High idle with an overheat

[Hard Likr]

92 VR. once warmed running good min 2 - 5 mins. Gauge normal is +\- 1/3 off the bottom. After an hour or more ride gauge creeps up to slightly over 1/2 and idle vacillates to between 1.8 -2.4k and fan is coming on. I'm still in the first 500 miles after purchase. I have done nothing with the rad. Based on how I found the air cleaner, I expect old afreeze and low levels. Pulled the rad cap once, while back, not for this but to check and in doing so it seemed normal only in feel of removal and replace so I need to inspect closer.

 

Question: because these symptoms show up together, they seem related. Is that possible? Likely? Ideas on a fix.

 

i have too many other questions for here. I have thought that it would be a good idea to get on somebody's bike that is right to see what right is or they on mine to I'd needed areas of attention,

 

thx in advance.

[Marcarl]

High temp could be due to the drain setting on the drain valve located bottom and center of rad. It's a plastic nut with the words off and on embossed on the face. The word 'off' should be at the 2 o'clock position.

Once you have that figured out, it's time to sync the carbs to eliminate that being an issue. You might find in the process that once the carb linkages get warm that they might be hanging up.

[Prairiehammer]

92 VR. once warmed running good min 2 - 5 mins. Gauge normal is +\- 1/3 off the bottom. After an hour or more ride gauge creeps up to slightly over 1/2 and idle vacillates to between 1.8 -2.4k and fan is coming on. I'm still in the first 500 miles after purchase. I have done nothing with the rad. Based on how I found the air cleaner, I expect old afreeze and low levels. Pulled the rad cap once, while back, not for this but to check and in doing so it seemed normal only in feel of removal and replace so I need to inspect closer.

 

Question: because these symptoms show up together, they seem related. Is that possible? Likely? Ideas on a fix.

 

i have too many other questions for here. I have thought that it would be a good idea to get on somebody's bike that is right to see what right is or they on mine to I'd needed areas of attention,

 

thx in advance.

 

Firstly, the slightly over half way up is not overheating. With a marginal cooling system that is normal. A good condition cooling system will run only slightly cooler.

Secondly, the fact that the revs increase as it gets a tad too warm, indicates a lean condition. Two likely culprits: a vacuum or air leak in the induction system; and or a partially plugged pilot circuit in one or more carbs. Lean condition will cause the slightly higher than normal temperature and then the overly high revs will tend to raise the temp. Vicious circle.

Begin by searching for a vacuum or air leak by spraying carb cleaner around the carb boots, the "Boost Sensor" and it's hose, the synch port caps, etc. Any sudden increase in idle speed indicates a leak.

Lower the idle speed to under 900 rpms.

Check the pilot screws (idle mixture screws) for their current settings. Do this by screwing a pilot screw in until it GENTLY bottoms, counting the number of turns to seat the pilot screw. On a normal engine, it is typical about 2½ turns in to seat. Note also, when you GENTLY seat each pilot screw, whether the engine idle speed changes; the idle should drop. If it does not, then you have found a dirty pilot circuit.

The idle picks up when that faulty cylinder starts to fire consistently because it is starting to transition to the mid range fuel delivery.

A poor carb synch will also contribute to your over revving. Probably number two carb is open more than the rest at idle. Number two cylinder is also where the vacuum advance (Boost Sensor) receives its signal. If you pull the vacuum hose from the number 2 synch port (removing the vacuum signal to the Boost Sensor) and PLUG THE PORT, when it is over revving, does the idle speed drop?

Finally, is it a California intended Venture? What is the full VIN?

[Hard Likr]

EEeeew a carb answer. Thank you very much for jumping in. I was really hoping that I would get an answer that didn't involve the carbs. Having gone that way, requires a little more disclosure. I always think when I read other posts and the postee reveals other conditions that didn't come out in the first post " Well you DA, why didn’t you say that in the first place?" I gave the carbs a good strong cocktail of Berryman's, Seafoam and one other item all in the same tank over two tanks after a thorough painting of the carb interiors with carb cleaner and got a favorable response. Far less coughing and sputtering during the warm up and afterwards. Then I also did reset the pilot screws - thinking those are the ones that you have to drill the covers off. All are at 2.5 turns. But reading your replay seems to imply to do that while running which I did not. One other item. those 4 tubes that come out on the sides, well one on the right has come out and I cant for the life of me find where it goes back in. Air cleaner was replaced and it was the dirtiest that I has ever seen, even as an example in a book.

