Feed back lines 300 xp 88

charlie_kula

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Hello,<br /><br />Can the feed back tubes from the crank case to the manifold cause excessive smoke at startup?<br /><br />Will restricting them lower smoke?<br /><br />Thanks :)
 

Dhadley

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Re: Feed back lines 300 xp 88

Theyre probably already plugged or partially plugged up anyway. <br /><br />Several things can cause excessive smoke on start up. Some is normal. What plugs are you using? What oil? What ratio? How deep is the motor sitting in the water at rest?
 

charlie_kula

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Re: Feed back lines 300 xp 88

QL77JC4, standard oil, VRO mixture, the water level is about 2 inch above the fake exhaust outlet at rest with engine zero tilt. It is a deep V-shape on the hull.
 

charlie_kula

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Re: Feed back lines 300 xp 88

Here are some pics:<br /><br />
DSCF0007.jpg
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DSCF0117.jpg
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DSCF0017.jpg
<br /> <br />
INFRA2.JPG
<br /><br />
infra28.jpg
 

Dhadley

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Re: Feed back lines 300 xp 88

Looks like everything is OK except for "standard oil". That doesnt tell us much. What brand and type?<br /><br />Are you still running the VROs or has the motor been upgraded to the non-variable type oil pumps?<br /><br />If there is a fuel restriction the oil pumps will pump extra oil. With V8's there can be no line restrictions. No primer bulbs, no 90 degree fittings, no bulkhead fittings, 3/8" ID hose is a must, etc.
 

Dhadley

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Re: Feed back lines 300 xp 88

BTW -- The pics dont come up for me....bummer.
 

charlie_kula

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Re: Feed back lines 300 xp 88

OK, now I think I fixed the sore links to the pics.<br /><br />The oil is a mix of Evinrude XD50 Synthetic oil and some crap mineral oil the gas station dude poured in before I had time to stop him. <br /><br />The carb cover is solked with fuel and the engine takes fuel allright! Also the top end is very good, over 60 mph.<br /><br />But the smoke at cold starts, it is too much!
 

Dhadley

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Re: Feed back lines 300 xp 88

Its normal for the airbox to have some fuel in it. No big deal.<br /><br />If your sure the fuel delivery system has no restrictions (check it as per your service manual for pressure and vacuume) look at the anti-siphon valve in the tank. I'd remove it if it were mine on a V8.<br /><br />60 doesnt seem much. What rpm will it turn at WOT?<br /><br />Good pics!
 

charlie_kula

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Re: Feed back lines 300 xp 88

Well it is a pretty big boat, 24 foot. It is actually 63 mph at 5500 rpm.<br /><br />Do you know where to get service manuals?
 

Dhadley

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Re: Feed back lines 300 xp 88

At 5500 your only using about 225 hp or so. You might as well get a V6 and save carring around the weight and dragging the big gearcase.<br /><br />I would bet that getting close to 70 wouldnt be that impossible.
 

Dhadley

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Re: Feed back lines 300 xp 88

Reducing pitch is always our last resort. Its hard to tell in the pics (good pics by the way) if the motor can be raised but try raising the motor if possible. Especially with that 4 blade prop. Is it a Hydramotive?
 

charlie_kula

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Re: Feed back lines 300 xp 88

It is a Mercury Revolution 4, 21". I have OMC Raker 22" ready for next season. Will hopefully give some extra mph.
 

charlie_kula

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Re: Feed back lines 300 xp 88

Originally posted by Dhadley:<br /><br />Are you still running the VROs or has the motor been upgraded to the non-variable type oil pumps?<br /><br />
Tell me more about the non variable pumps. What brand are they? Are the pulse driven like the VRO's?
 

Dhadley

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Re: Feed back lines 300 xp 88

They are the newer style pumps from E/J. They pump oil at a consistant rate rather than a variable rate. They do vary some but are basically a constant rate. The newest ones have 4 wires I believe and have a repalcable outlet nipple. E/J started using them about 10 years ago.<br /><br />Can the motor be raised?
 

charlie_kula

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Re: Feed back lines 300 xp 88

The engine may be raised maybe 2 more inch. The previous owner used a powerlift. Problem is to keep the prop from slipping. Also you have to keep a tight eye on the water flow indicator, when running so elevated. He made about 67 mph using a Raker 24" @5500 rpm. But it was a balance act!<br /><br />Have you got an URL link to E/J?
 

Dhadley

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Re: Feed back lines 300 xp 88

See? I knew it would get close to 70 pretty easy. The 24 Raker has more bite and lift than your Revolution. Not bad for a 3 blade prop, huh? I'll bet the lift had a fair setback also. Play with the set up to gain rpm. Those motors dont come alive until after 6000 rpm.<br /><br />You can use www.evinrude.com, www.johnson.com or www.brp.com.
 

charlie_kula

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Re: Feed back lines 300 xp 88

Until they blow up or what? <br /><br />I have heard the 4 litre engines do not like over reving. The crank shafts pushes up into the pistons causing a horrible mis sound.<br /><br />Have you ever trashed a V8? If so what caused it?
 

Dhadley

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Re: Feed back lines 300 xp 88

Look at the rev limiter on your motor. Its at 6700. E/J V8 outboards love rpm. Everybody set them up like a V6 and were unhappy with the results. Thats the main reason OMC quit selling them in the states but they were still quite popular overseas. <br /><br />Have I ever blown one up? Yep. We did a pair on a 27' Eliminator race boat. Mild porting, RCH heads etc. Had one of the fuel pumps quit and leaned her out at about 103. <br /><br />Have I seen others blown up? Sure. Were back to the same old reasons -- water in the oil tank, water in the fuel, dirty carbs etc. Same as any motor. <br /><br />I saw a couple 3.6's that guys wired the power packs side to side like a V6 rather than top 4 and bottom 4 like they're supposed to be. One of our "helpers" did that on our offshore race boat once. Sure it was my fault for not checking him before they tested. But I kinda had to yell at the driver for not coming back to the dock when he knew something was wrong. Trust me, from then on I did the testing.<br /><br />Yep, it burned a hole in a piston. The fix on the day before a race? We took the V8 off my fishing boat and raced that. No big deal. <br /><br />As for "over-reving" a two stroke needle bearing motor, I really dont know what that is. As long as it has a load the rpm is only limited by the rev limiter and once you by-pass that, by how much air it can get in and out.
 
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