we built our own 16hp longtail mud motor, we have a welding business and after rebuilding one for my brother in law decided i wanted one also, my question is for everyone that has a factory made model, at idle what type of vibration do you get with it on a scale of 1 to 10 and then at WOT

we are running a single cylinder honda clone engine and i am not sure if the vibration is just due to the piston being off center of the frame and a twin cylinder would have less or if some vibration is just common with long tail units. it is not bad at any rpm over idle but i didnt know if this was a common issue with them

thanks

Mine has very minimal vibration at ideal or WOT... 23 hp

I ran a 9 hp for years and had minimal vibration with with that motor also.

If the motor runs smooth and your swivel bolt or pin is not way loose, you may be dealing with a bent shaft, bearing issue or bent prop... Hard to say without looking at it.... Just some ideas...

yea if ithe shaft is out of round you could have it straightened or install a center bushing in the drive shaft housing. also do a forum search for static balancing a prop. heck i have heard of not enough grease in the driveshaft housing making one vibrate. if its a home job you could have to much angle on your u-joint. just a few of the dozen things you can try.

thanks for the responses, it is not a bad vibration, just was wondering if factory models vibrated at all or basically ran as smooth as a car etc. at anything above idle it is pretty smooth, the prop is balanced and i have a center bushing installed, i am not concerned about it, it is not that bad but just needed a comparison with a bought model
thanks

well mine is an 86 model with upgrades, but 3 different props and they all did the same. at high idle i hit a spot with vibration, my handle will shake some if you dont have your hand on it. but the new GD guide says that its normal.

thanks, that is kinda what i was looking for

http://godevil.com/documents/Go-Devil%2 ... Manual.pdf

look at page 7 bottom of paragraph.

I talked to a guy who works on engines and he told me that the Harbor Freight motors are a direct spin off of the Honda engines EXCEPT the aftermarket engines don't have the quality control of the others and it is hit and miss if you get a good one. Chances are you have one that isn't as well balanced in the crankshaft causing the vibration that your having. My .02 run the piss out of it and save some money for a Kohler that has a 3 year warranty

yea this is an old thread but i just finished my home build which is a blatant GD rip off, but the 9hp lifan i have on it vibrates more than my 16hp vanguard. my guess is the cylinder angle. it does smooth out just above high idle.

thanks for the info, we have already sold the 16 hp longtail, along with the boat and mercury we had for it, guy we sold it to loved all of it and had to have it. I have enough parts to build another one in the shop now, but we are looking for a GTR and a 17-18 foot boat to run catahoula lake a little quicker with a load. If we dont find a reasonable deal before september, may have to build the second one, i probably will try to find a used 20 or 25 hp if i do. you can find a good deal on a used go devil in that hp range for what a new name brand motor cost.

thanks again
brianb