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120 runing rough

Started by MakoHD, April 14, 2019, 04:42:50 PM

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MakoHD

M8
120ci cp pistons
Compression 11:1 front cylinder 190psi rear cylinder 200
Ported heads, 1mm over size valves, high lift springs
62mm HPI
D&d exhaust
Few months back the bike sumped due to that it had the stock oil pump.
I put feuling pump and cam plate. But whent it sumped it got really really hot and my old man didn't pull over ridding 2 up. When he got home the bike was sizzling hot. I let it cool down and when cranked it up she had  a small knock, sound like piston slap coming from the front cylinder, we decided to keep  ridding the bike because it was running great but it just had that noise that came and left. Well he was ridding on the high and the bike started to make noises and it shut off. It would only crank up when you give throttle...
what I've tried
New spark plugs
New cables
I have spark in every cylinder
No rocker arms broke
Put new intake seals
Changed MAF sensor
The bike idles bad and runs bad, it's not drivable. I'm about to pull it apart and go to a 124 because of the piston slap but I'm afraid that when I put it back it'll still have the same issue.  What can cause this? The compression test readings are as of today.

BVHOG

Broken cylinder spigot would be my first thought on the noise. As for the rough running an intake leak could be the culprit. Do a leak down test to make sure the valve seal is where it needs to be.
If you don't have a sense of humor you probably have no sense at all.

happyman

if it was sumping for many miles and boiling hot, would think the complete motor is toast.  does it have a nasty odor when you remove the dip stick by chance. if so you can bet its serious.

BVHOG

Also that piston slap noise could be a head gasket leak
If you don't have a sense of humor you probably have no sense at all.

rbabos

Quote from: happyman on April 15, 2019, 07:17:49 AM
if it was sumping for many miles and boiling hot, would think the complete motor is toast.  does it have a nasty odor when you remove the dip stick by chance. if so you can bet its serious.
I agree. Time to start over.
Ron

MakoHD

It's been runing with the piston slap for 2000 miles. I've had motors cook up because of sumping and 10000 miles later still kicking it. bike turns on idles rough, like if it were runing on one cylinder. I'm going to do a fuel pressure test this afternoon and I'm going to make sure that both injectors are workingt. This is when a good scanner would help big time. I would love to see live readings on everything. I know  the motor is not 100% but it shouldn't be running like this with the compression that it has. Has anyone every heard of this motors jump timing? Can't see how, but you never know... for the intake leak I put a new intake seals, 4 new plugs and 4 new wires, maybe the coil has an intermittent problem. Could be anything I'll let you guys know when I figure it out. Thanks for the input.

86fxwg

April 15, 2019, 05:38:36 PM #6 Last Edit: April 15, 2019, 05:45:14 PM by 86fxwg
If its missing or completely dead on 1 cylinder, hit the pipes with a temp gun, the one that's dead will be much cooler. At least u will have a idea what cylinder is the culprit.

Killing a cylinder will or should help u find what cylinder is knocking to. It works in the auto industry.

Check ALL electrical connections, chances of ignition part failure is pretty slim as the bike is almost new other than ur fingers being in it!


86
86fxwg 06flhx 10flhx

VDeuce

I'd do a leak down test. Got a camera to peek in the cylinders?

Lots of reports of stuck rods when they sump real hot like that.

happyman

Most certainly. Also if the motor was boiling  hot, you will not are hand the diode stick. Also chances are you will not be able to turn it out by hand.  When you get it out a d your inside it has an oder you cannot believe.  Al's when you look at the wheels they will be of a yellow  to gold color I would call it. It will be the oil level line on the wheels . It's a smell and a sight to behold.

MakoHD

This thing has 60 psi of fuel. I'm
About to put a match to it....
changed throttle body
Changed crank sensor
Changed AF sensor
I'm about to change the bike and start fresh lol

HD/Wrench

 Pull your Crank position sensor and take a look at it . I have seen where they sump and get so hot it is melted . at that point the crank is hurt . Just went through that here Used GRC with the larger pin they make Stanley has been doing cranks for a very long time .

