1989 xr4 150 that sat 3 years issues.

[paulosur]

i think you should start it at night without cowl, screwdriver and check boots and entire length of plug wires.
feedback survey breakfast hours

 

[Lt1z350]

So been on the water a few times and it’s been hit or miss. Since last time I have picked up the sierra plug wires for this motor which didn’t change anything as I had a auto wire that was zero resistance sort of a race wire for these new gm coil on plug cars that generate 65k. But I put the correct on it anyway. I can still hear a cylinder going in and out at times so ran it on the lake a couple times trying to blow it out as I can still see quite a bit of carbon on pistons. A temp gauge straight up and down compression test still gets me the same as cold 125 on every one. Most pop to 90 on the very first crank but 2 are a little slower but still on 5 cranks reaches 125 psi. Wot with 2 people gear so on it’s hitting 55 but low rpm only around 4700 if this tach is right and now pulling plugs can see cylinder 3 is the one giving me issues. Cylinder 3 hot hits 60 on first crank but still 125 by the 4th and 5th no more gain just as others. Hot or cold I see the same 125. What I don’t like besides it being clean is it always looks to have water beads on the end of it. I checked the torque on head gaskets and someone way over torqued them so I do not know if I can get a leak from there and having so good of compression don’t see it being a cracked cylinder or hope not.
These plugs I had to idle in to get on the trailer so while on the trailer I ran it up to 5000 held it for a few seconds then shut it off and this is what I got from it. I didn’t try to do a wot on the water and check plugs but if I need to I can figure something out. If it didn’t have the cylinder that seems to come and go randomly and over rough idle at times I’d not think anything is wrong. That and the lower rpm on wot not reaching 5k rpm. I can hear it as not super clean but not so bad it’s like the motor is sick. Someone with zero mechanical knowledge probably wouldn’t be picking it apart like this as it does sound better then others I have heard around on the water. Lol
More then anything that water drops is what I’m hoping to find an answer on before pull the head off and start looking for something I possibly cannot fix easily.
I had been fighting the fuel pump since taking off the electric one it wasn’t wanting to hold as the cheap eBay kit was junk so I got a new quicksilver with the center body so feel like that’s now good to go. Also changed spring on the tension on the hot foot let that up a little.
Thanks again for any help here and advice.

 

[Lt1z350]

So actually blown out on cylinder 1 and 3 even though 3 only showed the water on the plug. So even better I guess as 55 mph and 4500 rpm this thing will fly when it’s strong on all 6 cylinders. I might have the heads checked and take .005-.010 off them as run 93 anyway in this.

 

[Dukedog]

ya might check tha "deck" for being flat also......

 

[Lt1z350]

ya might check tha "deck" for being flat also......

Yea that’s what I was thinking. The one is original to the motor and it’s beat bad. The other side as had been replaced and looked good. Probably had a blow out on that side. The gasket is water logged and ate up some. I build v8 motors so will Check the deck also. Feel like it’s a gasket failure from just rot almost. The whole fire ring shifted some as no support behind it at points from rot.

 

[Faztbullet]

What's the cylinders look like as classic sign of it being hot numerus times

 

[Lt1z350]

What's the cylinders look like as classic sign of it being hot numerus times

Really not bad at all. One has a couple scratches I can feel other then that all look good no scuffs signs of being too hot. It had 125 psi on all cylinders hot so I’m not really concerned too much on the few scratches I see in that one hole.
This thing went nose up big time trying to plane so I got to looking at the motor height. The guy I got it from was not at all boat smart. So he had the motor at max height so on plane half the holes out of the water on pickup so I’m sure sucking air. I noticed that putting it on plane and trying to trim for more speed the water pressure was dropping so I had to tilt all the way back. Lucky he was afraid of the higher speed so I’m sure it wasn’t pushed hard by him often. He was second owner so not sure how setup of course prior. He towed with a big 4x4 suburban on 33s so my guess is he raised the motor to tow and not have to tilt motor to where it puked fuel possibly. That’s how this guy thinks as was my neighbors son. So I lowered the motor 3 inches put the bottom of boat level to just above the intake holes. Maybe 1/2 above so not too much more drag and should plane faster.
I got to reading and if I take .025 on the heads it can bump low and mid range some so going to do that as run 93 anyway even at this price. They say more torque will make boat more efficient anyway as less throttle to get to target mph. It’s got a 24 pitch prop so can cruise 35 at low rpm and more torque will help that also. Now just got to find someone to do the heads gaskets on the way as I’m in East Tennessee and not much around me for machine shops.

