Topic: bolt part number (preceded by kvetching & rambling)

[francesb]

Hey all,

Just spent an incredibly frustrating day wrenching. I planned on replacing my exhaust. removed old one , realized my new exhaust is at my mother's house in Jersey. Drove out there (one hour), visited a bit (30 minutes) and returned (one hour). When I returned, I looked again at the bike, and again saw the eight stripped out philips head bolts. I had ignored them earlier, because I could remove exhaust w/out them. However, I could not install new exhaust without removing them (which I cannot do, being a NYC curbside mechanic w/out an air wrench or something that will get a stripped bolt out of an engine block).

Now that I've told this frustrating story, here's my question. Can someone provide me with the parts number for those bolts? I have a Cb750 K3.

Part of me is not even sure that those are the bolts I need, since it appears that with the new exhaust, the flanges get bolted into the engine block, which was not the case with my old exhaust. Of course the "new" exhaust is a used one I bought off ebay for $40, maybe its just not compatible with my bike (even though seller assured me it is).

On the bright side of things, this gave me the oportunity to clean my flanges, which look fantastic, and I got to meet some neighbors. One of them told me that he's seen my bike on the street, and assumed it belonged to a woman because women ride 750s while men ride bigger bikes.

grrr.

[frostypuck]

I'm not sure I understand your problem, do you mean that your exhaust doesn't require the flanges at all? Instead of the half-moon shaped wedges and star shaped collar, your flange is built on, right?  You can remove exhaust studs by spinning two nuts onto the stud and using the innerr one to turn out the stud. I believe the screws used to hold on the later exhausts were philips-style screws, probably M8, but had a tapered head. partsfish.com lists the screw as an 8X22, but doesn't give a part number. I looked under a '76 750 for that info. BTW, they have them for .99/each
Chris in Boston

[francesb]

No, there are flanges on the old exhaust, but the exhaust bolts bolt them together, and my exhaust is not actually bolted to the engine case. Somehow there seems to be a tension fit that holds the exhaust into the engine case. When I removed the exhaust, there were eight stripped out phillips head bolts. ( And as I mentioned, i don't have the tools to deal with those bolts, nor do I know what they need to be replaced with.

The flanges on my "new" exhaust appear to bolt directly into the engine case, taking the place of those four, stripped out, impossible for me to remove, phillips head bolts.

So, I need to know either a. the parts number for those original bolts, or b. how long those bolts are so i can get bolts that are that long + the length of the flanges.

FWIW, I did order new exhaust bolts off ebay, and they are an exact match for the bolts that are causing the tension fit on ym old exhaust.

Is the new exhaudts just not compatible with my bike? It does seem like it will require some yanking to get it to fit into/onto the exist exhaust holes (terminology?)

thanks in advance.

[Jonesy]

A lot of the 4-to-1's I've seen are as you describe. Both myself and my uncle have K3's and I've seen both configurations, my bike with stock and his with aftermarket. The little spigots on the cylinder head are are each held in place with 2 countersunk phillips-head screws. The aftermarket exhausts do away with the whole works, bolting directly to the head as opposed to clamping onto the spigots, like stock pipes. Seems a bit redundant to me, and it must have to Honda as the design was later changed to having studs in the head with nuts that retained the half-moon clamps and clamp as frostypuck described.

OK, so now that we covered the history lesson, what do we need to do? Are there any parts of the crossed-slot left in the screws? If so, you can get an impact driver from Sears and remove them. You just place it on the screws like a normal screwdriver and smack it with a hammer. If there is nothing left of the slots in the screw head, you'll probably have to drill the heads off the screws, enabling you to remove the spigots and put vice-grip pliers onto the leftover screw sticking out of the head. Sears also sells a kit for removing damaged phillips-headed screws which has left-handed drill bits, so when the bit digs into the screw, it can back it out. Use a pick or screwdriver to dig out the old copper exhaust sealing rings from the cylinder head. You'll want new ones (You might already have them, but you didn't mention them) and they are available from cycle recycle, partsnmore, and all kinds of other internet suppliers. Now, most of the aftermarket 4-to-1's I've seen have flanges that don't butt directly up to the cylinder head, so you will probably need longer screws. If you have new phillips-head screws, take one with you to a hardware store and buy a set of allen-headed metric bolts with the same size and type of threads. This way you won't have to deal with stripped-out screws again!

Others might post some ideas for removing the stripped screws, so you might want to look at more options before tearing into the job, as if the screws break off flush with the cylinder head, it will be lots of fun trying to remove them then! (Read: major work involved!)

Good luck with it and let us know what happens.

[Bill Vaughan]

Living in Bergen County, I fully understand your frustration with the drive over here.

To get the parts numbers try the website listed below.  It has the exploded views and part numbers for all Honda morocycles.  Just follow the instructions on the website to get to the actual diagrams.  The part numbers for most bolts are such that the last few digits represent the length (in mm.), so you should be able to determine how long the original bolts were.

www.servicehonda.com/test

Best of luck.