I’ve had my “new” file 1998 ST1100 for less than one day. I’m very excited! However, I didn’t catch the misfire during the short test ride, and it’s bugging me already. I have a light throttle misfire that clears as soon as I get on the gas. Spark plugs were FINGER TIGHT on the left bank for some reason, but the misfire remains after tightening up all the plugs. I’ve ordered a new set of plugs. Are there other common things I should check or try? Does a light-load misfire sound like ignition or fuel? It does pop and crackle when lifting off the throttle, so I assume there’s raw fuel. Suggestions are much appreciated!
Misfire - noob questions
- Thread starter Cyclehead
- Start date
Since its a new bike to you you are going to start from ground zero. That means new plugs gapped correctly new fuel filter and air filter. You are also need to check all the fluids. About your slight miss the fact that the plugs were finger tight is a clue the previous owner was fooling around with the plugs....so that is where i'd be looking first.
I can tell you where I get mine and that is the Honda dealer. This is just me but I like oem parts. Another source is on line retailers like Partszilla, Many options are out there so search the maintenance sections of this forum. Also here there are members who excell at the upkeep of these machines. So don't be afraid to ask.
ReSTored
Site Supporter
Don't forget the small air sub filter as well, #11. I think the majority of owners just use the OEM ones. Check out Partsfish, Partszilla etc...... for pricing as there can be significant differences between vendors.
Partsfish AIR CLEANER 17211-MT3-000 $39.45 Partszilla cost is $51.37................
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If its an abrupt misfire, then its probably ignition related, but hard to say without seeing/feeling it. If it happens at a particular RPM then that also tends to be ignition related. If ignition related, then it could be either an issue in the plug caps/wires, or the coils themselves.
kiltman
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- Joined
- Apr 27, 2013
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- 68
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- Stratford, Ontario Canada
- Bike
- 2002,ST1100ABS
- STOC #
- 8826
There is a slight burgle popping when one lets off the throttle... normal. run a tankful of your favourite injector/carb cleaner before going anywhere taking the carbs off.
There can be a slight backfire if the vacuum tubes coming from the carbs are not sealed properly.
Fresh set of plugs wouldn't hurt, what are the colour of the tips of the plugs? they can tell you a lot on how the engine is running.
An electrical problem can cause it to backfire. culprits being the main relay and sidestand switch.
Has the bike sat for awhile before you had it?
There can be a slight backfire if the vacuum tubes coming from the carbs are not sealed properly.
Fresh set of plugs wouldn't hurt, what are the colour of the tips of the plugs? they can tell you a lot on how the engine is running.
An electrical problem can cause it to backfire. culprits being the main relay and sidestand switch.
Has the bike sat for awhile before you had it?
Slydynbye
Will ride for Pie
Slight misfire? I would bet the previous owner wasn't riding it enough.
Stop digging! Get a full tank of fresh fuel though it, change the fuel filter, change the plugs and Ride the heck out of it.
These bikes need to be exercised regularly or they have issues. Mine always runs better after a long ride.
You might add some Techron to the fuel before giving it a vigorous Italian Tune up ie Flogging
I agree you should replace the little sub filter, and maybe air filter if it's clogged. Hiflo makes an inexpensive one HFA1911.
Stop digging! Get a full tank of fresh fuel though it, change the fuel filter, change the plugs and Ride the heck out of it.
These bikes need to be exercised regularly or they have issues. Mine always runs better after a long ride.
You might add some Techron to the fuel before giving it a vigorous Italian Tune up ie Flogging
I agree you should replace the little sub filter, and maybe air filter if it's clogged. Hiflo makes an inexpensive one HFA1911.
kiltman
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- Joined
- Apr 27, 2013
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- 3,283
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- 68
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- Stratford, Ontario Canada
- Bike
- 2002,ST1100ABS
- STOC #
- 8826
Sage advice!
Now that you mention it, the previous owner said he rode it gently. Never over 55 mph! It’s probably just full of crud. I’ll tidy things up and get it reassembled tomorrow. I did clean out a small mouse nest beneath the carburetors.
I would suggest taking lots and lots of photographs of your carb assembly from every angle possible and filing it away for the future in case you do any disassembly (wish I had done that !)
Also, be extra careful if you remove the needles to make sure you know which carb they came from (there are some engines with two different needle profiles in pairs)
Seeing as you have the carb block off I would suggest having a look at the Air Cut diaphragms (item 13 in parts fiche image attached). Removing the set screws is a pain, strongly recommend lots of WD40 and tap the correct size JIS bit onto the screw head first and apply lots of downward force as your turn (I ended up using a Vessel JIS Torque Screwdriver and having to hit it very hard)
I also swapped the pipe clips for the 4 air hoses with Toryx ones instead of the slot screw (or Hex head works nicely also)
EDIT: forgot to mention, when working on the carbs its best to only use JIS screwdrivers and bits, the set screws are very very tight and if you try a Philips it will round the heads guaranteed
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I’m hoping I don’t need to go inside the carbs. If I do, is a gasket set mandatory or will they come apart without tearing gaskets?
I would suggest taking the photos even if you don't plan to go inside and just filing them (the photos) away, that way if you ever become tempted to start taking bits off you know you have a reference for your specific carb block.
with regard to the gaskets:
(1) The float bowl gaskets will probably need replacing if you remove the bowls so best to have a set of these.
(2) there are gasket sets and gasket sets ! The Honda set covers most rubber for a complete rebuild but not ACV or Diapraghms, on ebay you will see variations of the sets but beware some of them are plain wrong. There is an excellent guy in Texas (on ebay) who overhauls them and sells the gasket sets, he will keep you straight.
I have just been joggling my memory regarding the ACV (Air Cut Valves) and I think I had to do a partial block disassembly to get the set screws off two of my ACV's. In my case they were totally disintegrated so it was necessary. Perhaps either leave your ACV's alone for now or have a look at only one of them (the ones with the set screws directly accessible) and see if it is okay.
The main diaphragm housing doesn't have a gasket so you can remove the housings (although again use JIS screwdriver) and visually inspect the rubber. These are integrated with the sliders and VERY expensive to replace so extreme care is necessary.
Slydynbye
Will ride for Pie
Honda has excellent rubber, the bowl gaskets are often reusable.
Those hoses don't look that bad, but 22 years is a long time if they are original.
How many miles on the Bike? Does it seemed well maintained?
Those hoses don't look that bad, but 22 years is a long time if they are original.
How many miles on the Bike? Does it seemed well maintained?
Slydynbye
Will ride for Pie
Just make sure you flush out the tank and change the fuel filter before putting the carbs back in or you will end up introducing problems again when the dirty fuel clogs the idle jets.
and of course Fuel Cut Off Valve !
Either check diapragm or bypass .
Wish I had done this before I went fo rmy first ride in 45C heat in the desert and ended up having to call out a flat bed with emergency water (for me and my pillion )
Either check diapragm or bypass .
Wish I had done this before I went fo rmy first ride in 45C heat in the desert and ended up having to call out a flat bed with emergency water (for me and my pillion )