  1972  Count the fins. The iron XR-750 had shortened 883 Sportsters cylinders to make the 750 cc size. | ||
| Just_ziptab |
Iron XR-750,1971,right side pipes,single carb. More or less,a glorified Sportster. | ||
| Moxnix |
It's still very much worth owning, even it's a "bitsa," (bits of this, bits of that). If you buy it, get as much history as possible from the seller and his cousin, with signed letter of the history. I got to thinking, it might also be an XLR, the racing version of the Sportster of the era. If it's a race motor, it should have a front mounted magneto where an early Sportster generator would have gone. I bought a chopper once, just to get the XLR motor. With ball bearing mains, they are not great street bikes if you use them hard. In 1972, the alloy XRs had "superblend bearings," a barrel shape that was sort of an improvement, especially after tuner Johnny Goad devised a way to run a double row bearing in the right side case and the engines stopped blowing up. Buy it and put it on fleaBay or sell it to some collector. If you can trace the full history back to an original rider, all the better--price wise. Good luck. Maybe you can turn enough profit to buy a really nice ride. | ||
| Firebolt020283 |
drool... I have always loved the xr750s. | ||
| 46champ |
If it's a XLR it will be an 883 and should have a front brake. Most will have a Sportster tank not a XR tank. | ||
| Spiderman |
too cool, I always thought the XR750 was designed around the dual carb... | ||
| Trojan |
The easy way to tell if it is genuine Xr750 will be the amount of 0's in the price. If it is genuine then I would expect around 5 0's at least. Anything less than that will be a Sportster  | ||
| Aptbldr |
Link to folder containing eight pictures of nice example XR750. Amongst my favorite motorcycle models of all time. http://picasaweb.google.com/aptbldr/XR750?authkey= Gv1sRgCPyls52AqsCXrAE&feat=directlink | ||
| Shupe |
A quick history: The AMA rule for class C racing changed for the 1970 season. Before, you could run 500cc OHV or 750 cc flathead. Harley's KR750 flathead dominated. For 1970 it was 750cc, OHV or anything else. So the Brits would be able to run punched out 650's instead of 500's. H-D had to come up with a OHV 750 for the 1970 season, so they threw together a destroked Sportster and the Iron XR was born. It didn't do well. Overheating (iron barrels and heads) was common. Many DNFs. This was the season shown in "On Any Sunday" where Mert Lawill unsuccessfully defended his 1969 championship. In 1972 the all alloy XR came out and went on to dominate the dirt tracks for decades. What is unfortunate, IMO is that the R&D done for the alloy XR never filtered down to the Sportster, which soldiered on with iron hemi heads and barrels until 1986 (except for the limited production XR1000 of 1983-4). In 1972 they bored the Iron head out to 1,000cc and called it good. | ||
| Tom_b |
After reading my post i realized i made a mistake on the dates it has sat since 1992 and was purchased by the fellow i met in 1991. I did talk to the man this morning. He was able to give more info over the the phone after talking to his cousin. bad news is the bike is not an xr750. It was built in 1983 on a sportster engine by a local engine guru by the name of Paul Osborn. Paul osborn is owner of Truett-Osborn cycle shop and has been around for decades.He didn't know the exact displacement of the engine but said it started out as a 1000 sportster and was class legal in the twin open class. the frame is a custom built by a conjunction of kennedy cycle and star racing who both were big into flat track racing back then. While a very cool ride that i would love to have, he tripled the price he said he would probably sell it for. If it was an xr 750 would still be a GREAT buy. It is really close to a running bike that would compete in the NFTRA twin class would sell for. | ||
| Cityxslicker |
as soon as this damn house sells. I have a line on a 72 right side shift XL... and a box fresh never run original XR750 heads..... just need the exhuast, as I have the flat track kit already in the garage..... come one damnit. Buyz my house. | ||
| Moxnix |
Thanks for doing the legwork on this and giving us an interesting story. The sizzle can be just as good as the steak. Someone will want that bike. It's certainly worth owning, especially to someone who recognizes the Osborn origin or is interested in local racing history. | ||
| Skinstains |
T&O is some high class chit and I wouldn't mind owning that thing. Any chance you could get a pic or two of this mongrel ? Oh yeah, City, we used to call those 72's grenades...be carefull... | ||
| Moxnix |
71 & 72 XLs had a weak casting around the tranny, fixed in 73. | ||
| Aptbldr |
Short video, good sound, XR750 slidin' around a short dirt oval: http://www.youtube.com/watch?v=sk-mV4ybQgw | ||
| Aptbldr |
How many inches are gained with Uly swing arm?  wheelbase 1970 XR750, 57-in 2004 XB12R, 52-in weight 1970 XR750, 320 lb 2004 XB12R, 395 lb wt/hp ratio 1970 XB750, 3.6 lb/hp 2004 XB12R, 4.0 lb/hp |
