Western Wisconsin/ Minnesota Machine shop? 'Rebore?'

[arfstrom]

Okay, so I went to the local yamaha dealer, and the mechanic looked at it. His suggestion Skip honing, it, there was a obvious oil leak, so just rebuild it. The top of the valve springs he said was mushroomed, wouldn't trust them. New Pistons, The pistons were ping'ing on the valves. New valves, new everything, and rebore it. Any suggestions, I am going to create a new thread hoping for local MN/WI input after I copy the pic's here.

So has anyone done this, and Was it prohibitively expensive? this mechanic felt it would be $2,000. usd. (http://www.xs400.com/forum/showthread.php?t=11533&page=2)

Does any one with specific knowledge about the Western Wisconson, Minnesota machine shops, that have been really good with us? Pics are coming, same items, just I have to get my 7yo from school before I can put them up.
Pics will be posted on that other thread.

 

[16VGTIDave]

I'd suggest using a bead hone to de-glaze the bores at a minimum, assuming they are still serviceable. If the bores are gouged, then you will have to have them bored and honed, and get oversized pistons. Not worth it.

I believe it was the valve stems that are mushroomed. It is possible to remove 1mm or so from the valve stem by grinding it. Check your service manual for the minimum dimensions. And check to see if they are bent from hitting the pistons. If bent, they are scrap.

The pistons are probably fine. Unless they have huge dents and displaced metal from the where the valves hit, they will be fine - unless you have to bore the cylinders. Not worth it.

$2000 is probably more than your bike is worth. I'm sure you could find another engine for under $500. And have it running by the end of the weekend!

 

[79xs]

Ebay and the manual can be your friend. Roll the dice.. buy a used head/valve cover and set of cylinders with matching pistons off eBay. Review all the pictures and buy from a seller with good feedback. Also, buy a caliper and micrometer. Inspect all the parts when you get them. Short of rings, circlips, and gaskets, used parts can be fine if inspected well. Just my 10 cents.

 

[willem]

I fully agree it's time for either a new top end, or a whole replacement engine. Don't sink 2 grand into something you can replace for a few hundred bucks. I'm sure people here can help you with the exact and correct measurements. Keep in mind that I bought my Seca with a perfectly good engine for 125 euros. Most people here payed next to nothing for their xs400 actually.

 

[Scorpio1963]

When its comes to doing a rebuild the bottom end is going to be a big hassle especialy if you plan on replacing bearings.They are no longer made and very difficult to find.I paid $375 for my bike if it blows I`ll just part it out and get something else.

 

[xschris]

If you like these bikes as I do you will just keep your eye out for another motor/bike. I don't ever plan on getting rid of my 400's