82 GS400 8 valve, poor running/excessive blow by

[John Park]

So I've got the engine bolted in, trying to fit my tach cable and it just won't go it.are the tach cables different between the 400 and the 450?

Not that I recall. They're all a square peg in a square hole, so taking the cable off the tach and turning the inner while you shove it in may help. The big difference is that the 4 valve has the tach in the cover above the cam and the 450 is below; both have their quirks. The hole may be plugged with crud from falling over in the dirt.

Looks like that motor got seriously drooled on by a leaking petcock, but you'll have all winter to polish it up. Usually the valves will have tightened up and It Would be Advised to get the valve cover off and check the clearances before you go too far too fast. GS500 shims are identical and the zip tie method of swapping them is just so cool. There are two types of 450 valve covers with different gaskets so make sure you buy the right [later?] one.

When you discover a [probable] mid range surge, pull the carb slides out and juggle the circlip and two plastic spacers to move the needle up. I measure the projection [about 36mm] of the needle Before pulling the clips so you have a reference point and I think one whole clip slot is 2mm but you can juggle things to just go up one mm at a time. I think the 450 just sucks the slides up sooner than the 400 which makes sense. The 400 carbs will work fine on the 450 with just a needle adjustment and the mixture screws about 2 turns and a bit out.