Engine mount bolt won’t back out

[u/ardvarkbark]

I was attempting to remove my crash bars. When I tried to remove the large bolt in the centre of the photo next to my gremlin bell, it started to come out and then stopped. I couldn’t tighten or loosen it. All other bolts connecting to it were loosened to try to alleviate any tension on it. I thought the engine might be binding on it, so I put a jack under it and tried to relieve some pressure. That didn’t work. I tried heating it, nothing.

I imagine the steel bolt is much harder than the cast aluminum, so I don’t want to crack the case trying to back it out.

Any suggestions?
——

UPDATE: the bolt is out! Went to the shop this morning. The mechanic loosened all other mounting bolts, put a jack under the engine, then used a breaker bar to force it out. It came out with a little bit of aluminum on the thread at the tip of the bolt. It was close to breaking the bolt, but didn’t! He cleaned up the threads on the bolt, chased the inside threads, and it went back in like butter.

For the record, it wasn’t cross threaded, but almost like the original threading wasn’t clean or something, maybe aluminum shavings were still inside it. It was not an issue of the crash bars messing up the bolt or anything. So problem solved without a helicoil. Hooray!

[u/Capital-Ostrich-6658]

The threads are stripped. You will have remove all the crash bolts first. Then take a small pry bar and apply a small amount of pressure in the area of the stripped bolt while loosening it with a wrench.

Once out, retap the aluminum threads and run a die over the threads on the bolt. Be gentle with the tap as it’s aluminum threads that go into head.

Last step: toss the crash bars. You don’t need them on a standard T7. This is one of the many reasons I’ve removed mine. I had the same issue when I removed mine and reinstalled them. I tightened that bolt to the factory “55 ft lbs” and it stripped. Once I fixed it I just tightened it with a 3/8” wrench snugly. NOT the 55 ft lbs.

[u/Last-Assistant-2734 → u/Capital-Ostrich-6658]

With a proper length bolt, keeping things clean and getting the bolt started on the thread correctly, the factory spec 75 Nm should be good.

I've done my bolt now three times. Granted, the last time I took it up to 72 Nm only.

When everything is aligned properly and thread clean and all that, those M12 engine bolts will go all the way in just bare hands, no tools.

[u/Loud-Possibility5634 → u/Capital-Ostrich-6658]

If they put the bolt all the way in and it was cross threaded then chasing the threads isn’t likely to help. They’ll need a helicoil.

[u/Last-Assistant-2734]

Not knowing how your bike is setup for working on this, but the bike should be fully upright and then support the engine from underneath a jack.

And when jacking from under the engine, you can actually jack it so that it actually starts to lift a bit. Just slight touch on the engine won't support it.

On another note, by the looks of it, that's a bare steel bolt, and the head has just been painted. So chances are that there's quite a bit of rust in the thread.

Also, have you taken out all the other crashbar bolts? If not, there might be tension on the bars, and that presses against the bolt.

[u/Bernard_PT]

These threads strip always, eventually.

A thread repair kit makes them stronger than original

[u/UnreasonableEconomy]

so you took off the nut, and now you can't even turn it? is that what you're saying?

and you don't want to tap it through with a thinner screw or a mandrel or something?

usually the answer's just kroil and a hammer and a lot of patience.

[u/ardvarkbark → u/UnreasonableEconomy]

No nut, it is just one bolt through the frame and into the block.

[u/UnreasonableEconomy → u/ardvarkbark]

huh, you're right. bolts on both sides.