March 28, 2024, 05:02:48 PM

News:


88 flstc sluggish and backfiring

Started by hogget, April 02, 2021, 01:03:41 AM

Previous topic - Next topic

0 Members and 2 Guests are viewing this topic.

hogget

after sitting neglected in the garage for about a year, i pulled the heritage out for a run yesterday - started fine, but i noticed it was backfiring on overrun and was very sluggish on acceleration - otherwise ran ok for a 120 mile ride
today i checked the soft inlet manifolds for cracks - none - and replaced the voes hose - it was a bit cracked and tested the voes - its fine - filled with new fuel - but no improvement, still sluggish and backfiring
sounds to me like an air leak on the inlet side for the backfiring, but not sure about the sluggishness
any ideas???
thx rory

Scotty

Pull the carb off and take it apart and clean all the jets and passages in the carb.
Sitting around for a year + the fuel has probably dried and blocked the tiny holes in the jets and passageways.
While you have it of if you have the means replace the manifold with a one piece and new seals.

Hossamania

A couple new spark plugs probably wouldn't hurt either.
If the government gives you everything you want,
it can take away everything you have.

JW113

Yep, sounds like the textbook symptoms of gunk in the pilot jet circuit. As Scotty said, pull carb, clean everything. And don't forget those little holes in the bottom of the bore near the throttle plate (i.e. transfer ports).

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

RTMike


david lee

Quote from: JW113 on April 02, 2021, 08:02:59 AM
Yep, sounds like the textbook symptoms of gunk in the pilot jet circuit. As Scotty said, pull carb, clean everything. And don't forget those little holes in the bottom of the bore near the throttle plate (i.e. transfer ports).

-JW
had that happen before. blocked pilot jet after sitting and not draining the carb

hogget

thanks guys, will give that a go
should have said it has a screaming eagle carb on it - from new, but the same principle applies and it has a pilot jet, so i'll get to it

Burnout

Which Screaming Eagle carb?

Some of those carbs offered should never have been bolted onto a motor.....
They don't call me Ironhead Rick just because I'm "hard headed"

hogget

checked the carb (keihin 40mm pumper - 33 years and 40k miles)- pilot was blocked - back together, but no difference
changed the plugs (6 years since last set), seems much better,but still backfiring in the pipes on overrun - crack the throttle a bit and it stops, so will check the exhaust flange gaskets
will fit a fuel filter
thanks for the suggestions

Hossamania

In-line fuel filters don't work well in general. Check the screen on the petcock. I have seen them swell and deteriorate over time.
If the government gives you everything you want,
it can take away everything you have.

guido4198

Another vote AGAINST inline fuel filters. I've seen them be the source of more problems than they solve. If your tank and petcock are in such bad condition that you need a fuel filter...you don't need a fuel filter, you need to pull the tank and petcock and solve THOSE problems.

JohnnyCashPan

As long as you're chasing crud in the fuel system replace all rubber fuel lines.  If it sat for a year with old fuel in it, they could be flaking off internally.and adding to the problem.
Old, slow and fat...

hogget

thanks for the feedback - will have another shot at it today taking into account the above, because its still not running right

hogget

so, carb apart again, jets and passages cleaned and blown thru, new fuel line, no filter
tanks are in perfect condition - must admit i was surprised
screen in fuel tap is fine, had some loose crud on it but no way would that amount have restricted flow
checked exhaust flange nuts - all tight and dont appear to be leaking
took it for a ride - no change - still sluggish and backfiring
i want to think its fuelling, but not sure what else to check
thanks again for your advice
rory

Scotty

Quote from: hogget on April 06, 2021, 07:28:10 PM
so, carb apart again, jets and passages cleaned and blown thru, new fuel line, no filter
tanks are in perfect condition - must admit i was surprised
screen in fuel tap is fine, had some loose crud on it but no way would that amount have restricted flow
checked exhaust flange nuts - all tight and dont appear to be leaking
took it for a ride - no change - still sluggish and backfiring
i want to think its fuelling, but not sure what else to check
thanks again for your advice
rory

It has all the signs of being fuel but perhaps pull the nosecone cover off and check the pickup is not leaking or burnt it could be on it's way out.

FSG

Quote from: Hossamania on April 02, 2021, 05:26:36 AM
A couple new spark plugs probably wouldn't hurt either.

:agree:  brother did a LOT of work on a friends Evo Heritage last year only to eventually find a new set of plugs cured the problem

hogget

thanks scotty, i was thinking it might be electrical/battery but didn't know about the pickup (have had probs with batteries on other elec ign bikes recently)
will check that as well as testing charging circuit and running voltage - battery 'seems' fine - heaps of grunt to start and registers 12.7v with ignition off
thanks again

Hossamania

Check the tank vent, gas cap for air flow.
Could the voes be acting up, not allowing ignition advance?
If the government gives you everything you want,
it can take away everything you have.

