Author Topic: TU250X tuning  (Read 450 times)

Offline mr72

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TU250X tuning
« on: July 14, 2020, 06:00:38 AM »
As many of you know, I ride with my dad frequently. He's been retired a few years and spends a lot of his time tinkering with his motorcycles a tiny bit and cruising Craigslist for the insane bargain that may appear.

Back when I was a baby in the early 70s and we lived in a small town in Arkansas he used motorcycles for transportation. Back then he rode a TY250 and some Kawasaki 2 stroke 350 Enduro. He has done memories of these and seems to really prefer that kind of styling and feel.

So he found a neglected 2011 TU250X for $600 and we've been nursing it back to health. He seems to find it a lot more like his 70s Enduro than his other bikes. We put a pair of shinko 241s on it and my old superbike bars. He now rides it all the time and his other bike's just sit.

Anyway, the internet isn't blessed with knowledgeable forum like this one for tu250s. Information is hard to find. The bike has a power commander 5 on it and aftermarket exhaust with an O2 sensor eliminator, and it has been misbehaving, basically not holding steady rpm with light throttle at low rpms. I downloaded the pc5 software and we reflashed the stock map and then I made one +5% across the board and we put it on, bike runs better for it. I adjusted the throttle position sensor, it was kind of way off. Helped a little. Also idle was set to about 2200 rpm and I knocked it down to about1300, any lower and it occasionally stalls when revving down.

So now I'm trying to sort this issue where it won't hold revs. With the pc connected we put the throttle at 4% and it revs to like 3k rpm and gradually goes down almost to idle and then quickly back up to 3k. Takes about 5 seconds to do this cycle. My dad says while riding on the road it makes it very difficult to ride at neighborhood cruising speeds. Feels a lot like a vacuum leak, only place I can see where it might be is the intake boot o ring or the map sensor o ring. Anyone here have an idea? Anything else I should look at? I'd rather only crack this open once and have all of the parts I need on hand.

Offline Watcher

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Re: TU250X tuning
« Reply #1 on: July 14, 2020, 01:19:29 PM »
I wish I could help you.

The TUs are fantastic little machines.  We use a number of them in my training program, they're comfortable and surprisingly peppy and I wouldn't mind having one myself.  But I don't work on them, so I know nothing about them.
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Offline mr72

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Re: TU250X tuning
« Reply #2 on: July 15, 2020, 11:12:01 AM »
Yeah it's a pretty cool bike. This one had been pretty badly abused by the previous owner. They did a sort of half-caf(e)/rat-bike/IDK-what asthetic conversion that included these ridiculous Firestone tires that look like they belong on the front of a Model T, a 5" headlight, halfway decent aftermarket bench seat, lightweight stainless little fenders front and rear and a tail light that looks like someone swiped it off of a deuce coupe.

And on top of all of that, it had been wrecked. Headlight mount was bent very badly, handlebar was bent (oh yeah, some kind of ridiculous handlebar was on it), brake and clutch levers were both chopped off and only long enough to get two fingers on, likely because the brake lever broke in the fall, rear brake pedal was bent a lot, and it has some kind of aftermarket exhaust with a very off-theme carbon fiber looking muffler, my guess is this exhaust is for a DRZ400SM. I imagine the original exhaust was crunched in the "5 mph" wreck. And then the bike had been parked after being moved from LA to TX a couple of years ago and never ridden again. But even given all of that I was going to buy it if my dad didn't. $600 was insane to pass up.

We have it mostly straightened out. I haven't ridden it because I've been unable to ride until today, but it sure seems light and easy to handle. I think the tires my dad picked for it are pretty nutty for that bike but he really wants it to be a "scrambler" and I suppose it is by now. He says it handles fine on the road but I wouldn't trust knobby tires on TX paved roads with >60mph speeds. He's had it up to 65 mph which is admirable for the little 250.

I actually think in its current condition that little bike is going to perfect for my dad to take out to their place in the country where there are miles and miles of gravel roads that you have to use to get in and out. In fact, I think it's the perfect bike for my dad to have in general and I am encouraging him to take his little DR200 up to their country house and sell his Honda Shadow in favor of the Suzuki. The TUX is newer and has less miles on it, has fuel injection, and my dad doesn't like to go fast anyway.

I am going to try to help my dad figure out how to get some stiffer shocks on the rear and probably will drop in my cut-down stock GS500 springs into the fork to firm that up, since my dad is really much heavier than the rider that this bike was built for. But it is really the old school scrambler meets enduro vibe all the way. I think it's a perfect fit for him.

He told me today that the surging seems to be better or maybe gone. I'm still going to volunteer my time to do a PAIRectomy and replace those o-rings for him just for peace of mind.

Offline cbrfxr67

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Re: TU250X tuning
« Reply #3 on: July 15, 2020, 02:07:32 PM »
where pics?  :dunno_black:                                                                                           :icon_mrgreen:
"Its something you take apart in 2-3 days and takes 10 years to go back together."
-buddha

Offline mr72

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Re: TU250X tuning
« Reply #4 on: July 17, 2020, 06:39:30 AM »
here's a picture:



We went for a ride yesterday, I took my GS and he rode his TUX. The TUX seemed to keep up fine on the backroads and rural highway we were on. Up to about 55mph for long stretches with hills and much of the rest on windy and hilly 40-45mph intermittently rough backroads. It was a good ride. Seems the tires are fine on the road. He's super pleased with it.

My GS was high strung and spunky and marvelous.

Offline gruntle

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Re: TU250X tuning
« Reply #5 on: July 17, 2020, 04:00:28 PM »
verrry sweet bike  :D

Offline mr72

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Re: TU250X tuning
« Reply #6 on: July 28, 2020, 08:06:10 AM »
My dad says the surging is almost completely healed now, he thinks it was partly if not mostly due to bad/old gas that has finally been run through. He has put industrial strength fuel injector cleaner in the last two tanks and he is convinced that's improved it too. Either way, I'm glad it's working. He says the bike is "almost perfect" in running, which is great.

However, that universal type bench seat has proven less than comfortable. He bought a bunch of TUX take off parts including a stock rear fender, stock seats (stock TU has separate rider/pillion seats) and the rear seat hoop that was removed from his frame, stock mirrors etc. I think he's in the process of returning the rear end of the bike to mostly stock and he's planning to make a rack or basket of some sort to put in place of the pillion seat. He says the stock seat is more comfortable but he hasn't done a long ride on it.

This brings me to the next question, maybe you guys have some ideas? He's over 200 lb... maybe a lot more than 200 lb I don't know. But either way he's using up half of the suspension travel just sitting on the bike. I'm sure a big part of his discomfort on this bike is due to running out of suspension travel. These shocks are longer than most, something like 14.75", and aftermarket off the shelf shocks are hard to find. Apparently some years sportsters had similarly long shocks that can be used which will have much stiffer springs given the bike is 2x the weight to begin with, but that may be overkill. Anyone have any ideas? I think the shocks are likely not capable of damping a higher rate spring anyway, so it'll take entirely new shocks, preferably something rated for a 200+lb rider but on a sub-350lb bike. Given this is a $600 motorcycle, spending $300+ on shocks is not going to go over well, so finding some donor bike to shop for take-offs would be awesome.

As for springs, the forks are 37mm same as the GS. So I think I'll donate my cut-down GS500 springs to his bike and see how that works. They were too soft for me at 200 lb on a 360lb bike, but may be just right for him at 200 lb or so on a 320 lb bike.




 

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