TY 175 Flywheel and points questions

[Tee-Why]

Hi, my turn to ask some questions about the TY175 to those who may may be be able to help:
Due to poor spark, and checked the gap ok, I need to get at the points. I have downloaded the Yamaha manual and read up about this area.

Flywheel puller - what is the diameter and thread for the puller? Flywheel nut is RH thread I take it? Clutch basket nut LH thread (for interest)?

Contact Points - apart from the Yamaha part number, is there a generic Bosch or Hitachi part number that is an equivalent?

Any tips here for setting the timing?

I measured the points opening and closing with a multimeter, can only see it as AC voltage, correct? (Black wire - to casing)

- Roger B

[David Lahey]

Hi, my turn to ask some questions about the TY175 to those who may may be be able to help:
Due to poor spark, and checked the gap ok, I need to get at the points. I have downloaded the Yamaha manual and read up about this area.

Flywheel puller - what is the diameter and thread for the puller? Flywheel nut is RH thread I take it? Clutch basket nut LH thread (for interest)?

Flywheel nut thread RH
Flywheel puller thread LH 27mm x 1.0mm
Clutch basket thread RH

Contact Points - apart from the Yamaha part number, is there a generic Bosch or Hitachi part number that is an equivalent?

No idea. Whats wrong with Yamaha points?

Any tips here for setting the timing?

Set the piston at the recommended amount BTDC measured through the sparkplug hole and make an easily visible mark on the flywheel in line with the top front cover screw hole.

Clean the points and set them to the Yamaha recommended gap.

Run the motor with the flywheel cover off and use a timing light. Change the points gap until the timing is right. Closing the gap moves the timing closer to TDC.

When you get the timing right, measure the points gap. If it is less than 75% of what Yamaha says, fit new points.

I measured the points opening and closing with a multimeter, can only see it as AC voltage, correct? (Black wire - to casing)

Use the resistance setting on your multimeter to see where the points open with the motor stopped. A 12V light bulb powered by a battery is better than a multimeter as you can see it change brightness out of the corner of your eye better than you can see a multimeter change.

- Roger B

Roger my answers are in your text

Your weak spark may be due to other causes such as:
Failing condenser
Failing plug cap
Failing stator
Failing HT coil
Poor connection frame to HT coil
Poor connection frame to motor
Shorting killswitch or ignition wiring
Dirty connections in ignition wiring

Regards
David

[Tee-Why]

Thanks David, very helpful.

I have found a internal flywheel puller earlier today at 27mm. I thought mine was 25mm so I looked it over. Will get that item now.

I probably will get the Yamaha points, its just that the next nearest decent Yamaha dealer is nearly 3/4 hour away. The local one is crap and doesnt really want anything to do with 30y.o. bikes.
I just thought with an auto parts dealer it would be easier to get.

Actually I did that already with the flywheel mark, used a vernier to measure the 1.8mm and scribed a mark, but due to not running went no further.

My multimeter is digital, and on resistance was giving me some odd readings, so I changed to volts. Do suspect something wrong.
I might have to dig out the old moving iron meter.

I will have the opportunity to catch up with another TY175 owner to swap a few parts around and see what is the problem.
Cheers, Roger