277 rephase ignition details

Dustmeoff

XS650 New Member
Messages
4
Reaction score
0
Points
1
Location
Pittsburgh, Pennsylvania
I'm about to buy a 1975 xs650 and I plan to rephase the engine soon after. I've read all about the different ignition solutions and I have these questions.

If I stick with points for 277, is there enough space between the dual points to shift one 41.5 degrees? If not, that means the points solution is to run single point and a dual lobe ignition cam. That would give one wasted spark halfway through one intake stroke. Will this backfire? Harley has apparently done it with their older bikes which are effectively a 278 phase engine.

Second question - has anyone drilled the alternator rotor on a tci bike to add a magnet? I read a service manual for the tci system that said it references the time delay between the magnet passing the first and second trigger coils to determine advance. this makes me think that if there was enough dwell, you could add a magnet to the rotor and keep the fatory timing curve with a wasted spark setup.

Last question. I have a wr450 which uses a 12v powered cdi ignition with an advance curve very similar to the xs650. Has anyone heard of using the wr ignition module and pickup with a steel ring on the crankshaft? Either one ignition unit with 2 steel teeth on the rotor and run a wasted spark ; or two ignition units/2 coils/ 2 pickups/ 1 crankshaft tooth with stock wr advance curve.

Mike
 
Welcome. It sounds like you have done a great deal of research before posting this series of questions. I just finished a rephased engine and I am currently working to diagnosis a timing and ignition issue which caused the engine to fire ever so slightly to early. Based on my experience, I would not attempt to make my own ignition system. The precision of the placement of the triggers and the pick ups is much to complicated to replicate. I'm not saying that it cannot be done, but I suspect that 50% of the reason to purchase the bike and spend the energy to rephased it is in order to enjoy riding it. Building your own set up would keep it on the table being diagnosed with problems during the short Penn. riding season. You didn't mention if you were going to perform the rephase of the crank yourself or outsource the work. The decision to rephase the engine means you are not afraid of taking on a project. If you simply want a project, I would encourage you to take on the rephasing of the crank and cam yourself and simply buy a pamco ignition when the time comes. If you must go at it and do the entire ignition yourself, I suspect that most of your questions will have to be answered through trial and error because not very many people have put themselves to to this task.

Jon
 
Hi Dustmeoff been there done that when I rephrased mine couldn't afford a Pamco so rephrased the points by the time I'd got it right I had turned the motor over that many times it was all-ready run in.One set points has to be moved to a place its not suspose to be, setting that set of points was trail & luck, Pamco or simular only way to go, good luck with it
 
I agree with TonyC. Mr. Riggs came up with the best home grown re-phase ignition yet. I wish he would make a run of reluctors. It's the only part I have no clue how to make. I would buy a couple for future projects.
 
I messed with a WR ignition. It does work except the flywheel weight ends up being to light for the XS. Other than that I can tell you exactly what to do......here goes.

Don't rephrase your motor. No horsepower or true performance is gained. Sound and vibration do change but at a cost. The vibration is turned inward and strains the internals more, so to speak.
 
I'm about to buy a 1975 xs650 and I plan to rephase the engine soon after. I've read all about the different ignition solutions and I have these questions.

If I stick with points for 277, is there enough space between the dual points to shift one 41.5 degrees? If not, that means the points solution is to run single point and a dual lobe ignition cam. That would give one wasted spark halfway through one intake stroke. Will this backfire? Harley has apparently done it with their older bikes which are effectively a 278 phase engine.

Second question - has anyone drilled the alternator rotor on a tci bike to add a magnet? I read a service manual for the tci system that said it references the time delay between the magnet passing the first and second trigger coils to determine advance. this makes me think that if there was enough dwell, you could add a magnet to the rotor and keep the fatory timing curve with a wasted spark setup.

Last question. I have a wr450 which uses a 12v powered cdi ignition with an advance curve very similar to the xs650. Has anyone heard of using the wr ignition module and pickup with a steel ring on the crankshaft? Either one ignition unit with 2 steel teeth on the rotor and run a wasted spark ; or two ignition units/2 coils/ 2 pickups/ 1 crankshaft tooth with stock wr advance curve.

Mike

here you go on the 277 points conversion
http://www.650motorcycles.com/277ign.html
 
that's exactly what i was looking for, thank you.

I picked up the bike last weekend and i realize i have a whole list of things to fix before i can even consider starting the rephase. I want to get to a running fully functional bike before cracking the engine open.
 
Back
Top