09-28-2011, 05:15 PM #1
- Join Date
- Jul 2010
07 FX Cruiser HO won't go over 40mph?
My 2 friggin AWESOME cruisers have arrived here in Maine from Texas. One is perfect but the other has an issue. When taking off cold it won't accelerate at first, will "catch" and zoom up to about 40mph max. Will stay steady for a couple minutes, then slowly decels back to 10-15mph for a few seconds (20) then back up to 40mph max. Once warmed up, accels. ok, but not over 40 and will decel. after a few. Back at the shop I found a dead spark plug. Just replaced all 4 and will test this weekend. I called the prev. owner who said it did it to him also and the Yama dealer said to just add the Yamalube, said he did and it came out of it. Doubt it? I'm savy on fuel inj. cars and some models with a dead plug will trigger a lean condition due to the unburned fuel running by the oxy. sensor indicating a rich condition causing the ECM to compensate by leaning out the mixture. (huh?) Feels like your running out of gas till the mix is so lean the oxy. sensor will finally signal "more fuel idiot" and the car takes off. Pre-OBDII Mopars will do that. Will Yamaha's, cause that's what it feels like and if not, what say you? I'd also like to download the manual or just buy one so I can bone up on this system. Theory must be about the same? I'd like to fix it myself. Hey, what could possibly go wrong. Thanks.
09-28-2011, 08:00 PM #2
All of your ideas and theories sound correct, but it sounds like you are "over thinking" , which is fine. The FXHO's for some reason unknown to me, foul plugs once in a while. Change the plugs, check your flame arrestor/air filter for oil saturation, and please do not over fill the engine oil. Easily done on the MR-1 engines when over filled with oil it will puke oil back out and saturate your flame arrestor and of course restrict air flow.
There are several knowledgeable guys on the forum with these engines and a few threads on performance tips ranging from engine mods to handling mods. Good info on here.
Good luck and have fun.
09-28-2011, 08:40 PM #3
Unfortunately there is NO oxygen sensor on these motors, however it will do what you are describing when two things are happening:
#1: Faulty spark plugs.
#2: Low oil level. The HO-MR1 motor has a dry sump and a low oil switch at the reservoir that will trigger an alarm slowing down the motor and as the sump pump pumps oil into the reservoir the alarm resets and the process starts again.
09-28-2011, 09:25 PM #4
Could the 40 mph max be caused by the ski being in 'leaner mode', in addition to the clogged air filter and bad plugs ??
09-29-2011, 06:04 AM #5
Absolutely. There are definitely other issues thou...
09-29-2011, 04:21 PM #6
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