1955 Johnson RD17 25hp - Hard To Start

[jb93]

Fully restored, all new ignition components, rebuilt carb, water pump, head gasket, etc. Compression is 88/88. Set low speed needle 1 turn out, high speed needle 3/4 turn out for maiden start up. Pumped up 2 line tank and gas in the glass fuel bowl...which has new filter and gasket. I don't see any gas leaking from carb. Took 15 pulls to get started up and I couldn't idle it down without it dying out. Only way I could keep it going was higher speed on the throttle and that was running rough. I couldn't keep it going long enough to make needle adjustments and restarting was difficult. I got it running 4 times on about 50 pulls. I could only keep it running at medium rpm but it was not running very well. It seemed to perk up a little on high speed as a leaned out the needle...turning it in....but not great. It would die trying to lower rpm to adjust low speed needle. My biggest concern was the very hard starting. What should I be looking at?

 

[racerone]

Post these fact.----What is the compression ?----Will spark jump a gap of 1/4" or more on both leads ?---That is what we need to know.

 

[F_R]

Is RD-17 the complete model number, or is there a letter following that? Very important to know exactly what you have because there was a serious mid-year engineering change.

 

[jb93]

As noted, compression is 88/88. It will jump spark on 3/16 gap. Spark is good on top cylinder at 1/4 gap, but a little spotty on bottom cylinder. Ignition is totally rebuilt. When I couldn't get consistent spark at 1/4 gap, I took it to a friend of mine who restores outboards. He went through it with me and rechecked everything, including uses his meter to check out all the components and connections. He said all was well and suggested that I move my spark tester to 3/16 gap. I did that and it sparks good zap at 3/16.

FR...the model is the mid year change 17S. I put in a new lower driveshaft seal when I had it apart for restore. I read a few of your posts that said that seal was problematic.

Also..the flywheel magnets seem good. If I hold a screwdriver close it will pull it over and hold it.

 

[F_R]

Ok, so you know about the crankshaft seal problem. Is there any looseness in the main bearings? I'm not sure what "normal" compression is on that motor, but 88 seems a bit low. But I could be mistaken.

Flywheel magnets never go bad on motors made after WWII, so that is not a suspect.

Slow speed needle is a tad lean at one turn, but should at least start. Try 1-1/2 turns.

Sorry, but I don't have any other answers. I'm concerned about crankcase/cylinder wear, but I know I'm gun-shy on that subject.

 

[jb93]

FR. I didn't split the case, so I don't think I can check main bearings? The old crankshaft seal that I replaced looked to be in very good condition...so it
didn't appear any water got up in the powerhead in the past. It had been sitting for a long time and after soaking cylinders in 2 stroke oil it turned freely and no grinding noises...that was before I started restoration.

When I removed head cover the cylinder walls were clean and no scoring. A fair bit of carbon build up on the crown of piston, but the rings were free. I cleaned off the carbon build up on piston. There wasn't any cross-hatching of honing remaining, but I didn't think that was a bid deal? I rechecked compression this morning and it is 92/92. That is after running a bit last weekend, so I suppose the fuel mix in the cylinders might bring the compression up a tad. It was 88/88 dry before this weekend.

I'll open up slow speed needle to 1-1/2 and try again.

 

[F_R]

Sounds like you lucked out on the seal issue. By checking the bearings, I simply meant grab the flywheel and try to move it fore and aft. Bearing wear can be dramatic if the seal failed. But like I said, it sounds like you got lucky.

 

[racerone]

Did you adjust the heels of the coils to get the proper air gap between the magnets and the coils.----Poor spark is a leading cause of " hard to start " condition.---Did you use the timing marks on flywheel and magneto plate to get really strong spark ?

 

[jb93]

Did you adjust the heels of the coils to get the proper air gap between the magnets and the coils.----Poor spark is a leading cause of " hard to start " condition.---Did you use the timing marks on flywheel and magneto plate to get really strong spark ?

Yes sir...I have the ring gauge from FR and coils are set proper air gap. I don't have his timing tool, so I set the points at 0.020 at the high point on the cam. the points are new and I have checked the gap like 8 times. I sprayed electronic cleaner spray on points and ran a business card through them to make sure clean of any oil/grease. I am running new J6C plugs gapped at 0.025.

