98 Johnson Venom 200

[cbaker10]

Hey, a couple of months ago, I did a compression check on my outboard. Five cylinders hit at 60 or 65 and the top right cylinder hit at 90. I continued to run the motor through the summer because everyone said it was low compression but they were pretty consistent. The motor has a very slight miss when running at about 4800 rpms but runs fine at wide open throttle. However, the motor does not want to idle at all. While in neutral, the motor will usually choke out and die. Or when you shift it to the first notch it just want run good at all, I have to add just a little throttle past the first notch to keep it running. Anyway, a couple of days ago I decided to get another compression check done. All cylinders hit at 115 and the top right hit at 120, which sounds great to me. Does anyone have any idea what could be the problem and what should I start checking first. One guy said the power pack could be going bad but that will be a $325 guess so I didn't really want to try that just yet. Also while at idle on the water hose, I can pull the plug wires off one at a time and on two of the cylinders, it doesn't make it idle any different when they're un-plugged. I would greatly appreciate any help or advice.

Thanks

 

[Chris1956]

Re: 98 Johnson Venom 200

Use a timing light to see if all spark plugs are firing. If they are firing the carbs may be dirty. A OEM service manual is a good investment if you need to troubleshoot the ign system. marineengine.com sells them. Have the model number handy.

BTW - the 60PSI compression reading were likely incorrect. The motor would probably not run with that low of compression.

 

[JB]

Re: 98 Johnson Venom 200

Powerpac has nothing to do with compression, cbaker.

Almost any psi measurement on a 2 stroke can be an error, due to the many, many variables. When the cylinders do not all fit in a 10-15% span, however, you have a compression problem.

A case like yours, with one high and the rest fitting the span, I would be concerned, but: When you re-did it the result is excellent. Good show.

Now, the trouble. If the two dead cylinders (no change when pulled) are side-by-side you have a carburetor problem; if they are over-under it is more likely to be a powerpac.

Good luck, and let us know what you find.

 

[cbaker10]

Re: 98 Johnson Venom 200

Hey, thanks for the reply. I did a spark test the old fashion way by taking a plug out and leaving it plugged with the wire, then grounding it to the motor. The spark was white on every cylinder. What do you think could be the problem? Could this confirm that it is the power pack?
Thanks,
Chuck

 

[boobie]

Re: 98 Johnson Venom 200

To do a proper spark test you should have an open air gap spark tester and the spark should jump a 7/16 " open air gap. You can buy a tester at most parts houses for around $10.00 max.

 

[JB]

Re: 98 Johnson Venom 200

Read my post again, CBaker. You have a carburetor problem.

 

[cbaker10]

Re: 98 Johnson Venom 200

Alright guys, I took my boat to a marine specialist. He took all the carbs off and cleaned them. He said the floats and seals and everything looked good, but they were definately dirty. He also said the timing had been adjusted to 25 degrees before top dead center, so he put it back to 18 degrees. He also did the lync and sync, and he also found a vaccum leak behind one of the carbs. He fixed everything and cleaned the carbs. So we took it out today and put it on the water to try it out, when we first got there, it wouldn't even run. When you give it some throttle, it would just die. However, if you give it throttle while choking it, it would take off and run. So he adjusted the fuel/air mixture screws to where it would run. Now, it definately idles a lot better than it did before, but it still has a slight miss to it while at idle, but runs great on top end. It also has a split-second hesitation now when you give it full throttle to take off. It's like it can't get the gas quick enough or something. But anyway, do you all have any suggestions on what to try now? I'd really like to get it lined out before I have to store it for the winter.
Thanks

 

[Faztbullet]

Re: 98 Johnson Venom 200

These carbs CANNOT be adjusted on a hose or in a barrel, the engine has to be in the water, in gear moving to adjust correctly. Have the fellow who performed the work adjust them correctly as you paid for it to be done correctly..

 

[cbaker10]

Re: 98 Johnson Venom 200

We did take the boat out to the lake yesterday and he did make some adjustments to it on the water,now its idling better and runs good on top end but it has hesitation when you give it full throttle to take off. I was just wondering what could be causing the hesitation. He is going to meet me again to try and work it out, I was just wanting some different opinions.

 

[Faztbullet]

Re: 98 Johnson Venom 200

Sync & link is incorrect or the upper throttle bodies (butterflys) are not in sync with lower bodies..

 

[cbaker10]

Re: 98 Johnson Venom 200

Ok, we took it back to the lake and he adjusted on it maybe an hour and a half or so and it still just want idle. So, he took it back to his shop and began running more tests. He was checking voltage on the stator, and at one of the ignition coils, it's just reading 20, another at 120, and the rest are normal. He also found a dark spot on one of the coils in the stator itself, so he is leaning to this now. What do you all think about it? Could the stator be the cause of all of my problems? If so, where would you recommend for me to buy the replacement and about how much would we be talking? Thanks for any replies.

