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Honda 2004 BF50 Nasty Shake at Idle - Who can help. I've tried everything...Well almost

V

VIPTHELIFESTYLE

Member
First I'd like to say that the motor is running really well. Like super well but it shakes a lot at idle. Just took it from Newport to Catalina this weekend on a 12 foot center console dinghy. It was an amazing trip. My issue is the engine shakes a lot at idle. Almost seems really rough.

This is what I have tried....
1. Adjusted the idle screw...To factory spec (about 980) using a laser RPM gauge with a reflector on the flywheel. (I'm not messing around).
2. Used a can of SeaFoam with 3/4 gal of gas in a separate tank and ran it through the motor.
3. Changed water separator filter (clear bowl style), and inline fuel filter.
4. Used a can of SeaFoam mixed with 7 gallons of gas during the Catalina trip.
5. Synced carbs using carb sync tool so they were all "dead on b@lls" even. (Even pinched the hoses per shop manual when I synced them)
6. Changed the thermostat. (not related but what the hell it's been a while).
7. Installed new plugs, gapped to factory spec.

About the only think I haven't done is rebuild these carbs. Is that the final thing? I hope not.
If it is, does someone have the shop manual pages they can send me for this rebuild? I't a honda BF50 LTRA 2004.

Thank you in advance for your help...
HondaDude, if you're out there, I got another one for you ;)
--John
 
Try pulling the plug wires at idle to see if the rpm drop is the same for each cylinder. My bet is one is not firing but if that's the case I don't see how you passed the carb sync.
 
When you sync'd the carbs...did you pinch off three hoses or just two? Some of the older manuals only said to pinch two. It should be three.

Check the timing. Belt could be off just one tooth and sound good at high speeds but be terrible at idle.

Check valve clearances.

Mike
 
Mike, Thanks for the reply.
I only pinched 2 of the hoses, which is the 3rd one that I need to pinch?
I did check the timing belt and it looked tight, very little play.
So how do I check the valve clearences?
Thanks,
--john
 
Third hose is #29 in the parts diagram. http://www.boats.net/parts/search/Honda/Outboard%20Engine/2006/BF50A6%20LRTA%20VIN%23%20BAZS-3600001%20TO%20BAZS-3699999/CARBURETOR%20ASSY./parts.html

If you did not pinch off all of the hoses at the same time, it is very unlikely that they are balanced except by doubt luck.
I would rebalance before you tried anything else.


Just checking the timing belt tension does not check the timing.

There are timing marks on the flywheel and cam pulley. You will have to take the cover off of the flywheel to see them.

It sounds like you have a workshop manual. Check in the maintenance section under valve adjustments. That will show you the timing marks as well as a step by step as to how to check valve adjustments. It is a little too much to try to type out.

Mike
 
It is hard to really hear it. If it is the engine, the hood is muffling the sounds.

I listened using headphones. It sounds like the sound may be coming from the gearcase...like chatter of the clutchdog.
If the shift is out of adjustment a little, the clutchdog could chatter, then grab and not chatter as you accelerate and possibly push the gearcase a little more into gear.

If you can, retake the video with the hood off and hold the camera close to the engine for better sound. Shoot on the carburator side. Also...minimize any talking...when you talk it overwhelms the automatic audio circuit and overrides the sound of the engine.

Hopefully, others will jump in for second, third, forth opinions.

Mike
 
Not to denigrate your high tech tach, but it looks to me as if it might be a tad low on idle rpms. You can see that it seems to run ok for a while and then, it's as if it is "loading up" and one cylinder begins to drop out. This could be because the engine has excellent vacuum and is pulling more fuel through the idle circuits than the engine can burn at too low an idle setting. I would try adding another 50 rpm or so to idle speed and see if it improves the condition. If you can live with the additional rpms in how you use the boat, it would be the simplest solution.
 
