91 Production model distinctions !

[Steve Swan]

Please study this list and compare to your bikes features.

Let's see how many features found on lower vins we can find on the higher vins !

Anyone who has new or different observations, please post your findings, so the list can continue to update.

The main feature distinguishing early production from late production machines, the frame changed from LH horn mount to RH horn mount at vin 3950, to prevent fouling of lower brake line on horn under hard braking.

Therefore, this list denotes numerous changes within and between early production vins #1 - 3949.

This list also denotes differences of the early (up to 4148) exhaust muffler/baffle systems.


Detail Differences for Production Sandcast VIN’s 1- 4148

1. 12 mm nuts, fork clamp, 1-2157 (14 mm, 2158-onward )
2. short neck brake hose fittings, 1-2157 (long neck, 2158-onward)
3. No hose guide metal plate for bottom hose at junction box 1 - to 3950
4. 20.4mm wide nose on upper triple clamp, 1-3433 (22.4 mm 3434-onward)
5. no leveling ring on master cylinder reservoir, 1-2435
6. no “off-on-off” marking on kill switch body, 1-approx 800)
7. pointerless kill knob (1-441)
8. LH mount horn (1-3949)
9. grey body horn with grey wire sheath
10. some grey body horns noted to have black wire sheath
11. knurled Allen screw heads, brake caliper, 1-1256 (smooth, 1257-onward)
12. 66 mm choke arm up to vin 1120 (52 mm late production)
13. horizontal brass vented carburetor bodies, 1-302, late carb bodies have cast 90 degree "L" type vent
14. short neck fuel tap, 1-1937 (long neck, 1938-onward)
15. 19 litre fuel tank, 1-448)
16. 10 hole seat pan w/ 6 mm threaded hole so far to to VIN 1081. (late production 17 hole although some seen on machines after VIN 883)
17. upper triple clamp nose less acute angle, 1-3433
18. 16 t. counter shaft sprocket, E1-E3527
19. all early “8” chassis/engine bolts
20. thin lip alternator cover, E1-E2134 Two types. Smooth HONDA background and rough HONDA background
21. “Lotus Root” exhaust, 1-4148, no “HM300” stampings, no brake pedal relief (ditto late production)
A. long, cylindrical steel removable sound diffuser with no external fiber covering and not interchangeable with late production exhaust.
B. 5 mm welded seam (late production 7mm seam)
C. mufflers have no internal baffles, only a plate with a hole for which the long cylindrical baffle slips in to for support
D. 6 mm hex head removable screw fixes baffle to muffler body, this screw is not welded to baffle as in late type exhaust
E. bolt mount hole diameter 55 mm (late production 58 mm)
22. no vertical crimp markings on oil line (smooth) ferrules
23. smooth rubber fabric oil lines, E1-E436 (late production webbed fabric)
24. swing arm (rear fork) date stamped, left underside bushing area  Early swing arms (around first 300 VINs) full date in centre rear underside
25. oil tank date stamped, inside top rear mounting bracket
26. “8” bolts fixing rear sprocket to carrier up to 232 (302 has plain head bolts)
27. no diagonal brace on center stand, 1-1120
28. round, fin-less, non-webbed oil filter cover, E1-E4148 (there is a question on whether finless cover went past VIN2000 so needs further clarification)
29. 14 mm hex head, oil filter bolt to E4148, 12mm beginning 4149
30. driver portion of seat less thick, horizontal surface
31. passenger portion of seat angled
32. 2-hole air box bracket, 1-4006
33. no relief on upper air box cover, We have no information that "no relief" features on upper covers between VINs 674 to 1553
