Same ole Alternator problem?

WILLI1962

Joined
Jul 30, 2008
Messages
9
Location
Littleton, CO
My 91 ST is currently garaged due to elec failure. Mechanic says $1000 to $1100 to fix or replace the alternator. At max (highway speed, 3800 RPM) it is putting out 12.5 amps and at idle apparently 10.5-11. I've read several of the "How to's" but I've never seen how long the replacement is. My ST only has 37,000 miles onit, so seems a little early to expire.
 
From what I have read it is more of an issue of corrosion or poor contacts (dirty) that can happen due to a combination of age and miles. So the number of miles that you have doesn't mean as much.

Mine is still running strong at almost 50K on the bike. (quick find me some wood to knock on!)

It is a pretty big project but from what I have read you are better off swapping for the 40Amp based on cost and the amount of work required. I don't know your ability level with the wrench but from my readings it requires either pulling the engine or the rear swing arm. Most seem to remove the rear swing arm. The ones that went the engine route had high mileage and found a complete engine with alternator and less miles on a scrapped bike so they figure what the heck. Might as well drop in a fresh engine even though the only real issue was the alternator. For them the price difference was only in about $200. At least the cases that I can think of that went that route. The vast majority of those that have done the swap end up pulling the rear swing arm. If I recall it requires a special tool but I think there is one floating around that you can rent or borrow (I don't recall the terms).
 
As Keith suggest, find a known good VRR. Also, continuity check among the 3 yellow wires from the 28amper should show a-b-c, short short short. BUT, all three show OPEN to ground. Any other reading is a problem.

Ya prolly can't test the VR/R yourself, so swapping with a know good one is the way to go. I burned one up a few years ago (my fault) and a quick replacement (thanks, Robert) got me back on the road in short order for _ZERO_ dollars.

Using John Oo's laoner tool kit, you can DIY the alternator. It's about 6 hours. I've done several and could prolly do it today in 4, given a knowledgable helper and no beer. :D

I've helped with the engine swap method as well, but a little different. Patient was a 96, we installed a low-mile 94 so had to remove the 40 amper and from the 96 motor (bad third gear) and install it on the 94 motor. Sure was easy with both motors setting on the floor!

Keep us posted.
 
37,000 miles is nothing. Likely it's just the regulator/rectifier that's fried. But that's over 200 dollars brand new. Spend just a little bit more and upgrade to the 40 amp system and you'll never have an alternator/charging system failure again. Over 1000 dollars to repair your existing system is highway robbery.
 
Thanks all for your input and advice. Obviously I have several things to check, beginning with the elec connections. I will let you all know how it comes out.
 
WILLI1962 said:
Thanks all for your input and advice. Obviously I have several things to check, beginning with the elec connections. I will let you all know how it comes out.
Click to expand...

In case it helps you decide I just priced all the parts needed to do the upgrade from the 28 to the 40 Amp from Service Honda. The grand total including optional (but recommended maintenance items) came to $466.33. I didn't see what they charge for the VRR though.
 
So how many hours does it take to do the installation of the 40 amp alt? I believe the Honda Service says 6 hours. Is that about right? I'm trying to figure out which shops are fair. Honda Service said up to $900 just for the labor. I think that's a bit steep.
 
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