Johnson 115 2 stroke 2001 model, Engine shudder between 1200 & 2000 RPM

[tcaton]

Trying to understand why this is happening. Engine was not doing this when I purchased it and it started after about 60 days of usage. Is this considered normal?

[Waterbugtoo]

Could be a number of things and hard to diagnose on a message board. Take it back to the dealer and let them check it out if its that new.

[tcaton]

Did that. They replaced the carbs and said it seemed to run ok. No change from my point of view. Bombardier acknowledges that there was a possible problem with this model and year (some motors only) but I don't have documentation on it. I'm thinking about having someone else take me out for a test ride in the to compare. I'm not sure whether my expectations are too high or I have a problem but it worries me because it creeped in over time and my warranty is going to expire.

[seahorse5]

There is no problem with the 115's. The shuddering is the transition from the low speed jets to the mid range and high speed circuits in the carbs. It is normal on carburetor motors.It can be minimized if the spark and throttle are synchronized, called sync and link in the service manual. Make sure the carb adjustments are not set too rich, and that the engine will turn around 5500 rpm with its prop and a normal load. This is all explained in the factory manual.Another easily overlooked problem is proper thermostat operation. Running too cool can affect the motor at low and mid range speeds.