 

[Lt1z350]

Got heads back today took .015 off then chamber was 40cc now 35cc. I read some got to 32cc so didn’t want to push it too much but still gain a little.
Did the link and sync and was off pretty far. Idle timing was way retarded and max timing was only 20. I’ve read a lot of posts that 3 to 4 degrees atsv for idle and 23 to 25 btdc does this seem about right ? I set it to 4 atdc so right of the 0 on the flywheel and max timing is far left 25 shows as max I put it to 22 to start as cut heads that little bit.
So many threads on what to do. Oh and it did have the black box advance module still hooked up I took that off so the other adjustments were to black box settings I guess. But even the manual said 22 to 26 degrees so he had the timing pretty low for this motor that or someone just started turning screws on it randomly. Hope to have gaskets by Saturday and get on lake Sunday.
Was thanking of drilling two small holes in thermostat as some say they like to be a little cooler which will also help any pre ignition or spark knock.

 

[Faztbullet]

Thems old top hat heads...if you took .015 off cc's only increased by maybe 2cc . Trash stablizer,set at 22° at WOT cranking and set idle where motor is happy close to 2°

 

[Lt1z350]

He told me he took .015 but I’m getting 35/36cc I checked a few to be sure. So I guess he took a little more then he thinks. I don’t think they had been cut before as got 40cc on the first check. But it wasn’t perfect either and a rough ball park on it before I took them over. I guess cranking compression change will tell all once it’s back together.
I got wot at 22 already and will play with the idle in the water as stated for best idle. Thanks for the help. This is on a very light 17 foot Norris craft bass boat so should be a blast with it running correctly. Lol

 

[Lt1z350]

Oh and any other tips I’m all ears on this thing.

 

[Lt1z350]

Ok back together and what a difference idle is very clean but stays around 1000 unless I back timing way down to like 10 atdc. This is with it idling on the ears I almost cannot make it stall out unless goes to point it’s running bad. Any timing around 4/6 atdc which has great idle it’s just too high. I can see a tad bit of wetness in that middle carb so can a high float do this? It had issues pumping fuel when first got it so I lowered the floats until that stopped but at time didn’t have a measurement. Basically it’s flush or a little below level and thought that was low enough on them as no longer pumps fuel out the two vents in bore.
I did the link and sync a few times make sure carbs all the way closed all 3. Idle screw is basically barley touches case. Thing has throttle response of a rifle shot not super strong torqued motor if just pop it. So just got to get idle straight and will go water test it. Oh and it now pumps water steady rather then like it has a swollen prostate so I guess that’s first sign of a cylinder water leak on these. All seems great but this high idle. Or tach is off my snap on box won’t read it so can’t test it using one of those ancient car analyzers for idle rpm.

I do notice key off the tach is always stuck at last rpm it read. Then go key back on and never retuns to zero it’s always hanging at like 100-150 rpm before start. So maybe tach is 200 rpm off? It’s a quicksilver so don’t know if has any zero adjustments or anything. I know out of water I’m going to get a little higher like 900 they say is ok. I can get 1000 on this tach that about the lowest with out crushing idle timing.

 

[Dukedog]

don't pay any attention to tha idle timin'/rpm on tha hose as long as it does ok.. put it in tha water, under a load (in gear) and set idle rpm/speed with TIMING ONLY to whatever makes you and tha motor happy.... numbers are irrelevant..

 

[Faztbullet]

Yep....

 

[Lt1z350]

