No Compression on 1986 Vmax

[WolverineVmax540]

Today I got my Vmax up to 60mph and then it ran out of gas. I put more gas in it and when I went to fire it up I found I had no compression in the right cyclinder. I plan on taking it apart tomorrow to see how much of the piston is damaged. I was just wondering if anyone else has had this problem and or if any one has any advice on the matter. Thanks

[sxr1000]

Bummer,it sounds like it leaned up just before it ran out and burned a piston.

[WolverineVmax540]

Thanks

[jipcee]

How do you now there was no compression?
Compression tester are cheap you should buy one and test it.
Did you pull the starter rope immediately after it died to see if the motor was locked up?
If you take it apart don't forget to check the bore for gouges.
If there are no gouges but melted aluminum on the bore you can use muriatic acid to clean up the aluminum. Use a small brush and brush the acid on the deposits let it work for 10 seconds or so and wipe it off. If there is still alum. repeat until it is gone.
The acid eats the aluminum but not the chrome bore.

Let us know what you find.

[WolverineVmax540]

To check the compression my Dad held is hand over the sparkplug holes and had me pull the cord. I pulled the starter rope immediately to see if the motor was frozen. It pulled but it was harder than usual. It felt the same way to me as it did four years ago when I had a piston go the first time. We took it apart last night and found that the rings had melted on to the piston and there were marks on the sleve. Thanks for the idea about the acid we will try that but I think it actually marked the sleve. Can you use a hone on a chrome bore? If you can then I think that is all I will need to do to the sleve.

I do not know if the problem was caused by me running out of gas or if I blew a head gasket. When we took the head off it looked like I blew a head gasket because the top of the head where the piston goes it looks like it was sandblasted. Maybe it was one of these options or a combination of both.

Thanks for all the help!

[jipcee]

If there are deep scratches in the bore it probably needs to be re-chromed.
Try to get all the aluminum off the bore with the muriatic acid first and see how good you can clean it up with the acid.
When you say" I think it actually marked the sleeve" that MIGHT only be the aluminum from the piston that melted to the sleeve.
If you could take a picture of the head and the spark plug that came out of that cylinder and post them here that would help alot.
If it looks like there are pieces of the piston missing or broken off you will have to flush out the crank case to get all the metal out.
I would guess that you did run lean on that cylinder when you ran out of gas.

When you burnt it down four years ago was it the same cylinder, and how did that one burn down?

If you did damage the cylinder I would get it re-chromed and not sleeved. (unless it has already been sleeved)
U.S. Chrome in Wisconsin is the best around. I had one done there this year and mine needed welding in some of the ports that got chipped and welding up the scratches and it cost about $150. http://www.usnicom.com/

[Marc Machine]

Thanks for the tip on re-chroming. Wrote down the web address for futiure use. I hope I never need it but you never know.

[Vmax540]

Below is the message I got from Tom at Wiseco and talking on the phone he said a ball hone was best. You cannot take any groves out that will catch your finger nail, the chrome is too thin !


Hello Chuck,

Thanks for the inquiry. We recommend finish honing the cylinders with any where from a 240 to 400 grit, and recommend 280 grit as best. We do have a soft hone available that will do the job nicely. The part # is W6077 and will work for 63-76mm bores. You can find more information on our website at http://www.wiseco.com and can order off the website as well, if you like.

Best Regards,

Tom Davis x3109
Technical Sales
tdavis@wiseco.com

Wiseco Pistons Inc.
7201 Industrial Park Blvd.
Mentor, Ohio 44060
(440) 951-6600

[WolverineVmax540]

Thanks everyone for your help. Rebuilding my Vmax will have to be put on hold for a while because I leave to go back to college tomorrow. Hopefully when I get back in Feb. for spring break I can get it fixed and back together. Maybe even get it out on the trails for a test ride. Thanks again. I will try to get some pictures up of the piston and sleve in the next couple days if anyone wants to take a look.