 

Neither of you mentioned that it seemed odd for it to run fine for 30 min to an hour without the symptoms and then gets warmer and faster idle together near as I can tell simultaneously. And that it seems to shift from a normal temp at 1/3 from bottom of gauge and then shift to slightly over 1/2 green gauge. Strikes me then as a more properly referenced higher heat situation although it is not in the red which is true indication of overheat, but it is moving from good and proper operation to something less than good and proper at a higher heat condition. Last thing, I don't notice the fan being on in that lower heat normal but it is on in that higher heat condition. All offered in the attempt for full disclosure.

 

Whoops, maybe not. I have pulled off the air cleaner box in spraying the carbs. However, I do not know how to get that assumed blowback tube that comes up from the engine case and fits on the bottom of the air cleaner box. Does Outside air coming in there have any affect. Could that be coming around the air cleaner and providing too much air to arrive at the lean condition? And it begs the question - How do you get that sum b on there; can't see it and cant reach it as the box goes on. Don't mean to be sticking to you like the stuff you step on, but I'm trying to learn. Thanks again.

 

And no; Im in Atlanta; bike bought in NC. Wouldn't expect it to be CA. But don't have the VIN at the moment.

[GAWildKat]

If you are in Atlanta, we could try to hold a mini maintenance day at my house in Macon and try to figure out 2 bikes at once. My husband has a carbtune so we can do a carbsync while you stop by. Husband has an 87 that has electrical issues. I know next weekend we are busy, but almost any other weekend the rest of summer we are free. Pm me if you are interested is coming down. I can throw some burgers and dogs on the grill and maybe a few more 1st gen folks would kindly show up? I make a good sweet tea too lol.

[cowpuc]

May be totally out in right field here Likr but I gotta tell ya, I have yet to own a 1st Gen (all 83/84's in my history - no M2's like yours - yours may be different) that ran below the 1/2 mark on the temp gauge once warmed up. Always 3/4 gauge.. Also, it would not be unusual from my experience for the R's to drop when the fan came on.. Also, the fans only come on when they do get warm (real close to red zone) so the bike may just seem like its getting hot when it is in fact doing its normal thing.

If the bike is dropping R's with fan start up, it is possible that you have a weak battery or even a fan motor pulling hard BUT - even with a new battery the amp draw on that fan motor may produce an rpm change - IMHO..

Also, I never trust those anti-freeze resevoirs and that system (I am the same way with cars) and always have a problem with being nosey as to how much fluid really is in my radiator. There is a little tab on the actual Rad Cap on these bikes (again - 83/84's any way) that keeps the caps from being removed easily.. Couple weeks of ownership on all my 83's and that little tab is long gone so I can keep an eye on the actual rad levels..

Seriously, if your fan is coming on up near the red zone and going off somewhere right below that red zone - I highly doubt you have any form of an over heat condition..

As far as fast idle, figure out where that vac line goes, adjust the idle down if needed, spit check those headers to make sure she is hitting on 4, toss on a carb sync on her and go finish breaking that puppy in!

Best of luck Puc!!

[Patch]

"Gauge normal is +\- 1/3 off the bottom. After an hour or more ride gauge creeps up to slightly over 1/2 and idle vacillates to between 1.8 -2.4k and fan is coming on. I'm still in the first 500 miles after purchase."

 

I don't see a problem with the above? A question I do see often though in many forums whether bike or car related.

 

What I do see is a need to connect the high idle to the mid-range on the gauge, so lets do that. Like Kevin said, vacuum leak. Which also perpetuates heat! You need to get all the tubes properly hooked up, then let us know what the results are. If you had not mention not reconnecting every thing I would have pointed to the likely cause being intakes boots leaking! As the engine heats it expanses so if they leak it gets worse as the leak grows, and the rpm will hang high!

 

Not sure if you are referring to the PCV tube that connects to the bottom of the air box? If so remove it completely install it to the air box then drop it through the carbs and connect it via (very long nose pliers) at the bottom, note the shape and position it is in now, also check it for cracks.

 

Patch