Ok so gave that a shot and by the time i get it to idle low enough to go into gear ok it will now run hot and have no hole shot from timing being so low. Seems that now I got all 6 cylinders running strong it will not idle down enough and be able to sustain enough timing to run right. I pulled the carbs lowered all the floats made sure none weeping at idle. Checked all the small lines for leaks from cylinders to carb base. I even checked the butter fly alignment on all carbs to make sure closing all the way. Ran on ears sprayed the base of carbs Checked the base gasket sprayed that. Sprayed under flywheel so far zero leaks to be found. With timing so low it’s wanting to get hot at low rpm cruise and won’t cool back off until I run it up to the point it advances the timing I’m guessing as at 4000 rpm it will start to cool back down. Plus the hole shot is super weak with it on low timing to idle well. Something has to be pulling air where it shouldn’t and I’m just not sure where to check next. It also becomes very finicky when timing is so low and idling on muffs like try’s to stall won’t hold that idle point. Of course no idle issues when head gasket was leaking as I could at 4 degrees of timing actually turn the main screw back and forth and set idle. So the more I fix the worse it wants to play nice. Wot is unreal lots of power. Just need to square away this idle thing. If I set to a recommended number I have read about it’s idling around 1200 or so. High enough I’m not wanting to pull into gear as know it’s going to grind and bang and not good on this foot I have read. I’m also read a vacuum leak at idle can make it run lean. So I guess lucky my wife freaked at 65 mph and made me dial it way back. I’m getting close hopefully someone knows a common leak spot to point me to. It’s that or next is pulling carbs again and plate on the reeds to reseal. I did notice it’s got new gasket on the plate between the heads so not sure why they took that apart and did a reseal yet had original head gasket on one side. Like some other issue came from that middle plate. I just question if they went into it did they do something wrong.
Thanks

 

[Lt1z350]

Well curiosity got the best of me and with it not wanting to idle down I started tearing stuff apart. I found 2 pistons with scuffs /Burnt skirts blown out gaskets at the base plate and oil/water mix under the crank so maybe the crank seal was my vacuum leak? Can see 2 and 4 pistons are bad but they had 125 cold and hot cranking compression so I’m kinda surprised found this. The cylinder is all hood above the transfer ports and where rings ride. On the bottom it’s got some scuffs in the bore. Wot it ran great which seeing all this im just shocked for how good it ran. So debating 2 pistons and all new rings. Hone block clean it up and reseal the whole thing. I’m going to end up trading or selling the boat wife is dead set on a skit boat something with a deep v not a flat bottom that gets beat to death on the small chop this lake has most of the time.
But I want it to run well and be a good motor for whoever gets it with out spending a fortune. Been debating all new pistons but feel like rings on the other 4 will do just fine.
Even the front plate where reeds are in had a questionable gasket seal. So this thing really needed a total reseal to be good. Pistons and rings will be a plus for whoever gets it.
I might try to find another setup that’s beat a little as this is a fun project and make the next one run like crazy and do some mods to it. Find a little 2 seater with a 200 or 250 to mod. Seen a few around cheap as no one seems to want something that just goes fast.
But for now need this one right so can trade or sell outright. I’m seeing junk wirh bad dead jellcoat going for 5k so my boat being totally mint with built motor I should do pretty well. Plus get some fun out of it a few times and not bring her so I can see what this can really do with out someone screaming she is going to fall out. Lol
Thanks for any advice on the damage here and what it might have been affecting for performance and idle.

 

[Faztbullet]

Twas a dirt dabber nest somewhere at one time...

 

[Lt1z350]

Twas a dirt dabber nest somewhere at one time...

All that milky oil in the top of the lower ?
I did the water pump a couple months ago and it was spotless up there. It was getting hot while running low speed I thought it was the low timing but pulled the foot anyway and this time looking up in it I saw all that oil and water up from the bottom which wasn’t there last time I had it off. So decided to remove the plate between the cylinders that’s when I saw the piston skirt trashed and decided to just tear it down. I found a company that does a piston with Teflon coated skirts complete kit pistons gasket seals bearings everything really but the large seals on the crank shaft. Looks like piston rings 950 bucks. I can get those 8 bucks each not sure if should leave or replace they seem fine.
But all that mess in the lower was not there when did my pump so why I think the lower seal started to leak fuel/oil as not sure where else can come from.

 

[Faztbullet]

Teflon coating only for break-in ...its gone in about 3 hours running. just about every puts the black coating on

 

[Lt1z350]

Teflon coating only for break-in ...its gone in about 3 hours running. just about every puts the black coating on

If it’s like the automobile application that’s not true. I have tore down a 100k mile gm ltg 4 cylinder engine 275hp 2.0t and the skirts still have the Teflon on them if not damaged. I build auto engines and know the benefits and why they use it in performance applications. This is on a 6.2 supercharged zl1 with 30k on it. Just had this around for reference. The Teflon is made to help skirt from scuffing the bore. Very popular on any performance pistons today. Oh and this Nascar piston from an rcr engine. This is after a 500 mile race at 9,000 rpm the older Daytona motors so sustainable peak rpm through out the race.