MakoHD

Quote from: GMR-PERFORMANCE on April 16, 2019, 07:04:01 AM
Pull your Crank position sensor and take a look at it . I have seen where they sump and get so hot it is melted . at that point the crank is hurt . Just went through that here Used GRC with the larger pin they make Stanley has been doing cranks for a very long time .

yeah i tried that too. i think the tune might of gotten corrupted, have you seen that before? 

MakoHD

April 18, 2019, 07:46:22 PM #12 Last Edit: April 18, 2019, 07:53:25 PM by FSG
When I said I removed the rocker box cover I never removed the rocker arm and it kept some tension on the spring, not making it seem broken. I should looked closely. Lesson learned!!! Shame on me...

[attach=0,msg1293082]

No Cents

  what spring manufacturer made that spring?
Do you know what lift they were suppose to handle...and what cam was you running?
Did the valve touch the piston?
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

VDeuce

Yes, what spring? Concerning...

kd

The silver lining here is that it was a double spring set.  One spring was maintaining the keepers in the collar and that likely saved the valve, head pistons and even the engine as a whole.   :up:
KD

No Cents

 yep...he might have just got lucky with the other spring not allowing that valve to fall that had the broken spring.
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

MakoHD

I'm not 100 % sure what brand spring is it but yes they were designed to hold high lift. I use a 544 lift cam. No the valve never dropped. I'm replacing them all to different spring.

No Cents

  was your bike dyno tuned?
The piston showing looks awfully black...but that broken spring could of contributed some of it if it was ran that way for awhile.
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

MakoHD

yes it was but you can imagine how rich it was running with the valve spring broken. the piston are also coated on the side.

Sunny Jim

Wow Mako! I have just completed my first 117 build and my issues have been wide and varied. 640 ml of oil from the sensor hole in just 250 mile.
High pitched scream on closed throttle decel.
Oil pissing out of my external breathers.
I fitted the new backing plate with seal to the oil pump.
Sooo! After a lot of complaining I pulled it down to find the head gaskets are leaking and oil is saturating the piston tops. I tensioned  the heads as per Cometic instructions to the letter,But,it leaked. The machining on the head face is poor henceforth the leaking was initiated. Through the grooves of the aggresive milling tool used on the original heAd surface.
Composite gaskets might of worked but the Cometics leaked.
We are now resurfacing the Heads and starting again.
My M8 is one of the first so I also have my doubts as to the reliability of the oil pump.
Just sayin'

yobtaf103

June 17, 2019, 09:43:53 AM #21 Last Edit: June 17, 2019, 03:37:01 PM by FSG
Quote from: Sunny Jim on June 17, 2019, 06:08:01 AM
Wow Mako! I have just completed my first 117 build and my issues have been wide and varied. 640 ml of oil from the sensor hole in just 250 mile.
High pitched scream on closed throttle decel.
Oil pissing out of my external breathers.
I fitted the new backing plate with seal to the oil pump.
Sooo! After a lot of complaining I pulled it down to find the head gaskets are leaking and oil is saturating the piston tops. I tensioned  the heads as per Cometic instructions to the letter,But,it leaked. The machining on the head face is poor henceforth the leaking was initiated. Through the grooves of the aggresive milling tool used on the original heAd surface.
Composite gaskets might of worked but the Cometics leaked.
We are now resurfacing the Heads and starting again.
My M8 is one of the first so I also have my doubts as to the reliability of the oil pump.

Just sayin'

Maybe a daft question Jim ( presume it's an oil cooled motor), but did your cometic head gaskets have the sealing pattern around the oil hole in the head location ?
early 124 gaskets did not & had to plug oil hole in head, just wondered if 117 gaskets had same history

Sunny Jim

Not a silly question. Oil heads yes. The gasket has a seal pattern around oil hole but believe the oil was leaking into the cylinders.
I will attempt to put up a photo.

HD/Wrench

Does not appear to be leaking from that photo . We have had zero issues with leaks on the 124 and 128 with the MLS gasket .

Txwezl

sealing surface looks like it should've been cleaned better, composite gasket still showing.

Sunny Jim

The blacken areas are carbon. It's washes off readily with solvent.