03-30-2008, 03:17 PM #1
GP1200R engine re-build questions
This weekend I was able to tear down my buddy's 1200 XLT engine after he lost compression in the flywheel side cylinder. After pulling the engine I found that the piston in that cylinder was missing a chunk and the cylinder walls were scored. I did a total disassemble and found some of the missing piston chunk almost welded to the exhaust port and also on the cylinder walls. It was also evident that many small piece of metal were sitting in the case halves. I examined the bearings of the crank and the one removable bearing was very rough and had small bits of metal in it and there was one more bearing that was very rough. I have never dealt with the GP1200R engines before but I do know they have a Nikasil plating. I am looking for opinions on what to do. I believe I will have to go 1 oversize in all three cylinders and also have the crankshaft inspected. I believe I will go with pro-x pistons but what are some shops I can send my cylinders to, to have them bored and plated also the crank work? Also, aren't there a few different versions of piston types depending on your cylinder number? This ski took on some water before this compression loss happened, any ideas on what happened to make the cylinder lose compression? Are the metal cylinder base and exhaust manifold gaskets reusable?
Sorry about all the questions guys!
03-30-2008, 05:30 PM #2
- Join Date
- Mar 2008
SBT man, i dont care how much u clean the case there are still going to be peices of metal. If u wanti can get it for u at dealer cost just pm me
03-31-2008, 08:41 AM #3
03-31-2008, 08:57 AM #4
Avoid the SBT sleeved cylinders. With the 66V motors they do not have over size kits. You have a couple options. Send the cylinder to Millenium technologies for repair and re-nik or buy a replacement cylinder. Alot of times you can find a used replacement for the price of a repaired one. A picture of the cylinder and the power valve will help diagnose what happened. Do you know if it has wave eater clips? any other mods done to to it will also help diagnose the cause. Most common issues are dropped power valves and air leaks. How does the head look?
03-31-2008, 09:29 AM #5
This may be a good option for you. If he says its in good shape then its in good shape.
If you want to upgrade to a 1300 set up let me know via PM.
03-31-2008, 09:42 AM #6
i have good cyl and piston and crankshaft
pm if interested
sbt 1200r cranks dont last they loose lower rod bearings
they do warranty it but more down time!
03-31-2008, 09:21 PM #7
I was looking around and I never did see oversize pistons for the 1200R motor. There is no damage to the head what so ever and no damage to the power valve. I will get some pictures up on here.
Last edited by Metal4130; 03-31-2008 at 09:47 PM.
03-31-2008, 09:48 PM #8
03-31-2008, 09:50 PM #9
04-01-2008, 12:14 PM #10
judging by those pics, it looks like a valve definitly dropped down and hit the piston....
avoid SBT at all costs, IMO...
ebay has 66v jugs all over the place,, do you know if he wants to upgrade or does he just want to get it running?
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