It is currently Thu Mar 28, 2024 5:32 am




Reply to topic  [ 11 posts ] 
 Bogging down at high rpm 
Author Message
MMT 1000 Club
User avatar

Joined: Mon Jan 21, 2013 6:22 pm
Posts: 1094
Location: El Dorado-ish, AR
Post Bogging down at high rpm
Alright got a buddy with a GTR with mikuni, heads, roller rockers, the works, and when he is running about 3700 or so RPMS it seems like it boggs down and just sucks at life. Any ideas?

Sent from my Pixel XL using Tapatalk

_________________
'13 GTR35 Stage 2 w/ EVT Exhaust, 1750 Voodoo Custom by DFOU!!


Tue Dec 12, 2017 4:54 pm
Profile
MMT Elite Member
User avatar

Joined: Mon Feb 06, 2012 6:13 pm
Posts: 5605
Location: D'town, LA
Post Re: Bogging down at high rpm
Need more info. Is he trimmed right? Is this WOT? What size boat? Loaded? Light? What prop?


Sent from my iPhone using Tapatalk


Tue Dec 12, 2017 5:26 pm
Profile
MMT 1000 Club
User avatar

Joined: Mon Jan 21, 2013 6:22 pm
Posts: 1094
Location: El Dorado-ish, AR
Post Re: Bogging down at high rpm
trimmed different angles to see, and yes WOT, 1750 boat loaded with 2 people and duck shit, and gator tail 2 blade.

_________________
'13 GTR35 Stage 2 w/ EVT Exhaust, 1750 Voodoo Custom by DFOU!!


Tue Dec 12, 2017 9:12 pm
Profile
MMT Sponsor

Joined: Fri Jan 10, 2014 1:16 pm
Posts: 2107
Location: Gladewater TX
Post Re: Bogging down at high rpm
valve adjustment too tight,,, or tune is way off,,, or just starving . Y'all try pumping bulb while it bogged? Just throwing out ideas


Tue Dec 12, 2017 10:38 pm
Profile
MMT 1000 Club
User avatar

Joined: Mon Jan 21, 2013 6:22 pm
Posts: 1094
Location: El Dorado-ish, AR
Post Re: Bogging down at high rpm
Unfortunately I haven't been there when the crap is happening. I am gonna try some stuff in his boat in a few days and report back.

Sent from my Pixel XL using Tapatalk

_________________
'13 GTR35 Stage 2 w/ EVT Exhaust, 1750 Voodoo Custom by DFOU!!


Tue Dec 12, 2017 10:45 pm
Profile
MMT Elite Member
User avatar

Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
Post Re: Bogging down at high rpm
Basics. Air, Fuel, Spark.
Valve lash
leak test.

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


Wed Dec 13, 2017 7:00 am
Profile
MMT 1000 Club
User avatar

Joined: Thu Nov 04, 2010 7:38 am
Posts: 4323
Location: Cut Off, La.
Post Re: Bogging down at high rpm
Also, with those mods, he should be at better rpms.

_________________
Refurbishing a Prodrive


Wed Dec 13, 2017 7:39 am
Profile
MMT 1000 Club
User avatar

Joined: Mon Jan 21, 2013 6:22 pm
Posts: 1094
Location: El Dorado-ish, AR
Post Re: Bogging down at high rpm
yeah He normally runs 4400+ but said when it hits right around 3700 it acts like it is starving for fuel and nearly just shuts down, but if fine up until that point.

_________________
'13 GTR35 Stage 2 w/ EVT Exhaust, 1750 Voodoo Custom by DFOU!!


Wed Dec 13, 2017 1:18 pm
Profile
MMT Pro Member

Joined: Mon Aug 17, 2009 4:39 pm
Posts: 160
Location: Fort Payne, AL
Post Re: Bogging down at high rpm
It sounds like a fuel pump going bad, trash in the main jet or something preventing fuel delivery. I took my boat out once and it ran fine for a while then would bog down and die. I could wait a few minutes and it would crank and run for a short time and die again. The problem turned out to be the vent on gas tank. If your buddys engine runs fine but bogs at a certain throttle position that sounds like a lean condition(not enough fuel). He might try pulling the plugs and see if they are whitish. The pumping primer is a good suggestion also. Come to think it could be a clogged fuel filter as well. Hope this helps.

_________________
MarshMellow Performance


Wed Dec 13, 2017 3:39 pm
Profile WWW
MMT 1000 Club
User avatar

Joined: Mon Jan 21, 2013 6:22 pm
Posts: 1094
Location: El Dorado-ish, AR
Post Re: Bogging down at high rpm
So before I could really diagnose, my buddy took the guys head off (after compression was fine), and I had already figured out there was no spark going to the cylinder. Broke a head bolt off in the block by using the torques wrench incorrectly. So that is where I am at, trying to get a bolt out of the head and those damn bolts are hard as shit!

_________________
'13 GTR35 Stage 2 w/ EVT Exhaust, 1750 Voodoo Custom by DFOU!!


Wed Dec 20, 2017 11:44 am
Profile
MMT Elite Member
User avatar

Joined: Wed Jan 14, 2009 7:23 am
Posts: 6233
Location: Tarkington, TX
Post Re: Bogging down at high rpm
9mmx1.25

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


Wed Dec 20, 2017 3:23 pm
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 11 posts ] 

Who is online

Users browsing this forum: No registered users and 231 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: