nissan timing again

[Don Eskelund]

Thanks for the information Pinkmouse, but it doesn't solve my problem. The motor near breaks your wrist when it fires when you pull to start it, although it run fine once it starts. I am sure this is due to it firing to close to TDC. Is there an easy fix for this problem or should I go ahead and modify the breaker plate.

 

[pinkmouse]

Re: nissan timing again

is the motor all original.do you have the breaker plate in the right position? the points are set right i gather.does it do it all the time

 

[pinkmouse]

Re: nissan timing again

i have worked on many of these.only occasionally will one kick.does it do it always?actually my first question to you is when did this start happening.

 

[Don Eskelund]

Re: nissan timing again

Hi Pinkmouse<br />All is original and properly adjusted. It does it all the time. Gas is clean and water free, changed three times, drained and cleaned the carb as well. It is my belief the problem came on gradually until it was no longer tolerable. The motor is my aux. on a 23 foot Newick Trimarran and has more than a few hours on it. The problem is probably worn bearings which has put the cam out of sync. I know I should probably rebuild the motor and replace the bearings but hate to do this for a problem that in my experience has always been solved with a simple timing adjustment. The motor fires almost right at TDC. I am new to this list and am submiting this as a reply and hope you read it there. If not I will make another post later. Thanks again for your help. Everyone around here just says: "I don't Know".<br /><br />Don Eskelund

 

[JB]

Re: nissan timing again

Howdy, Don. Your problem was fairly common in big bore, fixed-timing two strokes in the old days. Big displacement chainsaws can do terrible damage to arm and shoulder if they fire too soon. The most common cause was shifted timing due to worn out timing cam which changed the dwell (set under static conditions) for a given gap setting.<br /><br />You can actually change the timing on your motor slightly by decreasing the open-dwell of the points. If your book has you setting the points at, say .020, close them down to about .015 and give it a try. The result will be that the points will break a few degrees later and give you a slightly weaker spark. It ought to be enough to tell you if the problem is really timing. Don't leave it there. <br /><br />If your mag has a removable (not cast into the crank) cam, replace it. If your points are not new, examine the part that rides on the cam for wear. If there is noticable wear, replace the points. <br /><br />Generally the cam will wear down before the crank starts to wobble. I doubt that you have worn crank bearings because the seals would go very quickly, robbing you of crankcase pressure with a dramatic loss of power.<br /><br />No guarantee that these ideas will solve your problem, but they have fixed many an arm-breaker.<br /><br />Good Luck.<br />JB

 

[Don Eskelund]

Re: nissan timing again

Hi JB, <br />Thanks for the input. I have tried closing the points down to the very minimun that would still spark (I even tried opening them in case I had lost all reason). It may have helped a little but not enough to save my wrist. The cam is on the flywheel and shows no wear. The original points were in the engine up until the time the problem became intolerable. They were in good condition, showed no significant wear on the fiber pad when compared with the new replacement points, and even the contact points themselves were in good good condition. Your post did make me realize that altering the thickness of the pad is a cheaper experiment than messing with the nonadjustable cast aluminum breaker plate. The concept of a two stroker with no timing adjustment is beyond my scope of reason as I thought the adjustment was to compensate for engine wear. My fear is that the bearings in these engines are so thin that when they go out of time you are already in a near steel against steel situation as far as the bearings are concerned. I am 47 years old and own two strokers that I bought as a teenager that are still going strong. My lawn tractor is 1967, my dumptruck 1968, my backhoeloader is 1972, as is the jeep I plow my driveway with. I do own one of those chainsaws which was probably made before I was born (with a timing adjustment). Around here 1987 is almost brand new and it frustrates me to no end when I can't keep it running properly. I think the real problem may be that if you want a small outboard these days you have one choice. The decal may say Mercury, Nissan, Johnson, Evinrude, Mariner, Hitatsu, etc., etc., but they are all the same motor, made by the same company in Japan. I have written Nissan but am waiting for an answer. If they have one I will pass it on to those of you on this list. Thanks again for your help and input<br /><br />Don Eskelund

 

[pinkmouse]

Re: nissan timing again

the bearings in your motor are ball bearing upper and lower. the rod is needle on the pin and crank.the only thing i can the of is maybe the commpression bleed is plugged.this is a little hole that is about a half inch down the cylinder bore.it bleeds into the exhaust port.

