Please Help!! 98 Sporster 1800 losing RPMS

[blackwellchris2000]

I recently purchased a 1998 Seadoo sportster 1800 with dual 75 "jet powered motors". It has been running great for a couple of months, however yesterday while at speed (7K RPMS) the left motor slowly dropped to 6k, and after a minute or so, dropped all the way down to about 3K. If i back it down and raise the throttle back up it will go back to 7K, but after a couple of minutes it repeats the whole cycle. Could this be (i hope) a throttle cable issue, or something more serious. That motor's carb was rebuilt about a month or 2 before i bought it. ALso I don't know if this could be related or not but the gas guage has been broken since I got it, and just before this issue started (like 30 minutes before) the speedometer quit working. I am pretty much a dummy when it comes to impeller or jets or anything to do with this boat as I have only work on standard outboards before so please "dumb down" any answers or suggestions you may have. Thanks alot - Chris

NEW INFO. Changed out the plugs and fuel filters...no dice. Compression is fine. Also figured out the speedometer issue. ANY IDEAS?!?!?

 

[timmyboy76]

take the airbox off the carb, and "throw" the throttle to WOT, while look'n inside the throat of the carb. You should see a "squirt" of gas, from the brass fitting. If not, then need to go thru carb and xcellerator pump. Also, trim the plug wires back 1/4in from boots' end, and since you mentioned it, re-check throttle cabl;e. Re-post ur findings.

 

[blackwellchris2000]

Ok, got it squared away, it was a cracked sparkplug that we took out and put back in (thought we had put the new one in).
Thanks for the info, but now she's running fine.