1996 Yamaha C25hp bogging

[Donman89]

Both plugs are fouling. Ans no I didn't do a sea trial which is probably one of the bigger buying mistakes I have made. I have bought and sold so much stuff throughout the years and I didn't take this one out because "it runs like a champ, perfect shape and no issues" I was told. It ran fine in the yard on the hose which I am uploading the video now to YouTube to post on here. I didn't do a sea trial because the guy lived and hour and a half away and I didn't get to his house until after dark. It also had a upper shift linkage that had broken previously and was rigged together with 2 couplings with a stud between them.

[Donman89]

I'll have to buy a timing light I don't have one at the moment. And I was gonna check timing but honestly I'm not sure where the timing is suppose to be and outboards are different than any cars or my Bayliner with the inboard/outboard motor. This is only my second outboard, my first one was a Johnson 4hp on my sailboat.

[TownsendsFJR1300]

Both plugs are fouling. Ans no I didn't do a sea trial which is probably one of the bigger buying mistakes I have made. I have bought and sold so much stuff throughout the years and I didn't take this one out because "it runs like a champ, perfect shape and no issues" I was told. It ran fine in the yard on the hose which I am uploading the video now to YouTube to post on here. I didn't do a sea trial because the guy lived and hour and a half away and I didn't get to his house until after dark. It also had a upper shift linkage that had broken previously and was rigged together with 2 couplings with a stud between them.

It happens, folks screw others (the old, buyer beware)..

I think you already posted on that broke shifter linkage, the powerhead has to come off to replace it as well (as I re-call).

Your original video, appeared to me, to be an ignition issue.

Again, looking at the parts fisch, you have one coil. I would look closely at the spark plug caps, where they twist onto the wires. There shouldn't be any arcing inside and fit fairly snug (probably not the issue). I'm not familiar wth how to check your particular coil, a shop manual should show how and the spec's..

Get the carb back together, make sure the float level is correct and go from there double checking spark (spin over quickly with the starter visually comparing spark that its fairly strong AT THE SPARK PLUGS. If its interemediate, time to start looking at ignition componants)

Get that done and go from there.


Good luck..

[TownsendsFJR1300]

I'll have to buy a timing light I don't have one at the moment. And I was gonna check timing but honestly I'm not sure where the timing is suppose to be and outboards are different than any cars or my Bayliner with the inboard/outboard motor. This is only my second outboard, my first one was a Johnson 4hp on my sailboat.

I have no idea how to even adjust it.

The main thing I would be looking at is if using the timing light (auto parts stores, at least in the US, lend them out for free with a deposit) and put it on each wire with the engine running. If its misfiring intermediatly, you'll easily see the "break" in the light when it doesn't fire..

I have a two stroke Weedeater, hedge trimmer that was acting up intermediatly once it hit a certain temperature. Put the timing light on it, got it to temp, then the light starting showing the misfiring from the coil (very simple system) but only at a certain temp. Replaced the coil, runs great again...

BTW, an investment in a shop manual if you plan on keeping that engine is worth its weight in Go.d

[Donman89]

Ya I bought Seloc manual from AutoZone a couple of days ago to learn some of the stuff with the motor. And Ya I do have to take the whole motor off to do the upper shift linkage. I just rented a couple compression testers from AutoZone and Oreillys. Once I get it together I may go try to rent a timing light. But I already had the carb apart by the time I started thinking about timing and firing.

[Donman89]

2007 T2 and Yamaha 25: 2007 T2 and Yamaha 25 - YouTube

[TownsendsFJR1300]

Looking at tha last video, question/comment.

What lenth engine shaft does your boat call for?

I ask in that your engine anti cavitation plate (the plate closest to the prop) is usually even with the bottom of the boat. Yours, in that second video, is WAY BELOW THAT. The engine sounds good BTW...

It appears you may have a 25" shaft engine on say a 20 " transom causing way too much drag. That wouldn't allow the engine to wind up (but would not explain fouled plugs). You can raise the engine if need be but it'll take some finagling. They may even make kit for that (dunno)

PM sent re the height.

[Donman89]

Ya I am gonna get a lift plate. Just trying to get the issues worked out first.

[TownsendsFJR1300]

Ya I am gonna get a lift plate. Just trying to get the issues worked out first.

That may very well be part of your issue. If there's too much drag, a known good engine without problems will have issues getting the rev's up..

As a side note, when they re-powered my boat, they had the wrong prop on it. It would get to maybe 4,900 RPM's WOT, accelerated like I was dragging an anchor (really, really bad). Once I got the correct SS prop on there, its a whole different engine/boat. Jumps out of the hole, will pull to 6,000RPMs (tops @ WOT),

[Donman89]

Ya it maybe Idk for sure. To me it seems like the motor should pickup and go even if it is to long. I just figured it wouldn't be able to go as fast as it should. I have also thought about the prop trying to bite to much but don't have enough power to rev up into the powerband.

[TownsendsFJR1300]

Its defnitly too long.

IMO, I would start with the KNOWN things that are incorrect.


(you can't fine tune an engine until its installed in the car. Similar situation here.)

[Donman89]

I figured out what it was. It was the main jet. Someone must have drilled it out before or something. I bought a new nozzle and main jet and it runs like a champ. It does definitely need a lift plate though because it isn't running nearly as good as it should. 2007 T2 with Yamaha 25: http://youtu.be/p1FDrMzPPMQ

[TownsendsFJR1300]

I figured out what it was. It was the main jet. Someone must have drilled it out before or something. I bought a new nozzle and main jet and it runs like a champ. It does definitely need a lift plate though because it isn't running nearly as good as it should. 2007 T2 with Yamaha 25: 2007 T2 with Yamaha 25 - YouTube

Don't ya love homemade engine hop ups???

And yes, its quite a different engine now....

BTW, it looks quite a bit quicker than 20 MPH (closer to 30). If you have a GPS you may want to check. The pitot hole may be clogged or the line pinched.

Congrates!

[Donman89]

Ya Idk why anyone would want to drill a jet out because it's not like the motor has anything done to it. Just a regular outboard. Ya seems to be running a lot better now for sure. I didn't realize the jet was bigger than it was suppose to be until I bought the new one and noticed a size difference. They are both the same size just the older ones opening was a good amount bigger. I almost didn't order a new jet but looked like it had been corroded once before and cleaned a few times. And I may try next time to use my gps speed to see what it's running. It felt a little more than 20 but the boat is so low on the water.

[TownsendsFJR1300]

That stuff the PO did, makes it much harder for everyone to fix an issue.. Its usually a given the jets aren't opened up, etc. Good eye on your end BTW..

The one video (on the muffs) looked like a good amount of smoke (2 stroke oil burning). Did that smoke lessen some with the smaller main jet? (I think its pre-mixed)