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Case's with no numbers,
- Thread starter greazzer
- Start date
start with posting a couple of pictures of engine......side cases, side and back view of engine. Also look on the top fin on the back of the cylinder head between the inner intakes see if there is a number cast on the fin. Some pictures might help narrow down the year before doing some disassembly to investigate more. What year is the bike? What are you doing with the engine? What are your concerns that you need to know what year it is?
Okay I will get some pictures tomorrow and look at that stuff, motor only no bike, was hoping to be a f2 or f3 was looking for a top end mostly for a big bore kit probably,tell me if I have a f2 or f3 if there is any issues with putting it on a k lower set of cases, ???
The f cylinder head will have a 410 cast into the tip fin. They are also black from the factory. You will have to do some machine work to the head to use it on the k bottom end or you will have oil leaks. I have some pictures in my galleries on this site as I have done this before. You have to watch the cam valve overlap with the F2 head, the valves hit with too much overlap. You also have to take compression into consideration with the f head as the chamber is quite a bit bigger than the K heads. If you get a good cycle x K head it will far outperform a f head and less hassle with parts fitting. Combustion chamber modifications may also be needed depending on how big of a bore you are going for.
Well I was told and the understanding that the f top end was the better way to go, cause of the larger valves, bigger combustion chambers, and had more compression, and ran a better flow, and from the jug up would fit with no mods , I was thinking about a 67.5 mm or 67 mm bore kit with a lightened crank and some super rods, along with all the necessary beefed up parts, stud's,chains, clutch parts,
Here's some of the pictures of the motor I'm trying to figure out what it is , thanks for your help.
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They do flow very well stock but you actually loose compression with bigger chambers unless you do a bore size that has compatible f2 pistons. Yes the head will bolt right onto k bottom end but you need to do some machine work to not leak oil.
Definitely not a F2 or F3 motor. Cylinder head looks like a K4 through K8, I would say you are looking at a 74ish K4 motor. You might be able to figure more out if you plan on taking this motor apart and looking at a couple of the internals.
If you had this head rebuilt with larger intake valves mild porting and a good camshaft you will have a decent motor with that piston size. Ken at cycle x has some nice porting options that will flow as well and better than the F head. You can run a cam with more duration in the K head than in the F head.
Definitely not a F2 or F3 motor. Cylinder head looks like a K4 through K8, I would say you are looking at a 74ish K4 motor. You might be able to figure more out if you plan on taking this motor apart and looking at a couple of the internals.
If you had this head rebuilt with larger intake valves mild porting and a good camshaft you will have a decent motor with that piston size. Ken at cycle x has some nice porting options that will flow as well and better than the F head. You can run a cam with more duration in the K head than in the F head.
Okay, well I guess that I will push the pencil around and see what I come up with, what is the difference between the two motors on the output drive,at the sprocket, one is set more outboard more than the other ones, where it changes where the sprocket set's, and what is the difference between clutches between the f2/f3 comepaired to the k motors ?
yes the output shaft is out a little further on the F motor but you can do the same with an offset sprocket as long as you dont have to go too far. The clutch stuff is a little different but most parts can swap. The F have a different transmission ratio. The F need bigger carb rubbers. 99% of the internals are interchangeable between all the sohc 750 motors. I can make suggestions on how to make stuff work if you let me know your intended application. Also take a look at some of the pictures in my gallery.
Well the motor that has no numbers, the sprocket set's out a lot more than the other ones I have, I have one 72k, one 74k, two 76k, and one 77k motors and the one that doesn't have any numbers, to choose from, what one would you think that would be the best one to work with, like I said I was looking at a bore around the 67/67.5 mm area, head done up,larger valves,new guides,ported springs, retainers, welded and lightened rocker's,good cam, rod's, lightened and balanced crank ,under cut gears,HD clutch and springs,hd rod bolt's and all hd studs, drive and cam chains, and anything else that will help to keep it together as much as possible, I also have a motor that has some RC parts on and in I was told, it has a rt side distributor, and who knows what inside, but when I got it, when it was running it was definitely not stock, it was loben something feirce ,I was told by the guy that I got it from he said that his brother built it back in the mid to late 70s, but not sure what was done , I will send a pic tomorrow
I have a thing for RC parts. If you want to sell i may be interested.
The Picture of the sprocket the case isnt bulged like the f2 case so Im about positive its a k case. maybe someone put a later output shaft in it? The sprocket looks like a weird aftermarket wider sprocket.. What is the plan for the motor? Street bike? racing? What are you trying to achieve with it? If you want something cool build the RC motor or sell it or the parts to help fund the new motor, honestly the parts available now days are better then the old RC stuff but I like to collect them and use some of them on my drag bike.
The Picture of the sprocket the case isnt bulged like the f2 case so Im about positive its a k case. maybe someone put a later output shaft in it? The sprocket looks like a weird aftermarket wider sprocket.. What is the plan for the motor? Street bike? racing? What are you trying to achieve with it? If you want something cool build the RC motor or sell it or the parts to help fund the new motor, honestly the parts available now days are better then the old RC stuff but I like to collect them and use some of them on my drag bike.
I was thinking about incorporating it into what I was going to build was my thoughts, it's going to be a street bike, here's a picture of what it looked like when I got it , will send some better pictures tomorrow
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I had a RC distributor but had to sell it couple years back. Look neat but pain in the but at times on the street and hard to get parts for. Would like to find one again. Would like to see more pictures and put me on the list if you might want to get rid of some of the rc stuff
I will do that, I'm on the road rt now but will be back home later tomorrow and get some more pics for you, I think that motor is a 74 year, I pulled it out back in October, to start to restore the bike and was looking to build some pieces up to maybe make things go a little easier
I would definitely be interested in seeing what you have and what you would want to part with.
Nice looking bike. Back in the day, my wife had a '57 Triumph pre-unit that had a Savior rear section welded to the frame. Never could get it to work right unless both of us were on it at the same time. Not to say we didn't ride the crap out of that bike, just that when either of us rode it solo, it felt just like my '68 Bonny with a true hardtail frame.
