Boyd and Stelling.

[firko]

Doc (and anyone else interested) I found the following reference to the TS400 full circle crank. The plot thickens:
"I remachined the taper on the full circle TS400 crank to accept a modern KX500 ignition that would fit under the RM370 mag cover bolted to a flat adapter plate, plus it has a small external flywheel, so yes more flywheel effect than the original rotar. The TS400 crank although not any heavier than the later TM cranks, does have a bit more effective flywheel weight because of its shape. The cylinder head is also a TS400 item, with the very outside fins cut off, and the remaining fins reprofiled on a CNC mill to mimic the works bike. The autolube pump area was trimmed back and welded up to make the cases look trimmer." from this guys photo story on building an RN400 "Replica" http://100megsfree3.com/ahrmanw/Machines.htm

[Doc]

I for one would really like to see this mythical full circle TS or TM crank exposed Firko. It's causing me sleepless nights! The TS crank 'may' have a slightly different shape but it's still a bobweight style and not full circle. Will email J.P.Morgan in the hope of getting more specific details but somehow I have a gut feeling there will be no conclusive answers forthcoming. Someone somewhere has to have had a full circle crank in their TM400 at some time maybe yes, but I'm near 100% certain the crank did not come from any TS400 I'd love to be proven wrong by the actual facts but they're hard to verify without any physical evidence presented  I shall once again put the question out there in the yahoo forum as there seems to be more 400 owners in the US these days. Some kind of fascination with untamed beasts is driving the resurgence in numbers is my guess

[firko]

The bike that supposedly has the above full circle crank with KX500 ignition is in itself a pretty nice bit of kit. The bloke has taken a humble TM400 and built as close a replica RN as you'd find without using hardly any real RN parts. I especially like the tank. In the story he states that he had a hard time finding a stock RN rear fender. I've got one on my TM/TS 250 but it's pretty shagged. I'd like to fit transluscent (opaque) white RN/RN mudguards to the B&S in my own humble attempt at getting the RN look happening with the bike. Does anybody make them similar to the TM or RN/RH style?

[Doc]

The translucient TM style fronts you can still find NOS via ebay. A lot of the coloured TS/TM guards listed on ebay in Thailand are painted but underneath is translucient. Worth checking out. The rears are harder to come by and I doubt you find a suzuki replica. Might have to use something from yamaha or such. Incidently after posing the question, a guy (George) in the US has not 1 but 2 full circle TS400 cranks, 1 definately came from a verified '75 TS400 motor (engine number was supplied so I double checked) and the other is unknown. Bought both off eBay for not a lot of coin. I've asked for a photo if possible so we can see what this mythical part looks like. Wait and see but it does appear they are real regardless of my doubts.

[facthunt]

Here is a full circle crank pulled from an L or M TS400. The plugs are non standard.

[facthunt]

This should show the relevant art numbers.

[firko]

Well there you go. The beauty of this old bike thing is that there's something to learn all the time. I get a tad annoyed when people expect me to be Mr Know-it-All about Maicos because even after owning at least 30 of the buggers over a 38 year period, I'm still learning stuff about them and I'm a long way from knowing all of the answers. I really respect Docs knowledge and love of Hamamatsu products but this goes to show that he's in the same boat as me. I guess we never stop learning.
According to Bob, the guy I bought the B&S from, this crank is the major component in civilising the TM400 engine. The engine that was in my B&S that he kept had this crank and DT400 Yamaha ignition along with lots of other little tricks that were more for smoothing the engine and giving it a predictable torque curve rather than ball crushing performance. That's what I want as my days of riding fire breathing monsters are long gone. My bloody Jag frightens me enough let alone a 50hp TM Suzuki. If anyone happens to have a spare full circle TS Suzuki 400 M or L crank they'd like to sell, I'll gladly take it off your hands.

[Doc]

yeah thanks for the photo Facthunt! like Firko I have learnt something new too and not about to argue/question a proven fact. Problem I still have trouble getting my head around is I have the A model , I have had an M model and I've also have the TM400 bottom ends and yet not one of these motors had the full circle when in fact, going by the year model designations in the parts books they should have all had it (except TM). How can some have it and some not?? The parts book lists the L, M and A models as having a differing part number but there is no matching diagram or reference that it is indeed a full circle design. The 'fact' is now proven they do exist but another fact is I am still yet to find one in any TS400 motor I have ever pulled down or witnessed pulled down. My TS400A is virginal when it comes to the centre cases being split, it's simply never happened or there'd be some type of tool or telltale marks on the bolts and fasteners etc..she's definately got the bob weight crank though and this is confusing the shite outa me..it seems a little at random that these cranks were utilized..I obviously just haven't been lucky enough to jag one yet  I don't particularly want a full circle crank as my TS400 rarely gets ridden but the mystery stems from the fact I had never seen one in motors I've pulled down.

[mx250]

How can some have it and some not??

Welcome to the real world Doc .

Its not the first time I've come across this sort of discrepence on Jap bikes. The Japs won't beyond changing spec mid model without telling. Some models, either early or late in the production run, I don't know, would include parts from the next or last model.

I haven't seen such a big variation before but I've seen shouldered spokes, plastic cap rather than alloy cap etc, and other detailed differences.