93 Vfr - Over-Heating Question

Hi all,

been a while since I've posted on here.

Unfortunately I come with issues, not pretty pictures... (I'll post those shortly)

So, after my RR started to melt and the bike started doing weird things at start up and on the road, I decided to upgrade the RR to a mosfet style RR and to do so I purchased the VFRness and the RR from wiremybike.com.

so after a bit of work installing the new harness and RR, the bike started running and starting great.

Now I have a different problem.... OVERHEATING!

so during a few city rides in Toronto, Canada - both totaling about 45 minutes or so, and in very cool conditions (15-20C) the bikes temp gauge had gone up to the red mark, both times!

I've never seen the bike run this hot. 

my fan comes on but seems like its on very late...

Tightwad, who supplied the RR and the VFRness, has been quite helpful, but now we're both stumped. 

has anyone experienced anything like this?

did I inadvertently fry something during install? crossing wires or something...

what could have failed to give me this type of problem?

what can I do to test?

is there a coolant pump on the bike?  maybe that has failed?

thermostat coil somehow got screwed up and now turns on the fan way too late?

so, I'm hoping that anyone has some suggestions for trouble shooting, so that I can start with.. then hopefully we can get to the bottom of this..

thank you all!!

ps. as I promised,  pictures attached...

cheers!

Attached Images

• [image: 20130908_173941.jpg]
• [image: 2013-09-08 21.00.30.png]
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Some more details would be nice.  Does the temp gauge creep up or shoot up?  Does it waiver at all?  Did you check to make sure you have coolant?  Is your radiator hot when the bike is hot?  Does your fan blow to the rear?  And how late does the fan turn on?

The water pumps tend to be pretty robust.  My first suspect would be the Tstat.  And the fan does turn on at about 3/4, I don't know if that is what you mean by late.

This is probably unrelated to your wiring.  Now that your recharging system is working, you may be riding far enough now to experience this cooling issue.

sound like you have a bad thermostat fan  switch and possibly stuck thermostat 

after living in the city with crazy start stop traffic.

 i simply take another thermostat and cut off the tabs holding the spring and plunger..

 then reinstall it.

 the hole is always open...allowing for free flowing coolant

. i also add a manual fan switch on ALL of my bikes.

Seems unlikely to have been caused by your electrical issues. I haven't had to deal with overheating issues but maybe you can get some troubleshooting ideas here: http://www.vfrdiscus...alues/?p=886982

hmm...

ok.

info:

the temp creeps up to half way up the gauge. after that is shoots up. at 3/4 or so, the fan comes on - I can feel it blasting hot air at my legs..

this all happens in the first 30 or so minutes in the stop-go traffic.

I've ridden many hours on end, before the RR started acting up - not a ride length issue.

I will start with taking a look at the thermostat. 

anything in particular I can inspect visually?

or is it best to just replace the thing?

new or used? OEM or aftermarket?

suggestions are welcome!

I"d rather have that fan blasting, and frying my knees, then having to sweat and worry about overheating!!

thanks, all!

I just told ya what to do..
Now.. you CAN down load the manual and inspect the thromo switch and the thermo..
Or you can add a fan switch and chop the thermo and never worry again!!

the temp creeps up to half way up the gauge. after that is shoots up. at 3/4 or so, the fan comes on - I can feel it blasting hot air at my legs..

In stop and go traffic that sounds quite normal to me. When it is even cooler and raining the temp gauge will go 3/4 at which point the fan will come on. It does however not reach the red mark on the gauge.
I once hooked the temp gauge up to a couple of resistors instead of the temperature sensor (an NTC Thermistor) and also measured the resistance of the thermo sensor when submerged in hot water to get a feel of how to interpret the temp gauge reading.
[image: gallery_5310_4809_105485.jpg]

Yeh  something   wrong  with  the  sending  unit   my  93  rarely  got  to 185.  

I looked in the manual, but checking/replacing the themostat (on a 3/4th gen) means removing the carbs???  :unsure:

It sounds like you Tstat is not functioning correct.  It opens up partway at 180 F, and thats why the gauge stalls midway, but doesn't open enough to allow the cooling system to function correctly.

Since your fan is turning on, then adding a manual switch may make you feel better, but I don't see it solving this issue.

You can test the Tstat by taking it out, and putting it in some water on the stove.  With a baking thermometer, wait to see at what temp and how far it opens.

I hope this helps.

It sounds like you Tstat is not functioning correct.  It opens up partway at 180 F, and thats why the gauge stalls midway, but doesn't open enough to allow the cooling system to function correctly.

Since your fan is turning on, then adding a manual switch may make you feel better, but I don't see it solving this issue.

You can test the Tstat by taking it out, and putting it in some water on the stove.  With a baking thermometer, wait to see at what temp and how far it opens.

I hope this helps.

adding a switch lets the person sit in traffic with fan on at all times..and let the temp level out .. not  go up and down like a freaking yoyo.

I looked in the manual, but checking/replacing the themostat (on a 3/4th gen) means removing the carbs???  :unsure:

YES!!!

 NO!!!

KINDA!!

its possible to get it out if you have the right tools.. its it a tight spot!

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[image: 2013-09-10160019_zps48152632.jpg]

[image: 2013-09-10160037_zps6217744c.jpg]

use a flat 8mm ratcheting gear wrench.. pop the shell remove the thermo. cut off plunger and use seal the the sucker back up..use a new gasket or gasket maker..

I looked in the manual, but checking/replacing the themostat (on a 3/4th gen) means removing the carbs???  :unsure:

I repleced the thermostat on my 3rd gen without removing the carbs. Like gll429 says: it's tight.

