Kawasaki 4010 (Gas) Revs/Puleses at top speed.

[brothaman]

Not sure I'm explaining that right. but,.. I'll start with some history.  I bought the 4x4 4010 mule with a bad motor.  I built the engine.  Bottom end up.  Fresh bearings, Pistons, etc.  Cranks up and runs with no issues.  However,.. doesn't seem to run faster than 20 mph and pulses at top speed like something is up with the governor.  It feels like its cutting back.  Climbing and pulling it seems to be fine,. It pulls hard and doesn't cut up.  But on the road flat out  Cuts back/Chugs/pulses/Revs. 

Not sure where to start. Kinda tired of thinking about it. Any Ideas?

Just a mention, I'm not trying to make it faster, just fixed.  25mph it good by me.  Hell,... for my purposes I'm fine with 20 mph as long as its' running properly.

[Travis]

Welcome to the UTV Board!

 the top speed is supposed to right at 25mph.

First off, whenever i have this similar problem with any engine, i start by running  some carb cleaner through it (pour proper amount or whole can in gas tank)  i usually do half a can for 4 gallon tank. and if that don't work

 i would check your valve clearances, check your manual for specs.

 Someone more experienced than me should come along soon. and will probably have a better idea than me.

 

[brothaman]

Top end should be in spec.  I'll run some cleaner through it.  Maybe an injector is clogged...  If that doesn't work, I might recheck the top end.  

 

[brothaman]

So, I've learned some more about this thing.  I bought the SXS from Sunbelt who leases these to construction companies.  I was told they are locked down to 17 mph for construction site work.  I clock 18 mph uphill by GPS.  Not sure how true that is, but my contact there says this is the case.  I don't see any aftermarket device attached like the dynatech thing I've seen.  

Could this be set at the ECM?
Can the ECM be reset to Factory specs?