Hi everyone,
First time posting on here, ,but been reading everything I can since I got my 99 challenger 1800 just over a month ago.
I had it out a few times getting used to it, and learning some of the ins and outs of a jet drive before really tearing it up. and once I did, it ran fairly good, but knowing the rotax engines from sledding, it seemed a little off. nothing terrible, but not quite all there for power / response.
First thing I decided to check, since it had brand new plugs, were the RAVE's. I know how gummy they can get, and how it can effect the performance of these engines.
So I gave them a pull to check movement, and they were a bit slugish, so I removed them for cleaning.
Well, what I found started to scare me. not only were they REALLY gummed up, but they were also broken. severely. two of them were each missing one corner, and the other two were missing two chunks. (one of each from each engine)
They were also already the "updated" valves with the groves
replaced them, and scoped the cylinders to do a quick check to see if they had caused any damage.... they appeared OK.
took it out again, and it was running a lot better, although I should point out that in my haste, the initial run I had a problem with the starboard engine not revving past 5k until it went to WOT at which point it jumped up to 7k. but wouldn't maintain any rpm in between. This ended up being my mistake in putting the rave on upside down, the valve was right side up, but the housing was backwards... easy fix.
Now my issue is, the engines won't run in sync above 5500, and the starboard engine wont rev past 6500. (port runs up to 7200)\
I've removed and cleaned the carbs, though they were clean. accel pump is working well. Carbs appear to be synced, as are the chokes. spark arrest is clean. throttle slack is about right, with the butterflies opening fully at full throttle.
impellers are clean and fairly smooth on the leading and trailing edges, wear rings are fairly smooth as well, although both are going to be replaced at the end of the season.
water reg has no visible leaks (could there still be an issue?)
compression test; 4 - 5 second crank, WOT, 158 PSI both cylinders.
both plugs read a for a perfect mixture
I don't suspect cavitation from an air leak around the shaft seals, only in so far as I would expect that to result in high rpm's with no acceleration. (am i wrong on this?), but I imagine a failing bearing might cause drag, but with no audible warning of failure?
I thought the oil pump may need adjustment, but again, the plugs don't appear to be overly oily,
I hope someone might be able to shed some light on my problem. The only other thing I was thinking, if it's even possible, is that the rotary valve timing might be off. Can anyone tell me what position the valve should be at at different piston positions (TDC or BDC )
Thanks in advance for any help, reading everyone's posts on all the other ins and outs of these boats has helped tremendously in trying to narrow down the possible issue.
First time posting on here, ,but been reading everything I can since I got my 99 challenger 1800 just over a month ago.
I had it out a few times getting used to it, and learning some of the ins and outs of a jet drive before really tearing it up. and once I did, it ran fairly good, but knowing the rotax engines from sledding, it seemed a little off. nothing terrible, but not quite all there for power / response.
First thing I decided to check, since it had brand new plugs, were the RAVE's. I know how gummy they can get, and how it can effect the performance of these engines.
So I gave them a pull to check movement, and they were a bit slugish, so I removed them for cleaning.
Well, what I found started to scare me. not only were they REALLY gummed up, but they were also broken. severely. two of them were each missing one corner, and the other two were missing two chunks. (one of each from each engine)
They were also already the "updated" valves with the groves
replaced them, and scoped the cylinders to do a quick check to see if they had caused any damage.... they appeared OK.
took it out again, and it was running a lot better, although I should point out that in my haste, the initial run I had a problem with the starboard engine not revving past 5k until it went to WOT at which point it jumped up to 7k. but wouldn't maintain any rpm in between. This ended up being my mistake in putting the rave on upside down, the valve was right side up, but the housing was backwards... easy fix.
Now my issue is, the engines won't run in sync above 5500, and the starboard engine wont rev past 6500. (port runs up to 7200)\
I've removed and cleaned the carbs, though they were clean. accel pump is working well. Carbs appear to be synced, as are the chokes. spark arrest is clean. throttle slack is about right, with the butterflies opening fully at full throttle.
impellers are clean and fairly smooth on the leading and trailing edges, wear rings are fairly smooth as well, although both are going to be replaced at the end of the season.
water reg has no visible leaks (could there still be an issue?)
compression test; 4 - 5 second crank, WOT, 158 PSI both cylinders.
both plugs read a for a perfect mixture
I don't suspect cavitation from an air leak around the shaft seals, only in so far as I would expect that to result in high rpm's with no acceleration. (am i wrong on this?), but I imagine a failing bearing might cause drag, but with no audible warning of failure?
I thought the oil pump may need adjustment, but again, the plugs don't appear to be overly oily,
I hope someone might be able to shed some light on my problem. The only other thing I was thinking, if it's even possible, is that the rotary valve timing might be off. Can anyone tell me what position the valve should be at at different piston positions (TDC or BDC )
Thanks in advance for any help, reading everyone's posts on all the other ins and outs of these boats has helped tremendously in trying to narrow down the possible issue.
