Specs & info

[Glyn.G]

Hi all,
I keep seeing posts suggesting see sticky notes ( specs and info ) at the top of the page but I can't find it anywhere. I am trying to find the correct BTDC for setting the timing on my GT380 engine number GT380-74812 which I believe is the M model. If I set everything up according to the manual and line the mark on the end of the crank gear up with the steel pointer the BTDC is near to 4mm which must be wrong ( the manual says 3mm ) as when I put the clutch cover back on the L on the propeller is either way to the left or way to the right and impossible to line up to the mark on the casing. I have it set at the moment at 2.1mm BTDC but the mark on the gear and the pointer is half a tooth out yet the L on the propeller will line up perfectly with the casing mark. I know the BTDC was changed slightly between the different models but how. Did they just change the BTDC measurement without changing the position of the indication marks.
Regards,
Glyn.

[GTandcbr]

Third comment here
viewtopic.php?f=2&t=12542&p=161677&hilit=Btdc#p161677" onclick="window.open(this.href);return false;

[karl pa]

On my GT380B , I had the same problem with the marks not lining up, I first put it together on the advanced side of the tooth, but couldn't retard the timing enough, so I took it apart again and installed on the retarded side of the tooth. Using a dial gauge I was able to set correct timing, but there is not much adjustment available.

[Glyn.G]

Hi,
So let me see if I have this correct. The smaller the measurement used BTDC, ie I have my points just opening at 2.1mm BTDC rather than the 3mm quoted in the manual means I am running on the retarded side, which is better than going on the advanced side which can cause holed pistons, or have I got that the wrong way round ?

Regards,
Glyn.

[yeadon_m]

Yes, you have that correct!
Mike

[Glyn.G]

Hi,
Great that will do for me as the bike is running fine at 2.1mm BTDC.
Many Thanks,
Glyn.

[Craig380]

To add to the above, the marks on the propeller are not, and were never intended to be timing marks: they are assembly marks to make sure the points cam is set up in roughly the right place on the production line at the factory.

On some bikes, the marks will be quite close to the correct piston position (on mine they were fairly close), on others they'll be a long way out.

Best thing to do is set up the timing using a dial gauge to around 2.1 / 2.2mm BTDC, double-check, then scribe lines on the 3-legged propeller accordingly. Then you can just refer to the marks, to static-time the engine.

[Vintageman]

I am running on the retarded side, which is better than going on the advanced side which can cause holed pistons,

If you are not running factory timing on your stock or lightly modified bike, but running retarded it simply means you may be loosing significant power. The factory preferred timing has a specified +/- tolerance as well... to adjust to you riding preference. My 380 work well stock or a tad more advanced for aggressive street riding (redline +) or lower rpm torque (4K-5K RPM).