1975 Suzuki GT185 timing problems

[enriquev9]

Hello gents!!!!

I have a 1975 Suzuki GT185 that I have been restoring. Recently I went about setting the timing and I think I have a problem. Here is what I did.

1. I used a timing gauge to set the gap with the cylinder at 1.83 MM before TDC as instructed in the service manual. This measurement is pretty much dead on with the lines on the points cam and generator

2. I used a timing light to confirm the timing. I found that I had to fully retard the left hand cylinder to get the timing marks to line up. I also had to fully retard the right side, but the timing marks don’t line up with the timing light.

I already had to rebuild the top end because the right side cylinder was fried when I checked the compression and opened up the cylinders.

My question is….
What is causing me to have to retard the timing so much?
Why can’t I get the right cylinder to time correctly?
Should I replace condensers and coils to help with timing?

Any help would be appreciated so I don’t burn up another piston.

[karl pa]

1. I used a timing gauge to set the gap with the cylinder at 1.83 MM before TDC as instructed in the service manual. This measurement is pretty much dead on with the lines on the points cam and generator

When you say this, do you mean you set the point gap at the marks, or did you set the points to begin opening at the mark? The mark is when points begin to open. Is the point gap set around .014 in (.35mm) gap? Are they new points? and are they aftermarket? Aftermarket points can have different cam heels which can cause this type issue.
I don't believe condenser or coils will affect this issue.

[enriquev9]

I used a timing gauge to find top dead center then rotated the crank clockwise until the gauge read 1.83 MM below to dead center. At that setting, the cam marks lined up with the timing mark on the generator. Finally I set the points gap at that position to .35 MM.

That procedure was from the service manual I accessed. Do you think I interpreted or did the timing procedure incorrectly?

They are new aftermarket points. I did notice that the cam heels in the previous set of points were different from each other. Hence my reason for buying new point so the heels would match. I had the same problem with the old set of points and was hoping this new set would be easier to time.

I have a funny feeling that the issue is the points cam also. If the PO Frankensteined a set of points….who knows what else was changed and what was pieced together. Are there any measurements I can take to verify I have the correct points cam?

[joethebike]

On my T350 and all other points equipped bikes I have owned the procedure is to rotate the engine until the rubbing heel of the points is on the highest part of the cam and then the points are set to the correct gap with the points gap screw. The timing is then set by rotating the engine to the timing mark at which time the points just begin to open. Adjustment is made by loosening the points mounting plate screws so the points just start to open at the timing mark.

[karl pa]

Do you think I interpreted or did the timing procedure incorrectly?

Yes, when the marks line up is when the points begin to open not be at full gap.

[jabcb]

The GT185 owner’s manual & service manual are here: https://www.oldjapanesebikes.com/mraxl_ ... /index.php

Page 37 of the owner’s manual has instructions for setting the timing.

Page 49 of the service manual also provide instructions. But those instructions are different & more complicated.

You confirmed that the timing marks on the generator are good. Use those marks & follow the instructions in the owner’s manual.

I use a multimeter to determine when the points open — set to resistance. It’s a good idea to disconnect the battery whenever measuring resistance with a multimeter.


In the typical language of an old geezer in the US, whoever wrote the service manual instructions could use whacked up side the head.

[karl pa]

. I used a timing gauge to set the gap with the cylinder at 1.83 MM before TDC as instructed in the service manual. This measurement is pretty much dead on with the lines on the points cam and generator

If your marks are dead on, I would just use the timing light to set the timing.
But you should set point gap at highest cam position as stated, before setting timing.
As for burning top end, could it be caused by lean fuel mixture rather than ignition?

[enriquev9]

Thank you for the help.

Looks like I have to go back and readjust the timing with your suggestions.

I’ll report back on the results.

[Alan H]

Basically, set the points gap at maximum cam/points opening, then set points actual opening at the 'marks on the indicator'. Never fails, and all my bikes on points are set like this.
NEVER turn engine in reverse direction.

[enriquev9]

I’m happy to report that I set the points gap at the highest point of the cam for each side individually, then timed the points just as they open using my gauge and marks on the generator. At the end I started her up, checked timing with a timing light, massaged the timing slightly with the light and BAM!!!! Now the bike is running smooth and with great power.