It is currently Thu Mar 28, 2024 2:02 pm




Reply to topic  [ 14 posts ] 
 Mikuni tuning problems 
Author Message
MMT Member

Joined: Sat May 26, 2018 2:46 pm
Posts: 10
Post Mikuni tuning problems
I have a 4400 black death that doesn't have crap for bottom end torque top end runs great, when I try to trim the motor down far enough to go in the mud it just bugs down to nothing. A buddy of mine thought it was running too rich so he messed with my carb and now it pops if you give it full throttle from idle and blows a decent amount of smoke. Its opening day of teal season so I am trying to fix this asap. I dont know crap on carbs so any input appreciated.


Sat Sep 08, 2018 11:45 am
Profile
MMT Sponsor

Joined: Fri Jan 10, 2014 1:16 pm
Posts: 2107
Location: Gladewater TX
Post Re: Mikuni tuning problems
The pop could be that ur plugs are fouled from being rich, swap them. Make sure idle air bleed screw is not too far in making carb fat at idle. Check valve adjustments. Bad fuel check. This is where I would start anyway


Sat Sep 08, 2018 4:44 pm
Profile
MMT Member

Joined: Sat May 26, 2018 2:46 pm
Posts: 10
Post Re: Mikuni tuning problems
Put new plugs in they were black so definately running rich, checked the valves they are at .006, drained the tank and refueled with 91 octane no ethanol, took it out yesterday and it would just barely get myself mt buddy and my dog on plane. Also have a new filter on it as well. I have the air idle screw turned out 2.5 turns from all the way in.


Thu Sep 13, 2018 12:54 pm
Profile
MMT Member

Joined: Sun Apr 15, 2018 10:34 am
Posts: 11
Post Re: Mikuni tuning problems
I have the same motor and it’s taken me a lot of trial and error to get it right. Was it running good before and then all the sudden started bogging? Have you done a leak down test? I would get a can of starter fluid and spray down places that could be leaking (intake, where rubber gasket attaches to the carb) how many hours on the motor?


Sent from my iPhone using Tapatalk


Fri Sep 14, 2018 5:19 am
Profile
MMT Elite Member
User avatar

Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
Post Re: Mikuni tuning problems
Glade should see this. Look I can bet this motor fails a leakdown test.

_________________
Bayou Surface Drive
337-351-0362
Tarkington, TX 77327


Fri Sep 14, 2018 5:44 am
Profile
MMT Member

Joined: Sat May 26, 2018 2:46 pm
Posts: 10
Post Re: Mikuni tuning problems
Took it out today got back and noticed I have oil leaking out of the bottom of the motor and also some oil on the spark plugs. I dont know crap about mechanics but know its not good. Any idea what the problem is? It wasnt running very good under a load before he messed with it but now it's worse. The more gas 128 hours on it.


Sat Sep 15, 2018 4:33 pm
Profile
MMT Member

Joined: Sat May 26, 2018 2:46 pm
Posts: 10
Post Re: Mikuni tuning problems
20180915_170944.jpg


You do not have the required permissions to view the files attached to this post.


Sat Sep 15, 2018 4:42 pm
Profile
MMT Member

Joined: Sat May 26, 2018 2:46 pm
Posts: 10
Post Re: Mikuni tuning problems
20180915_171150.jpg


You do not have the required permissions to view the files attached to this post.


Sat Sep 15, 2018 4:42 pm
Profile
MMT 1000 Club

Joined: Sun Oct 24, 2010 7:19 pm
Posts: 1103
Post Re: Mikuni tuning problems
It looks like your block is cracked.


Sat Sep 15, 2018 5:37 pm
Profile
MMT 1000 Club

Joined: Sun Oct 24, 2010 7:19 pm
Posts: 1103
Post Re: Mikuni tuning problems
It may be a shadow that I am seeing.


You do not have the required permissions to view the files attached to this post.


Sat Sep 15, 2018 5:42 pm
Profile
MMT Elite Member
User avatar

Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
Post Re: Mikuni tuning problems
Is oil dripping from the carb? Ill put money on leaking valves and/or blown head gasket.

_________________
Bayou Surface Drive
337-351-0362
Tarkington, TX 77327


Thu Sep 20, 2018 6:26 am
Profile
MMT 1000 Club
User avatar

Joined: Thu Aug 27, 2009 3:17 pm
Posts: 2624
Location: League City, Texas. It's where I play.
Post Re: Mikuni tuning problems
My buddy has a HD that did this. We rebuilt the carb etc.

It was low on oil, and the low oil would kill the motor when it was trimmed down. Just a thought, simple fix. Check it.

_________________

Kool-Aid Brigade


www.southernfowler.com


Thu Sep 20, 2018 7:58 am
Profile
MMT Member

Joined: Sat May 26, 2018 2:46 pm
Posts: 10
Post Re: Mikuni tuning problems
Long story short I got screwed and bought a motor that was shot. Was going to cost 1800 to fix the old one so went ahead and bought a new one for 2100. My question now is how do I tell the difference between the bps heads and briggs heads? I'm wanting to swap the heads over but want to know if the old motor even actually had the bps heads or not before I put them on. Or if I would be better off just having the stock heads on the new motor reworked. I swapped over the carb and exhaust but I need more low end torque bad before duck season comes in.


Tue Oct 23, 2018 9:57 pm
Profile
MMT 1000 Club
User avatar

Joined: Wed Oct 07, 2009 8:18 pm
Posts: 4310
Post Re: Mikuni tuning problems
Take it from me, who has done my fair share of head porting. I just recently picked up an engine with BPS performance parts. Yes the heads have some decking (not sure how much), SS valves and the port work is well left to be desired. This was on a 4400 with mikuni carb and black death intake. The intake wasn't gasket matched much less port matched, the intake adapter wasn't even close to matching the intake, the list goes on and on. But to answer you head question, you would be better sending them off to someone or doing yourself if you know what to do rather than just bolting on BPS stuff. Now the guy could have gotten a bad set, but i doubt it.


Wed Oct 24, 2018 4:33 am
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 14 posts ] 

Who is online

Users browsing this forum: No registered users and 230 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to: