I bought my son a sunl 70 for christmas we got it all set up and runs great drives great awesome toy. The problem is that it is an automatic. When he tries to go up a hill or gets into some mud he is stuck and I have to go rescue him. What can I do to get more low end power it has none. I pulled it up to a curb on the street with no rider and it will not climb it. The top end is awesome it will haul my 190 lbs at 35 mph. It just does not have any low torq. Any help other than buying a motor equipped with a manual tranny?

 

There are alot of complaints about the sunl tranny being geared too low. I saw someone here was able to get a bigger rear sprocket and chain to get it some more bottom end. Thats all you can do except sell it and get one with a semi auto.

 

We have a sunl 70 and it performs satisfactorily with a 70 lb rider on moderate rolling hills around the yard and pasture (rises of 50 to 75 yards at 30 to 45 degrees). I've seen starts and stops on these hills but, on occassion, after a stop, a left or right turn is required to regain momentum. If I hold the handle bars with no one on the bike and give it gas on concrete, it will spin the tires.

This is pretty much the limits of the bike, however. If you add a heavier child, say 90 plus lbs, the performance is noticeablly diminished.

So far, the 70 cc has held up to my daughter's riding habits. I can see however, that if I had a son or if my daughter were to become more aggressive, the 70 would be inadequate. I can also see that performance would be unsatisfactory with any significant mud.

There's only one way that I can think of that would increase bottom end power: a sprocket change. A larger rear and/or a smaller front could help. A larger rear sprocket would likely require removal or modification of the "stump jumper." I'm not sure about the front. Unfortunately, I dont know where to get the sprockets needed. Perhaps someone has done this and can let us know.

For what it's worth, I think that some of the people who have bought brands similar to the sunl have ended up with bikes that have transmissions geared even higher. Perhaps they have found sprockets and can chime in.

Rodney