glenn

[redhatsuxx]

90hp 1990 mercy with low high speed rev in neutral i have the shop manual and just done a compression test on all 3 cylinders 130, 128,130 psi all good within tollerance rev max currently only 4500 correct should be 5500 ish wheres my problem?

 

[achris]

Re: glenn

90hp 1990 mercy with low high speed rev in neutral i have the shop manual and just done a compression test on all 3 cylinders 130, 128,130 psi all good within tollerance rev max currently only 4500 correct should be 5500 ish wheres my problem?

Let's start with some punctuation... That lot up there is hard to read....

So, the problem is that you only make 4500rpm at Wide Open Throttle, yes? Try a smaller pitch prop...

Chris..........

 

[redhatsuxx]

Re: glenn

4500 in neutral nothing to do with prop

 

[achris]

Re: glenn

In neutral, it could be that the lever will only open the carbs enough to go to 4500... Not a valid test anyway... What do you get on the water, in forward gear at full open throttle? You should be making 5000-5500....

Chris........

 

[JB]

Re: glenn

4500rpm with no load on the engine is an invitation to disaster. Adjust the neutral throttle stop so that it won't go over 2,000 in Neutral.

 

[achris]

Re: glenn

JB,

If he has the standard Merc control box for that engine, there's no adjustment for throttle in neutral.... Just requires operator attention...

Chris.......

 

[JB]

Re: glenn

There is no neutral throttle stop on the engine? ACK!!

 

[achris]

Re: glenn

There is no neutral throttle stop on the engine? ACK!!

Nope... Is on the small tiller engines, up to 15hp, but not on the bigger, remote control ones.... Yep, you can rev them to destruction

Chris.........