So, I put a set of SLP twins on my sled, along with the recomended Slp head (12-530 domes, to lower static compression) And it won't rev past 6 grand on the stand. I had the sled running pretty well last year with the Hot Seat single, and all I did was add the twins, and head. I've checked the carbs, reeds, compression (105 both sides) checked the pipes, and can for obstructions, lowered the jetting from SLP's recommended 520N to 450. By that time I was most of the way thru a box of beer, and then I noticed the broken fuel tank neck........ What a great weekend. I had the box reprogramed by Hot Seat, to remove the DET 2 years ago. Anyone have any bright ideas?

sounds like your exhaust valves are not opening , 6K is about the high a motor will go with them closed. did you clean them? 450 MJ is very lean with twin pipes , I think 480 would be safe

Sorry, I forgot, both power valves clean, belows good, holes clean. The reason I dropped the jets to 450 was I was thinking maybe it was so rich it wouldn't rev................

put your stock head back on and see how that runs. the orings are reuseable and long as they dont have nicks in them. 105 is very low , 120~130 is normal with twins and stock head could put you around 140.

Put in lighter exhaustvalvesprings. twinpipes must have lighter springs to open properly

PUT IT ON THE GROUND AND TRY IT. MY 800 WITH TWINS BREAKS UP AT 6000 RPM AS WELL. (ON THE STAND)

Same on the snow, pinned, it stays at 6000.

450s are way to lean for those pipes on that sled at sea level. FWIW, my buddy burned his down a -5F with 500s in it during a 1/2 mile run. Do you have the carb vents plugged into the airbox? Bypass the temp sensor and try it again.

carb vents in stock location, in gutted airbox. bypass temp sender? If I unplug it, the light flashes when running, and still only revs 6000

What ev springs do they recomend for the twins?

double check the temp sensor and wiring harness to it. By changing the routing of the pipes, you may have heated the harness causing a short.

Now this might sound stupid. Check to make sure your headlite is working. My 02 800xc would not go past 6000 rpm. Dimmer switch was bad and low beam didnt work. Got both beams working rpms back to normal. Dont know why or how even polaris couldnt explain it, although they have heard of it. Good luck

COME TO THINK OF IT MINE DID THAT AS WELL WITH THE UPDATED VALVES AND STOCK SPRINGS. I GOT UPDATED VALVES WITH NEW SPRINGS AND WORKED OK FIRST YEAR. SECOND YEAR I TRIED THE STOCK SPRINGS AND IT WOULDNT PERFORM WELL. HAVE THE VALVES BEEN CHANGED. IT WAS A KIT WHEN I GOT MINE. VALVES SPRINGS AND BELLOWS.

If 105 lbs. compression is all it has when you pull it over until you have the highest reading, that is way too low. Of course on a gauge that is known to read properly. I would run around a 470/480 main if at sea level. As mentioned, do not expect it to rev out on the stand. Something to try would be to remove the ves springs, and see if it revs out. If it does, you have too low of cyl pressure. The green/yellow springs should be fine at sea level.

Update, compression 135 lbs. (Snap-on, there is a differance) Changed coolant sender, put on stand, heat pipe, 8300 rpm. Thanks for your help!