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MB HD4000 PROBLEM UPDATE
http://mudmotortalk.com/mmt_v2/viewtopic.php?f=3&t=8161
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Author:  fowl habbit [ Tue Mar 02, 2010 2:22 pm ]
Post subject:  MB HD4000 PROBLEM UPDATE

I give the motor about half throttle and it just winds way up to about 4100rpms and the boat just sits their. It has a brand new prop on it so I know thats not it. The boat will eventually take of but very slowly and I cant get more then just me up on plane. Even with a empty boat and just me im can only turn 3800rpms now once it finally takes of. I have a 1652 G3. I would really like to figure out what is wrong. I have absoultly no hole shot. pulled the plugs they are a nice brown paper bag color so I dont think its fuel related. Thanks for any help

Author:  craig [ Tue Mar 02, 2010 2:33 pm ]
Post subject:  Re: MB HD400 PROBLEM

Try putting it in gear.

Author:  fowl habbit [ Tue Mar 02, 2010 2:49 pm ]
Post subject:  Re: MB HD400 PROBLEM


Author:  craig [ Tue Mar 02, 2010 2:58 pm ]
Post subject:  Re: MB HD400 PROBLEM

If your squeezing the throttle and turning up 4100 rpms and your not moving then the engine is not in gear! Maybe a clutch or wiring problem.

Author:  WestEndAngler [ Tue Mar 02, 2010 3:05 pm ]
Post subject:  Re: MB HD400 PROBLEM

Lose wire? Shorting out somewhere... I agree with Craig sounds like its not engaging all the way for some reason.

Author:  fowl habbit [ Tue Mar 02, 2010 3:12 pm ]
Post subject:  Re: MB HD400 PROBLEM


Author:  fowl habbit [ Thu Mar 04, 2010 12:43 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Took the upper and lower cover of the motor last night checked the clutch it is working fine also checked the kep way in the bottom gear it looks great both gear and belt look great. I have no Idea whats causing the problem. Ever since I put the Mikuni carb kit on I cant get on plane as quik and feel like I have lost power. Im only turning about 3800 and was doing that and better when it was stock. Anybody have and Idea what I could try

Author:  bjg [ Thu Mar 04, 2010 2:17 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Ive come to the concluesion that I need to see this engine with my own eyes because You are describing out of the ordinary problems.

Aint that right Craig. ;)

Author:  fowl habbit [ Thu Mar 04, 2010 2:40 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  bjg [ Thu Mar 04, 2010 2:50 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Ship the engine to me, Ill fix it then you can come pick it up and Ill give you a class on it. How does that sound?

Author:  woffman [ Thu Mar 04, 2010 5:13 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  craig [ Thu Mar 04, 2010 6:36 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  drake1 [ Thu Mar 04, 2010 6:58 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Who did you get the carb from? Did you change out the needle and seat for a fuel pump? What size jets are in the carb? What is th eexhaust that you have? You stuck a bigger carb on it that is sucking more fuel and more air, therefore you need better flowing heads to move it through and a better flowing exhaust to get rid of it. Advancing the timing will also help you burn the fuel better. You changed nothing else or hit nothing just before sticking this new carb on?

Author:  Glider [ Fri Mar 05, 2010 10:28 am ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

I am assuming you got the electronic rev limiter. Disconnect it and rewire back to stock. Try running the engine. If it runs fine I would suspect incorrect wiring or a faulty rev limiter. It could cause hard to explain problems and "might" also cause incorrect tach readings depending on how it is wired. If it runs the same look to your carb as others have mentioned.

Author:  fowl habbit [ Fri Mar 05, 2010 11:20 am ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  drake1 [ Fri Mar 05, 2010 5:59 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Stock motor with no head work required a 160 when we ran them. Also check the rev limiter. Cut the green wire and run it.

Author:  fowl habbit [ Fri Mar 05, 2010 6:24 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  indybill [ Fri Mar 05, 2010 8:17 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Sorry to ask this but is it a short or tall transom outdrive?(3 bolt or 4 bolt pattern) How tall is the boat transom?

Author:  fowl habbit [ Fri Mar 05, 2010 9:11 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  indybill [ Sat Mar 06, 2010 9:10 am ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Sorry I miss typed the pattern Number. How many bolts are holding the upper housing on the outdrive?

Author:  fowl habbit [ Sat Mar 06, 2010 2:31 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  caddobrook [ Sat Mar 06, 2010 5:29 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

Have seen similiar problems before. The motor will run up fine on land and even run decent with no load but as soon as you put load on it, it stutters.

(only thing that is confusing in your post is that you say you can sit there in gear and run up to 4100 rpms-and no movement-that would not be what I am talking about-that does sound like an engagment problem of some sort)

If you think it is a carb problem and not a clutch problem, then check/change the air filter. While at it I would change fuel filter and plugs as well.

It is a cheap "check" either way to see if that fixes it...

The above cleared up problem on latest one....

Small engine mechanic told me it was air filter.

Author:  fowl habbit [ Sat Mar 06, 2010 6:16 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  deadbird8 [ Sun Mar 07, 2010 10:14 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  craig [ Mon Mar 08, 2010 7:26 am ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE


Author:  duckman [ Mon Mar 08, 2010 12:42 pm ]
Post subject:  Re: MB HD4000 PROBLEM UPDATE

I have the same motor. I had problems like that also.

1) When you put the motor in gear, do you hear a thunk noise, like the clutch is engaging.

2) There is a big white plug under the wire cover. Mess with that and see what happens. I toke the connector off and solder all the wires together.

3) How old is the motor, the clutch wires. Are they solder or connector. If it is a connector, take off the connectors and solder the wires on.

Did all the above and never had anymore problems.

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