V4 1987 Looper Low Compression & Backfire In One Cylinder

[Faztbullet]

I found that in the reeds, god know how it got there

That goes in the hole on the carb body at 6 o'clock position. It got ingested when engine was running. Check all 4 carbs as it could have came from a different carb...

 

[Bosunsmate]

Id just get on the water and see how she runs once you've checked these carbs over for the missing piece. As you never know when the tropics are going to heat up and start bearing those big rainmakers down this way. You may find that it has all the power you need with its compression.
And definitely 50:1

 

[Riley C]

Hi guys,

So I got it in the water and it was easy start warmed up for a bit and then hit 90km. So not bad. Lean sneeze gone. However,

1. After a bit the idle was too low or timing is off. IT doesn't like 900revs.
2. Slight knock at Low idle 1-3k revs goes when higher revs. Can get to 6800 easy
3. When jumped in for ski, the engine would conk out as soon as you put it into gear, or under load. That's the strange one.

I have a new vacuum fuel pump to replace the old vro. Once I have done that it seems a whole new fuel system. Hopefully that's the issue?

if not I'll get mechanic to tune.

What do you blokes think?

 

[Bosunsmate]

No2 seems your biggie to me and probably explains #1 too and probably #3 as well.
Have you tested your bearings?
Move each piston to tdc and with a screwdriver with some cloth on it check for play on the piston by putting the screwdriver through the sparkplug hole
A mechanic would just do a link and sync and charged you a few tanks of fuel for it

 

[Riley C]

No2 seems your biggie to me and probably explains #1 too and probably #3 as well.
Have you tested your bearings?
Move each piston to tdc and with a screwdriver with some cloth on it check for play on the piston by putting the screwdriver through the sparkplug hole
A mechanic would just do a link and sync and charged you a few tanks of fuel for it

Thanks Bos,

I will look over the bearings. When I had the head off there was only slight play side to side of the pistons, not really in out if I'm making sense.

The above issues wasn't like this until after I put everything back to gether . I read in the manual initially that any carb or fuel changes etc requires timing or lync and sync again???

Im learning a lot.

 

[Bosunsmate]

Thanks Bos,

I will look over the bearings. When I had the head off there was only slight play side to side of the pistons, not really in out if I'm making sense.

The above issues wasn't like this until after I put everything back to gether . I read in the manual initially that any carb or fuel changes etc requires timing or lync and sync again???

Im learning a lot.

No worries, I can always help out a fellow ANZAC
Yep i get what you mean exactly, its the technical language id get more stumped on. Slight play side to side is normal with the rings and pistons cold. Good info that no in and out although its only ever being TDC ive tested that at so im not sure if you did it at that.
Timing isnt hard to do. Bottom one is just set at how low you can get the motor to idle when fully trimmed down in the water at when its warm, ie the lowest possible so it doesnt stall when it goes into gear. Ive mine so low people think its conked out but shes just on the very verge of conking out but never does and they are always surprised when they hear a grovel from it in the next second or two.
Max advanced timing is important as too much can lead to predetonation/heat/piston destruction. Too little and you dont get your max speed. You need a timing light for that. Search Joe Reeves timing methods up the top of the forum page for this Johnson/Evinrude Section.
Link and sync is checking all your butterflys close at idle, open simultaneously and at the right time and to full horizontal position all to be done in proper sequence determined by the timing marks on the cam thing where all the linkages join up

 

[Bosunsmate]

id also look at your sparkplugs and compare the colour. 900rpms sounds high to me, i dont have this motor but id of thought it should be sitting comfortably around 600-700rpm. Someone around here will know it for proper.
BTW the reason for low as possible idle speed is not just lower fuel consumption but is important for preserving the gears in the gearbox

 

[Tassie 1]

90 k's sounds PBG for a donk with marginal compression numbers,
though can't tell what boat it is from the profile pic,

only comment l've got is the high wot figure @ 6800,
what prop have you got on the thing?

