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Author Topic: VERY BASIC motorcycle maintenance questions  (Read 577 times)

Rich Mintz

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VERY BASIC motorcycle maintenance questions
« on: June 25, 2013, 11:09:38 PM »
This question isn't even directly Enfield-related, but I think there will be useful advice here:

In addition to my Enfield I own a SYM Symba (100cc motorcycle). I bought it used. It's seen some wear.

Its rear (driven) sprocket bolts to a flanged roller which in turn pulls a cush drive. The sprocket is held to the roller by 4 non-standard bolts and standard 8mm hex nuts. I recently discovered that the bolts and nuts are loose (not connected), so the sprocket and the roller are held together by physical compression only. (I had to take the rear wheel assembly apart to figure this out.) I don't think it's a new problem.

I tried to reattach the nuts to the bolts, but they wouldn't screw on. But the physical compression forces are strong (it's the rear axle, after all) -- the sprocket pivots improperly, but the drivetrain still works. So I put the thing back together and kept riding while I waited for the replacement OEM parts I've ordered from Taiwan.

I've ridden the bike a long way in this condition. But today on the road the sprocket and roller pulled apart just enough that the chain no longer drives the bike, so I have to repair it properly.

I don't know why the bolts won't accept the nuts, but both the bolts and nuts are filthy. (And the washers long ago wore away.)

I'm having the bike towed back to my garage and I'm going to try to fix it tomorrow morning. I guess I'll start by buying 4 replacement 8mm nuts at the hardware store on the corner and seeing if I can get the bolts to accept them.

(1) What can I do to increase the chances that I'll be able to get the nuts and bolts together? When I have everything apart, how can I best clean the filthy, worn bolts without [further?] damaging the threads? Do I use WD-40? PJ1 contact cleaner?

(2) When I say the bolts are non-standard, what I mean is that they have very, very thin heads. They need to be very, very thin in order not to catch on the axle fork while the sprocket is rotating. The heads have hex-shaped edges (in a standard size), but because they are so thin you can't really force them very hard without bending or stripping them. What is the proper way to screw something like this into a nut?

(3) Is there a name for bolts like those with very, very thin heads? Where does a person go when he needs an unusual fastener?

Thanks in advance.

ERC

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Re: VERY BASIC motorcycle maintenance questions
« Reply #1 on: June 25, 2013, 11:14:25 PM »
Basically to the people that manufactured your bike. ERC
2-57 Apaches, 2-57 Trailblazers, 60 Chief, 65 Interceptor, 2004 Bullet, 612 Bullet chopped.

Arizoni

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Re: VERY BASIC motorcycle maintenance questions
« Reply #2 on: June 26, 2013, 12:31:59 AM »
Quote
(1) What can I do to increase the chances that I'll be able to get the nuts and bolts together? When I have everything apart, how can I best clean the filthy, worn bolts without [further?] damaging the threads? Do I use WD-40? PJ1 contact cleaner?
Just about any oil based solvent and an old toothbrush should clean off the accumulated junk.
Back in the old days, we just tossed them into a pan of gasoline but what did we know?  ???

Hard to start and hard to screw on are two different things.
Hard to start may be because the lead in chamfer on the male threads is damaged or it doesn't exist.  If this tapered area doesn't exist, careful work with a small flat file can recreate it so the threads will engage the female threads better.

Hard to screw on after they are started nuts may be self locking.
These nuts can have a small dimple in their outside that forms a bump on the inside.  The intent is the distorted threads on the inside will slightly interfere with the male threads.  On some, the deformation is large enough to be visible when looking thru the nut.
If the nut is self locking it's a good idea to oil the external and internal threads before screwing the nut to the bolt.  This can keep the nut from tearing up the male threads.
Quote
(2) When I say the bolts are non-standard, what I mean is that they have very, very thin heads. They need to be very, very thin in order not to catch on the axle fork while the sprocket is rotating. The heads have hex-shaped edges (in a standard size), but because they are so thin you can't really force them very hard without bending or stripping them. What is the proper way to screw something like this into a nut?
Use a box end wrench or a socket.  You may have to grind or file it to remove the chamfer that leads into the hex so it can maintain as much engagement as possible.

Quote
(3) Is there a name for bolts like those with very, very thin heads? Where does a person go when he needs an unusual fastener?
Special.  As was mentioned, the original maker is the best place to go for a replacement.
If that is not possible a standard hex head bolt can always have its head thickness reduced by filing or grinding off the unwanted material.  The catch here is that often, special bolts not only have a reduced head thickness but they also have a reduced hex size to clear things that are close to them.
« Last Edit: June 26, 2013, 12:34:57 AM by Arizoni »
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

D the D

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Re: VERY BASIC motorcycle maintenance questions
« Reply #3 on: June 26, 2013, 12:34:59 AM »
SYM has a US webpage http://alliancepowersports.com/ with contact info.
Cute little retro looking scooter-bikes. My favorite niece and her mom come from Taiwan which has taught me your Symba, though really cute, will be nothing but trouble!  ;D
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

AgentX

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Re: VERY BASIC motorcycle maintenance questions
« Reply #4 on: June 26, 2013, 01:21:05 AM »
www.mcmaster.com is a great place to go for unusual hardware, but even they may not have exactly what you need if it's something specifically produced for one machine.

Rich Mintz

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Re: VERY BASIC motorcycle maintenance questions
« Reply #5 on: June 26, 2013, 02:45:42 AM »
Thanks all for the practical advice! Will report back.

Btw, I did order OEM replacement hardware, but it comes from Taiwan via a distributor, so I'm not holding my breath until I get it.

D the D

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Re: VERY BASIC motorcycle maintenance questions
« Reply #6 on: June 26, 2013, 03:58:47 AM »
Things from Taiwan seem to take forever.  Longer than the UK.  I don't understand it considering that packages from India and Austria take a week.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH