running poorly when warm

[edtheguy]

Hi guys,

 

I have a 1988 Venture Royale that runs fine when cold and as long as the temp gage shows it's

at or below the halfway point. In warmer weather it seems OK until I need to stop for say a red light, thats when I notice the temp gage go above half and the bike starts to run poorly, sputtering upon acceleration from a stop but seems to clear up when the tach gets up to 3 grand. Any ideas on what's going on? Have changed coolant with no help.

 

Thanks

Ed

[Neil86]

Does the tachometer appear to be reading correctly when this happens or is it dipping down and bouncing back up?

[Peder_y2k]

Likely a fuel mix problem. The pilot screws may need adjustment for better idle mixture. Carbs may also be dirty and need cleaning. Used any SEAFOAM or TECHRON in the fuel lately? If not, give it a chance to work.

-Pete, in Tacoma WA USA

[cowpuc]

Hi Ed

While its possible your getting a little coolant into the cylinder I highly doubt it.. It just doesnt sound like a coolant related problem.. It sounds to me more like a fuel related problem or maybe dirty plugs..

 

First swap out the plugs so you have that covered. Also, while you have the covers off to swap out the plugs, in a very dark garage - let the bike idle and watch for electrical leakage on your plug wires, caps and around the coils.. If theres a lighting storm happening, its loosing much needed energy to the plugs.. I have also had plug caps go to high resistance - not a bad idea to replace the caps too unless you are certain they are in good shape - they screw on and off the wires coming from the coils.

 

Fuel related: Without hearing it run its hard to say whether its starving or getting to much fuel.. Spuddering indicates to much fuel, hesitation indicates starvation. Check your air filter and make sure its good and clean so it gets the air in needs. Check the four overflow lines leading back onto to the frame for dampness at the end of each line - indicating your floats are set to high or a sticky float valve. Another good idea for this is to check under the bike after it has set idling for a couple minutes, if you find a small puddle of fuel under it this is a good indicator you have float height/float valve troubles.

Have you ever checked your carb diaphrams for cracks or holes? If so and they are good than you are familiar with your carb slides = something else you can do (if its sputtering = running fat) is lower your slide needles some. I recently experienced something very simular with my 83 and lowered my needles 64 thou.. Fairly easy and cheap to do..

Also check your intake manifolds (rubber ones that attach the carbs to head) for cracks, air leaks here can cause hesitation.

Another thing you can try is either Seafoam or Chemtool in tank carb clean. I know lots of folks that have had good luck with Seafoam but I have had better luck with the stronger Chemtool stuff myself.. Also, at Walmart, the Chemtool is about half price (3.97) of the Seafoam (7.97).. There is also a dip tank Chemtool carb cleaner that you do not want to confuse with the in tank Chemtool cleaner, this is a 1 gallon container (19.97) - the in tank stuff is (I think) about a 12 oz bottle.. I have used the dip tank very successfully too but this is way more involved (carbs gotta come off - taken all apart and the process needs to be done carefully cause the dip tank stuff is VERY strong and not friendly to rubber and hard on aluminum..

Hopefully this helps somehow getting that MK2 purring and you smiling again!

Puc

[cowpuc]

Does the tachometer appear to be reading correctly when this happens or is it dipping down and bouncing back up?

 

Likely a fuel mix problem. The pilot screws may need adjustment for better idle mixture. Carbs may also be dirty and need cleaning. Used any SEAFOAM or TECHRON in the fuel lately? If not, give it a chance to work.

-Pete, in Tacoma WA USA

 

I gotta learn to type faster... :rotf:

[saddlebum]

It ispossible you could have bad or dirty float or needle and seat. Do you notice gas dripping on the ground when idling, or enrichment valve sticking open. Also you can try Four new plugs. See my most recent post about an issue I had. The plugs in it were new but it took four more new plugs (same make and type) to cure issue. Last if your valve clearance is too tight, the valves may not fully seat when the engine is real hot.

Edited July 27, 2014 by saddlebum

[cowpuc]

Oh yea,, try a carb sync too,, never have done it without the bike really appreciating it...

[edtheguy]

Wow, you guys are an awesome group, so glad I joined.

I will start with the easier fixes first. I had the carbs rebuilt about a year ago , so will rule carb issues out at this point. Thanks again fellas.

[edtheguy]

Oh yeah, sorry, but to respond to your questions:

 

Didn't notice anything strange going on with the tach

and no discharge below engine after riding when parked.

 

Only happening when temp gage goes above half.

 

Thanks again

[edtheguy]

I know this is an old thread, but still having some issues.

When it gets warm tends to idle erratically to the point where it may die. Temp gage only a little above normal. Is there a way to have the fan actuate at a lower temp ?

[CaseyJ955]

Sorry your still having trouble.

 

Silly quick things to look at and try before going "in".