I did notice that the armature plate was a little wobbly even when screwed down tight. I used a punch and made 4 marks 90 degrees apart on the ring below the plate that is supposed to hold it steady. It didn't seem to make a lot of difference. The armature plate is not really wonky, but it does wobble a little if I put pressure on one side of it. Should I put some more marks on the ring below it to try and tighten it up even more?

 

[jb93]

I just saw a Youtube video about armature plate wobble. I HAVE THE RING UPSIDE DOWN!!! The aluminum ring under my armature plate was chamfered side up. It was that way when I took it apart, so I figured that is how it went back. Video showed how flat side up makes the wobble go away. Note..the video credited iboats, so I am sure the thread is in here somewhere. I bet this will help. Yes? Here is the video http://www.youtube.com/watch?v=hQt07cXXfbM

 

[F_R]

Absolutely, flat side goes up. But don't be surprised if it is then TOO tight, due to your hammer & punch "fix". You may have to replace that ring now. That's OK,, there are thousands of them out there in our goody boxes.

 

[jb93]

Flipped ring and de-punched the marks I made. Smooth and mo wobble! BUT, I have 3/16 gap spark on top cyl and none on bottom. If I ground plug the bottom cyl is sparking at plug. All ignition components are new and checked with meter. Points are new but I polished them with 320 paper, sprayed with electronic cleaner, wiped with business card and regapped at 0.020. I haven't fooled with setting up in a barrel to try and start due to spark on bottom cyl. Should I since it sparks at the plug? If not then what is next step?

 

[racerone]

You need to revisit ignition work.---A good magneto on those will fire a 1/4" gap with a " snap " that you can hear.-It will do that all day long.--Some thing was overlooked in the magneto repairs.

 

[jb93]

You need to revisit ignition work.---A good magneto on those will fire a 1/4" gap with a " snap " that you can hear.-It will do that all day long.--Some thing was overlooked in the magneto repairs.

Understand. I just don't know what it could be. All of the components are new and checked out after assembly with meter. If I flip the coils, the bottom cyl still doesn't fire 1/4 gap but does spark the plug. The only thing I didn't check in my swapping of coils and condensers was the plug wires...as the top cyl wire is too short to move to the bottom cyl. The wires are brand new though. I guess I could put on another new wire to see if that helps bottom cyl??

 

[racerone]

What brand / kind of wire did you use and where did you buy it ?

 

[jb93]

What brand / kind of wire did you use and where did you buy it ?

Purchased a set of pre-built Ford tractor spark plug wires from Tractor Supply. They are 7mm copper core. Good or no bueno?

 

[jb93]

I tried another one of the tractor plugs, which are (based on other posts) the correct wire to use...7mm copper strand core. No spark. I read a few old posts that talk about how to build a spark plug wire. It says to cut the casing and flare the wires out around the rubber outer and then crimp on plug connector...which gives more contact area. I took the boot off one of my prebuilt wires and it is crimped to penetrate the rubber and make contact with the wires inside the casing. That can't be as conductive as the way building a wire is described. I'm going to build me some wires and see if that helps. I feel sure it is not any of the ignition components, so I am focusing on the wires. I'll post back either way. I'm cautiously optimistic.

 

[jb93]

I made up new terminals on spark wires. No effect. I have very sporadic spark at 1/4 gap. Sparks fine at the plugs on both top and bottom if I ground them against the block. So...all new and verified ignition components, points set, etc. What else can I do to get some good spark?

 

[jb93]

I am still battling this spark issue. With all new components, points set, etc. I still only have weak spark on the plugs. In comparison, my 57 Fastwin pops hard at 1/4" gap. The only thing I haven't replaced is the flywheel and the armature plate. The plate is well grounded (verified), so I'm left to believe the flywheel magnets are weak. I have read about building your own magnetic charger, and way over my head. Is there somewhere you can recommend that would recharge my flywheel. I'm concerned about buying a replacement flywheel that is also over 50 years old.

 

[HighTrim]

The post WW2 flywheels are much improved, and have never had a 50s OMC with bad flywheel magnets. Maybe if you left the flywheel off the motor for a hundred years or so it may weaken, but nothing you will have to worry about. I doubt that is the issue. I find your symptoms are almost ALWAYS dirty points. Even when new, they often need cleaning and dressing. Wrap wet/dry around a hacksaw blade, and polish those buggers to a shine. Blow off with compressed air. Dip business card or paper stock in acetone and run that through. This is after verifying they are set correctly at 020. How is the coils air gap? Maybe too big?