QT50 Yamahopper Cafe - Issues
- Thread starter kwazykid
- Start date
JustinLonghorn
No Purple Hearts, No Blue Ribbons
Re: QT50 Yamahopper Cafe - New Engine In!
Hell yeah man, that thing sounds great and moves!
Hell yeah man, that thing sounds great and moves!
kwazykid
Been Around the Block
Re: QT50 Yamahopper Cafe - New Engine In!
It's so close! We got a few things finished yesterday. It finally has a center stand, no more wood block. It took us 2 hours to modify the old center stand. We had to keep changing it due to the new muffler being lower. I distressed the tank and actually really like how it turned out! (poor/lazy man's paint job). Cloudrider got a higher wattage headlamp to accommodate the 6v battery and it works well. We worked a little with the carb and it's running well. We played around with the placement of the taillight but didn't like it in any position so Cloudrider is going to find an alternative. No pics, it was too dark when we finished last night. I'll get some up soon.
It's so close! We got a few things finished yesterday. It finally has a center stand, no more wood block. It took us 2 hours to modify the old center stand. We had to keep changing it due to the new muffler being lower. I distressed the tank and actually really like how it turned out! (poor/lazy man's paint job). Cloudrider got a higher wattage headlamp to accommodate the 6v battery and it works well. We worked a little with the carb and it's running well. We played around with the placement of the taillight but didn't like it in any position so Cloudrider is going to find an alternative. No pics, it was too dark when we finished last night. I'll get some up soon.
kwazykid
Been Around the Block
Re: QT50 Yamahopper Cafe - It's Scootin'
Sorry for the lack of updates recently. I was busy moving to Ohio. And I've been without internet for a week. We have managed to get the bike to a really good point.
Cloudrider found a fender when he was in California that I cut up and mounted.
Here's a shot of the electronics under the cowl.
And here's some shots of the whole bike.
I'm not sold on how the tank turned out. I was going for a rugged, beat up look but it's not quite there yet. I'll take some sand paper to it soon and see what it comes out like.
Questioning the precision of the speedo, I used a gps speedo on my phone. Earlier this week I was hitting about 37 mph and got it up to 43 on a nice hill. Today I took it out and was hitting about 40 on flat road and hit 47 on the same hill! Close to the half ton! More pics soon!
Sorry for the lack of updates recently. I was busy moving to Ohio. And I've been without internet for a week. We have managed to get the bike to a really good point.
Cloudrider found a fender when he was in California that I cut up and mounted.
Here's a shot of the electronics under the cowl.
And here's some shots of the whole bike.
I'm not sold on how the tank turned out. I was going for a rugged, beat up look but it's not quite there yet. I'll take some sand paper to it soon and see what it comes out like.
Questioning the precision of the speedo, I used a gps speedo on my phone. Earlier this week I was hitting about 37 mph and got it up to 43 on a nice hill. Today I took it out and was hitting about 40 on flat road and hit 47 on the same hill! Close to the half ton! More pics soon!
cloudrider
New Member
Re: QT50 Yamahopper Cafe - It's Scootin'
Hey kwazykid, I'm glad you're enjoying it. I miss it already. I guess I'll have to build another for me, actually, for your mom and younger brothers. I really like what you did with the fender. It's hard to believe the difference from what it started out as. Here's a pic of the fender as I found it at Myrons Mopeds in Fullerton, CA.
It was originally the rear fender for a Sparta Fox. Myrons is almost like a moped museum, tons of old stuff. He sells new Tomos bikes too.
Hey kwazykid, I'm glad you're enjoying it. I miss it already. I guess I'll have to build another for me, actually, for your mom and younger brothers. I really like what you did with the fender. It's hard to believe the difference from what it started out as. Here's a pic of the fender as I found it at Myrons Mopeds in Fullerton, CA.
kwazykid
Been Around the Block
Thanks for the compliments guys!
I took it out for a ride today and was having a great time! There's this great hill close to my place and my speedo (not sure on accuracy) read close to 60mph. If that is the case then Hooray! I hit the Half Ton!
Well, the very next stop sign proved to quell my excitement a bit because the engine died immediately. When trying to kick it back over the kick start was quite stiff but loosened up after a few cycles. I kicked it 15 to 20 times with no luck. I began to walk it back home. About a block later I tried again and it started after 5 or so kicks. It seemed to run fine but again died at the next stop. I got it started again and made it home but had to keep the throttle open a bit in order to keep it running. I talked to Cloudrider a bit and he suggested I try to adjust the idle screw. It might be running too lean as well and pushing it so hard caused an issue. I'll see what I can figure out. Any other suggestions?