34. 2-hole air box brackets 30 mm, 1-4006 (24 mm 4007-onward)
35. pillion rest/muffler bolts 146 mm, 1-1221 (148 mm, 1222-onward)
36. upper crankcase vin pad 11 mm wide (late production 19 mm)
37. no casting dates on early crankcases (E1-not known after E254)
38. no casting divots at crankcase base of #4 cylinder hole
39. exhaust pipe clamps, “fat” fins, 1-2435
A. #1/#4 clamps, no relief on back side of fins (not interchangeable with #2/#3)
B. #2/#3 clamps, relief milled on back side of fins (not interchangeable with #1/#4)
40. “8” bolts fix master cylinder clamp to master cylinder up to 2157 (late production plain head, chrome)
41. early lower frame steering head has steering damper gusseting, noted on frames up 1100 then random to vin 1588
42. caliper backing plate more deeply finned all sandcast
43. upper brake hose steel neck fitting straight,1-2157 (late production has bend)
44. no rubber boot on upper brake hose to master cylinder, 1-2157
45. sand cast cam chain tensioner body, E1-E1106
46. 10 mm rotor bolt (E1-E1080) (12 mm, E1081-onward)
47. acorn hex head bolt, starter cover shown in Manual but never reported on a machine so not fitted in production.
48. narrow counter shaft, E1-E3527
49. 8x80 left rear crankcase bolt, E1-E219
50. No guide lugs as cast part on junction box for top brake hose (up to VIN 1927 identified)
51. no rubber cushions for air box mount bracket & air box upper body (until 4006)
52. short knurled ring nuts on speedometer/tachometer cables, 1-2157
53. wiring harness 32100-300-040, 1-3479 (32100-30-050, 3480-onward) May refer to European delivery only
54. no wire clip fixed to horn to guide tachometer cable (1-3950)
55. left side horn mounting bracket, 1-3950
56. frame has LH horn mount, 1-3950 See number 55 above
57. crank shaft has 10 mm threaded hole for rotor fixing bolt, E1-E1080 (12 mm, 1081-onward)
58. webbed fabric oil line, smooth ferrule, 303-2435
59. chrome hex head brake line bolts, 1-2720 (zinc plated 2721-onward)
60. 5 mm flanges on exhaust spigots, 1-665 (6 mm, 666-onward)
61. date stamped lower triple clamp
62. round captive 6mm nuts on battery box, fixing regulator to battery box (late production, square nuts)
63. small side cover grommets 1-1120 (“240” middle part number)
64. exhaust spigot flanges, radius on each long diagonal side, (E100 has 4 radius type.)  (E342 has 2 radius type and 2 thin 5mm straight type.)
65. RH oil gallery plug, solid, 1-1106 (bored hole, 1107-onward)
66. rear M6 cylinder head/cylinder fixing bolt “special” type, same as four underneath cam carriers, 1-1106 (“normal” 8 head bolt, 1107-onward)
67. no locating rib on speedo/tach rubbers, 1-3433 (locating rib, 3434 -onward)
68. sandcast cam carriers, oil pump, clutch center spider, gearshaft bearing housing, E1-E338
69. no holes in ends of rear wheel cush rubbers, 1-302 (late type have holes) Subject of a recall for early machines
70. no garter springs on valve stem guide seals, 1-338
71. piston oil control rings have helper springs, E1-E338
72. front oil gallery plug smaller diameter than later plug
73. adhesive aluminum vin tag, RH steering head, no manufacture month/year
74. riveted on aluminum vin tag, RH steering head, containing month/year of manufacture, beginning 9/69 (Sept. last month of sandcast manufacture)
75. red plug key, per HONDA factory brochure (?? on first few production bikes??) Red plugs provided for dealer use has been suggested
