hard_y_rd
XS650 Guru
Anyone know the bolt size in the rear hub for the sprocket?
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5twins is right on the 1.25 pitch. The length of the one I pulled today from my '82SJ is 35mm. I don't know if the same length bolt was used throughout all years of 650 production.
I wish mine were 35mm long. I could use that on a wheel I'm adapting and spacing the sprocket out on. I did just acquire a later 16" spoked rear wheel though, I'll have to check those sprocket bolts. Longer would be good.
hard_y_rd
XS650 Guru
The reason I asked is because one of the thread holes was boogered up so i took the bolt to my auto local parts place and the guy said this was the tap for the hole. Even had a nut on the bolt. So i took his word for it, spun the tap in. Wrong tap. He gave me a 10 X 1.5. Oh well. Guess i'll stick another bolt in there.
5twins, what length bolt did you find in the 16" spoked rear wheel? I changed my rear sprocket last night, and when cleaning the female threads in the hub, it looked like a 25mm long bolt would be long enough to engage them fully - I don't see why 35mm like I have would be needed for the stock setup (assuming they are stock - maybe a PO had changed them; I have no way of knowing).
One wheel uses longer bolts. The holes are deeper on one or the other. I just don't recall if the mag or spoke wheel uses the longer bolt.
Leo
Leo
I'm thinking it must be the mags because all the ones I have and have checked are "spokies". I haven't checked that 16" wheel yet but from a quick look, they appear to be the 25s. I'll confirm later today sometime.
My rear hub with the 35mm sprocket bolts is from an '82 Heritage Special with the "double-laced" 48 spokes, originally a 16" wheel converted to 18". It appears to have threaded steel inserts cast into the hub to receive the sprocket bolts.
I saw some at a hardware store and they were longer ones, probably 35mm. So I think that is a "normal" hardware store length for a bolt of that diameter. Longer will aid you in removing them from the inside when they break off... On the mag wheels you can probably get to them with the bearings out. Might take a special homemade tool. Such as a mini-vicegrip with two rebars welded on at right angles... I think the store was a Hedahls in North Dakota.
I went out and looked at the wheels I have. A rear spoked wheel of my 75. It has open ended holes but they open into the brake side. Using too long a bolt may interfere with the brakes. Those bolts are 20 mm long.
The 75 front wheel has a bottom in the hole and use 20 mm bolts.
I have a couple sets of 81 mag wheels with a rear drum. On the fronts the holes go all the way through and use 25 mm bolts. The rears go all the way through and use 20 mm bolts.
On the disc brake mag the holes go through and can use 25mm bolts on both brake and drive sides.
On the brake and sprocket bolts the threads don't go all the way up to the head. There is an unthreaded portion that goes through the disc or sprocket.
I measure from the head to the end of the bolt. I don't measure the head too, just the gripping part of the bolts. Add 5 mm for the head if that's how you measure.
I don't have any of the 82 up spoked wheels, so I can't say anything about them. I assume they are the same as the older spoked wheels.
In the hardware stores I visit there is no standard length of bolt. They have them in 5 mm increments.
Leo
The 75 front wheel has a bottom in the hole and use 20 mm bolts.
I have a couple sets of 81 mag wheels with a rear drum. On the fronts the holes go all the way through and use 25 mm bolts. The rears go all the way through and use 20 mm bolts.
On the disc brake mag the holes go through and can use 25mm bolts on both brake and drive sides.
On the brake and sprocket bolts the threads don't go all the way up to the head. There is an unthreaded portion that goes through the disc or sprocket.
I measure from the head to the end of the bolt. I don't measure the head too, just the gripping part of the bolts. Add 5 mm for the head if that's how you measure.
I don't have any of the 82 up spoked wheels, so I can't say anything about them. I assume they are the same as the older spoked wheels.
In the hardware stores I visit there is no standard length of bolt. They have them in 5 mm increments.
Leo
We've about beaten this one to death, I guess. I measured just the shank length, not the bolt head. Mine also have the top 5-6mm unthreaded; also require a 17mm socket - I think most 10mm hex-head bolts are 15mm. As near as I can tell, the depth of the threaded steel inserts cast into the hub is about 3/4 inch (19mm), so a 25mm long bolt would engage the threads thoroughly when tightened against a lock tab/washer and the sprocket. 35mm definitely isn't needed for the stock setup, but for whatever reason, that's what's on my bike. 5twins, if you could use them, PM me.
