YT125 rear suspension build

[dieseldigger]

Love this little trike for cruising around at the lake but it's killing my back! Time for some rear suspension. I found a YTM200 roller with a rear suspension kit but it won't fit the 125/175 frames so I'll have to modify it to fit. The 200 swingarm is way too long , so I have to shorten it. Does anyone out there have a pro-tec or S&D kit that they could measure the swingarm length? Pivot to axle. It'll probably be easiest to cut the tubes out and make a box section arm using the existing pivot tube and carrier brackets. I'll have to fab a top shock mount and chain tensioner. Get a 520 front sprocket and probably some YTM200 rear brake cables.
First step is a little frame strengthening around the swingarm pivot.

[ATC King]

I'm on the fence about permanent modifications to a good frame, considering most of those kits were for when suspended trikes hadn't filled the market and now many are available.

I do hope you get a solid build out of it though.

Shortening the existing swing arm, the way it's made, is probably going to be more work than you think. Starting from scratch may actually be easier. I think the kits for the 175 actually had a very short, cast aluminum swingarm.

[dieseldigger]

A little bracing around pivot. Shortened the swingarm 5". Mocking up for sprocket alignment and shock placement.266903266904266905

[dieseldigger]

Got back at the little 125. Finished the swingarm and the top shock mount.267160267161

[dieseldigger]

Modified the chain tensioner to a spring type. Widened the ridiculously narrow yt pegs with the ytm donors.
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[dieseldigger]

Figured I might as well freshen up the engine. New top end, seals, clutch plates with heavy duty springs, rebuilt injection pump and new recoil spring.
Rebuilt a gen 1 250r shock I had laying around.
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[dieseldigger]

Realized the 250r shock is WAY too stiff both in spring rate and valving for this kind of suspension leverage ratio. Ended up using a 79 Suzuki RM100 shock I pulled out of the shock pile.
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[ATC King]

That turned out nice.


Kudos on keeping the oil injection too. It certainly makes refueling simpler. Something to think about is a lot of people remove it from bikes and trikes, but I don't personally know a single person who's removed it from their boat engine, which is more expensive to rebuild.

[dieseldigger]

Still waiting for the top end to be finished. Gotta order some cables too. Going to try to make an airbox by modifying the original and using a Uni pod filter.
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[dieseldigger]

Well, finally finished. Works great. Lifting the rear end changed the steering geometry enough to allow the front end to bite WAY better. Opening up that ridiculously restricted airbox made a world of difference in power for the little 125. I've gone from a 110 stock main to a 160 and I think I'm going to be up over a 180 before it's correct. Just been cruising around on it breaking in the top end. Haven't had it on the main a whole lot yet. LOL. The rear suspension makes this a whole different riding experience as you might expect. Terrain that used to bounce you around, try to kick you off and destroy your spine, is a piece of cake now. It's too bad Yamaha wasn't able to suspend these things from the factory. It really makes it a fun little trike.267986267987267988267989

[dieseldigger]

1981 185s is next! 1st gen 250r front end with probably a 200x based rear end. Unless someone has a suspension frame or kit I can buy......!!!!
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[Zoila]

I have to say very nice job of that rear suspension. You should make & sell kits, there are alot of people with 125/175 out there wanting them.

[Trialf3]

Sell me that swing arm for the yt125. It looks great.

[newc14]

This is an amazing build, and probably what I will end up doing unless the Trike Gods feel generous, the planets align, and I find a four leaf clover. If all that happens, maybe I'll be able to find a Pro-Tec kit.

Would you be available for contact regarding the details/specifics of this build?