76. around E600/E700 began having “mixed oil lines, i.e., smooth and webbed fabric, both line types still using smooth ferrule
77. around E338, lower case date stamped, upper case no date stamp
78. weld seams on frame gussets lower than late production weld seams (late production has higher weld seams)
79. lower connections, oil line to engine, smaller, less "beefy"
80. round hole in speedo/tach mounting rings, 1-302 (303-onward oblong hole)
81. 11 mm mirror stems, 1-302. Threaded to unthreaded portion of post has an actual step, appearing machine turned. Mirror stem at clamp end smooth. (Later mirror stems 10 mm without machine turned step and a circle outline visible at clamp end.)
82. Later LH horn mount frames have no gusseting for steering damper, highest vin w/ gusseting 1865
83. Early clutch cover have thin lip in “10th hole” area, later covers have thick lip. Thin lip known up to 1788, thick lip start date unknown
84. Relief on upper case of airbox, 673 recorded as the highest VIN without relief. If you have a higher VIN let us know
85. Profile of relief of frame down tubes in front top air box area less acute, relief has rounded hand hammered appearance on early frames, 1-302. Later frames this relief appears as result of a machine stamped operation, flattened acute “V” in appearance.
86. Cast bosses with untapped 6mm holes of upper crankcase in the primary chain "tunnel" area for what appears to have been intended to fix a guide for upper primary chain, approximately the first 200 crank cases.
87.  Neutral switch has no chamfer to accommodate pushing through O-ring, replacement switch has chamfer
88.  Smooth background of HONDA logo on alternator cover, up to around E835, wrinkled background after approx.E835, both covers thin lip type.
89. Bearing, countershaft outer drive, 1-5306, plain outer race.  5307-onward, outer circumference of race grooved to accomodate retaining ring.
90.  radius on welded seam of oil tank, front upper RH corner.  (up to 302)
91.  17 mm hex/acorn head nuts fixing upper shock absorber to frame  (on random vins up to 248)
92.  Backing plate, rear brake, inside: four ribs around the center (axel) hole with (later type) and without (early type) the round bosses. Straight or plain ribs (early) vs. ribs with round bosses (late.)  Suspect round bosses were for mold ejecting pins.  Early type plain ribs create 4 distinct 'holes'.  Later type does not have 4 distinct 'holes' as seen in early type.  Later type has 4 distinct round bosses; as noted prior, likely for mold ejecting pins. 
93.  Evin 1-563, the cyl.head oil gallery counterbored holes are the only 2 counterbored holes in head, unlike cyl.heads Evin 564-onward there were 4 counter bored holes.  the pre-564 heads could only accommodate 2 O-rings, as per noted in early parts books. This need further clarification as later heads seen with 2 holes only
94.  Spline on rear brake pedal to Frame 3000 - From clamp bolt hole to where pedal arm is welded to spine clamp is a ground off casting flash line Later brake pedals do not have this casting flash. On under side of spline clamp end, casting in front of the threaded bolt hole has a square cut off on raised casting whereas later brake pedals have pointed raised casting
95.  Rear pillion foot rest mounting plate reinforcement welded. On early bikes the reinforcing pieces are hand welded in place. Later mounts are spot welded in 2 then 4 places.
96.  Chrome 10mm headed M6 bolts used to affix front fender stays to forks on very early machines. Maybe restricted to first 100 machines

