Need clarification on GS450 timing TDC piston location

[Gorminrider]

not paying close attention, but In case it helps, This is from the HAYNES manual. Specifically for the 450. (the Haynes is more for GSX but has addendum for the 80's 450s. Might be clearer than your Clymer...

use browser's "Right-click, save as..." and zoom into the downloaded jpg to better see the crank's timing marks shown lower right


GS450CamTiming.jpg

[OldTwin]

I beg to differ on the correct piston to be at TDC when timing marks are properly aligned. With RH timing mark aligned to the index mark, RH piston is at TDC and cams are properly timed with both valves closed, and rotor magnet is aligned with RH sig gen module in order to fire the coil...CW rotation of the crank from that point actuates the ex valve next as would be expected. Let's not overcomplicate this.

I also question if the PO may have swapped out the timing rotor from a different motor? My comment regarding 360 vs 180 degrees was to clarify that intake valves beginning to open indicates TDC at the start of the intake stroke vs TDC at the start of the power stroke...360 degree difference.

[John Park]

I beg to differ on the correct piston to be at TDC when timing marks are properly aligned. With RH timing mark aligned to the index mark, RH piston is at TDC and cams are properly timed with both valves closed, and rotor magnet is aligned with RH sig gen module in order to fire the coil...CW rotation of the crank from that point actuates the ex valve next as would be expected. Let's not overcomplicate this.

I also question if the PO may have swapped out the timing rotor from a different motor? My comment regarding 360 vs 180 degrees was to clarify that intake valves beginning to open indicates TDC at the start of the intake stroke vs TDC at the start of the power stroke...360 degree difference.

Regardless of which piston gets first billing, the RH one is at TDC when the cams are installed. Using the LH one at TDC would put you 180 out.

At this point I'd also wonder if the pin is in the end of the crank for the rotor alignment. I think they're pressed in, but that was thirty odd years ago.

[Nessism]

I've deleted all my posts out of this thread except for this one of course. There are too many cooks in this kitchen and it's frustrating by the lack of a proper Suzuki factory service manual.

Any time I've installed the cams on a GS 4 cylinder engine I always begin the process by putting the #1 cylinder (the left most) at TDC. I have no idea if Suzuki specifies putting #2 at TDC for the twins though since again, I don't have the proper manual.


Good luck to the OP. Hope you get it figured out.

[sacruickshank]

OP here.

Thanks to all for the insight on this confusing topic. The clymer manual definitely states TDC for the right hand piston, the position for the 1 indicator on the exhaust cam shaft, the grooves on the ends of the cam shafts, and the # of pins between the 2 and 3 marks. It falls apart on clearly locating the signal generator for my bike ('83 45).

Fortunately, the '83 450 shares many same parts as the later GS500E's, including the aforementioned confusing signal generator. Some additional searching yielded this seemingly definitive answer from the gstwins forum. Hope that's not bad form to paste in a link to another forum.

http://gstwins.com/gsboard/index.php?topic=52765.0

[OldTwin]

Hmm, so if your rotor timing marks are really intended to align to the sig gen modules (per GS500 procedure) with RH piston at TDC and cams properly indexed, you should be okay, no? Could be your Clymer manual is in error, would be worth your while to acquire the Suzuki manual to confirm the correct procedure.

[OldTwin]

Here's a shot of my Clymer timing procedure for reference, particularly figure 22...you can see the start point is alignment of the RH T mark with the index mark in the casting... curious to know exactly what your manual says.

WIN_20170125_20_20_38_Pro.jpg

[recycled64]

http://www.ebay.com/itm/1980-88-SUZU...tWesP5&vxp=mtr Hope this helps-

[sacruickshank]

I have the same manual, albeit downloaded from BikeCliff's website. For the GS450 they reference fig 24, which is difficult to read.

I'm all set at this point based on the info from the gstwins forum I posted earlier.

Thanks again.