Lost rpm"s

[ara23]

I have a Honda 75 HP, 1999 model. It was turing up 5000 rpm's and now has dropped to 4000 rpm's. The carbs are clean, timing was checked, new CDI unit installed, still only able to turn 4000. Engine starts easily idles good, runs fine, just does not turn the rpm's

 

[ara23]

Re: Lost rpm"s

i have also done a compression test, all cylinders 145-150, all electrical components in spec and also have changed both fuel pumps and bypassed fuel filter, still only gets to 4000 rpm's where before it would go to 5000 rpm's

 

[cp]

Re: Lost rpm"s

Some thoughts: Is the tach working right - could it have gone bad on you? Is the control cable advancing the throttle all the way - could something have slipped such that your throttles are actually not going full open? Have you tried using a portable fuel tank - maybe there is a restriction at your tank's fuel pickup? Good luck.

 

[ara23]

Re: Lost rpm"s

The tach is working, and I am also showing a loss of speed on the GPS. The control cables are advancing all the way, have also tried different tanks. Took to dealer today and was told it is definitely a "carb problem" Will be changing the jets and have been told that should correct the problem. Will post results

 

[cp]

Re: Lost rpm"s

Please do let us all know the results. It's interesting that they "Will be changing the jets..." since you've got the same jets in there that you previously were able to get 5000 rpm with. Or did you change altitude? If as you said, "The carbs are clean..." then those high speed jets ought to still be working just as good as when you did get 5000 rpm.

 

[ara23]

Re: Lost rpm"s

Finally got motor back from dealer, changed jets in all 4 carbs and problems went away. One if the jets had a split about 3/8 inch long in it.

 

[cp]

Re: Lost rpm"s

Wow wonder how the jet split like that . Did your dealer let on whether this is a problem others might see on their carbs? Oh well, at least you're back to running OK. Thanks for posting the final result.

 

[ara23]

Re: Lost rpm"s

Just some more info, I had cleaned the carbs myself and removed and installed them. (to save some $$$$) I had found the split in the jet by accident. I was spraying carb cleaner throught it and saw it spray out of the side. Dealer had not seen one split before, as for what caused it, they dont know. When I informed them about the split, we decided to change all 4 jets. I asked why I was not getting the rpm's, with the exisiting jets, all they could tell me was that 1 or more of the jets were still dirty. Also was told that it is easier to change the jets vs trying to clean them.