engine mount nut won't go in nut shaped groove

So I have my kz650 engine mostly mounted but the nuts that in the front mount that Go into the nut shaped grove won't go in. I have the engine in the garage so it's really cold outside and I'm thinking the aluminum shrunk so much that the nut won't fit now? I had bagged up everything before so I could keep it organized but these Damn nuts aren't going in. Strange. I tried finding a pic but I can't. And my phone is messed up.

Most likely you have the wrong nuts.

Some 650s use a single long threaded rod for the front mounts, and some use the two separate bolts (approx. 4" long) and nuts.
The head of the bolt fits into the engine casting, coming from the center out, so you can install a nut from the outside.
Sounds like this is where you are having trouble, that the head of the bolt is not fitting the casting in the engine?

Maybe you are installing the bolts backwards, from the outside, and trying to put the nuts in the center/inside?
Install the bolts so the nuts are on the outside/left and right side of the engine.

2 short bolts on the front top mounting??? Isn't that supposed to be 1 long bolt?

The B1 has 1 long bolt; the C1 has 2 shorter bolts. Strange but true. LOL Ed

Both my B and D have two bolts at the upper front,(triangle plate). The heads on them index into a recess in the case. They run from the inside out with the nut on the outside. They're 10mm x 1.25mm pitch, to fit with case savers one is 65mm, the other is 95mm long.

rstnick wrote: Some 650s use a single long threaded rod for the front mounts, and some use the two separate bolts (approx. 4" long) and nuts.
The head of the bolt fits into the engine casting, coming from the center out, so you can install a nut from the outside.
Sounds like this is where you are having trouble, that the head of the bolt is not fitting the casting in the engine?

Maybe you are installing the bolts backwards, from the outside, and trying to put the nuts in the center/inside?
Install the bolts so the nuts are on the outside/left and right side of the engine.

This what my parts break down catalog says for a KZ650B.

Front .......Upper left bolt #1 cyl....72mm long .............. Upper right #4 cyl.....46mm long

Lower left...... 84mm long ........ lower right same 84mm long

rear left 219mm long ....... rear right 250mm long. The other 4 rear bolts that hold the brackets on in the rear are 40mm long ..... Maybe your trying to fit one of these in the upper right front when you need the 46mm long one.

(Your picture Rstnick shows what I have on my bike).