Pro RMK Turbo Rebuild Questions

[Jshlee3]

I'm in the middle of putting in some RKtek pistons and had a couple of questions after getting the engine apart. To give some background it's a 2013 pro that I recently put a boondocker non intercooled turbo on running 7psi 50/50 av gas 91 octane at 9,000'; roughly 120 miles on the turbo running the starting numbers from boondocker. 700 miles on the sled. The pistons were done for preventative maint. and because it sometimes died in reverse.

So to get to my real questions. I got the cylinder apart and it looks good, pistons look good but I noticed right above the exhaust ports it looks like the nisil coating is worn right in the transition where the rings would be squished back into the bore. Is this normal? Pics attached I'm pretty sure im looking at aluminum. Second question is with piston wash (or lack of) and plug color. Everything looks "hot" to me pistons, plugs and pipe have a white color to them and not the normal black color I'm used to on most 2 strokes I've owned. I just changed the fuel filter with a SPI after market unit, the ride before that the pistons were brown. I haven't done a fuel pressure test yet but that's in the plans after the rebuild.

So to sum up my novel what do you think about the cylinder wear above the exhaust port and piston/spark plug/ exhaust color? Any advice would be much appreciated.

 

[TheBreeze]

IMO wash looks good to me. The grey appearance in the pipe is lead deposits.

 

[theshadowrider]

Do you have pictures of the pistons, intake and exhaust side? That will help tell what's going on. Also I would be careful with the SPI filter. I tried running one and my egts would keep climbing on a long pull. I kept turning up fuel and still high egts. Seemed to not flow enough fuel and this after a few rides. Changed fuel filter to oem and took care of the problem. Obviously there could have been other things going on. When I cut the filter apart it did not seemed to be plugged but defiantly different filter material than oem.

 

[Clarke673]

I use fuel filters for Gm trucks. Cheep and rated for the 55 psi fuel pressure. Also a good 3x the factory size. Swap them out religiously.

Curious as to your thoughts on the rk tek kit.

 

[MrIQR]

I use fuel filters for Gm trucks. Cheep and rated for the 55 psi fuel pressure. Also a good 3x the factory size. Swap them out religiously.

Curious as to your thoughts on the rk tek kit.

Got a part number or year make model? OEM GM part or aftermarket?

 

[Jshlee3]

Thanks for all the input guys. For some reason I don't get emails anymore when people post replies.

I ended up taking the block to Doug's Balancing in Denver to have the cylinders checked out. Turns out the spot I thought was wear near the exhaust ports was just where the Nikasil coating was a different color. He was also impressed with the pistons and gave me the background story on how they were designed. Evidently they are Wiseco pistons made to RKTek specs. He also thought the piston wash looked good and showed me where it was coming in from the transfer ports and what to look for.

I think I'm going to ditch the SPI filter while I have it apart. I noticed after installing it something felt different when riding the sled although it could just be in my head. I would be very interested to know the GM part number of the filter you use if you come across it.

Thanks again for the help I will post an update once I get it back together and take it for a test ride.