Thanks for getting back to me! 

The mechanism I have is the reduced mechanism for a surrogate diesel, so less species and reactions than a complete mechanism. The issue I have is that I need to be able to compare different diesel mechanisms but with the limits I am unable to run them. The majority of the species are the reaction intermediates which are needed to simulate the combustion. I will look at if there are any species that can be removed, my only fear is that it would then not run properly.

I have the student version of Chemkin on my personal machine, however at university I have access to the academic version, but with the current situation I do not have access to it. 

Thanks again for getting back to me!