Rough running at high rpm after 200hr service

Thanks, I was hoping for a magical answer that didnt involve pulling both carbs off and repeating the cleaning/inspection :)  Makes total sense though. 

The thing I am struggling to make sense of is the fact that it ran fine for 45 minutes before the problem showed up.

After numerous full power static runups it now runs smoothly but only can get up to 4300rpm. Im starting to wonder if I have a debris clog somewhere. 

Jim Isaacs wrote:

Are those carb mount flange clamps tight, and the carbs firmly seated?

I will check, that is a definite possibility. As part of this 200hr service I replaced the rubber boot as part of my upcoming 5yr rubber replacement so that could be the problem.

Just thought I would give an update on the problem.  Turns out it was pretty simple, I had a torn membrane diaphram on one side.  Not sure how this happened because I just replaced it with a brand new part the week before during my 200hr carb engine service.

Looking back on it, it does make sense with what I experienced.  The engine roughness was pronounced only above 4000rpm, below that it was pretty smooth.  The roughness decreased as i descended from 10,500' down to my precautionary landing at near sea level.

Anyway, it runs smooth as silk again.

We have had the same problems.

It seems that the the connection between the ceramics and the metalpart of the Rotax sparkplugs is weak.

We mounted NGK DPR9-EA9 and the problem is solved.

K.R.

Gerard Hanstede,  Netherlands