Some later FX bikes don't have the boss on the right side of the frame for forward controls.

ps all of them are in the FX family - big twin frame and sportster forks, until the FXWG came about and confused everyone.

 

Forgot about that Boss... but yes... FX would Not have it, since???? IDK... guessing late '70's

 

Welcome to the forum. What range are the numbers? Do they appear authentic? If you’re not sure then you could post partial photos. For example, 2C12+++H7. Even if they match you may find the frame number characters are not all identical to the engine number characters because some changed during the 77 model year.

Is there a crankcase production number under the left case? (R-H production number for 77 is inside the gear compartment and obviously not visible on an assembled engine.)
Anything stamped on top of the cases near the rear engine mounting bolts?
Any ID stamped at the back of the cases? For example, A123. Look at the back edge of the R-H case about level with the bottom of the oil pump. Then check the corresponding position of the left case.

Does the frame have an ID plate/sticker on the R-H front downtube?
Does it have two-hole blocks to accommodate passenger footpeg brackets? If so, do the blocks appear original?
Lower left rear forging number should be 47654-73.
Lower R-H rear forging number should be 47652-73.
Steering head should have forging number 47591-35A. It may be on the R-H side and sometimes, but not always, upside down. On the other side you may find a DIF (Interstate Drop Forge) hallmark and a forging die number, perhaps in the 60s?
Left side of the frame top engine mount may have a date code consisting of one letter and one number. The characters may or may not be hidden by the top engine mounting bracket.

Any ID stamped on the R-H fork stop on the lower triple clamp? Any ID on the front of the trans case on the R-H side just below where the lid attaches? If either or both parts have ID then the letter(s) may help determine their model year.
Eric

 

I think 1979 was the year of the F'ed up engine numbers...

 

This is a 1978-1/2 FXE. Not correct for the year is the luggage rack on the back (1st offered in 1979). Additionally the FXE came only with e-start (no kicker) so technically that is incorrect as well. Your 1977 FX would look similar to this with the gauges mounted on the handlebars as well as the gas tank.



In 1978-1/2 HD switched to the Ham Can cover and backing plate due to continuing EPA restrictions. The cover remained in use until the Shovel models ran their course



The 1977-E1978 FX bikes (and Sportster models as well) used the oval cover and pigsnout backing plate (due to EPA crawling up their butt about pollution control). These only had a run of 18 months. I have only seen two pig snout backing plates come for sale over the last several years. The 76 and earlier oval backing plates are numerous however.




Tank decals were different for 1977 FX model bikes. They looked like this



Exhaust system was either the 2-1 collector or the staggered duals. The header pipes do not have any markings on them. The 2-1 collector muffler does have a part number on the bottom & I also believe the staggered duals also have a part number on them as well.




As Joe 12RK mentioned for 1977 & 1978 FX/E models HD cut off the right front frame tab that could be used for forward controls.

This tab pictured below.




When I bougght my FXE I thought someone had cut the tab off. I called Wasco Frame Service (great place to do business with if you need frame reapired) and talked to the owner because i was ready to take the bike down to the frame and send it to him. He informed me that HD cut the tab off.

1977 was the first year for the FXS Low Rider 1200. The FX 1200 was the intro level "bigger" bike (up from the Sportster model). The FXE was one pay grade above that. Speculation is that the tab was cut off to ensure buyers didn't get the cheap FX/E models and then buy the parts to change it over and make it look like the more expensive FXS series.

I see the gauges come up on the flea as well as the gas tanks. very rarely do I see the exhaust system, and when they do appear they are not cheap, probably because there are not many around.

 

I agree. But the bike being discussed is said to be a 77 model. And during the 77 model year some characters changed, as I mentioned above.
Eric

 

I am Unaware of "characters change" in 1977...but am Listening...

 

For 1977 Shovel numbering, some characters changed during the year. For example, notice the width of the D and H on this very early 77.





D and H are still ‘wide’ on the second example. Also notice the width of the 4.





But on the next 77 the D, 4 and H are slimmer than before.





Same thing applied to some other 1977 Shovel engine number characters, generally speaking.

Are exceptions possible? Apparently so and one in particular is a certain 9D which is higher than my third example yet its D, 4 and H are wide. And its 9 is rounded.
Also not following the apparent trend for 1977 is the 2F (FXS-1200), with its engine 4 and H changing to slimmer versions earlier than some other models.

Does the above also apply to 1977 Shovel frame number characters? Sometimes yes, sometimes no.
Eric

 

Great information and photos! Thanks to all who posted as this shows me the right way forward. I will post some pics of the frame and provide numbers in the next few days.

 

Nothing wrong with rebuilding back to original specs, but keep in mind, there was basically one big twin frame (aside from the newer FXS and FLT) and mixing and matching between models was easy and common. To me, a well done "period correct" bike is just as attractive. All depends what your goals are.

I see you're from Coopersburg. You may want to check out McKeever Custom Cycles in Emmaus. He knows old iron as good as anyone I've met.