Cycle Mechanics | Yamaha 125/175 Hop-Up

I love the old performance modification articles. This guy Don Vesco looks like the man and apparently knows his shit when it comes to modifying 2-stroke bikes. If anyone reading this has any old enduro/dirt bike magazines from the 60’s or 70’s they want to sell, i’m interested.


5 responses to “Cycle Mechanics | Yamaha 125/175 Hop-Up”

  1. Brian says:

    Awesome. I have to do the hop-up. I’m tired of getting dusted by you guys in the 175s.

  2. Carson says:

    I imagine that the bottom ends are the same between the DT125s and 175s. I’d be interested to see if the stroke is the same for both motors, if so, you could probably just pop a 175 top end on a 125 bottom end. You’d definitely have to open the cases up to allow for the extra girth of the cylinder skirt on the 175 cylinder, but you might be able to get away with it without having to add any meat to the cases.

    I’ve been toying around with the idea of doing it to my 250 with a 360 top end, but 110 CCs worth of girth is a lot more than 50.

  3. Ed says:

    The strokes are the same. The ct/ 4 bolt dt 175 cylinder on the dt 125 bottom end was a common mod.

    The hop up article for the reed valve ct2 175 is a great read. You can find it by scouring the web.

  4. jeff says:

    I have a 69/70 ct1 175. I want to put a 75 dt175 cylinder and head on the ct case. Is this possible?

  5. Bill Van Velzer says:

    I remember having the cylinder mods done back in the day for my CT-1 and the difference was like night and day. There’s no doubt I was competitive in the 250 class. Reliability suffered though, as it was a screamer and shorter engine life was the price I paid. It was more temperamental, too. But when it ran, it really ran. I still smile just thinking about it.

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From Past

Published - Jul 30, 2018

Bowers beach ride

Saw a cool fiero. Got stuck behind some slow ass Harley’s on Rt9. JP’s Wharf Crabs. Fishtown tavern. Tired.