Overheating - Please read, this is not another fan switch and blade swap question.

I too am voting for the head gasket but if you read the previous posts he said the combustion leak tester did not show combustion gasses in the coolant. I am leaning toward a manufacturing defect in Assembly, a blocked galley or even a casting crack in a head.

 

tinkerinWstuff see the above.

 

I have been studying the original post and I want to know why the left side goes cold? This is a circulation problem. Either the coolant is cold or there is none in it. Have you pulled both radiators and checked for flow?

 

The cold left side rad isn't an issue any longer. It was just cold because it was so low on coolant.

 

Is that because it's spitting the coolant out but it's not returning?

I had a thought and it's a wild one. What if the timing advance is erratic? I have seen this happen before, mysterious overheating at speed but putt around and it's fine. The ignition module fails when it gets hot (warmed up) and advances the ignition timing off the chart. The bike over heats at speed or in normal operation but is fine at idle or even in circumstance when the module itself is cool. It got me to thinking when you said the the trouble starts when you let the bike get hot and cycle. I have seen erratic timing in ignition modules that were getting overheated. Like I said, "a wild one." Thoughts?

 

Any progress on this issue? Inquiring minds want to know.

 

No I haven't worked on it in quite some time, pretty frustrated with the whole thing. I really don't want to pull the heads until I have proof that is the issue. Probably going to try a comp. test next. Just need to get my hands on a tester.

 

Can rent one for free at Autozone...
OEM/Compression Tester Gauge Set (27138) | Compression Tester Gauge | AutoZone.com

 

As someone earlier said, need to go through all possibilities, no matter how dumb??

A couple of points:

1. A second set of eyes looking at what your seeing can sometimes read a different story.

2. Is it possible to have the t/stat in back to front ( yeah, I know STUPID question but... !!) you may not have done it, but you know how it is. you dismantle something and re-assemble it assuming that how you took it apart is right, but not always so.
Happened to a mate's car once, haven't pulled one out of a VFR so I don't know if its even possible)

it certainly is an intriguing problem, hope you solve it before pulling the head.

If you do the compression test and it fails I would still hold off and get a knowledgeable mate around and let him go over your diagnosis (for that second set of eyes)

 

I know its been a while but i think we made a discovery! I bought a pressure tester and pumped the system up to about 20lbs cold, and just let it set. It took about 15 minutes to finally drip on the floor but the radiator on the left side is seeping around the end cap.

Has anyone had problems with these rads leaking? It is the seal between the center finned section and the end cap.

 

I found these guys online, but they only work on aluminum radiators.

www.motorcycleradiators.com

 

I have been wondering what has been going on with that bike. It sounds like you are on to something. Any leak will cause you the headaches you have been having. Take it to any radiator shop and see if they can fix it or just get a used on off eBay.

 

2 years of this :shocked: ... sorry, not helpful ...

ACE

 

Head Gasket?

My bike sat for many years while we had kids. Shoulda changed the Rad Fluid, so it did rust inside.
The rust flakes made their way to the Upper Rad and plugged it mostly up;


I actually set up an Acid Loop with the ZEP version of CLR, with a 12V Aquarium pump,,.. ran it for a week;


Had air building up under the Rad Cap too,,.. it was faulty Rad Cap Rubber, Fluid not returning from Resoviour;


3 rad caps were bad, 4th was OK.
Found all the old rubber Over Flow hoses (30 years old) were leaking at all connections,,.. just cut a 1/2" rubber off all ends, was then OK.

Still getting a little hot and gaining air under the Rad Cap,,.. driving me nuts.
So, took some of the used rad fluid out, put in clear container and shook it for 5 seconds, as well as a fresh unused Fluid,,.. Used stuff foamed up like Sody Pop (full of CO2). I gots a Head Gasket Failure.


It shouldn't foam up.
Examined another set of heads from another motor and they ain't flat anymore.
All those On/Off temp cyclings have slightly warped the head.
I'll be Milling them, then back togather (fingers crossed).

Not sayin you gots any of these issues, but,,..
Good Luck.

See how well pictures work?!,,.. more pictures people,,..

 

Sounds like a corroded water jacket around the exhaust port.

Combustion gases wise, given the path, mixing and temperature for the bubbles fresh coolant would react with the gases to give a false negative. What's the pH doing? Up down?