CBR 1000F "Hurricane" 1987-1996 CBR 1000F

Engine studs. One is a different size. Why oh why

Old 09-15-2017, 12:43 PM
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Default Engine studs. One is a different size. Why oh why

Thought I'd share a laugh I had while stripping my bike. I've got the engine apart, and was getting ready to split the crankcase. So I'm unbolting away, in a pretty good mood so far, and lo - one of the engine studs is loose.

No biggie, says I, I'll just pop that right back in. Test fit (before locktite, from painful experience learned) and it jams up, still sticking up maybe half a cm past the others. Okay, go a little harder. Same result. Run a tap into the hole, clear out all the crap that was in there. Run back in. Same result. Oil it. Same result.

Okay so maybe it needs to be baked in. Case is apart and cleaned by this point. Wait until the wife is getting ready for bed one night. I start whipping up a batch of banana chocolate chip muffins for the kids in the morning. She's all appreciative, not realizing that the muffins are only part of a clever ploy to cover the smell of baked crankcase, which will be going into the oven after she's in bed.

Like a ninja, I get the crankcase in for a quick warm, maybe 30 mins at 220 F. Stud in the freezer. Comes out good and toasty (only a little smelly) so run bolt in. Still won't go. Flash-cool the end of the bolt using those cans of compressed air meant for cleaning computers. Still no joy. By this point, I am so done with this damn stud. I'm not quite ready to take a torch to the case, but drastic options are starting to look more and more attractive. Decide to take a breather, put down the tools, maybe enjoy a nice (only slightly oily-smelling) muffin and give it a think

Revisit a couple days later. Turning it over in my hands and I happen to notice that this stud is different from the others. The unthreaded section at the top of the stud is longer than the others. The stud itself is longer than the others, and with a noticeable flare at the bottom. Could it be that the wrong part was used at some point in this bike's sordid history? Did the previous owner just run in a random stud instead and could that be the source of my problems? I'd love it to be that simple, and I've been filming this engine job, so I go back to the footage and see that when I removed the head, there was one stud that was clearly longer than the others. It was all so obvious!

I'm thinking this is good news, just need to find a replacement for like ten bucks or whatever. Go online to order a new one. Get a good look at the fiche. Turns out the engine takes studs of 153 mm length *but* there's also a second part listed of 158 mm length and by the blinding late-night glow of my LED screen I can just see a faded line pointing to the answer. This 158 mm stud is used in the exact position that my stud fell out of. Just one, half a cm longer than the others.

By some logic that clearly exceeds my small understanding of engine design, those perennial jokers at the Honda plant decided to go to the trouble of manufacturing a second size of stud to be used in this exact position and I just spent the better part of a week trying to figure it out. I can only assume that they did it for giggles. No documentation in the FSM or Haynes, so they are clearly in on the joke.

Of course the stud fits just fine, it just happens to be a bit longer than the others. Why would I have ever thought differently?

At least the kids liked the muffins
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Old 09-15-2017, 02:21 PM
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Long Live online Parts Catalogue's
Old 09-15-2017, 03:15 PM
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Oh for sure. Couldn't count the number of times they've saved the day
Old 09-15-2017, 07:11 PM
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Just another ploy by Honda to try to keep maintenance in house, they changed the carbs on the MK3 so all the adjustment screws are now hidden from view and hard to reach just to make the job harder.
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