Sorry for the delay in response.
Thanks Mike. I did sync now with the 3 tubes pinched...Stupid manual showed only two.
Unfortunately, same issue.
I added a few more RPMs and the issue seamed to go away for a while but then it returned.
So I'm starting to think it's a clutch dog thing. I noticed the shaking/chatter/knocking is at it's worse when the boat speed is higher than the motor speed. For example if I'm in gear and go from 2000 rpm and right down to idle RPM in gear the noise happens a lot until the boat gets to trolling speed.
Mike and folks, does this trigger anything in your mind? I just had the lower unit removed, pressure tested, and resealed by a mechanic. He didn't see any issues.
Just an FYI I do have an aftermarket 3 blade Stainless Prop. It's the Solace prop with the same pitch as the factory prop.
 
If fuel is left in the carburetors all the time then the wee jets and passageways maybe plugged.-----------My bet is doing a proper cleaning of the carburetors will make the issue " go away "
 
I am with Racerone. If the engine is not running smoothly, there are probably still some issues with the carburators.

The stainless propeller could be causing two different issues. First, make sure it is installed properly and tight.

1. If you were getting the proper rpms with the aluminum that you had (around 5500 rpm or so), replacing the aluminum prop with the same pitch as the aluminum will cause you to lose rpm and possibly cause extra strain on the motor. I have found in most cases, when you change from aluminum to stainless, than you should drop down one pitch to keep the same rpms.

2. When you are running a stainless propeller, it takes a longer time to slow down in rotation when the motor slows down. If that is the case here, the prop and prop shaft turn faster than the drive shaft and the clutch dog will ratchet until it slows down to match the speed of everything else. You can see what I mean, by turning the motor off, and have someone shift the motor into forward. As they do that, be sure you sure rotate the prop counter clockwise by hand so the clutchdog syncs into gear. The prop should lock into place. Once it does, rotate the prop by hand the other way (clockwise). You should hear a ratcheting.

Is the ratcheting the same that you are describing? Then that is your answer.

The noise will probably go away then, if you put an aluminum prop on.

Just a thought
 
man i had an 03 or 04 h50 that idled just like that. I pulled the carbs apart changed everything in there, everything looked clean, synced...still couldn't get rid of a bit of slight miss at idle. I was selling the engine and called myself beat on that one... I agree though check the manual for the rpm, timing cogs and marks to be safe, it wouldn't surprise me though if you had to take the carbs apart and clean them. Mine had sat, redid the carbs was huge improvement, took them apart several times but could never get rid of the slight miss at idle.

If you go to clean the carbs hondadude had given me some good advice on here on what parts to buy and cleaning, remove,replace the jetsets..

http://www.marineengine.com/boat-fo...removing-all-of-the-carbs&p=323365#post323365

That one was enough to make me realize i'm not a carb person! It was the first carbed motor i've had in a loong time. If i had known beforehand and i was keeping the motor i'd have thrown my hands up and took it somewhere....drove me a bit bonkers that one. Good news is that taking them apart is fast enough though but after a couple times for me it was getting old =)

Hope you have better luck.
 
Bought 2 Honda 9.9 motors , owner said they would not idle and said " can not find a shop that can fix them ".-----------Cleaned carburetors and both ran nicely after that.-------A magnifying glass comes in handy to look for and inspect the small holes found in these carburetors !
 
thanks all guys. it makes a great help of mine. I have a honda bike and I faced that the problrm. Now I ve gotten the solution from this form.
as well as I have a
honda repair manual
shop. thatswhy always I need updated information about honda. eagerly I am hoping all of u will help me a lot.
thanks............
 
So I did just that and you are right. The sound I'm hearing at deceleration is the prop ratcheting until the boat speed matches the propellor speed.
Now there are several of these same engines around me with the same prop and they aren't making that sound.
Is there something I can tighten to stop that ratcheting?
 
@neversummer
I actually did. It turns out that the stainless prop was a little heavy and the clutch dog was pretty warn. I had the clutch dog replaced and the issue went away turns out it wasn't a miss and wasn't motor related but actually lower unit/heavy prop combo good luck.

neversummer said:
VIP, did you ever sort this out?

I am interested -- I have had the same problems off and on, same motor
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