I took it out for a ride today and was having a great time! There's this great hill close to my place and my speedo (not sure on accuracy) read close to 60mph. If that is the case then Hooray! I hit the Half Ton!
Well, the very next stop sign proved to quell my excitement a bit because the engine died immediately. When trying to kick it back over the kick start was quite stiff but loosened up after a few cycles. I kicked it 15 to 20 times with no luck. I began to walk it back home. About a block later I tried again and it started after 5 or so kicks. It seemed to run fine but again died at the next stop. I got it started again and made it home but had to keep the throttle open a bit in order to keep it running. I talked to Cloudrider a bit and he suggested I try to adjust the idle screw. It might be running too lean as well and pushing it so hard caused an issue. I'll see what I can figure out. Any other suggestions?
cloudrider
New Member
Hmm, so you normally hit about 40mph on the flat and it's twisting around 10K rpm when doing so. If you are going down hill with the throttle wide open and hit 60mph, that means you're twisting close to 15K rpm with the same amount of throttle setting that would normally only get you 10K. I think you overheated it. Not enough fuel and oil to keep it cool and lubed at that high of revs. I know you're running about 38:1 fuel to oil and you are using that expensive full synthetic Motorex 2T oil but twisting that high with out it being loaded to need more fuel/oil probably overheated it.
kwazykid
Been Around the Block
I messed with the idle screw and got it to start no problem. I took the screw a full turn in and it was idling a little fast but not bad. I backed it out half a turn and took it out for a spin. It seemed to run just fine. Maybe it was a minor overheating. I'm gonna do a plug chop to figure out how rich or lean I'm running. I'll just have to accept that she's not meant to travel faster than 40mph.
cloudrider
New Member
It sounds like you didn't hurt it too bad, and i don't really think the idle screw had much to do with it or at least was an unrelated issue. I know the jetting was pretty close if not a slight bit on the rich side when I had the bike here but a proper plug chop would be a good double check.
Erskine
Over 1,000 Posts
See ....... the only way you're going to slice through that half ton barrier without melting the engine is with one of these fairings:
http://www.vintagebike.co.uk/pictures/1970-50cc-roton-kreidler/#.UDdh-MFlRf8
There are 3 very sound scientific reasons why:
1. You know you want to.
2. It would look beyond cool.
3. More surface area to put stickers on.
I rest my case.
http://www.vintagebike.co.uk/pictures/1970-50cc-roton-kreidler/#.UDdh-MFlRf8
There are 3 very sound scientific reasons why:
1. You know you want to.
2. It would look beyond cool.
3. More surface area to put stickers on.
I rest my case.
kwazykid
Been Around the Block
Wow, with all that surface area for stickers I could break a land speed record! Beyond cool is a place that I wish to go someday. I've been considering lately how a 3/4 fairing would look on it, I just don't have time or money right now for that, maybe in the future.
What I do have right now is a father that has been bitten by the mod-bug
Cloudrider has already been improving upon our original design. He found a 60cc direct swap jug for the QT engine and has already got an order into MLM for a new pipe that will help with low end. As of right now, off the line is just too sluggish to keep up with traffic and I don't feel safe when I've got cars right on my tail after a stoplight.
What I do have right now is a father that has been bitten by the mod-bug
Cloudrider has already been improving upon our original design. He found a 60cc direct swap jug for the QT engine and has already got an order into MLM for a new pipe that will help with low end. As of right now, off the line is just too sluggish to keep up with traffic and I don't feel safe when I've got cars right on my tail after a stoplight.