 

[pinkmouse]

Re: nissan timing again

these motors are pretty good. only problem i ever see has to do with owner neglect.bad gas and plugged cooling passage.

 

[JB]

Re: nissan timing again

Yo, Don. Hmmm. That little popper must have worked right at one time. It can be made to work right again if we isolate the part that wore out, broke or changed value to cause what still sounds like premature firing of your plug. You have clearly taken a logical approach to troubleshooting and eliminated several possible suspects.<br /><br />I wonder if the mag could be going maverick at such a low rpm. Maverick is a trick we used to do with chainsaw engines on racing karts. We made the plug fire on the expansion of the coil field rather than the collapse of the field. The result was about 20 degrees of advance. If overdone it burned holes in pistons and folded forged steel rods in half. That may have nothing to do with your problem, but putting the theory in the pot may trigger a more likely idea.<br /><br />I don't think all kickers and aux's are made by one maker. At least into the middle 80s OMC made their own. I have a '84 Johnson 2hp that came off of a sailboat and is engineered like the bigger OMCs...very servicable. I believe that the OMC twins from 4 to 8hp are similarly well engineered, though I haven't had one newer than mid 70s.<br />I am surprised to hear that your Nissan is so difficult to tune and service. <br /><br />I will review my magneto theory and maybe come up with a new idea. Meanwhile, check your coil for low resistance from points (open) to ground and higher resistance from the plug lead to ground. I didn't notice that you mentioned your capacitor (condenser). If you haven't replaced it, do so. (Only a capacitance checker can verify that it is good. If it has lost it's capacitance it might be allowing too fast a rise in the primary of the coil).<br /><br />Hang in there and let us know anything new that you learn.<br /><br />JB

 

[Don Eskelund]

Re: nissan timing again

Ahhh, I think Pinkmouse may have the answer. Compression release. I am not a real mechanic, but I do remember those buttons on the old Triumph motorcycles that you had to push to get the motor to turn without breaking your leg. This Nissan has been an exceptional unit. The boat will do bursts of 20+ knots under sail and is just a few feet off the water. This is much like having a salt water firehose dousing the whole boat and everything on it, including that poor little kicker. I believe the motor may have been near submerged from time to time but always came up running, has never failed to start when I needed her, or stopped running for any reason except lack of gas. I suppose the conditions on my Trimarran would qualify as owner abuse. It does bother me that there are so few small outboards to choose from and apoligize if I vented some of my frustration on every manufacturer I could think of, but I'm sure they all sell the same motor, although I have not actually seen one under a Johnson cover, I'm pretty sure the Evinrude is the same as mine. <br /><br />I'm not sure quite where this compression release passage is located, or if I can clean it out from the exterior, but will see what I can find this afternoon, if I can make the time. Thank you all for your input and help! I've been trying to solve this for more than a year now and may have got the answer in less than a day. This list is a great place. Thanks again to all who responded, especially to you pinkmouse.<br /><br />Don

 

[pinkmouse]

Re: nissan timing again

don, evinrude not the same.to check the bleed hole,either the head has to be removed or pull the power head.it's the size of a paper clip wire

 

[Don Eskelund]

Re: nissan timing again

Hi Pinkmouse, JB, Others,<br /><br />I removed the top of the unit rather than the head. From the outside of the port the compression bleed appears free and clean. I assume I am seeing the whole channel and that it goes strait through the clinder wall, and has no channel machined into the side of cylinder wall that can't be seen from the outside of the port. I was hopeing it would be that simple, I had hoped I was somehow mistaken about the motor firing so close to TDC. I own two of these motors and my dad has one as well. This is the only one with this problem but is also the only one that has points. The other two are electronic.<br /><br />I don't know what a magneto going maverick is, but I'll get out the meter and see if I can find anything that might be irregular wiyh the coil (etc.) as JB suggested. It kicks so bad it broke the key that holds the flywheel on. (I said: Ahh! there is the problem! The flywheel, thus the cam, isn't properly alined! New key, same problem. It had just broken. The condensor is new. There is also a charging coil on this engine that trickle charges the batteries. All the wires are in good shape. ??????

