You can always bore a cylinder larger...untill you get to its limit, but then you can always sleeve it.

 

I was just noticing how the factory manual says to replace the cylinder if it's out of spec, and the microfiche only shows a standard piston. I know some cylinders are plated or coated and cannot be bored, didn't know if the 700 was one of them.

 

You guessed it, its plated but companies do redo the plating.

 

The 700 cylinder is plated and would have to be repksted if you bored it. Not many pistons avsliable for overbore sizes for the 700 for this reason. If it runs the drive it. Fo a compression check if you wanted but unless you just wanna build it up tgen go ahead but unless you see reason to tear it down dont. You will want more power soon enough and tear into it lol.

 

Yeah the black oil and unknown history just had me concerned. My buddy who thinks I should tear into it is a two stroke dirt bike guy. He buys used dirt bikes and always pulls the jug first thing. Probably a lot more common to open up a used 2 stroke with unknown history...

 

The OEM cylinder is aluminum but needs the help of the nikasil coating to stand up to the task. You can bore and re-coat the OEM aluminum cylinder to a larger diameter, 103, 105 and 105.5 mm pistons are common for the 700 and widely available from a number of piston manufacturers. You can also put a steel sleeve into the OEM cylinder, negating the need for the nikasil coating.

Two stroke engines typically require much more frequent rebuild cycles for the top end components (piston, cylinder bore/hone, rings, circlips, etc) which is likely why your buddy jumped to that first. But you've got something he's probably not as familiar with....valves....and those leak too. So before you go tearing anything apart I would suggest a compression test and a leakdown test. You may just need some valve work or you may need a piston/rings/bore AND new valves/seats. Find out what you have in front of you so you don't end up replacing the wrong parts or fixing only a portion of the problem.

 

if its wore very much it will smoke. if u pull it down its gonna have white marks in the nikasil almost guaranteed, so if it comes apart plan on 200+ for nikasil or go ahead and get another cylinder either standard bore or big bore. might as well throw a crank in it too while its down since thats the 700s weak spot

 

Several aftermarket cylinders available as well. Cylinder Works make aftermarket cylinders, various sizes with matching Vertex Pistons. Moose Racing also makes aftermarket cylinders, not sure about various sizes but definitely Moose Racing makes a standard bore size. These cylinders come with NSC (Nickel Silicone Carbide) plating.

Then I have seen that Wiseco makes a Cylinder Sleeve Insert. But I have not been able to find much information on it. Maybe Lucky700r knows more about this.

I will be going with a the Standard Bore Cylinder Works Cylinder and matching Vertex Piston 11:1 soon. The price is good and I like the idea that each piston is hand mached to the cylinder. Also KB Motorsports has sold several of these kits and has only had very good feedback.

Then I will look at boring and sleeving my OEM cylinder with the Wiseco Cylinder Sleeve for a spare. And maybe get a CP Piston, 12:1 compression ratio. I believe good engine builders like Kenz can mill the top down to make it an 11,5:1 ratio, the highest you can run on premium pump gas.

 

Hey thanks for the replies. Like Mad Dog said, I need to do the compression and leak down test to see what I've got, it's all speculation until then. It would be nice to know if the hours could be read off the ECM...

 

Compression test won't work due to the release mechanism. But leak down will

 

I hesitate to disagree because I haven't done a compression test on a 700, but with the 660 which also has a factory decompression mechanism the result was simply a lower range for the spec not an inability to run one at all.

Looking at the manual for the 700 I see they spec 64psi +/- 8. This is obviously way lower than the actual compression in the cylinder head while running which in the 660 was around 180psi, but I assume that range is listed because of the factory decomp. Now how accurate or reliable reading compression is when having to overcome a factory decompression mechanism I do not know and perhaps that is what you are referring to when you state that it won't work.

 

For the compression test, is there any special adapter I need? I remember on the 660 none of the automotive testers would fit the spark plug hole...

 

Bring your plug in with you to the store to compare the threads if you are going to buy an adaptor and or tester. The spark plug for the raptor 700 is small and not a standard size. I had a hard time finding a fitting that was the right size.

You can do a compression test. Its all in the manual of what the ratio should be with the decompressor. Between 30 or 40 PSI i believe.