stock zenoah running eratic? whats the cause

hi ive just pulled a stock motor out of a mates boat that had a flip a cupple of weeks back and a good dunking in the water. we instaled the motor into my boat to give it a run . but now it dosent seenm to be running it wont idle and runns verry eratic as in seems to jump rivs etc. like rivsup high stalls dosent just idle over .
would this have somthing to do with the coil is it the red (magnedo) is that what its called ??. or is it somthing to do with the gray (coil). im i on the right track with this .
the motor seems to realy jump around rpm and not be smoth .and dosent seem to want to idle. the motor was filled with fuel oil after flip over but wasent used for a cupple of weeks . would this be bearings or more of a spark timing ignition problem.
as idd like to get this motor running to have as a back up motor. enny info or help would be great .

thanks in advance:unsure:

Hate to say it, but it sounds like it may have ingested water while still running and bent the crank. You might want to take it apart and inspect the crank, connecting rod, roller bearing, piston pin.... Cranks twist sometimes when this happens. Also check that the flywheel key has not sheared.

thanks marc, that sound termanal ,haha , the motor did seam to run ok in my mates boat for a good hour . then it started playing up . he thort it was his radio gear playing up . but then he wentout and installed a mod motor. and gave me this motor. whull im waiting to get my mod motor back from getting repaired . to hopfaly work this time .
and i was going to use this stock motor till i get mine back.

is it easy to tell if crank is twisted. also im gessing ill nead to buy a fly wheel puller to get the fly wheel off to inspect every thing and in the wors case re build it.

so imm gessing you dont think it has to do with the red ignition coils etc..

Well before taking it all apart, you can start by eliminating the easy stuff...check the fuel lines for air leaks. Check the carb to make sure it's tight on and not leaking air. Also change the spark plug while you are at it. It's easy piece of mind. You can then move on to swapping the coils with some you know work and keep going in your troubleshooting. Check what you can on the outside before taking it apart. Go by process of elimination.

To see how to take engine apart without special tools, you can see this article.

www.modelgasboats.com/Magazine...h_Teardown.html

marc wrote:

Well before taking it all apart, you can start by eliminating the easy stuff...check the fuel lines for air leaks. Check the carb to make sure it's tight on and not leaking air. Also change the spark plug while you are at it. It's easy piece of mind. You can then move on to swapping the coils with some you know work and keep going in your troubleshooting. Check what you can on the outside before taking it apart. Go by process of elimination.

To see how to take engine apart without special tools, you can see this article.

www.modelgasboats.com/Magazine...h_Teardown.html

hi marc , thank you for your great assistance . im tending to think it might be somthing in the ignition . ive change carbs and checked for air leeks , also we did have the jug of checked what we could . it will only idle at say 1/4 throtal . but ennny lower and it sems to realy jump around and if you try to let it idle it just dyes . the revs seem to jump up and down by them self with out moving the trotal at al when it is running.
i dont have enny spere coil or ignition parts laying around . but i gess it wouldent hert to have some as spares . moter did run ok for anbout 3/4 of a hour befor it started playing up on my frends boat . so im hoping it is somthing simple like coil. could you let me know if coils or electrical systems do make motor run like this or do thay usaly just stop copleatly.

hi i have found that the bearings around the crank seem to have play in them . i can hold the fly wheel and move it in or out about one to two mm, also it has play in the crank from end to end i can move it say up and down . and can move it in onto the coil pick ups. i can also see where the coil pic up has scrapped along the fly wheel.
would this be causing my problems . if so should i go and pull the rest down and just replace the bearings. or would there nead to be more done. also on the poston looking in throw the exaust post i can see under the ring lip down to the botom of the piston is got a shinny spot lo9ke its been rubbing on the bore slitly....
every think els seems fine . enny suggestions what to do would be great....

Crank movement in and out is not a problem if it's within say 30 thou or less...the UP and Down play is a problem however. At the very least new bearings and seals would be in order. You would be better to check the crank for trueness also and inspect the connecting rod, piston pin and bearings as well as the piston and ring. I get the feeling it may have suffered water ingestion. If you can't do all the other stuff, at least try new bearings and seals and see what it does.

thanks marc for your help with this . ill try new bearings as thay are verry noisy and have lots of play up and down and back and forword movment. well if its no good ill just keep this one for parts. and await till my other motor i had to send back to the guy that i got the mods from is returned . or i might go and order a omin motor. as ive got a mate with one and it goes real good.

just means im with out a boat motor for a cupple of weeks.. haha.... dam and the weater is realy fining up over hear....

marc wrote:

Crank movement in and out is not a problem if it's within say 30 thou or less...the UP and Down play is a problem however. At the very least new bearings and seals would be in order. You would be better to check the crank for trueness also and inspect the connecting rod, piston pin and bearings as well as the piston and ring. I get the feeling it may have suffered water ingestion. If you can't do all the other stuff, at least try new bearings and seals and see what it does.

Hi marc how do i check the crank for true ness. i have removed the crank and do noticse that the two loabs or the counter whait setion . the part some guys macheen down to give a difrent profile... well i can see that one side is difrent to the other like one side is twisted more then the other buy about one to two mm. is this what you mean by a twisted crank . as i cant realy find enny think showing what a crank should look like when its say twisted. i do have a new crank but it is for a zikk full circle crank. i gess with out shaving the casings down to fit. but im gessing it wouldet be enny good to use from what ive read .

well ive installed new bearings and seals. all the movement that was there befor is gone i think the bearings were flogged out, was signs of rust on the bearinmgs and around crank where bearings sate. . new crank bearings /seals new piston pin bearings and new ring. motor has better compreshon now and dosent seem to jump when pulling the pull start and no play in the crank at all like it did befor. will start it tomorow and see if it runns.