 

[Don Eskelund]

Re: nissan timing again

Hi JB, <br /><br />Resistance from points (open) to ground is 0 ohms. Resistance from plug lead to ground is 4.9 K. ohms.<br /><br />I am not sure what this means so I await your input. Nissan wrote and told me the proper point gap should be .013 inches, questioned if I was using nissan parts, (I am, and they match the originals) and that besides that, they didn't know what to say. Hope you can be more help that they were.<br /><br />Thanks<br /><br />Don

 

[JB]

Re: nissan timing again

Hi, Don. Rats! Your coil seems okay, and I was going to question the key in the flywheel next. Your engine is defying theory and I don't have hands-on with the small Nissans. Someone out there has seen and fixed this problem. I wonder if it has a built-up crankshaft that has slipped. From what you have written I gather that the problem has been progressing for a long time and that you decided to address it when it threatened to jerk your hand off. That progressiveness suggests something changing gradually . . .wearing out, plugging up, bending, shifting. I don't see how carbon buildup could cause preignition when starting, but I think I would pull the head and examine the piston top, compression release bleedhole, etc. for excess carbon.<br /><br />Other than that, I am at a loss. If I think of something I will post it.<br /><br />Good luck.<br />JB

 

[Don Eskelund]

Re: nissan timing again

Hi all, <br />I am begining to think this may be a crank problem as well. I went to a mercury dealer and begged a parts book for a few minutes. The crank is pressed, three pieces. I remember the motor had a terrible vibration when I first bought it that would spin the compass out of true. I returned it to the dealer a couple of times and was told there was nothing wrong with it, and then started getting nasty. I changed from a 2 blade prop to a three blade (for an unrelated reason) and built a new motor mount that had rubber bushing to isolate the vibration. This seemed to solve the problem, or at least made it bearable. I'm not sure if I should keep going and examine the crank or just revert to the original plan of modifying the breaker plate so that I can rotate it and adjust the timing. I would guess a motor like this should fire between 3 and 3.5 mm below TDC. I would shoot for 3.2 or 3.25 mm below TDC. I don't know how much of a job it would be to true the crank up and know no one in my area who I would trust the job to. Still searching for suggestions and coments. Thanks!<br /><br />Don

 

[Don Eskelund]

Re: nissan timing again

Oops, that should read; "and then they (the dealer) started getting nasty". I try to keep my calm and act as a gentleman no matter how angry I might feel inside.<br /><br />Don

 

[Don Eskelund]

Re: nissan timing again

Hi all,<br /><br />JB is right when he says this motor is defying logic. I split the crankase today to take a look at the crank and it appears to be fine. It is three pieces and has little room to slip without the counter wieghts banging into the side of the case. Clearance from the top wieght to the case is about 0.011 in. with no indication of contact or wear. I feel dumber every day!<br /><br />I,ve been through the gas, carb, ignition, crank, cam, and compression release port. What else is left?

 

[joered]

Re: nissan timing again

try using it for an anchor

 

[Don Eskelund]

Re: nissan timing again

Hi Joered,<br />Not a bad idea as long as I forget to attach the rode. Here in Maine we say "I took it off the transom and chowdered it".<br /><br />This has become a challenge that I would really like to overcome.<br /><br />Don

 

[pinkmouse]

Re: nissan timing again

did you pull the head? might as well.i have never seen one as bad as what you are saying.never seen a 2 blade on one of these motors. the cranks never go out.how long has the problem been getting worse,weks,days,or years.one more question did you by it new.one more thought,are both magnets on the flywheel.