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1978 IT 250 Port Map
- trailblaze
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1978 IT 250 Port Map was created by trailblaze
Cheers fellow enthusiasts, I am in the process of rebuilding a trashed '78 DT 250 MX and try to figure out some proper power for that bike. Could anyone supply me with a port map of a '78 IT 250, so I can compare it to my jug and start my modifications from there on?
Thanks in advance!
Thanks in advance!
24 Jan 2025 13:40
#1
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- Ht1kid
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Replied by Ht1kid on topic 1978 IT 250 Port Map
Greetings from Tennessee
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24 Jan 2025 17:55
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- RT325
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Replied by RT325 on topic 1978 IT 250 Port Map
Greetings from NZ. All trail DT's IT'S & genuine mx race models plus YZ's are 70x64 around your year except for the last IT250 by memory which might be "84L model went long stroke. So maybe any IT or YZ from "72 on within reason would wake it up. Need pipe & compression of course but I'm sure ya onto all that. I put a long strike 360 crank in one of my DT1 250's but had a DT1MX cylinder & head as well so it sure went well. But that was a life time ago.
24 Jan 2025 20:06
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- RT325
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Replied by RT325 on topic 1978 IT 250 Port Map
Found this below in this link here. Not sure if it helps. yamaha-enduros.com/index.php/forum/74-76...0b-cylinder-port-map
www.3wheelerworld.com/showthread.php/125151-yamaha-porting-book
www.3wheelerworld.com/showthread.php/125151-yamaha-porting-book
24 Jan 2025 20:47
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- trailblaze
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Replied by trailblaze on topic 1978 IT 250 Port Map
Thanks folks, that's good information. So anything IT/YZ with 70x64 is interesting to me. Maybe someone has got a cylinder sitting somewhere and is feeling the itch to make a map
I think I will go all in with weight reduction, suspension work, bigger carb and reed block and a custom or modified pipe. Electronic ignition and some work on the air intake will make it complete.

25 Jan 2025 06:56
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