Agree with Mark and HT1 kid regarding the points and condenser.
Also, setting the timing with a DTI is very straight forward and Mark's instructions are very good.
 

hi all great info thanks, helped frame it in my mind a little better
dial gauge is:
imgur.com/a/6CzPcT2
i chose it as it has a 14mm adapter so it can fit straight into the spark plug hole but as i say trouble deciphering 1.8mm BTDC on it
points checker: online bike manual said black wire from points to + (red) on points checker, black (-) on points checker to earth on frame
shoud it be black with white stripe to (red) + on point checker as that is the wire goes to ignition coil?
i will upload a photo of my working method tomorrow
so: setting points opening,? I preume i losen off the points screw so its completely closed then the at 1.8mm BTDC i insert  feeler guage and set point to rcomended gap (ignition on off/kill switch wont have any bearing on the test?) with the advance locked up with probe, unsure about preload on dial guess that means some pressure from piston?
thanks again in adv
D


 

What bike are we talking DT1? can't use a dial gauge with the head 'on' as angled plug hole gives a false reading.

..sorry yeah a 76 DT175C USmodel

Do NOT gap the points with a feeler gauge!  Go lock the feeler gauges in a closet.  FEELER GAUGES ARE NOT USED AT ALL FOR SETTING TIMING!  You need to get the points to open at 1.8mm BTDC, that's it.  DONE with timing.  (Sorry to use caps but manuals and some of the posts here can be confusing).

(If, and this is usually not necessary, you want to check the point gap after setting the timing to make sure it is within the range given in the manual, then you rotate the engine until points are at their widest and use feeler gauges to make sure point gap in within range.  DO NOT adjust the gap again or you'll screw the timing up!)

Yes, there are some "quick and dirty" methods to set the points gap at some setting and timing "should be close enough to run".  But you've invested in the tools and you seem to have a strange problem going on so it's best to set timing properly in my opinion. 

Anyway, one wire from points checker to points wire and other to good ground.  Points wire might be black out of the stator but black/white at coil.  Do you have a black or black/white "loose wire" where stator harness plugs into main harness?  Should be on the stator harness side.  You might need to use that as some 175's had a diode in the wire.  Or reversing the meter leads should work. 

Nice dial gauge!  Metric even!  One revolution on the large dial is 1mm.  When the probe is traveling up towards the gauge, you count the black numbers 10, 20, etc. for tenths. If probe is traveling away from the gauge, like it is when piston is going down, you use the red numbers.

So after gauge is zeroed at TDC, you would slowly rotate the engine clockwise until the needle makes one full revolution and then almost another revolution to the red "80".  That's 1.8mm BTDC. 

Thats just about the best way of timing a 2T motor with a 14mm spark plug hole.

If new points are fitted, it's very simple to determine exactly when they open with a cigarette paper, as shown at 15.36 of this video:

The only difference from the video is the cigarette paper needs to be long enough, to protrude out of the point's adjusting hole on the flywheel.

This method of timing is faster than anything other than a strobe light, and the micrometer tool is pretty much all thats needed, other than feeler gauges to set the initial points gap, if they have been replaced.

That "Buzzetti" tool does not even accurately find TDC.  You need a dial indicator or degree wheel to find TDC or you are almost certainly off several degrees right there.  If your starting point is incorrect, then your timing is incorrect.  Those are just the facts.

And using cigarette paper or cellophane to detect point opening is better than trying to eyeball...  but again, not anywhere near as accurate as the Yamaha method of using a meter.  I have personally checked the difference and with the cigarette paper method you'll end up roughly 2 degrees advanced from where the points actually open.

Good stuff for a quick repair on the trails, but if you're going to invest money in tools to do it right, best to get the right tools.  Nothing is more accurate than a dial indicator and points checker.  Again, just facts. 

If someone doesn't want to get the correct tools, then RT325's method of gapping the points to get "close" is likely to get you just as close as using an inaccurate TDC starting point with vernier and cigarette paper. 

Digger65 is on the best path in my experience. 

I agree 1000% with MarkT dial indicator is simply the best and most accurate with point checker or buzz box and a light also works. It’s really not that hard especially since you have the right tools for the job 

Micrometer type timing tools are more than accurate enough for trail, trial, and MX bikes. Establishing TDC with any method other than a piston stop and degree disc, can never be wholly accurate, as there is always the possibility of observational error.

The main advantage of a micrometer tool over a DTI, is the simplicity of having a positive stop, which determines the exact piston position, in relation to timing advance in mm. There is no possibility of observational errors, and on motors where the timing is determined by the points gap, which might need to be turned to the firing point several times, the positive stop, makes things far easier!

Employing cigarette papers to determine points opening, is something which isn't quite as easy as using a micrometer timing tool, but once it's been tried a couple of times, is much easier than messing around with meters, and disconnecting wires, so meters can be used.

The micrometer timing tool can be used on any engine with a 14mm spark plug, but the cigarette paper points opening, can only be used when new points are fitted, or the originals have been very well cleaned.

Timing on these old engines is far from mission-critical anyway. The TY175 trials motors stock timing is 1.8mm (22 degrees), but they run a good deal better set to 28 degrees. The Rex TY175 dual map electronic system, has a 30 degree high rev setting.

Changing from points to electronic is probably the most effective bolt on alteration on one of these engines. I would guess timing scatter is something that these engines don't like much, which is eliminated when electronic ignition is fitted?

All of this is down to personal choice, though, and if you are familiar with using a DTI and meter, stick to that method.

Where'd we get too with this.
Here's what i'd do.
My dodgy plans change depending on the circumstances.
OK DT175 so has center plug head.
Good dial gauge you showed an image of.
1.8mm btdc. Points just moving at that as will be shown by the points checker [if that was you're meter i saw] or analogue ohms meter.
Did i forget hold it on advance if has "that" flywheel.
Then mark the flywheel to the case for next time.
Or if it has a pointer tab that "should" aligns with a notch in the flywheel window then tweak the pointer to make it align but shouldn't need much bending unless someones flattened it.
As i said--just what i'd do on this one.
In fact, a good way to get a close starting points for gap is to [with it set at 1.8] loosen the points screw & set the points just touching & then check forward an inch & back an inch over that opening/closing point while referring to your 1.8mm dial gauge mark or your 'now pointer tab' that you've set & you likely will hardly need to alter the point from there.
Trouble is they move a little while tightening the screw but practice makes perfect with slight tweaking & re-tightening, you'll get there.