Logo
FULL SITE MENU

225 johnson1999lost top end speed and tack

D

denboy

New member
"I am the original owner of th

"I am the original owner of the boat and engine..New it could do 5500rpm and 43 mph. Now it will only do 5100rpm and 38mph besides that it runs great.I had all carbs rebuilt,new fuel pump, timing checked,new head gaskets,compression checked,prop checked with no results.Where do I go from here."
 
"I had a problem once with the

"I had a problem once with the fuel restriction warning horn sounding at WOT. Instead of fixing the actual problem, the shop "detuned" my engine. They deliberately retarded the timing a few degrees, resulting in a loss of top end RPMs and speed. The warning horn didn't sound anymore, but I had a loss of performance. Based on that, I would look very carefully at the WOT timing. I corrected the fuel problem myself, re-timed the engine at WOT, and the performance was back.
Hope this helps."
 
"I like to thank the people wh

"I like to thank the people who responded to my problem but let me add to the problem of lost top end...This problem was noticed two seasons ago but I let it go to the end of the 2008 season.The boats bin out and back into the water.The hull has bin checked,there is no extra weight and the tack has bin certified.The timing has bin checked ,so to off set it would only be putting a bandaide on the real problem.So I believe mechanically something has changed from factory specs but can not put my finger on it"
 
"Maybe you misunderstand the p

"Maybe you misunderstand the point of my post.
I am not suggesting that you offset your timing to bandaid the problem. Not at all. I am merely stating that if the timing is retarded by just a few degrees at WOT, it can cause the loss of top end RPM and boat speed that you are describing.
I guess the thing I am saying is if it were me, I would double check and triple check that timing...even though it has been checked as you say by your mechanic.
I had to run my boat in the water, full speed, trimmed out, at 5500 RPM, with the engine cover off, leaning over the back, with a timing light. All this to find that indeed the timing was not right, even though the mechanic said it was. Now, you may not want to do that, but I did and I found the problem.
It would be very feasible to me if your mechanic, after all that work, tried to do a static WOT timing, in the shop and not on the water, (or with a test wheel), and it may be just a bit off at this moment. Or maybe he wants to be conservative in his settings so that he absolutely reduces the risk of any powerhead damage from timing that is too far advanced.

Re-reading your posts, it is unclear whether the problem developed gradually to the point it is now, or if it showed up after all the work you had done.

I just know that from my experience, such symptoms can be caused by retarded timing at WOT, and I had to verify it myself to fix my problem."
 
I did misunderstand the post o

I did misunderstand the post on timing and thank you for re posting..My mechanic did check the timing first and said it was off a little and adjusted it but I don't know what or how he adjusted it.The problem was there before all the work and the same after all the work.I will ask him about the timing..
To add more too this .I had this problem for at least two seasons but waited to now because the boat and engine were still performing good but deceided something may fail and should look into it..During all the work we switched props to see the effect but the results are confusing.I went from a 17 pitch down to a 15 pitch and the rpm went to 5500 but the speed stayed at 38mph.I expected the speed to drop off.I went back to my prop 17 pitch and the rpm dropped off to 5100 and the speed stayed at 38mph?
 
"I wonder if it is possible fo

"I wonder if it is possible for carbon deposits to build up over time in the exhaust adapter and associated exhaust pathway, causing increased back pressure and a resulting loss of RPM. Have any of the experts seen such a case? Realistically, I guess it would have to be a very substantial restriction, if it was even possible. Maybe the carbon could build up and effectively reduce the size of the exhaust pathway.....or maybe a small nest that has gradually collected carbon and clogged a bit over the years...YES!!! now I am guessing. Good luck."
 
"carbon does build up,....esp,

"carbon does build up,....esp,in ring grooves,and piston tops...there are numerous de-carbon products...this is also done,on every tune up..."
 
"I don't mean to stick my

"I don't mean to stick my nose in the conversation, but what year, model and hp are we talking about?

My blown 200hp had a problem with slightly lower rpms for a period of time before it got fried.

When I took it apart, I found that one of the cylinder sleeves had turned a little in the block(not the problem cylinder that blew), covering the intake ports by 1/3.

Has there been a compression test done?

My apologies if I am off the mark with this observation."
 
Too add more to what has bin d

Too add more to what has bin done to solve the problem.The compression was checked with all the other work that I stated in my first posting..Every spring de carb is run through the engine along with filters being changed and spark plugs...
 
"Compression test procedure:

"Compression test procedure:
Besides making sure the engine is warm, what is the proper procedure for running a compression test. '95 225 Ocean Pro"
 
Go back to the 15 " prop.

Go back to the 15 " prop. You will get out of the hole quicker and take some strain off the rods and wrist pins. If your top end speed is unchanged the smaller prop will prolong engine life by reducing wear and tear. You'll be running around and doing hole shots in 3rd gear instead of 4th.
 
Back
Top