Any tech heads out there ??

[michael king]

Hi Sparkys.I have a need for knowledge regarding a yamaha tdm 850.i have just done an engine swap like for like so i can rebuild the old engine,then re-install it later this year,it has normal 3phaze alternator and regulator/rectifier box.The 3pin connector where you unplug the alternator from the loom had been getting hot unbeknown to me,suspect dry soldered joints as the bikes 1993 model.it got so hot its partially melted the plug in connector.As its a sealed unit i decided to re-do the connections with 15A 'chock strip' type screw connectors then tuck them away in a IP rated enclosure,i marked the 3 cables so i knew which paired with which,And i meant to take a photograph so that when i replace the old engine i know which of the 3 cables goes with which,but like a clot in my enthusiasm to crack-on i forgot to take a pic !! dooohh !!,i have them paired up correctly in chock strip and it now runs cool to the touch but when i put the old engine back in i wont know which was th top one and which was bottom left&right...Question is does it matter which way round the 3 phases are connected to the reg/rectifier or will it still generate fine which everway round ( fingers crossed ) but if it will only work connected in a specific way how can i find which order to connect them in.I'm an ex-armature winder ( but not since 1980's) so have good general knowledge..Any help at all very much appreciated in advance.
Kind regards.
Mike.

 

[TJ Anderson]

Hi

Its fine, the polarity of the 3 phase alternator (AC) won't affect the output polarity from the regulator / rectifier (DC). So it won't make any difference which way round the 3 wires from the alternator are. Simple 3 wire 3 phase in and 2 wire DC out. The pick up is on a seperate connector so can ignore that. Interesting engines on the TRX/TDM's, parralel twins but they sound like v twins cause of the 270 deg firing order. Always liked the TRX better out the two

 

[michael king]

Hi TJ,you clearly know your ---- Many thanks very much for that,,what a relief ! ..they are a great engine aren't they Yamaha recon its the best they ever built with its 10 valve and dry sump.i have the earlier 360crank version (sounds like an old bonneville or xs650 ),the 270 was used from 96 onwards which they poached from the trx launched in 95 in Japan.If im honest i also prefer the trx out of the two bikes but the race crouch and short travel suspension make it uncumfy for long distance on me old bones nowadays.I can now ride worry free thanks to you pal.
Thank you again.
Kind regards.
Michael.

 

[Marti]

Both brilliant machines! My 1999 VFR800 went in for a MOT this morning ready to be moved on for something lighter and more manoeuvrable and a TDM could just fit the bill.

 

[michael king]

Hi Marti.The tdm is only 8k lighter but yes its way more manoeuvrable for sure.For me its bike number 57 on the road since 1978 and i can honestly say its the cumfyest bike ive ever ridden.I'd defo recommend a test ride at least.
Ride safe pal.
Regards.
Michael.

 

[TJ Anderson]

Hi TJ,you clearly know your **** Many thanks very much for that,,what a relief ! ..they are a great engine aren't they Yamaha recon its the best they ever built with its 10 valve and dry sump.i have the earlier 360crank version (sounds like an old bonneville or xs650 ),the 270 was used from 96 onwards which they poached from the trx launched in 95 in Japan.If im honest i also prefer the trx out of the two bikes but the race crouch and short travel suspension make it uncumfy for long distance on me old bones nowadays.I can now ride worry free thanks to you pal.
Thank you again.
Kind regards.
Michael.

No worries mate, keep safe out there and stay shiny side up!

Also.....I've learned something too....I didn't know the earlier TDM'S were 360 crank.

 

[TJ Anderson]

Both brilliant machines! My 1999 VFR800 went in for a MOT this morning ready to be moved on for something lighter and more manoeuvrable and a TDM could just fit the bill.

That's a wonderful engine in the 800fi. Sounds great with gear driven cams. I much prefer it to the VTEC that followed it.

 

[Marti]

Easily the best bike I've owned although I have a thing for Yamahas. They always came up with the original thinking solution. The TDM, the Majesty and X-Max scooters. Even the XZ550 if you can go back that far.