Can I put a Yamaha 175 engine in place of my 125?

[bobotech]

I am just curious. I have a nicely running 125 but would not mind more horsepower. Is the 175 a bolt on affair or do you need to do more than just swap engines?

I'm also pretty sure that you can just swap the front forks from a 175 onto a 125 trike, correct?

[atc350xer]

According to another board member, you could put a 175 head on your 125, even simpler.

[bobotech]

Really? So that would in a sense make my current engine a 175? And what about the carb? Would that need to be rejetted?

[cox]

The bottom end is the same on both machines from what i understand. You do need the carb and i dont know about the fuel pump. The forks from a 175 bolt directly on the 125. Done in about an hour, awesome upgrade....
http://i53.photobucket.com/albums/g55/Bodar/Trikes/HPIM3457.jpg

[Grizzlypeg]

According to another board member, you could put a 175 head on your 125, even simpler.

Would have to be head, piston and cylinder to increase the displacement, assuming it is correct that both have the same stroke.

[cox]

It is, i believe you can also use a it175 like 1979 or something and get a manual clutch out of it as well. I know the whole topend is needed to swap over as well as the carb and exhaust. The 175 has a vacuum operated fuel pump, and the 125 is gravity fed. So i dont know about that.

[Vealmonkey]

Once again, the 81 and 82 yt125 are totally different from the 82 and later 125. You can put a 175 top end on an 82 and later 125, but you don't have as many clutch plates and fibers as the yt175 engine has. And the 82 and 83 yt175 clutch packs are slightly different. So you can have more power for your 125, but you won't have as heavy duty a clutch as the yt175 has. Now the yt175 clutches might swap over, never tried myself, but you would need the whole clutchpack at least and possibly the clutch cover. Also the yt175 has a larger gas tank and has a vacuum operated fuel pump and the yt125 does not. Also the cover for the yt175 fuel tank has an air inlet and airhose intake system that the 82 and later yt125 does not. You can also swap the top end for a 77-78 it175 and get a way better stock ported cylinder and piston and it has way better port timing as well. and if you really want to do it up, you can make the yt175, not sure about the later yt125 cases, a manual shift if you are feeling really crazy. You can also swap out the ytm200 front forks for the
yt125 or yt175 forks, but you have to swap out the yt175 steering stems or make a custom sleeve for the ytm200 forks. The ytm200 forks are way better than the yt175 forks. And of course the yt175 forks are a bolt on swap for the yt125 forks, no mods at all. Then all you need is to find you a Pro Tec bolt on suspension kit!!!!!

[bobotech]

Well I was asking about the YT175 engine because someone has a complete engine for sale. They said "would be great for go-kart" so I'm assuming that it is complete with the tranny and all.

I bought a set of 175 forks today, do I need to change the axle or spacers or anything? The front end is complete minus the axle and spacers.

[Vealmonkey]

You can't use the yt125 axle and spacers on the yt175 front ends. The yt175 front end is wider than the 125. The complete yt175 engine will bolt in. There just will be no vacuum fuel pump and the exhaust between the yt125 and yt175 is different. If you go aftermarket exhaust it won't matter depending on what exhaust you use. Bassani exhaust were engine specific, most other exhaust makers would fit either engine.

[bobotech]

You can't use the yt125 axle and spacers on the yt175 front ends. The yt175 front end is wider than the 125. The complete yt175 engine will bolt in. There just will be no vacuum fuel pump and the exhaust between the yt125 and yt175 is different. If you go aftermarket exhaust it won't matter depending on what exhaust you use. Bassani exhaust were engine specific, most other exhaust makers would fit either engine.
Here is a set of pictures of what I bought today.
http://s904.photobucket.com/albums/ac245/bobo_snyder/YT175%20fork/

What do I need to get for the front end now in the way of parts. The shop I got the forks at didn't have any more parts.

[Vealmonkey]

You still have some parts to buy. You will need the axle and hardware. You will need the front brake drum set-up or you will have to make some spacers. You will need a front brake lever and the barrel and the spring and the adjuster nut for your brake cable. Not sure what swaps out headlight wise, but if you have 82 and later yt125, I think all the headlght stuff swaps out, but can't remember exactly. Get placing that ad for parts in the classified section. You can still get all the brake cable bits at the dealer.

[bobotech]

Okay sounds good. So from looking at my pictures, is that the correct fork assembly that will work on my trike?

[Vealmonkey]

Yes, that is a yt175 fork assembly and it will work on your bike. Now get shopping for the rest of your parts. Best of luck. You will enjoy your new front suspension once it's all in place and working. The front brake is a nice touch also. But even better is if you find the rear suspension. They are out there, just haven't seen one in a while.

[bobotech]

I see the front backing plate and shoes for sale but what about the drum itself? Where do I find that or is the rim itself act as the actual drum?

[bobotech]

Oh never mind. I see the drum is part of the axle and hub assembly.

[cox]

I knew vealmonkey would chime in and set this straight. I have all this info written down somewhere but because of my teenage years, i dont have the best memory anymore, lol. I didnt know about the 175 clutches being different than the 125's though. I was thinking of pulling the 125 motor and swapping out for a 175 as i have a spare i have rebuilt. So instead of just the topend ill guess ill swap the whole thing. I have hit the bottom of the barrel trying to find the IT175 parts here locally.... lol I guess im gunna have to go look at the machines, TO THE BATCAVE!!!