Enfield 50's 700 Twin vs 700 Trailblazer

[triplethreat3d]

Can anyone explain the difference between a T7 (1954)  series 700 cc twin and the later Trail Blazer SMP (1957) series production models? I realize the Trail Blazer models where to badged as Indians but would like to know how the engines compare and if there are any advantages of one versus the other in terms of parts.  considering  a project purchase and need all advice available. Both appear to be complete and on frames.
Thank you in advance to anyone who can help.

[Scottie J]

I'm restoring a 58 Trailblazer right now, and I believe the biggest difference is that in 57 the 700 twin introduced a new set up that allows you to replace the cams without having to disassemble the block.  Other than that, I think they're basically the same.  You might want to check out this post from Graham from last summer.  It really clarifies the differences between the different production years.

http://www.enfieldmotorcycles.com/forum/index.php?topic=14686.0

http://www.enfieldmotorcycles.com/forum/index.php?topic=14686.0

[ERC]

The early motor has a different crankshaft than the later years. Also a different oil filter set up and a Magdyno for charging. Parts wise your probably better off with the later one.  ERC

[rotorwrench]

The 54 models had different cylinder heads. If you look at a picture of one closely, you can see this. They still had a seperate oil filter from the oil pump/gear cover. They hadn't started using alternators yet in 54 so they were using a Lucas distributor/dyno set up. I think they were still using a smaller carburetor but it was still an Amal Monoblock. The small journal crankshaft were used up to 56. The con rods were not using bearing shells in 54. The crank changes made it possible to use replacement half shells.

Royal Enfield fielded a lot of newer changes on the USA market first so in many cases the Indian bikes recieved these changes before the home market UK ones did as far as production is concerned. The USA bikes tended to see some rough service here so RE was trying to beef up a twin that was originally designed as a 500cc so it needed a lot of beefing up as a 700cc (692cc) especially under harder service conditions.