Scotty

Quote from: FSG on April 06, 2021, 11:32:19 PM
:agree:  brother did a LOT of work on a friends Evo Heritage last year only to eventually find a new set of plugs cured the problem

Not wrong and cheap to do as well.

JW113

Popping and backfiring on deceleration? A common culprit of that is old dry or cracked intake manifold O-rings, the ones that go around the manifold spigots and against the heads. Also, check your VOES (if you have one) to make sure the little diaphragm in there is not cracked. Need a Might-T-Vac or something similar to check properly.

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

kd

.... and exhaust gaskets or muffler joints.
KD

hogget

while i'm at this, does anyone know where to get a new air cleaned for the screamin eagle carb - it has k&n F026A6 on it, but can't find that anywhere online (it too is 33 years old)

hogget

checked the pickup - looks ok to me, but i've never seen one before
have checked voes, new plugs, exhaust mounts to heads and and muffler are ok
haven't yet checked gas cap venting, manifold o rings or battery/charging - this will take another week because i'm doing the 100/100/100/100 ride (on the 100th day of the year, bike and rider >= 100 years old, 100 mile ride and at least 100mph) tomorrow and then out of town
thanks again for all your suggestions - i'm sure we'll get there in the end
rory

hogget

meant to attach this pic of the pickup
[attach=0]

Scotty

Looks like something melted in the pickup in the top left corner.

FSG

Quote from: Scotty on April 07, 2021, 11:59:44 PM
Looks like something melted in the pickup in the top left corner.

you can see it running down the wire


Hossamania

How was the voes checked? What was the pressure number? Vacuum lines in good shape? Vacuum T not hard and cracked?
If the government gives you everything you want,
it can take away everything you have.

rigidthumper

That pickup is toast. Replace it before continuing to troubleshoot. It may not be the only issue, but it certainly is an issue.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Burnout

April 08, 2021, 07:46:36 AM #28 Last Edit: April 08, 2021, 09:19:30 AM by Burnout
Yes, the bedding compound is melting out of it. = junk

I've never seen one (that looked like that), that wasn't bad.
They don't call me Ironhead Rick just because I'm "hard headed"

Scotty

Quote from: FSG on April 08, 2021, 01:03:50 AM
you can see it running down the wire

You have better eyesight than I have mate I only seen that when you pointed it out and I looked hard at the photo yesterday  :banghead:

hogget

ok, pickup on order, voes checked as per manual, using the human mitivac - was surprised to learn that at low vacuum, ie, accelerating, ignition retards - vacuum line replaced

JW113

Yep, it sure does. To help avert detonation (pinging) under load.

-JW
2004 FLHRS   1977 FLH Shovelhead  1992 FLSTC
1945 Indian Chief   1978 XL Bobber

Hossamania

The voes can be tuned also. The bigger cruisers operate at a different value than the lighter bikes.
If the government gives you everything you want,
it can take away everything you have.

FSG

QuoteYou have better eyesight than I have mate

well I had to get some benefit from the double cataract surgery I had in June '19 , near sight in the left, far sight in the right, I can see clearly now   :scoot:

hogget

ok, have the new pickup and went install it - then trying to disconnect the old one, i traced the wiring to the ecu thats under the oil tank - where the wires go into the ecu it looks like theres some shiny stuff around the wiring entry (sorry cant get a pic of that) - i'm thinking that whatever problem fried the pickup may also have damaged the ecu :emoGroan:
i see in the manual how to test the pickup and ecu, but it doesn't say how to remove the oil tank to get to the ecu - i see some rubber mounts front and rear, but not sure if the tank will come out easily - any ideas/hacks for getting to the ecu? - or is it just pull everything off?
really appreciate the help i'm getting here
rory

Scotty

The ignition module is either behind the splash guard in front of the rear wheel or under the seat but been a while and not sure if I am confusing the later 90 models.
Don't have to take the oil tank out.

hogget

ok, had a look today - my ecu is under the oil tank
can see that removing the plastic mudguard would make it easier to get at, but theres bugger all room between the starter/trans case and the ecu - i'm guessing i need to remove rear wheel to get at the guard and make it easier to get to the ecu
just trying to minimise the heavy lifting i need to do as i'm recovering from broken ribs
thanks again
rory

