Sprocket Questiion

[Vealmonkey]

I'm putting a mx175 engine into my yt175 trike. I know the mx175 rear tire is way larger and the sprockets are geared to make the engine run in it's best range in the dirtbike. What kind of sprockets would I have to run on the
yt175 to run the mx175 engine in it's best range while on the trike? I would guess the transmission gearing is different between the dirtbike and the trike. I was trying to search the forums and didn't really notice anything that addressed this situation. I would also guess as people are putting dirtbike engined based trikes together that they would have run into similar problems. There is one thread that says for every 2" you reduce wheel diameter, that you should increase the front counter sprocket one tooth or change your rear sprocket 3 teeth less. IF I followed that formula on the
mx175, does that mean if I go from the original tire diameter to say 20" which would be the tires I am running on the yt175, the resulting addition or subratction of teeth should give me the proper rpm range for the mx175 in the trike? Maybe members that have built a dirtbike based trike can chime in on this and give me an ideal if this is good or bad info?

[JohnR.]

That formula you are using is a little flawed because it is assuming that you are keeping the same size sprocket on the rear but if you're going from a dirtbike to a wheeler you're not going to have the same size rear. What was the stock rear gear on the MX175 and what was it on the YT175? What was the stock rear tire diameter on the MX175 and what tire diameter are you running on the YT?

John

[Vealmonkey]

The data for the mx175 and the yt175-front sprocket, rear sprocket, rear tire

mx175 fr-15 rr-45 3.5x18-4pr

yt175 fr-11 rr-39 20x11x8 or
18x11x8

No idea of the 3.5x18-4pr tire circumference