You are one of MANY 4900 users who have contacted us with clogging troubles (as you will note on the top of our 4900 product page in red type). What color position(s) are you having clogging problems with, and what is the severity of the clog(s)?
The 4900 uses ConeColor Pro HDR inks, which are the same as ConeColor Pro for the 7880/9880, 7890/9890 (with VM + VLM), but with the addition of orange and green inks to make the HDR set. You can find the ConeColor inks and refill carts for your 4900 here: http://shopping.netsuite.com/s.nl/c.362672/sc.11/category.67617/.f
Please let me know if you have further questions or if there's anything else I can help you with.
Best regards~ Dana