[Steve Swan]

We now have 81 differences between vins 1-4148 and 4149-7414. Vic brought the 81st detail difference to our attention when we were under the tent.

[Steve Swan]

We now have 84 differences.

Difference #82 is frame w/o steering damper gusseting.

Diff # 83 is thin and thick lipped clutch covers.

Diff # 84 is no relief to clear frame tubes on upper case of air box.

Now that it's Winter, what differences can you guys find on your vins ?

Please post !

Thanks Marty & Bo for writing in !!!!

[Steve Swan]

We've got 85 differences now !

Special thanks to Allan, Chris, KP, Marty, Andy, Steve F, Vic for your help contributing to this list.

How many more differences can we find ?

Keep the posts coming in !

[Steve Swan]

We now have 86 distinctions, Vic wrote in with the 86th.

We are 14 away from 100 distinctions !!!!

[Steve Swan]

Let me say I updated this list with what i found on 2157.

With all the great posts we've been having of late, including talk on Wayne's #748 we need to update this list again.

Wayne and anyone else, if you read this, as you notate your machines distinctions, coud you please compare your findings to this "master" we have here and keep a list of your own. After you have completed your findings, could you post your list on our BB so i can then update this list. We should have a nice few distinctions to add, size=2]The more we can narrow down [/size]i feel certain.

[WHAT VIN THESE DISTINCTIONS OCCURED AT, THE BETTER CHANCE WE HAVE FOR MAKIN OUR MACHINES CORRECCT,

[Bickle]

Hi Steve, I think you should be referencing Wayne's bike as #576 ?
Steve

[Wayne]

I wondered that? Do we refer to our sandcast by the motor or frame number?

[Steve Swan]

Thanks, Steve ! Of course, #576.

I don't know there is a rule for referencing vins, if the topic has to do with the chassis, we've referred to frame vin, if topic is engine related, engine vin.

Generally it seems we refer to the frame vin, unless we are referring to a specific engine detail.

Usually, bikes are titled by frame vin. And of course, "the last sandcast" is E7414 whose frame vin is as yet unknown.

[rickhahn]

Steve I was checking out Early Production model distinctions
I would like to offer a little bit of info on No 41 on the list
Early lower frame steering damper gusseting 1-1266.
I have frame No1001588 with the gusseting and also frame
No 1001023 with no gusseting .
One can only wonder how this came to be.
Rick
 

[Steve Swan]

Great observation, Rick !

That bit of info is simply classic sandcast as far as adding to the non-sensical nature of there being no seeming rhyme nor reason to when these various distinctions  "started and stopped" vin-wise.

I would postulate Honda had a certain number of frames made up, some of the frames had steering damper gusseting and others did not, these 2 different frame types were available to the assembly line at the same time.  Would postulate whether or not the frame had steering damper gusseting made no difference to the purpose the frame was intended for.......  to be stamped with a vin and to have an engine installed on the assembly line to roll a motorccyle off the line into the distributor's  hands for delivery to the dealer for retail sale.  In other words, the gusseting had no impact on function and did not matter one way or the other, whether the gusseting was present or not.

I would still stick to the common belief the frames made earliest had the gusseting, as the higher the vins, was when the steering damper gusseting was no longer present.  Not aware of any of the earlier vins without the steering damper gusseting, but who knows.  Per rick's observation, i suppose we could say earlier vins means vins prior to 1023, unless someone finds an earlier frame vin than 1023 with no gusseting !!

Thanks, Rick, for sharing this very interesting observation you made !

PS - I have noted your observations on #'s 41 & 82.

[Nielsen]

Usefull info here ?

http://www.satanicmechanic.de/enginemods.shtml

I don`t know if we can believe it
Please use google translation from German.

[rickhahn]

Steve , I think I have found another variation , The oil drain plugs had a 12mm thread but the head size changed from 19mm to 17mm . I note that the part Number 92800-1200 does not change for  both the oil tank and the sump pan plugs.When Honda did this change one can only wonder.
In the owner's manual there is reference in using a 19mm spanner / wrench.
Rick       

[Steve Swan]

Rick noted a while back, the 12mm sump pan drain plugs, according to the owners manual, requires a 19mm wrench for removal.  And he notes the actual distance of these drain plugs, across the flats, is 17mm.  And the oil tank drain plug and the sump drain plug are the same part number.  (and same pn 92800-12000 throughout all sohc 750 parts manuals.) 

Page 38 of the 69.5 and the 69.7 Owner's Manuals BOTH instruct removal of drain pug, using a 19mm wrench.

Three questions arise.......  1.  Is the 19 a typo and intended to be 17 ?  2.  Was the early and/or late pre-production sump drain plug 19mm and Honda did not make the change in the Owner' Manual ?  3.  Are any early production drain plugs 19mm across the flats ?

Can anyone weigh in on this ?

[Steve Swan]

Mark Buettner had a great idea, to include ALL distinctions of ALL production sandcast machines. 

We now have 89 distinctions !