Timing

[Virago85]

On my 77 1750 175 it say in order to set timing there is three punch marks for my primary timing on the flywheel and two punch marks for my wot and not to use the two punch marks instead you have to put an aditional mark on the flywheel doing something with a dail indicater if it hasnt been done my ? is i beleive it has been done I have a mark on my fly wheel about a half inch to the right of the two punch marks has anyone ever done this and does a half inch to the right sound right pls pls help

 

[Virago85]

Re: Timing

Onther ? on my tach I have pole setings for 1,2,3,4,5,6, depending on how many pulse's my motor sends out any idea what mine should be set on

 

[Virago85]

Re: Timing

come on guys help me out

 

[Clams Canino]

Re: Timing

I think they're waiting for a translator. <br /><br />-W

 

[Virago85]

Re: Timing

Ok if theres something Im asking that your not understanding pls let me know and I will answer the best I can I realy could use some help here

 

[rodbolt]

Re: Timing

hello<br /> the punch marks are for timing. on some motors there was a timing change. merc used the dialindicator method for years to correctly set the pointer at TDC and at the spec for WOT advance. it can be done with a TDC indicate and a cloth tape and a bit of math. 360* divided by the circumference will give how mwnay degrees are in each inch. so now the first thing is to insure that the TDC tab is actally correct by using a dial indicator to properly find TDC. make a mark at .05" BTDC and .05 ATDC on the flywheel. slit the difference in half and make a third mark. that is now TDC. your dial indicator should read 0 when you bring it upnow. look at the tab and adjust it as nessasary. then moving the flywheel sounter clockwise the prescribed amout look at the tab pointer and see if its inline with the proper punch marks. this jives the refernce points to actually test it with a timing light. timing aint voodoo nor hoodoo nor even black magic. its a mechanical interface that allows the spark to occur at the position of the piston either before or after top dead center. at least on a two stroke you dont have to contend with an exhaust stroke you have a 12 pole altenator that willset at the 12pole or 6 pulse setting. Ihope your tach has a tag on it.<br />any other questions ?

 

[Virago85]

Re: Timing

Ok Ty for your time I do not have a pointer are even a place for one in the manual it states to use the opening in the cowel and that the reason for the dail indicater is to find where 15 degress is on the fly wheel it says to bring the f/w to tdc then set the dail indecater to 0 turn the motor clockwise untill you reach 100 on dail indicater then turn counter clockwise tell you reach 69 on indicater now with the opening in the cowel put a mark on the flywheel this will be your 15 degree mark for wot my ? is I dont have a dail indicater but i have a make on my flywheel to the left of the two punch marks I beleive the mod has been done but was hoping for some in site again thanks for your time

 

[rodbolt]

Re: Timing

in that little window on the flywheel cover should be an arrow. you can get within a few degrees using a screwdriver and find tdc. after that use the math to find if the flywheel is marked correctly. dont just guess or you may find what detonated pistons look like in real life.

 

[Virago85]

Re: Timing

I have tdc but not sure about how to do the math to find 15 degress thanks again for all your help

 

[Virago85]

Re: Timing

Can some one help me with the math on this

 

[Moody Blue]

Re: Timing

Using a piece of string measure the circumference of the flywheel as accurately as possible. Record this number. Alternatively, accuratley measure the diameter and multiply x 3.1415 to find the circumference. Use the following equation.<br /><br />circumference x (15*/360) = distance on circumference<br /><br />example: flywheel is 8" diameter<br />-> circumference is 25.132"<br />-> 25.132 x 0.04166 = 1.047"<br />This is the distance along the flywheel circumference that is equivalent to 15*<br /><br />Now I have a question. How can you determine TDC ?

 

[Virago85]

Re: Timing

There is a scibe on the fly wheel And when I bring the # 1 up to where it rocks the scribe lines up with notch in window

 

[rodbolt]

Re: Timing

I use a cloth sewing tape on some of the old motors. its accurate enough. if you measure the dia make sure you measure just the part that the marks are on and dont include any ledges for a rope start. either way is fine.most old motors dont have reliable marks or they are missing. and I need tooccasionally find the advance point of other cylinders(indexing)

 

[Virago85]

Re: Timing

so use a cloth sewing tape to measure around the flywheel from tdc to tdc and then measure across for dia

 

[Virago85]

Re: Timing

ok heres what I have dia' meashureing strait across flywheel i got 8&11/16 inch which is 22 cm going around flywheel i got 27& 3/8 inch which is 69.5 cm where do i go from here is this the measurement i need

 

[Virago85]

Re: Timing

so I guess 27.3/8 circumference would = 27.362<br />the dia is 8.11/16 which is 8.7 inch <br /><br />so 8.7 multiplied x 3.1415 = 27.33105 circumference<br /><br />27.331 x 0.04166 = 1.13860946<br /><br />1.138 is my 15 degress which would be 2.9 cm is this right

 

[Virago85]

Re: Timing

ok if these measurments are correct my 15 degress should be 1.138 inch or 2.9 cm <br />my mark is at 1.260 inch or 3.2 cm would you say its safe to say the mark is right

 

[Virago85]

Re: Timing

I guess at the most it would be is almost 1.5 degress off right

 

[Motor Boater Bill]

Re: Timing

Now divide your circumferance (27 3/8, or 27.375) by 360, and that is how many inches equals one degree of rotation. Then you can measure to how many degrees before or after TDC you wish.<br /><br />27.375 divided by 360 = .076<br /><br />To get 15 degrees BTDC multiply .076 x 15 which equals 1.14 inches.

 

[Virago85]

Re: Timing

so bacicly 0.2 cm is 1 degree so would you think I would be save if my timing was 1and ahalf degres high not sure if it is are not dependeing if i done every thing right