1972 LT2 Yamaha project.

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11/4/2018 10:32 AM

Got a old bike my dad bought new and since I don't really wanna just sell it, I figured I'd make it a good town bike. Seems to be loosing rpms when you throttle up in neutral and will die if you don't throttle down. Needless to say this makes shifting and accelerating and adventure also. Was just wondering if anyone knows if it possible to put an Enduro 250 motor or something else a bit bigger than the 100 that's currently on it?

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11/4/2018 11:10 AM

What were the Yamaha models of that year? DT2, was a 250?

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Sometimes, Gravity just sucks.

11/4/2018 12:04 PM

Not sure, I've only just started looking at restoration options. Pretty sure this is a LT2 100.

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11/4/2018 12:15 PM

I know the 125/175 top ends will fit one another from that era. Not many options for the 100, displacement wise. A DT 250 is a physically much bigger engine than the 100. May ruin the bike by trying to graft one in there. If it is timed, good compression, clean fuel system, it should run fair.

It is an old bike, though, and just may be tired.

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11/4/2018 12:28 PM

Sounds good, was just looking into options for replacement if possible. Carb was just serviced about 2 months ago. don't know if the compression was checked. it does run, just starts loosing power once it's warmed up. Was told it could be flooding, but after a week of playing with the setting screws I've not been able to improve it any.

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11/4/2018 12:36 PM

RT2 - 360?

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Sometimes, Gravity just sucks.

11/4/2018 12:50 PM

JT-60
GT-80
HT-90
LT-100
AT-125
CT-175
DT-250
RT-360

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A big thanks goes out to Donnie at Morgantown Powersports and RJ at Beaver Creek Cycles

11/4/2018 5:36 PM

If it's losing power when it gets warm it is either jetted to rich or you have an electrical problem that is showing up. Remember that stock jetting for a vintage motorcycle needs to be adjusted to run the crap fuel that we have at the pumps now. Test your coil.

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11/4/2018 5:57 PM

The Debbie Downers are here. schweeett….

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11/4/2018 7:07 PM

Here is what my dad bought for me around 1984. Had 2 of them, one for parts, one to ride. Rode it all over, school, work, mx track. Heavy pig, but it was all I had, So, fond memories, I guess? Notice the dual spark plugs. Mine had the compression release welded shut, and oil injection removed. Painful to start it. This one recently popped up on Craiglist:

https://omaha.craigslist.org/mcy/d/1972-yamaha-360-rt2-enduro/6735979892.html

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11/4/2018 8:14 PM

You say the carb was serviced 2 months ago. By who? I would be a little suspect. Looks like parts are still available to rebuild the top end. Rebuild the top end, go through the carb, check everything.

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11/5/2018 12:53 AM

There is an o-ring around the main jet that if damaged, describes what you are experiencing. They get hard over time and deteriorate. Easy peasy fix if that is the issue.

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A big thanks goes out to Donnie at Morgantown Powersports and RJ at Beaver Creek Cycles

11/5/2018 6:08 AM

Whymee wrote:

There is an o-ring around the main jet that if damaged, describes what you are experiencing. They get hard over time and ...more

Had one of those O-rings go bad on a 76 YZ80. It always ran rich, as unmetered fuel was leaking past the o-ring.

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