 

[mekkamaz]

Re: 98 Johnson Venom 200

With all due respect for the really pro mechs, I?ve found a lot of threads when they take the motor to a "pro" and ends the same or worst right after leaving the shop..Come on, mechs, earn a good rep!!!! that said I guess timing is incorrect, and gives that hesitation...It happens to me in a couple of J?s and timing has to be advanced...maybe that retro to 18 instead of 25 deg shouldn?t been done, check your manual for the propper timing....As for the stator and all that test........, correct the spark advance and re-test, you?ll feel the difference!!!

 

[daselbee]

Re: 98 Johnson Venom 200

Proper WOT timing spec for a 1998 200 is 18* BTDC @ 5000 rpm.

 

[CharlieB]

Re: 98 Johnson Venom 200

Slight miss at idle may be caused be still slightly lean idle on one cyl, and/or a slightly leaky reed valve on one cyl.

If fattening up the idle mixture makes no further improvement I'd want to LOOK at the reed valves to ensure all are seating.

A stator will NOT cause an intermittant idle miss, don't fall for a new stator, it will cost a bunch, and won't cure your problem.

 

[daselbee]

Re: 98 Johnson Venom 200

A stator will NOT cause an intermittant idle miss, don't fall for a new stator, it will cost a bunch, and won't cure your problem.

Agreed. ^^^^^^

You say two voltages were down, but the other 4 were normal....First question I had was "What's was the value?" How does anyone know whether it is "normal"?
Why didn't you post the value? You did so for the two odd cyls....

And just so you know....whatever the normal is...I use 200v DVA volts....it all comes from the same place...the stator. So it is not likely at all that the stator can output 4 "normal" voltages and two low ones.

See the question here????

 

[cbaker10]

Re: 98 Johnson Venom 200

I really appreciate all the replies, this thing is about to drive me crazy.

mekkamaz: When I first took it to this guy, he put everything back to specs according to the mannual. Like you, I wish he would have left the timing alone because it seems to have caused me to loose about 5mph on top end. What exactly do you mean by spark advance?

charlieb: i have definately seen some improvement when the idle mixture is adjusted, but it just want get rid of the intermittant miss. He did tell me all the reed valves are seating properly. What else can cause a lean mix and so on? He also said the recirc valves seem to be working properly.

daselbee: the reading on the other four were around 150, which is what the mannual calls for. What else could be causing the low readings?

Do all of you pretty much agree that it is still just out of adjustment, nothing major? It really runs great on top end, comes out of the hole good, and even starts good. There's just something up with the idling. It's like it has to sneeze and then it dies, as well as the slight miss while idling. Also, why could it be possible to pull the plug wires off of three cylinders one at a time while its idling and it show no change in how it runs?

Thanks guys!

 

[daselbee]

Re: 98 Johnson Venom 200

1. Low reading on the two odd cyls can be caused by the coils at those cyls, or by a bad powerpack. I would concentrate first on getting those voltages all even across all 6 cyls. Then I would address the slightly low 150 DVA volts...I like to see about 200 at idle. I know I have a good hot spark then.....Swap coils around first to see if the low voltage follows the coil. If not...powerpack time, but only after the proper testing of the pack.

2. How were the carbs cleaned? If he skipped the throttle body side plates, he has missed a critical area of cleanliness for good idle.
If he misses cleaning the emulsion tubes that extend down into the black carb bowl, he missed another critical area.
You say that when he gives it throttle to take off, it bogs. Tells me that it may be starved for gas at that point in time, and that would lead to those two areas in the carb.
Do not over compensate by turning out the idle screws to 8 or 9 turns...they should be at around 5 turns out on all 6.

Link and sync. He should not have to be out on the water for an hour adjusting...adjusting...etc. It is a pretty solid system and once clean and outputting the proper voltages, it runs. The two bottom carbs on each side (#5, #6) are independently adjustable to the throttle shafts of the respective upper carbs. This is a very critical adjustment. All six butterflies must be CLOSED at idle, and must open in complete unison. Takes me about 45 mins to set it up right.

 

[CharlieB]

Re: 98 Johnson Venom 200

Print daselbee's response and follow it, to the letter.

 

[mekkamaz]

Re: 98 Johnson Venom 200

Proper WOT timing spec for a 1998 200 is 18* BTDC @ 5000 rpm.

Yep, @sea level??

 

[mekkamaz]

Re: 98 Johnson Venom 200

I mean timing, adjusted propperly as you open throttle, it advances also from say 6-8? idling to 18 or 25? WOT. As I say, I have this hesitation on two diff. motors and changing timing done a lot of difference!!!.. Not very recommended, but if you can adjust it by a timing light WOT on still waters is a good way......Yeah, I know....someone gonna say not to, but if you are careful enough you can do it, and check timing marks also......I have done this myself...still one piece!! lol. One was a 235 VRO Johnson and 235 Evinrude.