 

Have you got fresh NGK plugs? Inspection of plug caps and HT leads where they leave the coils for the notorious green gunk? This next one will sound irrelevant but it matters. System grounds, cleanliness and integrity of all grounds and connections. I know it only happens when warm but electrical issues can produce some counterintiutive symptoms mimicking other unrelated issues.

 

Perhaps it's time to remove the plugs, check gap and read them to see if one plug is inconsistent with the others.

 

Check for patancy of the overflow tube setup from the top of the carbs. This one is critical, were the carbs synchronized after the rack was reinstalled on the bike? What your describing would fit really well with the carbs being out of whack with each other or less likely some out of spec float levels. It's amazing how badly a "tech" can **** up float levels and synchronization of carbs. Synchronization is reasonably simple but takes a touch of love and care, not unlike making a perfect tortilla.

 

When you had the carbs done did you R&R them on the bike yourself or did the shop/person that did the carbs remove/replace the rack from the bike. I know there is a thing known as bench synching (it does get it closer) but this does NOT replace the need to do it again with the carbs on the bike at op temp.

 

What is your elevation? Hows the air filter looking? How old is your battery? Current mileage and mileage of last valve adjustment?

 

When warm idling as the issue is presenting is there any unusual smoke or smell.

 

If you have an IR thermometer or a willingness for the downpipe spit sizzle test (thats how I do it) then thats another quick thing you can do to see if one hole is not pulling it's weight while the issue is presenting.

 

If your using ethanol tainted fuel, stop. Especially do not let it sit with ethanol in it. Always wash it down with pure gasoline if you do need to use ethanol. Ethanol and carbs dont really play well together, especially for storage. Sometimes ethanol is all you can buy, unfortunate indeed, but dont store it with that stuff inside.

 

I know this was mentioned above but it bears repeating, the carb rack needs to be fully seated into the intake boots, and the air box needs to be firmly seated atop the carbs, the air filter MUST be in place. If you have a K&N style filter try going back to the pleated paper filter just for fun. Once the carbs and air box are securely seated the hose clamps only need be decently snug, not wicked tight.

 

What happens when the symptom is presenting and you apply the choke?

 

Oh, to A your Q, you should be able to find a different fan switch, I think there are some Ford PNs that work right over and drop the trigger temp a little bit, but I'm really thinking this route may be premature, at least before a few other things are ruled out.

[GreenMtnHunter]

What happens when the symptom is presenting and you apply the choke?

 

Which caused me to wonder: Is the choke cable actually working? My better half frequently forgets the choke on her Star, and the beast runs like...doo-doo until I remind her to return the button....

[RandyR]

patancy

 

I learned a new word today.

[WRIDR]

"Patancy, Nature Of Obstructing Deposits And Bacteriology."

 

Heheheh... sorry Guys, this is the best we could discover, on the second page of Google searching.

 

FWIW: There's also another word, or miss-spell of this one: "Patency", but we give up.

 

Rgds, WRIDR

[videoarizona]

I know this is an old thread, but still having some issues.

When it gets warm tends to idle erratically to the point where it may die. Temp gage only a little above normal. Is there a way to have the fan actuate at a lower temp ?

 

 

I'm trying to think of what would cause your problems related to heat.

I keep coming back to fuel issues....maybe a fuel line that is leaking (air) when hot ..creating fuel starvation. Heat causing the carbs not to function properly...ie, the needle sticking...

 

Or something like a coil/plugs/wires breaking down in the heat....

 

Carb intakes to manifold cracked and leaking air when hot.....

 

To maybe something as simple as the main fuse or ground is getting hot and not making connection much. A dirty ground or loose ground could cause the engine to stumble as well...

 

Good luck....

[saddlebum]

When you start your bike up on a cool morning do you even need to use the choke or does it fire right up without even using the choke? If it fires instantly on a cold morning without using the choke and then starts to spudder when it gets warm I would be inclined to think the fuel enrichment valves are sticking open. That's not an uncommon problem and quite often when carbs get rebuilt this also gets overlooked by bike shops that do the rebuilding. Another thing to look for is fuel drpping on the ground while idling indicating a malfunction needle and float.

[edtheguy]

Wow. Thanks for all the info guys. I have a lot of checking yo do.

[CaseyJ955]

"Patancy, Nature Of Obstructing Deposits And Bacteriology."

 

Heheheh... sorry Guys, this is the best we could discover, on the second page of Google searching.

 

FWIW: There's also another word, or miss-spell of this one: "Patency", but we give up.

 

Rgds, WRIDR

 

It was a misspelling on my part, Patency is the correct spelling. A healthy dose of dyslexia means this can happen when I blaze past spellcheck. My apologies for the confusion, I should have chosen a different word.

 

From Merrian=Webster for "Patent" (same spelling as the copyright protection)

"4 : affording free passage : unobstructed a patent opening"

From Dictionary.com

#2 "Medicine/Medical. the condition of not being blocked or obstructed."