SoyBoySigh
Been Around the Block
What an awesome little bike! I can't help but think of a few improvements - I'll bet it stops well, what with the weight, but I still love the look of an over-sized drum-brake. The main reason to re-build some wheels - maybe there are some BMX aluminum rims out there for cheap. Most of 'em are 36 hole, matching with most drum hubs. The rolling inertia would be cut in half, going from a chromed-steel rim to an aluminum one, and on top of that go down to a tire and tube with a quarter of the mass. The thinner lighter bicycle spokes and softer tires might even help with suspension. Or, the right diameter of wire-spoked drums might just bolt straight up to some kind of Honda Monkey style rims, for a fat 8"-10"-12" scooter tire. Something like a CB350 drum would probably just tuck right into rims like that. And there are plenty of Aluminum rims made for those bikes these days. I still like the BMX idea though, rather than fatter tires I think weight is the biggest consideration. And me, I'm so pre-occupied with wheels and wire-spoked wheels it's like some kind of fettish. Damn I just love the shaft drive on this thing. Anyway yeah, I'm thinking you could save a heck of a lot of weight on those wheels with some alloy rims, and at the weight and attainable speed I wonder whether bicycle tires would be reasonable. Probably not something you'd get past a safety inspection though. Ha ha. You don't NEED to do all that shit though, as your creation is beautiful enough as it is. - That's the thing you've pulled off here, is making one of these putt-putts BEAUTIFUL. Who'd have thunk it? An amazing transformation. This is going up on my screen saver along with all of the other great café bikes of the world. The QT sure is an interesting design, with the engine moving integral with the swingarm, much like a modern scooter's CVT tranny - this must simplify the shaft-drive a whole lot - no shaft jacking I'd bet. They could have done a typical CVT style, it was around at the time - but this design probably saves a massive amount of weight over a typical lay-out. As such, I see it as imperative to build the rest of the bike as an ultra-light. Obviously, you don't wanna dump a huge amount of cash into this, but there's potential to use one of these things for a really competitive racer. Even an Electric, a motor in-line with that shaft would probably cool a lot easier, with the air-flow. Or a 50cc fossil class racer, obviously. Gotta be another barrel and head that could fit to that motor too.... Back to the chassis I think some kind of brazed chromoly or alloy would cut the weight down big time. Or even carbon-fiber. I mean, what with the way it all hooks together there's so little attachment points to factor in, it could be so simple. That main motor mount could utilize the crank of a standard bicycle frame with a polyurethane bushing to fill out the difference, so maybe there's a crashed/cracked carbon-fiber bicycle that would donate what's needed, it wouldn't need any construction done. I also think the telescopic fork is a lot of weight on something this size - there are those small springer forks made for banana seat bikes, maybe that would weigh a lot less - with some friction dampers like an old Girder fork. Then again, the fork sure lends an appearance of a "proper" motorcycle to the whole thing, as does the tank and seat. Your solid welded frame has gotta reassure the rider that the thing's not gonna fold in half and eat his nuts off. But yeah, what I see in this bike is an awesome race scooter that could blow away all of the modern stuff, not by making more power (though MAYBE that can be dealt with too) but by stripping away all extraneous weight. Maybe some kind of stream-lining on it, or the rider laying flat out superman style wearing a speedo just like Rollie Free! A small fairing would go a long way on this thing, the thing's so small that really the only thing to streamline would be the rider's ass. Compare that to the typical 50cc scooter. They've probably got rules about having to use the original frame, but heck you don't have to put the seat in the normal position. Maybe one of those reclining bicycle set-ups would mate to it. That's the one truly ridiculous thing about those streamlined bicycle racers ... well the most ridiculous thing - is that they don't simply stick a 50cc engine in there. I'm not saying this is what you should do with YOUR bike of course, I'm just saying, the GT50 is such a simple lay-out that you could put it on practically anything. I wonder if that shaft-drive hub would mate to a skate-board wheel, or one of those powered side-walk "scooters" -it's a huge power up-grade for one of those little things. Know what I mean? It's just such a compact complete engine and drive-train it's ridiculous. I guess the shaft-drive robs a lot of power, which is what I've always criticized about the typical CVT drive scooters out there these days. Gave my kid $ for a scooter for her 14th, didn't wanna cramp her style and TELL her what to get - she bought a Jazz/Metro. It really chaps my ass that we didn't fix up my old Passport instead, 'cause there's so much you can DO with them. The really trick thing would be to figure out which of the clone engines would fit to a KZ250/KZ305CSR belt-drive pulley, and save that much power over the chain-drive - then you've got something as clean and tidy as the shaft but without all of the power losses. That's what I'm trying to figure out now - which is to say, I've got ENOUGH bike projects. But this build is inspiring. Even on top of all the other shit I'm already doing: the KZ café for the kid and my DOHC Honda, another DOHC Honda in the near future for the kid, and the old C70 Passport and spare C70 frame which is begging to become a duplicate "his and hers" matched pair of duelling pistols - STILL, even with all that on the books I'd still love to dig up an old QT50 and play around with all the images swimming around in my head.
-S.
-S.
