As I am having issues locating a set of mc21 cases and i do have a set of MC18(5K) cases, can I use these cases to build up an engine suing a 21 crank and cylinders? Done a read of the forums but its not clearly answered as a yes or no.

cheers,

C13

Hi Mate
There is a topic on that . I am shore it said if you machine 2mm of the crank they fit.
or japan auctions or e-mail onerace@starhub.net.sg.

thanks I have been following that thread along with previous others. Question should have been posed differently, what is the disadvantage of using MC18(5k) cases for a mc21 engine build? I do understand I can get 21 cranks to fit with machining. Is there anything else that would need to be done?

If it is easy to machine the mc21 crank to fit the mc18 cases it should be a advantage over the 21 cases as the porting on the mc18 is a bit better.

i fitted a 21 crank in my 18 as i got it new from fire foxracing . they were supposed to sell me a new crank for my 18, but due to a mix up it was sold to some one else. to remedy this( as i had paid) they had a new 21 crank which they sent me . this obviously didn't fit so i sent it back and they machined 2mm off it to make it fit!
runs fine and had no probs with it at all!
maybe as the 21 crank is now lighter than standard it spins up faster.

Txs DB & NSRDU

I will touch base with a few machinists and see what it will take.

cheers,

C13

You may find that your MC18R5 cases only support neutral whereas the MC21 has a 6 position GPS (gear position sensor) cable coming from the gearbox.

I'm not 100% sure of this but your PGM3 may need that feed to allocate the ignition curve to each gear.

If this is the case I'm not sure if theres a workaround. Others may have tried this and have a solution. Perhaps you could somehow choose a safe map for all gears and lock that in with a bit of solder somewhere?

Or use the PGMII???