Does anyone have any idea as to what might cause this type of problem, our last trip out to the dunes my daughter's quad was running great ('02 Polaris Scrambler 50) until we went on a long ride and through some larger dunes. It was doing great on the flat ground, had plenty of power and would reach top speed no problem, then trying to get up a hill it lost all power, she kept the throttle pinned, but the tires wouldn't spin, the rpm's were really low, I'd lift the back tires and it would speed up until a load was put on them, then it would bog and wouldn't even try to spin the tires. On the previous trips it would never bog, if the hill was too steep the tires would just spin and dig, they'd never stop spinning until she let off the gas. Here's the part I don't understand, I was going to check the clutch and see that everything was ok, but before I tore into it I tested it in my garage, I can sit my 220 lbs on it and hold the front brake and give it the gas, it will spin the rear tires and push the front tires across the concrete floor while their locked up skidding along the floor!!!! Then I tried pulling the rear brake as well, this barely stops it and it bogs, but the rpm's are still much higher than they were in the dunes. Let off the rear brake and lean back and it will pull the front end up and take off!!! Now what would cause this bogging in the dunes??? The quad was being used a lot and I even noticed it wouldn't pull me around that well one night I tried it out, this has never been a problem before, I've ridden this thing up small dunes before that it wouldn't even attempt to go up the last time out.

The only mods it has are a new CDI unit with no rev limiter and larger front sprocket, both of which have been on for a while, I didn't change anything from previous trips.

I would assume it has to be a simple problem. One question about the CDI, should I have re-jetted after putting this on, it has run great the first few years so I didn't even try jetting it. Just a thought, but I don't think that's the problem as it has been fine for previous trips, but I could be wrong.

 

I have the same problem with my dauters pred 50. What we have found is that the plug is fouling out because the bike is running alittle rich from the factory as other people on here have had the same problem. We just pull the plug, clean it off, and it runs as good as new. I haven't had the time yet but I want to lean the needle one notch and see if that helps. I have been very surprised by how much power that 50 has and the size of hills that it has climbed. Good luck with yours and hope this helps alittle.

 

Thanks for the info, but I don't think I have the same problem. It has been great the past few years, this is a new problem, I'll still look into that though, maybe the slightly higher altitude contributed to it, could cold weather make a difference?? It wasn't that cold, just cooler than our usual riding conditions, like 60 as opposed to 75 or 80??

I just tested it again today and without doing anything different than last weekend I am able to pull BOTH brakes and it will still move forward when given full throttle, I can't even make it stop now!!!! So this is much different than last weekend when a little hill would stop it and it would just bog like crazy. I don't know if it could have something to do with heat??? When it gets hot it may lose power???? I just don't have a clue as to what might cause that. We're going out again this coming weekend, I'll check it out first thing on some hills and see how it does and then after a lot of riding I'll try it on the same hill and compare to see if it's only a problem after riding it a lot.

Right now the thing has amazing torque for that little engine, I just need to find out what caused the power loss the last time we were out. Any other ideas???

I just checked the air cleaner and it was a bit dirty, I cleaned it and also changed the fuel filter just to rule that out as a possibility. Everything seems fine now, we'll see what happens next weekend...

 

Have you removed the restrictor from the head pipe? A washer that sits between your head pipe gasket and the head pipe... take it out and throw it away.

 

All restrictors were removed the minute I got it home when new!!!! The best mod I've made is the aftermarket CDI, it's almost twice as fast as stock with this upgrade and a taller front sprocket.

This problem only showed up the one time, I haven't had it out since, just trying to figure out what the cause could be before our next trip.

 

.

Temperature, Altitude and Humidity on Jetting dramatically impacts how a 2 strock performs.
For details, surf bottom section of: - Press here for Web Page link -

Just wondering, did you recently clean your air filter??? Silly question, but our Pred-90 had a dead spot when going above 3/4 throttle in my -20s winter weather. I thought is was lack of properly set jets. It was. But what really compounded the problem was our dirty air filter. Something I missed during my last 2 end/end maintenance cycles. For a picture, surf: - For picture, press here -


Note: You may want to bookmark http://justkdx.dirtrider.net/printcarbtuning.html Good stuff that might come in handy in the future as well....


Hope this helps...

.

 

JBennett, Might be a little off topic but where can I get an aftermarket CDI for my daughter's 2002 50? Great bike just to slow.

 

I know there are a few places for aftermarket CDI's, but I have Trinity Racing local to me and was able to have them order one for me. It was a few years ago, but if I remember correctly, it was under $100 and you couldn't just plug it in and go. I had to rewire a few things and get rid of the safety tether which was never used anyway and it can now be started without the ignition key if you kick start it, you can only shut it off with the on/off switch by the starter button. I remember this being a bit of a problem to figure out, but after calling Trinity and some trial and error, I figured it out and it has been trouble free for a few years since installed. I think I had to reverse the wire on the on/off switch to make it work properly, it was sort of a pain, but worth the trouble in the end. The only problem if you can consider it a problem is cold starting, it starts just fine, but for some reason revs pretty high for a minute or two, so you have to stay with the bike and hold the brake or it will move on it's own, not much of a problem, just different than stock, may have to do with the automatic choke, not sure, but after the inital warm up it's fine for the rest of the day.

I did this mod along with the larger front sprocket at the same time and this made a huge difference. She can ride with the 80's and 90's in the dunes and stay with them for the most part, their top end in faster, but not by much when they're stock. She even pulled on a Dinli 90 the last time we were out, he must've been having problems as I don't think that would be normal. Then her quad started acting up so the others were going up the hills that hers was dying on, hopefully it does better this trip, if not I'll try re-jetting, that's the only thing that may make a difference. I'm debating whether or not to move her up to a 90, they're not much bigger in size and not much faster, I might be better off putting a 70 kit on hers and running it for a few more years until she moves up to a 150 or something. Not sure, our riding season is nearly over, I'll have to do some research over the summer and figure out what to do for next season.

Here's a link to Trinity Racing, I know there are a few other kids racing sites (Hetrick and WRH) I've just never had any experience with them although I've heard good things about them reading other posts. I went with Trinity as they are local to me and had what I needed at the time.

 

JBennett, have you got the Scrambler 50 working yet? I was thinking maybe your aftermarket cdi could be fried. Sometimes those little electronic gizmos don't act up untill they get good and hot from the heat of the motor. Question - What gearing did you go to? I put an after market cdi on my sons Predator 50 and was sold a 19 tooth front sprocket (15 is stock) and it doesn't seem to wind out as it should, too tall I guess. Stock the Predator goes about 15 but with the new cdi and front sprocket it goes about 18, I was hoping for more. Appreciate your feed back and hope you got yours going.
Cutttervac

 

Either engine over heating, losing power and/or the jetting needs to be adjusted to these long runs and heavy loads of running in the sand.
These units will be sensitive to tire pressures also.
Only other thing that comes to mind is the tranny bearings may be wearing or you need to replace or replenish the fluid.
Check and see how easily it rolls on a hard surface, easy is good but if you feel a drag it might be time to service the brakes.
To tight of achain adjustment will also limit the capability of the quads speed and power.