1988 johnson 225

[bbay15]

Hey Guys,
I need a little help with an engine I purchased over the past winter.It is a 1988 Johnson 225 with nose cone,lwp,new stator,power pack and power head.I finally took it out this past weekend and heres the problem,btw the motor is on a 21' Hydrostream Voyageur with a 8" setback (jackplate)with a 25 pitch Mirage
When I throttle up the engine seems to have a lack of power,when Im running at wot the tach is about 5200rpm then the motor picks up and rpm is about 6000(my tack only reads to 6000)then drops back off again.It seems to be fuel or spark.There was all new fuel lines,filters put on it.
Any advise would be greatly appreciated
Your Northern enthusiast !!!!

[Costa]

I had a similar problem with mine and changed the plugs from L77V to QL77V. the QL plugs are resistor plugs, only thing i could figure were the interference from the non resistor plugs and were causing the ignition to cut out.

[bbay15]

Thanks for the reply Costa,I will try this and let you know.

[bbay15]

I tried to get these plugs in Canada and they dont make them,I crossed them to an NGK plug and picking up Friday.I also talked to a marine mechanic today and he suggested that it may be a reed valve,bad coil or plugged main jet in one of the carbs.Boat goes into shop Tuesday.

[jphii]

QL77JC4. You are better off running Champions. HERE is the application chart.

[lokinutz]

Does it do it early in the day when the electronics are still cold, or only after they are nice and hot? You should get a FACTORY service manual (ebay) and check ignition using a peak volt meter exactly how the manual shows.
A bad reed won't do that, and if it's a plugged main jet, that cylinder will show a different plug reading than the other 5...also, how do they look?

[bbay15]

Thanks for the replies,The original plugs are Champion 77's,they all look good with no heavy oil residue.I guess I will cancel the NGK and go with original.As for the electrical,the boat is warmed up and idled out for some time,it seems to act this way almost immediately.I know a coil breaks down when hot but this takes the cake!All electrical,stator,timer base,control module,power head was replaced over the winter.All compression # are good,so Im at a loss.As I said earlier,it seems a little slow out of the hole and once up on plane it revs to 5100rpm then suddenly jumps to 6000rpms ????then back to 5100rpm.

Again thanks for the replies,all info is good.

[racer]

You mentioned new powerhead, does it have the stock jets? is the timing set correctly? sounds like it is rich and cleans out then drops back off. You can try wot the back off the throttle a little, if it gains rpm its rich

[bbay15]

The boat is in the shop right now awaiting diagnostics.The mechanic here still has no ideas although he did mention a main jet being dirty.This past weekend took off one of the fuel filters(it was clean) and tried fuel right from a 5 gallon can,still did same thing(surging).Hopefully getting back this week to try out!! Thanks again for the ideas.

[john j 80 viking]

You mentioned new powerhead, does it have the stock jets? is the timing set correctly? sounds like it is rich and cleans out then drops back off. You can try wot the back off the throttle a little, if it gains rpm its rich

bbay15, this is the post that may have hit the nail on the head. You may be four stroking. Stock jets should be 64's and 65's.