Dear Friends,
I have a problem that puzzles me... my 2006 ZForce 800 EX is not running fast at High gear, reaches about 17mph. It's got 566 miles on it. I'm wearing seat belt and light on dashboard is off. The diff lock seems to work fine, at least on the dashboard lights up correctly 2wd, 4wd and lock. When shifting to dashboard reverse light turns on, goes off when in L or H. Perfectly runs in Low and Reverse. While in neutral it reaches 7500rpm, which indicates the engine is running good. There seems to be a limiter somewhere that causes the unit not to run fast. Any suggestions? Need help. please.

[2015 Z Force 800 53/Trail EPS]

Dear Friends,
I have a problem that puzzles me... my 2006 ZForce 800 EX is not running fast at High gear, reaches about 17mph. It's got 566 miles on it. I'm wearing seat belt and light on dashboard is off. The diff lock seems to work fine, at least on the dashboard lights up correctly 2wd, 4wd and lock. When shifting to dashboard reverse light turns on, goes off when in L or H. Perfectly runs in Low and Reverse. While in neutral it reaches 7500rpm, which indicates the engine is running good. There seems to be a limiter somewhere that causes the unit not to run fast. Any suggestions? Need help. please.

One problem may be that there were no Z Forces prior to 2011 so in 2006...well maybe you meant 2016 and if so low fuel pressure and/or volume can cause it to run fine in neutral but not under load. Some with this problem found water in the tank and in the fuel filter...others had to replace the pump. Test it and take a look ate the filter. Its behind the air box. PITA to get to but while there get a larger one with a steel body for EFI and replace it. The other thing people have found that have these types of problems is that they have been running the OE paper filter in dusty conditions and the engines are getting less then 1200 miles before needing rebuilt so do a compression test...and a leak-down test. If you have not set the valve lash..do so, it's over due.

You are correct it is a 2016, I had a typo... valve lashes are checked and correct, we did an engine rebuilt 3 weeks ago. Compression is fine. Engines runs great. Fuel pump is working fine. Replaced fuel filter and air filter. Runs great in Low and Reverse, but lacks power on High gear. Will only run on High gear around 17mph. Any more suggestions?

[2015 Z Force 800 53/Trail EPS]

You are correct it is a 2016, I had a typo... valve lashes are checked and correct, we did an engine rebuilt 3 weeks ago. Compression is fine. Engines runs great. Fuel pump is working fine. Replaced fuel filter and air filter. Runs great in Low and Reverse, but lacks power on High gear. Will only run on High gear around 17mph. Any more suggestions?

If you are sure there is nothing wrong with the engine, fuel system and electrical system then it has to have something to do with the loading of the clutches so pull them and do a complete inspection and cleaning. DO also pay attention to the splines on the end and..the wet clutch. Tough to test it but under the loading of high range when the shoes are bad it will slip and find a point that holds the RPMs down, stops the primary from shifting out and stops accelerating. It would get worse when it gets hot. I assume during the rebuild that was all inspected though.