hogget

bit the bullet today, removed rear wheel and plastic fender - no way was i getting the ecu out without at least removing all the oil tank mountings (not so easy either) - couldn't get a socket onto the ecu mounting nuts because of the lack of clearance
i slid the oil tank to the right side of the bike without pulling the oil lines off and that enabled me to undo the ecu nuts and almost slide it out the rh side - but  need to follow and unplug the voes wire to completely remove it - i'm sure if hd had thought about it they could have made the ecu even harder to remove - thanks god they didn't
can see that there is melted plastic where the wires go into the ecu and it failed 2 out of the 4 continuity/resistance tests in the manual (as did the pickup/sensor) so i'm guessing that it needs replacement as well
i will be mounting the new ecu either onto the plastic guard or under the seat so that i never have to go through that bs again
thanks again for all the advice - will update when i get the new ecu and pickup fitted
rory

hogget

here's some pics of the ecu - guessing it shouldn't look like that
the next problem is getting the pickup out of the nose - the connector on the end of the wire is too big to fit thru the hole in the nose - manual says to remove the pins from the connector and pull the wires thru one at a time, but not sure how that could happen without cutting it up - or is there a better way?

Scotty

Wire ends pop out of the connector and then all 3 wires pull through hole together not individually.
I don't bother with those connectors anymore I just cut them off and replace with a deutsch connector.

hogget

thanks scotty - will give that a go
called frasers, ecu is $450 and a month away - have ordered an ultima ignition for 250 - it replaces the pickup and the ecu
will see if i can return the new pickup
will probably be a while before i can update this
thanks again for all the help
rory

hogget

 :teeth: :teeth: :teeth:success!!!!!
fitted the ultima ignition and took the bike for  a ride today - runs perfect
not before i thought i had more problems when after starting and idling when i put my helmet on, it stalled and would not restart - that happens when you forget to turn the fuel on
the ultima was super easy to set up using the instructions - in my case all the 6 switches set to 'off'
looking forward to riding rather than wrenching after problems with the ignition on one of my other bikes - turned out to be plugs
many thanks to scotty and others for all your help - its invaluable. i'm sure it would have taken me a long time and much frustration to discover the source of the problem
rory

hogget

thought i'd better check timing with a light and have read about the options of checking through the crankcase hole as well as thru the primary inspection hole - took out the crank plug to mark the rotor and forgot to refit it
didnt think much oil had come out until i realised there was oil spots all over the bench next to the bike and over my manual
long story short - the static timing was spot on - didn't need to change it at all

kd

You can buy a clear see thru plug that you install to check the timing with the engine running.  :wink:
KD

hogget

thanks kd, what i'd read about them was that it was hard to see the marks thru the clear plug with all the oil splashing around, so thats why i went the primary cover route. as it turned out, when i tried to paint marks on the rotor and inner primary, the paint just ran because of oil - i then pointed the gun thru the crank hole and could see the mark clearly. lots of stuff on the left side of the bike now have a nice oil mist

jsachs1

FWIW, there's a piece on the market, EZ TIME, that bolts on to 2 inner primary bolts, that is degreed/has numbers. You mark the alt. rotor at TDC. line up the zero on the EZ time, fire up the engine, and set your timing with your timing light.
John

hogget

thanks John, i have read about them, but wanted a quick fix. first time in 33 years i've had to check the timing - i think i'll hold off buying the ez time for another 33 years
rory

FSG


98fxstc

June 15, 2021, 04:42:34 PM #48 Last Edit: June 15, 2021, 04:46:35 PM by 98fxstc
Have not seen those before, will be be getting one next time I have to check my timing.
I have tried the clear plastic plug and a paint mark on the flywheel and had my face and everything else covered in oil.

hogget

even with the ez time, i think you'll need to drain the primary or you'll still get oil everywhere

Ohio HD

These are the only style clear plugs that I found usable.

The long threads let you screw it in until it touches the flywheel. Then back it off 1/2 a turn. It's then close enough to act as a wiper for the oil on the flywheel giving a better view of the timing mark. I also used Teflon tape so it doesn't vibrate out or in when the motor is running at higher RPM to get the advanced mark.



Scotty

 [attach=0]

Mine is similar to that one and cheap to buy in Australia as well

kd

This is one I've had since the late 60's.  It has shaped lenses like a magnifier on each end and magnifies clearly up to 1" away from the inside lens.  It picks up the timing line right from the edge of the hole as it comes into view.  First pic side view, 2nd standing on a thread size blade of grass and 3rd is about about 3/4" away.
KD

kd

KD

hogget

so, was happy with the ultima ignition  module and moved on to other projects. yesterday was time for annual service on the flstc and everything went smoothly until i checked the charging voltage - 12.5v bike off or bike running (i use a battery tender to keep battery topped up)  - pulled the reg/rec plug from the primary case and one of the wires was melted - just like the ecu, so not surprised it wasn't charging. alternator is putting out good ac volts, so have ordered a new reg/rec. last reg/rec was replaced 16 years ago (feels like just yesterday) so am wondering if thats normal? - have replaced the reg/rec 4 times in 33 years
any insights?
thanks
rory