 

[Riley C]

90 k's sounds PBG for a donk with marginal compression numbers,
though can't tell what boat it is from the profile pic,

only comment l've got is the high wot figure @ 6800,
what prop have you got on the thing?

Hi Tassie,

PBG? Pretty Big Gutts? lol

Mate it's the standard prop I assume, painted stainless??? Got a 1/4 drill hole i have never seen before on a prop behind each fin. The WOT is also with some trim up...

The boat is a Fibreglass 16ft Matra, 4 seater. I think the Super Cheap Auto gauge I got isnt up to the test maybe. I did another cold test today. WOT on three at 95 PSI and one at 90.

I just re-flushed carbs today after installing a vacuum pump and doing away with the bypassed VRO. I'm praying I'm getting there. So much reading for a plumber turned consulting engineer.

 

[Riley C]

id also look at your sparkplugs and compare the colour. 900rpms sounds high to me, i dont have this motor but id of thought it should be sitting comfortably around 600-700rpm. Someone around here will know it for proper.
BTW the reason for low as possible idle speed is not just lower fuel consumption but is important for preserving the gears in the gearbox

Boss,

Thanks mate, I appreciate it.

The spark plugs had a little fouling and all looked the same, some oil. They are new and NGK 10's, maybe need new ones and go champion?

Cant believe you can get your revs that low. At 900 mine want to die, would you put this to timing?

I have sync the carbs, there wasn't much there to do really. I changed the position of the cam roller follower as it was heavily worn one side to being flat. Upside down trick.

Ill check Joes forum.

Being this is a low revs issue, I would assume then I don't need a timing light to do the bottom end then.

Also when you say bottom one is this the idler screw? You nailed it in saying bring the idle up enough so I don't conk when changing to gear, as that's the primary issue.

 

[Riley C]

90 k's sounds PBG for a donk with marginal compression numbers,
though can't tell what boat it is from the profile pic,

only comment l've got is the high wot figure @ 6800,
what prop have you got on the thing?

 

[Riley C]

id also look at your sparkplugs and compare the colour. 900rpms sounds high to me, i dont have this motor but id of thought it should be sitting comfortably around 600-700rpm. Someone around here will know it for proper.
BTW the reason for low as possible idle speed is not just lower fuel consumption but is important for preserving the gears in the gearbox

See photo of this slightly cleaned plug. All of them had the fouling look, I put this down to no thermostats being installed and the temp never going over 150d/f????

Should consider thermostats I guess. Previous owner never had them.

BTW, I'm not a big fan of the Seloc manual, it's not very user friendly. Doesn't even have a pic breakdown of the engine.

 

[Tassie 1]

G'day again,
PBG = Pretty Bloody Good lol,

looks a fast boat, can't say l've seen one before, certainly not here in Tas anyway,

probably been passed by a few in Vic at the ski spots there,

you're right about the Seloc manual...worst one out there imho...factory manuals are better if you can find them,

 

[Riley C]

G'day again,
PBG = Pretty Bloody Good lol,

looks a fast boat, can't say l've seen one before, certainly not here in Tas anyway,

probably been passed by a few in Vic at the ski spots there,

you're right about the Seloc manual...worst one out there imho...factory manuals are better if you can find them,

Cheers Tas

Hahaha yeah I should have caught onto that. Or BGG Bloody Great Guns

The MAtra is a Tennessee Ski boat that's not in production anymore. A few of them here in QLD, they are not bad. Prob would have preferred getting a Pride or Haines really. But for 3k with a Brooker trailer and this damn engine I thought wasn't bad at the time.

It's bloody terrible that manual, cant believe I spent $40 bucks for it.

Do you think I should be putting thermos in? I have read mechanics with the 140 didn't like thermos at risk of overheat. Without them I think it runs too cold....

TDC is the marking yeah, have you had experience tuning yourself?

