Hey guys –
I was hoping folks with more experience could help me think through a few things. I want to build a mud motor for a small boat that I will have to load/unload from a pickup bed by myself, so complete motor weight is key. The boat is rated for up to 10hp but the transom weight restriction won’t allow for the predator 420cc, so I really am stuck with the 212cc. I was hoping some of you could educate me on if I can get ~10hp out of a predator 212cc without having to mill heads, change cams, etc. Also, given that this rig is going to be taking me into some very remote locations reliability and longevity are my biggest concerns.
From what I’ve read, here are the first steps:
1). The mud motor’s prop shaft shouldn’t turn over 4500rpms. From what I have read I can adjust the throttle screw to hit around 4500 rpms without having to remove the governor. Is this correct? Would I need a billet flywheel at this level?
2). K&N style air intake.
3). Robertson’s torque tube exhaust.
4). Rejet carb at around 36-38, 140 emulsion tube. I’ve read the mikuni’s are great but you have to run an inline fuel pump. Not planning on having battery on the boat so the mikuni is out.
5). Upgrade to a decent spark plug, gap at 25.
6). Thinking about 18lb valve springs given floating valve issues but am concerned about this beating up the stock cam and lifters. Anybody have advice/info?
7). Also thinking about the 8 degree timing advance but have heard some folks have had issues with the aftermarket timing keys shearing apart. Anyone have experience with this? Does is even do anything with a stock cam?
Has anyone out there done similar mods on this motor and put it on a dyno?
What other beginner mods have I missed? Like I said, not trying to make 20hp but I need more than 6.5! Thank you all so much!
I was hoping folks with more experience could help me think through a few things. I want to build a mud motor for a small boat that I will have to load/unload from a pickup bed by myself, so complete motor weight is key. The boat is rated for up to 10hp but the transom weight restriction won’t allow for the predator 420cc, so I really am stuck with the 212cc. I was hoping some of you could educate me on if I can get ~10hp out of a predator 212cc without having to mill heads, change cams, etc. Also, given that this rig is going to be taking me into some very remote locations reliability and longevity are my biggest concerns.
From what I’ve read, here are the first steps:
1). The mud motor’s prop shaft shouldn’t turn over 4500rpms. From what I have read I can adjust the throttle screw to hit around 4500 rpms without having to remove the governor. Is this correct? Would I need a billet flywheel at this level?
2). K&N style air intake.
3). Robertson’s torque tube exhaust.
4). Rejet carb at around 36-38, 140 emulsion tube. I’ve read the mikuni’s are great but you have to run an inline fuel pump. Not planning on having battery on the boat so the mikuni is out.
5). Upgrade to a decent spark plug, gap at 25.
6). Thinking about 18lb valve springs given floating valve issues but am concerned about this beating up the stock cam and lifters. Anybody have advice/info?
7). Also thinking about the 8 degree timing advance but have heard some folks have had issues with the aftermarket timing keys shearing apart. Anyone have experience with this? Does is even do anything with a stock cam?
Has anyone out there done similar mods on this motor and put it on a dyno?
What other beginner mods have I missed? Like I said, not trying to make 20hp but I need more than 6.5! Thank you all so much!