Was debating on getting an MX400 head so I can put a compression release on it, the bikes I've had in the past had one and I liked using it to help slowing down. Thanks, Tony

See this thread: yamaha-enduros.com/index.php/forums/74-7...amber-volume?start=0

and these pictures with MX on the left and DT on the right, for 75-76.

Thanks Jay, it looks like the only big difference is the fins that are cut down for the exhaust pipe on the DT. I'll also take a look at the thread you posted a link to. Thanks again!

The combustion chamber looks way different to me.

I didn't look that close at it, I was more looking at the fins but you're right from Jay's post the MX has a different compression ratio.

Schu, you are correct, and the other thread shows that the volume are different and resulting compression ratio on a DT400 could be disastrous unless the exhaust port was raised or you used an MX/IT/YZ cylinder.

Machine ________Part Number_________Combustion Chamber Volume in CC_____Weight of head in pounds
75 MX400_______510-11111-01-00______42.0_____________________________________4.1
75/76 DT400____500-11111-00-00_______54.7_____________________________________5.0

Stock DT400 head is 6.4:1 compression ratio, MX/YZ would be 8.33:1 if it was put on a DT400. A Webco high compression head only brings up the DT400 CR to 7.04:1, and they probably raised it as much as possible without reliability problems.

on using the 1977 IT 400 cylinder and my 1978 dt 400 head...i could not use flat washers on the head case the studs dont stick out enough cause the stud hole is a lot higher built up on the DT head then the MX head