Members Rides

my first bike

Members Rides

NField Gear

47 Guests, 3 Users
voodoochild, Ice, kodai
Welcome, Guest. Please login or register.
Did you miss your activation email?
May 24, 2016, 10:27:05 pm

Login with username, password and session length


Author Topic: Understanding Parts Catalogue: Royal Enfields  (Read 1239 times)


  • Neophyte
  • *
  • Posts: 3
  • Karma: 0
Understanding Parts Catalogue: Royal Enfields
« on: April 21, 2013, 04:18:37 am »
I am from india.
I am having a Machismo A350 2000 model with AVL engine. While going through parts catalogues, I came in some confusion about Part Numbers.  Some examples are as under (catalogues pares are attached):

Stud tappet cover (Metric)   145119/a(A 350)   145119/a (350 & 500)
Tappet cover         814010   (A 350)      814010 (350 & 500)
Tappet cover gasket      500430   (A 350)      500333/b (350), 510253/b (500)
Decompressor shaft      500500   (A 350)      500335/a (350), 500500/f (500)
Decompressor lever      500503   (A 350)      500503/b (350 & 500)
Cam assembly Exhaust      500429   (A 350)      500429/e (350 & 500)
Cam assembly inlet      500428   (A 350)      500428/e (350 & 500)
Oil filter element      500613   (A 350)      500613/a (350 & 500)

What is the concept of this “a”, “b”, “c”, “d”, “e” etc in part number?

When ‘Tappet cover’ & ‘stud’ is same, how the ‘Tappet cover gasket’ & ‘Decompressor shaft ‘ are different for A350, 350 & 500?

Is the oil filter element can be fit to each other?

Besides the bore-piston & crank shaft assembly the tappet cover, decompressor shaft, decompressor lever are also a rare part for AVL engines (because they are quite cheap as and dealers are not interested to stock these 30-50 Rs parts.). I have seen many machismos with CI tappet cover, they have either lost the decompression function or converted like CI with hole in cylinder head. 

Presently the parts are only available with new parts numbers like a, b, c etc and dealers says that there is no problem with these a, b, c.

Can anyone explain the mystery?

AVL engine Model details in brief are as follows for india:
Machismo A 350 Model: Year 2000 to 2003 with CDI ignition system & spacco carburetor
Machismo 350: Year 2004-2009 with TCI ignition system & BS26 series carburetor
Machismo 500: Year 2007-2009 with TCI ignition system & BS29 series carburetor


  • Grand Gearhead
  • *****
  • Posts: 5,792
  • Karma: 2
  • "But it's a dry heat here in Arizona
Re: Understanding Parts Catalogue: Royal Enfields
« Reply #1 on: April 21, 2013, 01:53:31 pm »
I cannot speak for how Royal Enfield sets up their part numbers but here are a few rules the jet engine company I worked at (before retiring) did it.

For any part, it started out as a "no change" design.
As time passed there were occasional changes made to the drawing and each change received its own change letter starting with "A".
None of the changes allowed for this type of revision could effect the interchangeability with the original design.
These changes could be something as simple as rewording a drawing note to adding a view to clarify the drawing.  Tolerances on dimensions could be change as well as long as the change did not effect interchangeability or function.  This was often done to improve manufacturing methods or reduce the parts cost.

Because a "change letter" type revision did not effect interchangeability we (as a company) did not include the letter in our part number.
Other companies do sometimes include the change letter in their part number and I believe that this explains the presence of the "a", "b", etc you are seeing.
It also explains why your dealer said the part could be used to replace the part number with the lower letter with the same part number with a higher letter.

If the proposed change did effect interchangeability or function, a new drawing and new part number was required.  The next higher assembly drawing would also be changed to reflect this new part number.
Likewise, the Maintenance manuals would require revision to reflect the new part number.
This assured that design improvements such as fit, durability and reliability would be incorporated into the future engine or sub-system assembly.

2011 G5 Deluxe
1999 Miata 10th Anniversary