Topic: CB 750 Project 1 - Rides Well but a few tweaks needed

[timbo750]

Great explaination mystic. For some reason the coil is in great condition but the ends of the wires are melted from overheating.

[timbo750]

Finally got to the broken bolt in case, the bad news is it wont come out. First tried a left hand drill bit with no luck, the tried an extractor and broke that off. Now I am going to try and drill it out to the thread edge as the pilot hole is very close to dead centre.

If anyone else has any great ideas let me know. i am fearing the engine will have to come out. 

[Jerry Rxman Griffin aka MuthaF'er]

Great explaination mystic. For some reason the coil is in great condition but the ends of the wires are melted from overheating.

Normal. Not much extra on the ends to crimp new connectors and that shielding is tricky to try to save.

[Terry in Australia]

Finally got to the broken bolt in case, the bad news is it wont come out. First tried a left hand drill bit with no luck, the tried an extractor and broke that off. Now I am going to try and drill it out to the thread edge as the pilot hole is very close to dead centre.

If anyone else has any great ideas let me know. i am fearing the engine will have to come out. 

Did you post a pic of the broken bolt Tim? When I pulled Mike's K2 engine apart, the bottom alternator cover bolt must have been bashed in with a hammer, it was a hex head (not internal hex) bolt in a place where you couldn't fit a socket or open ender etc to turn it, and the head had to be cut off to remove the cover.

I had enough "meat" to grab then weld a nut onto, but when I attempted to turn it, it just broke the bolt off at case level. Like you, I tried drilling it but the bolt was too hard for even my best drill bits to even make a mark on, so I offered Mike another set of cases, but he was adamant that he wanted to keep them, so I said that if there was a leak, he'd have to sort it.

Luckily, so far there are no leaks, I think I either used two gaskets or made a thicker one, and used a Selley's blue silicon sealant (carefully) that I've had excellent experience with in the past. (I installed a new water pump on my son's XF Falcon 10 years ago, and didn't see the special alloy gasket until after I decided that it didn't come with one, and used a little of this stuff to seal it with, and it still doesn't leak.

Anyway, if you haven't posted a pic yet, please do so we can all throw useless suggestions in your direction.    

[timbo750]

Yeah it was broken off clean at the case. When I first pulled the engine apart the bolts were of all different lengths and I suspect that a bolt that was too long was used and so was still torqued to the bottom of the thread after being broken and was stainless to top it off. The left hand drill bits are cobalt so drilled through with no issue and then stepping up the holes worked quite well.

Then I realised that I forgot to align the drill on 2 plains so was straight left and right but not up and down. However I did eventually manage to get about 3- 4 thread and then shortened the bolt in use and used a bit of lock tight so it wont vibrate loose. Fingers crossed there are no leaks. And the cover is now on.

[Terry in Australia]

That's a clean engine Tim, be very careful when you first go to fire it up, make sure the little drain tubes are connected to the carbs so you don't get any drips on the engine paint like I did, which caused instant wrinking, fcuk it........

[timbo750]

Thanks for that Terry. I cleaned the carbs a long time ago and think I may pull the apart agai  for peace of mind, also I think the bowl heights are not set.

[Terry in Australia]

Yeah, I rebuilt a set of carbs with new kits I bought on eBay Tim, and I bench synched them while I had the opportunity, and was 'rapt that the bike fired up right away and ran cleanly.

Only a little bit of fuel dripped out, and only because it was on it's side stand. I've got a new set of drain tubes in a box too, so I really should have installed them before I fired it up, but I was too excited, ha ha!

[timbo750]

I would love to have the same result.

[Terry in Australia]

You will mate, put the time in to do it right and it'll be fine, they're pretty simple old engines.

[calj737]

weld a bolt onto the end of the sheared bolt. then turn out the new bolt. NEVER use "extractors" as they suck and snap off.

[Terry in Australia]

I think Cal means "Weld a NUT onto the end of a sheared bolt" Tim, but that only works if you have enough meat left on the sheared bolt to do so, and if the sheared bolt was jammed into the engine case like mine was, you'd be lucky to get it out, mine just snapped again under the welded portion, and there wasn't enough meat to try again.

Drilling the remains out and heli-coiling the hole would have been a good fix, but some idiot had bashed an unbrako (super hard) bolt into the hole, and my drill bits wouldn't even mark it. Some people shouldn't be allowed to own tools......

[timbo750]

I have done the welded nut before but this time it was flat against the case. I have also had the broken unbrako before and was surprised how easy a  ew cobalt drill bit went into it compared to the standard.

[timbo750]

Back to the questions about coils.

I have 2 sets that are different and thouht one set was K and one F but thats not it. The K coil have damaged leads and they appear to be fixed and unable to replace just the leads. The othet set do not have fixed leads and are essentially the same size but different where the leads fit and won't just bolt straight up. They are also 3ohm and from what HondMan says that can be an issue on the stock ignition system. The photos show both types.

[seanbarney41]

replaceable lead ones may be for GL1000?...no sohc4 coils with replaceable leads

[Terry in Australia]

Yeah, I tried my new P&N Cobalt drills on my busted bolt Tim, but they didn't make a mark on that fcuker, if you like, you can bring yours over and show me how, ha ha!

The old fixed lead coils are the "correct" ones for your bike, the later DOHC 3 Ohm coils are designed for electronic ignitions, and they failed on a fairly regular basis, I just bought new ones to replace the OEM ones in my Goldwing, they were cracked and only worked intermittently.

You can buy joiners for the OEM leads and some guys have operated on their coils with dremel tools and silicon to install new 7mm copper cored plug wires, but honestly, you're better off just buying new ones. Genuine Honda coils will cost as much or more than new Dyna 5 Ohm coils, so my advice (for what it's worth) would be to buy some Dyna's. Cheers, Terry.  

[timbo750]

Ok, just to clarify. The coils I have with out leads are most likely  dohc coils and can fail. So I should get a set of dyna coils instead.

Terry ,  have you found anywhere  local for decent prices or am I just better off buys from somewhere like dynoman.

[Terry in Australia]

The crappy exchange rate isn't helping at the moment, last time I bought them Z1 Enterprises in the US had them for around $120 US Tim, but I haven't priced any recently? Cheers, Terry.

[calj737]

I have done the welded nut before but this time it was flat against the case. I have also had the broken unbrako before and was surprised how easy a  ew cobalt drill bit went into it compared to the standard.

I did mean weld a bolt onto it as I interpreted the bolt sheared flush to the case. Obviously the weld on bolt needs a head to turn against, but I fully suspected Timbo knew this.

[Terry in Australia]

How do you weld a bolt to another bolt that's sheared at case level? Explain.......

[redwillis1978]

Stud welder.

[timbo750]

I can see how that would work, although might be tricky on a 6mm bolt.

[redwillis1978]

1/4 stud is perfect. Wait to cool then heat the case and turn with a double nut.

[Terry in Australia]

I'd love to see that work, I own a stud welder and there's no way in practise (as opposed to in theory, where anything might work) a stud could be welded to the sheared remains of a broken bolt that's been jammed into an engine case, and have the weld integrity to remove it. We're talking about a small spot weld here, with no weld material to fill gaps etc. Nice idea, but no cigar.....

[calj737]

TIG weld the end of the new bolt to the end of the sheared bolt. Even the filler rod won't pool against the case, it will just suck under the ends and bond the two bolts together. I didn't say it was super easy or didn't require some skill, but short of EDM its a damn surefire way to get the bolt out with an extractor snapped off in it.