I've asked in other threads but not received any responses, so I'm giving this question its own thread.

What top speed are owners seeing with their LT-A50's? (The 2-stroke version, 2005 and prior.)

I have removed all of the restrictions, increased the main jet, opened up the airbox, etc. It was able to do about 15 MPH with the restrictors but lacked low-end power. Now it has LOTS of low end power but still tops out at about 17 MPH. Given the huge improvement at the low end I was expecting more at the top, too.

I'm not interested in heavy-duty mods (milling the head, new pipe, etc.). I'm impressed with the low-end power now but wonder why that's not translating to more top end as well.

Is there something else on this machine that limits top speed?

 

We just picked up one of these quads for our daughter, in near perfect condition, and I found the top speed to be around 15MPH.

I would guess the limiting factor is probably the transmission. I was wondering if a slight change in gearing would enhance the top speed without sacrificing low end power. That's what I will try when her skill level improves.

 

Changing the gears is simply trading low end for high end. I don't want my son to lose the low end (for climbing hills) so I'm not going to change it for now. Currently the unrestricted and rejetted machine can do 18-19 MPH on level ground and ~10-12 MPH climbing pretty steep hills.

My big question is why the top speed isn't higher. *My* theory is that the engine RPM's are being limited somehow. It might just be a power thing... moving 200 pounds (150 ATV + 50 son) might just be this engine's limit without more modifications.

 

engine only spins so fast. with out increasing the engine speed (rpm) or gears you will top out at the same speed. only thing diffrent is how fast you get there. I have a lt80 with a moore race motor. stock they spin about 6800 rpm( I think) mine now spins about 12,000 rpm and double the HP. lots faster top end!!!!!!!!!!!

 

does this thing have a chain drive? why not try going up a tooth up front on the sprocket or down a tooth on the rear?

1 tooth shouldnt hurt the hill climbing and you would get a few mph

 

I've considered that, but there's no free lunch - changing the ratio to improve the top end will have an effect on the bottom end. The front sprocket has ten teeth, so moving one tooth either way has a 10% effect. That would change ~18 MPH by ~1.8 MPH for a grand total of just under 20 MPH.

The rear sprocket is something like 30 teeth so there's more to work with there, but again - I don't want to lose the bottom end. That's why I'm beginning to think the answer is in the engine's top RPM.

Thanks!