Like  I said thermostat   ...

the temp creeps up to half way up the gauge. after that is shoots up. at 3/4 or so, the fan comes on - I can feel it blasting hot air at my legs..

In stop and go traffic that sounds quite normal to me. When it is even cooler and raining the temp gauge will go 3/4 at which point the fan will come on. It does however not reach the red mark on the gauge.
I once hooked the temp gauge up to a couple of resistors instead of the temperature sensor (an NTC Thermistor) and also measured the resistance of the thermo sensor when submerged in hot water to get a feel of how to interpret the temp gauge reading.
[image: gallery_5310_4809_105485.jpg]

so, my meter gets to the same mark as in the second image from top left.

this is where the fan has turned on - maybe a few milimeters down the temp gauge, but it has a really hard time bringing the temp down...

the temp then just hovers there, unless I get a long stretch of highway like riding in a high gear.

I like the idea of a manual switch, but installing one, may be a different story.

anyone done this?

is there a tutorial floating around?

thank you all for the information!

it will be most helpful, when I get to looking after this over the weekend.

regards!

PS:  as gll429 knows, I've not been a stranger to removing the carbs on this bike... had to do it a few times when he helped me with re-jetting... your help was MOST APPRECIATED!

I guess I'm at a decision point...

To install a new thermostat

or

To bypass the thermo and install a manual switch..

pros and cons?

PPS. does a thermostat from a 94-97 fit the 93?   asking because there is  a  new one on fleebay for cheap... granted hadn't checked with my Honda dealer to see what a new one runs...

thank  you all!!

I looked in the manual, but checking/replacing the themostat (on a 3/4th gen) means removing the carbs???  :unsure:

YES!!!

 NO!!!

KINDA!!

its possible to get it out if you have the right tools.. its it a tight spot!

[image: 2013-09-10160006_zpsda2d7db1.jpg]

[image: 2013-09-10160019_zps48152632.jpg]

[image: 2013-09-10160037_zps6217744c.jpg]

use a flat 8mm ratcheting gear wrench.. pop the shell remove the thermo. cut off plunger and use seal the the sucker back up..use a new gasket or gasket maker..

Even tighter when you have a CA bike with a the PAIR air pulse pump in the way..Have a few Band aids ready as busted knuckles and scraped skin is a guarantee!....

Also make sure you do not have coolant air gaps in the cooling system. Give it a good burping session by running the engine for a while with the radiator cap off and give all the coolant hoses you can find a few good squeexzes to further agitate the coolant in the system and drive out any bubbles and air gaps......

Even tighter when you have a CA bike with a the PAIR air pulse pump in the way..Have a few Band aids ready as busted knuckles and scraped skin is a guarantee!....

Also make sure you do not have coolant air gaps in the cooling system. Give it a good burping session by running the engine for a while with the radiator cap off and give all the coolant hoses you can find a few good squeexzes to further agitate the coolant in the system and drive out any bubbles and air gaps......

if anyone still has the damned pair set up on a 3rd or 4th gen.. TAKE IT THE F#@$ OFF!! shhhheeeeeeessshhh!

 follow my set up and do the grounding  R/R mod while you are at it.

PPS. does a thermostat from a 94-97 fit the 93?

Yes, it is the same unit.

does a 6th gen thermostat fit a 4th gen?  :unsure:

does a 6th gen thermostat fit a 4th gen?  :unsure:

Lets  see  BikeBandit  part# 609947  for  the  97

And  the 05  part#  609940

Nope  the  same  sorry.

VFR750FL-V ('90-'97) thermostat is Honda pn. 19300-ML7-003 (which suggests that the same part was used on the RC24 VFR700F/750F).

VFR800Fi thermostat is Honda pn. 19300-MBG-003, and the same part number is used by the VTECs.  So, one for the 750s, and one for the 800s.

Ciao,

gll429 erote
use a flat 8mm ratcheting wrench..





In my toolbox now;

[image: IMAG2215.jpg]

;-)

So had a strange and unexpected result over the weekend.

sorry for no update - got poisoned by some bad squid on Saturday... you can guess where I spent my Sunday and part Monday... ugh.

Anyhow, on Saturday morning, I went for a longer ride.  It was  a cold morning and we were out on the freeway.   No temp issues.

got back into town, close to noon, and it has warmed up some by now, and the bike is heating up again.

so, I spent a bit of time, cleaning all the connectors with some "flux-off" electrical stuff. 

I then tinkered a bit with the mixture screws. 

ran the bike, screwed the mixture screws all the way in and listened to it.. stumbling and rumbling. rode it down the street.. awfull...

then, I turned them out the recommended 2.5 revolutions.  now the sound has normalized. rode again, still some stumble, and loss of power...

I turned them back in by a 1/4 turn. rode again.  now the sound is good, the power across the RPM range is great, and lo and behold - after about 2 hour city torture ride - no overheating...

not sure what the issue was, but it seems to have subsided.  

I still may switch the 'fan switch' next time I have the tank off, just so I have a peace of mind...

also, now that I'm on the carburetor issue - I wanted to get the bike dyno'd ... anyone here do it? where did you do it?

I would like to find a place that can help me optimize the power output, as a result of the dyno results.. does anyone do this, for the public?  and how much does it cost?

maybe a complete waste or money and time, but I feel like I've done all this work with sourcing out the TBR exhaust, redoing the crabs (dynojet kit) etc, I'd like to see if I've done anything for it...

A carb balance did wonders for me as far as smooth power delivery.  I can't say I felt a difference on the butt dyno though.