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Louie, Technician
Category: Motorcycle
Satisfied Customers: 12668
Experience:  25+ yrs. experience
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I have a dune buggy, it has a Chinese motor built by Chery,

Customer Question

I have a dune buggy, it has a Chinese motor built by Chery, it's an 800 with aftermarket turbo. The motor comes in the chery qq3 car in China and it is also used in the John Deere gator 825i for reference. The redline of the motor is 6500 rpm. Intermittently it will bog at 5400 and won't go any higher. It has good fuel pressure, turbo is good, injectors are good. It runs perfectly at low rpm and idles fine. When it's not under load it will hit the redline most of the time, just when it's ran on the road it acts up. It has obd2 but no port to connect to. It has a tps, o2, knock, and tmap sensors. It also has an alternator with it being a car engine. Where should we start?
Submitted: 2 months ago.
Category: Motorcycle
Expert:  Louie replied 2 months ago.

Hi and welcome to JustAnswer, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, let's try check and review the basics (if have not been done); have you tried to remove the spark plugs and determine burn color of the tips?

Customer: replied 2 months ago.
I checked the spark plugs. I'm attaching a photo. I can't even tell you what the gap is because I can't get my gap tester under it
Customer: replied 2 months ago.
By the way the previous owner said they had the spark plugs gaped that way because they turbo charged it and they said the turbo would blow out the spark if it wasn't gaped that way. Maybe meaningless information but it's information I have so I figured I'd share it with you.
Expert:  Louie replied 2 months ago.

Offhand, consider experimenting since this is after all a Chinese engine and an aftermarket turbo:

  • try new plugs;
  • gap 0.7 ~ 0.8 mm or narrower if stock ignition system;
  • re-gap to 0.8 ~ 0.9 mm if high performance ignition system particularly the coil and spark plug wires;
  • turn down the boost;
  • different fuel / octane;
  • different timing / deg BTDC (if able).

Possibilities are:

  • leans out in higher RPMs (most likely);
  • weak spark (likely);
  • leak (least likely).