 

[Tassie 1]

I'd put the thermostats back after testing them,
taking them out is really just a short term " fix" or a get ya home in a emergency type thing,
look for a IR temperature gun thing, they're good to check different bits and pieces

have no experience with the 140,

only timing l have done has been on a few chryslers and a 115 yammie, that one was only a few weeks ago and is still running haha

have heard of Tennessee boats but not seen one in the flesh,

 

[Bosunsmate]

Hi, i dont have much time to answer as im trying to get some stock from the shop before the summer revellers clear it all out so will reply later but definitely stick the thermostats back in.
They work by keeping pressure back on the water system and if they are out then the motor will run cold at neutral and will almost inevitably cause your low power at idle and takeoff. Just put them in a saucepan with a bit of wood or something for them to sit on and check that they open up and close as the water heats up (probably around 70 or so deg celsius (a detail i cant remember) . I just check they open well before the first signs of boiling.
Good news on your compression, that 5psi down one wouldnt give me any dark thoughts when i was out on the water

 

[Bosunsmate]

Boss,

Thanks mate, I appreciate it.

The spark plugs had a little fouling and all looked the same, some oil. They are new and NGK 10's, maybe need new ones and go champion?

Cant believe you can get your revs that low. At 900 mine want to die, would you put this to timing?

I have sync the carbs, there wasn't much there to do really. I changed the position of the cam roller follower as it was heavily worn one side to being flat. Upside down trick.

Ill check Joes forum.

Being this is a low revs issue, I would assume then I don't need a timing light to do the bottom end then.

Also when you say bottom one is this the idler screw? You nailed it in saying bring the idle up enough so I don't conk when changing to gear, as that's the primary issue.

I wouldnt bother about changing spark plugs, unless you have spare coin to chase up a 50/50 chance.
Id put your 900 solely down to the thermostats being out. I need to idle mine up around that until its warm then i put down the warm up idle lever and she drops right down .
Correct you dont need a timing light on the bottom end as its all done by as low as you can get it before conking out (when shes warmed up!)
I would be a bit wary about high your top end is, if you can do with not hitting 90kph id adjust the max timing advance in a bit until you can make sure using Joe Reeves method that you arent sorching your pistons.
Also do check your steering system as if something gives way at that speed its really serious. I always wear the lanyard line for that reason (it kills the ignition instantly). I know down here in Aus and NZ we havent had any high profile recent tragedies but in the Uk and elsewhere many people have being maimed/killed by steering system failure.
Not wanting to sound like a stick in the mud, but when ive check all mine over and wear the lanyard line then im definitely in the best head space when out there

 

[Bosunsmate]

See photo of this slightly cleaned plug. All of them had the fouling look, I put this down to no thermostats being installed and the temp never going over 150d/f????

Should consider thermostats I guess. Previous owner never had them.

BTW, I'm not a big fan of the Seloc manual, it's not very user friendly. Doesn't even have a pic breakdown of the engine.

Yes they need to get hot to run properly, id just give them a clean with a solvent and put them back into service. I had to do that with my weedeater that was flooding out today too.
I dont really use manuals. I go on intuition as often manuals can appear misleading. I always read up on the online versions first just in case there is a trick you really have to watch out for.
They are all free and pretty much all models are on here, just scroll the line to the right to get to the most recent motors
http://www.boatinfo.no/lib/library.html

 

[Bosunsmate]

By the way you can have something called a cold seize by running without thermostats. (i think ive said my piece!)

 

[Riley C]

Yes they need to get hot to run properly, id just give them a clean with a solvent and put them back into service. I had to do that with my weedeater that was flooding out today too.
I dont really use manuals. I go on intuition as often manuals can appear misleading. I always read up on the online versions first just in case there is a trick you really have to watch out for.
They are all free and pretty much all models are on here, just scroll the line to the right to get to the most recent motors
http://www.boatinfo.no/lib/library.html

Thanks guys.

Ill have to buy them as they were never in there.