Possible Overheating? 1985 VF700

So I bought this bike as a project and put a decent amount of money into it to make it a reliable daily driver and so far it's worked out pretty good.
My only real problem is what I think to be overheating after a long ride.

On a ride up to columbus ohio from around the Dayton area (about 80 miles) I got off the highway into the town only about 2 miles from my destination and i noticed my idle was almost completely gone. Once i stopped the RPMs would drop under 1k and then the bike would stall if I didnt give it gas. And when taking off from a stop it would take a couple seconds to start revving up. Other than that one situation its served me fine.
I'm thinking i should do a coolant flush and get the lower temperature fan switch.

Can anyone offer any help?

 

So, did you change the coolant in it after you bought it? The bike has a temp gauge on it. Was it overheating or not?

 

That's the thing, It was pretty high on the temperature guage but it didn't show it quite all the way up to hot. It was showing about 1/3 max the whole way on the highway but as soon as I got into town it shot up until it stalled and I had to wait 5-10 minutes to go 1 more mile to my destination.

And I put new coolant a few months ago but I'm not so sure I flushed it completely.

 

You may have had some air trapped in the system. Check the coolant level again, also look at the overflow bottle make sure the coolant is at the proper level there. If both are full the radiator could be partially clogged.

 

Consider replacing the rad cap.

 

Have you considered looking at the carbs? It sounds to me like it could be a jetting issue caused by dirty carbs. A coolant change is regular maintenance so there's no reason not to do that, but I'm not sure it will fix what you describe.

 

Well just about a month ago the carbs were cleaned and needles and i believe idle jets were replaced along with an oil change (Some oil got into the gas because floats stuck)
Ever since then i've checked the oil every time i ride (at least 3 times a week) and no trace of any gas
Also this problem ONLY seems to happen after it gets really hot.

This information might also help. When i was on the highway on that trip just about 10 minutes before getting there, i thought i heard a gurgling noise coming from the radiator (maybe air escaping from the system or something worse?)
And after i got to my friends place i checked the overflow and it was filled almost all the way up, quite a bit past the max level.

 

Install a manual fan switch. Then go after the thermostat as it sounds like it is sticking. Has it ever been replaced? I bet that is the problem.
Since your going to do the thermostat, change the coolant, use a aluminum low silica formula. Any suggestion? don' know the U.S types.. Mike R. in Calgary..

 

that gurgling was the system puking into the overflow bottle. I agree with mrich12000. check that thermostat pronto!

 

Well I've seen some posts in other threads about replacing them with a thermostat from something like an Integra or CRX etc.
I kind of want one for a lower temperature anyways. Does anyone know which one is compatible with a 85 VF700?

 

An early (late 80's) Integra or CRX use the same thermostat. I have the part numbers at home somewhere. Getting that from an auto parts store is cheaper and you can get a lower temp part - both are good things!

 

Yeah, if anyone has the part numbers for the thermostat i would love you for a long time.
Also another thought, i heard about this same problem (RPMs dropping at higher temperature) and it was brought up that it could be valve clearances at that heat?
I think its a valve adjustment time, any thoughts on that possibility?

 

It seems like I've been posting this info a lot lately!

Here you go, with fan switch info as well:


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Thermostat (generic replacement)
Stant Superstat 180 degree #65848, gasket #27266
Stant brand numbers
160° - 35366 BT 336 160
170° - 35967
180° - 35368 BT 336 180
1975-1991 Honda Civic All 3 door(hatchback) and CRX models
also 1986-1991 Acura Integra, all engine sizes.

Housing Seal 54x2 o-ring

Fan Switch
Honda Part Numbers
Fan switch 37760-KET-003 37760-MB4-770
GP Sorenson Part Number: 40-5001 ($14.99 @ Advance Auto)
NAPA FS130, about $28 from NAPA. Turns on at 191-197F (ascending) and off at 182-187F (descending). The element is about 1/2" longer than the Honda one, but it screws right in and it has the two bayonet connectors found on early V4's.

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Good luck!

 

Got a chance to look under the front valve cover before my valve adjustment. The cams look worn but im not sure how badly they are worn or if it will cause a problem.

 

Your cams look fine. Make sure you lash them NO tighter than .005. Best to run at .006 and use two feeler gauges when adjusting. They may make a little noise at .006, very little. It's a safer lash at .006 vs .005. Your bike will run the same.

I use a manual fan switch on mine for city riding. When in the hot summer I get into a city I just flick it on and the bike and me stay cool. Just run a wire to the one fan connector where it plugs into the harness. Use the connector with the single black wire (ground). Solder to that then run to one leg to a switch lug. Run the other switch lug to ground. That's it.

 

I don't see anything wrong either, but it's not the cam lobes that are the problem - it's the rocker arm contact faces. You need to pull the cams to check those, so I doubt you'll want to go to that trouble. If the clearances are close (i.e. not grossly out of spec) and the engine doesn't make noise you are probably fine.

 

The problem is adjusting the valves it seems there is way too much space. You can see from the pictures but according to the Honda manual where I have to put the feeler gauges has like 1/4 of an inch as opposed to .006 inches.

Can anybody help a noob out?
Also: scored a pair of lockhart mid fairings already painted to my scheme for $110, I'm happy

 

Here is a link to the recommended lash settings.

Use two feeler gauges when setting - as this is the choice of champions.

http://www.math.uwaterloo.ca/~rblander/V4_valve_specs.txt

Hope this is of help.

 

Well I have the clearances but the manual tells me to gauge an area where there is way too much room and Its so extreme I don't want to make it .15mm unless I know its the right place

 

Not sure I follow...the lash is set using a pair of feeler gauges - one gauge placed between each tappet stem on the cam follower and its associated valve stem.