Raptor Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Has anyone put a big bore kit in a 660? I recently purchased a '01 660 and during the replacement of 2nd gear I had the cylinder measured and noticed it was getting egg shaped, so I bored it out. I went right underneath the Big Bore with a 110mm Piston. My question really consist about having nothing but problems ever since. Motor doesn't seem to want to turn over most of the time, and if it does, it drags. I have even more recently crack the cylinder jug, and pulled the threads of the front left ear of the jug. So I am currently getting it welded back together and going to put time inserts in the block to re-enforce the strength of the jug to the bottom end, but I am also curious if there is something else I should do to re-enforce, so that I am not cracking heads and jug's all the time. Should I jet it? Should I advance the timing? If someone out there could help me, that would be great. Thanks in advance.
 

·
Super Moderator
Joined
·
17,061 Posts
First off welcome to the forums, sorry a problem is what got you here but we'll do what we can to help.

I've done a piston install on this bike, in fact the same piston about 3 or 4 times now. I'm assuming you're using a 101mm bore, not a 110mm. The most common problems with piston installs gone horribly wrong is improper clearances between the piston and cylinder walls and improper ring gaps or installation. If you're sure you followed the manufacturer's recommendations on all of these areas then we can move on.

A couple of things you may want to look into:
Compression check - find out if rings seated and address camshaft concerns mentioned below
Plug chop - check to see if you're getting the right amount of fuel into the cylinder
Timing - Should be and always stay stock. Make sure cam is not installed 180 degrees out or decompression pin is not installed backwards. Also make sure timing chain is still taught and that automatic tensioner hasn't stretched it out.

Re-assembly can be a real pain and can often leave you with confusion or misplaced certainty about where they go. The head and jug bolts are not all the same and each needs to be used in a particular location. Improper location or too much/too little torque can cause all sorts of problems. I seperated my jug and head from the bottom end one day at the track because two bolts had been accidentally switched from their respective places. This took me some time to figure out even with the help of mechanics and knowledgeable family members.

You shouldn't need to reinforce any part of the cases, cylinder, or head with the kind of setup you're using. Now that it has been broken however a little strategic help might not be a bad thing.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #4 ·
Hey thank you!! I would have joined anyways, but yes it helped me get the deed done a little faster!!

Well I will let you know that I have placed an order for a new cam chain, which I am going to assume that it is the same. Being the 2nd time in this motor, I decided to pay a little more attention to the way things looked!! :thumbsup:

When I disassembled the motor this time, it looked kinked, so I just said forget non-sense, I will replace it. Ok so I already feel a little under the weather about motor work, but if you don't mind me asking, how can you check the plug chop?

I did read the instruction's before installing the motor, because I have delt with sport bike motors for the last 4 years, but not this single cylinder stuff and for some odd reason, I have seem to have lost my mind!!

Well thank you for all of your help, I will probably be asking more and more question's, sorry for the inconvience....


Talk to you soon....
 
1 - 4 of 4 Posts
Top