Jonsboat | SouthernPaddler.com

Jonsboat

dawallace45

Well-Known Member
The main idea for the trip away was to see family and the parents new house and also to try out the Jonsboat and do a little fishing , well the Jonsboat is a ripper , it got positive comments from people all the way down , people come to have a look at it and called out questions when we stoped for fuel as well , a few people asked where they could buy one and several asked if I'd thought about building and selling them [ which is all very well but those people all seem to be absent then it comes time to lay down the cash ]

I tried the boat out at Turkey Beach first off , just my brother and myself , we tried some low speed manoeuvres to see how she handled then checked it out a bit faster , it handled real well , but when we tried to see how fast she would do the motor started breaking down at around about 27-28 km/p/h , it seemed that the hotter it got the more it broke down [ missing under load ] , I'd changed the plugs before we went out so they were brand new plugs , when we got back to shore I put the old plugs back in , they broke down under load too , it seems to me to be electrical but I'm not 100 % sure , normally that sort of thing would be plugs but not this time , it could also be plug leads , so I will change them first , could be the coil packs , they look fine and give a very good spark but they may be playing up when they get hot , the getting worse when it gets hotter has me stuffed , I really don't know any thing much about electronic ignition so don't have any idea if that could be the problem , if you've got any suggestions please let me know

I tried out the 2HP trolling motor and found that the little motor would push the 16 ft Jonsboat at 6.8 KM/P/H against the last of the run out tide , a little slow for travelling big distances but fine for trolling , one problem was that while the bracket I made up to hold the 2HP motor was fine for the motor height while it was in the water it still held it too low when tilted up and the leg trailed in the water and created a rooster tail at speed and caused a bit of splash over into the back of the boat

The next day I took off the 15 Johnson and the 2HP Evenrude and put my brothers 25 Mariner on , it was like it was made for this boat , we clocked it at 40 km per hour with my Wife , Brother , Dog [ Mischief ] and my self onboard , it also turns very well with no skid thanks to the keel and bilge runner strips , it has the smoothest transisition to the plane I've seen so far , with most boats I've been in there is a definite hump from displacement speeds to planing speeds , not so with this one , smooth as silk all the way

My Brother reckons that this boat goes better with his motor than his 13ft alloy boat does

All in all I towed the boat about 2500 km what with getting there and travelling to different beaches and rivers , we only got to go fishing once for a few hours as we were having too much fun trying it out to see what it could do and cruising around , my wife was the star of the day with one good Whiting , small Flathead and a very large ocean toad , I caught a Stargazer and my brother caught a small whiting [ foul hooked ] as we only had a hand full of bait that was that ,

One problem I did encounter was that I'd been having some problem with arthritis in the spine for a week or two before I went away that had been getting worse every day , as I can't take the anti-arthritis medication because of the asthma it was pretty much unchecked so I was a very sore boy by the time I went away , now couple that with twisting around to pull the motor up all the time and you have a recipe for disaster so the last few days I was in extreme pain and pretty much living on codeine and not able to get into the boat at all , so the last few days was taken up with going for drives to check out the area , but all in all I still had a good time

I had a bit of a problem with the tie down straps wearing on the painted gunnels and need to find a way around that , it probably wouldn't have been so bad if the paint had time to cure and the roads weren't so rough and the distances so long but those were outside of my control

Regards
David
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,976
171
86
Okemos / East Lansing Michigan
Dave,

Here are some things to check on your engine missing while hot & under a load.

Spark plug gap. If it's an electronic ignition, maybe 0.040" to 0.045". That's in inches, I don't know about metric equivalents since my calculatror committed suicide. If your ignition is points and condensor (magneto), then about 0.025" is good.

How did the spark plugs look when you removed them? They should have had a light tan covering of carbon on them. If they were white, it's probably running too hot (can be caused by too lean a mixture). If they were black and sooty, it is definitly too rich, leaving beind extra carbon from incomplete combustion.

Spark plug leads. May have to be either carbon core or copper. Make sure both ends are fitting tightly. May be contamination on the outside of the insulation of the leads. Carefully wipe down the leads with a rag with gasoline on it. Dust, grease, etc. can build up and the spark runs as well on the outside of the lead as it does on the inside. Coral dust is a really bad contaminant for doing that.

If your ignition is not electronic, but points and condensor, replace the points and condensor. Gap the points at about 0.020". Set timing to fire at about 1/4" before the piston reaches top dead center (TDC), as measured vertically in the cylinder.

If the above does not cure the problem, you may have a carburetor (fuel injection?) running either lean or rich. If it is too rich the engine will stutter (begin to fire only every other time) under load and produce extra smoke. If it is too lean it will run up to speed, then wane off. Could also overheat if it is too lean.
 

dawallace45

Well-Known Member
Jack

Plugs looked fine , cap fine , electronic ignition

Will check out leads with my multi-meter tomorrow , was out on the local dam in to boat today so didn't get to check out motor , inspected and cleaned the leads last week after it started playing up , seemed fine with visual inspection but that doesn't mean much

Motor hadn't been run for a year but carby had been drained after last running so carby pretty clean , started second pull , mixture seems fine , sort of leaning to coil packs

Regards

David
 

Kayak Jack

Well-Known Member
Aug 26, 2003
13,976
171
86
Okemos / East Lansing Michigan
Try one more test. Run the motor in the dark. If spark is running along the outside of your leads, you'll see the fire. It should be blue. If it's yellow, take money to the store for new coils and leads.