Sync or jetting ?

[Robbarrie]

Went on a long ride, only to discover that the bike will get hotter the faster I ride it. If I ride steady any length of time at 4000 rpm or above the bike will eventually get to go into the red zone. Anybody have or had this problem ?

My rad is fine, and the I run a whole bottle of water wetter in it. I ride it heavy now and again but I always have to slow and wait for the other guys so it seemed to get that cool down period.

As long as I'm up/down on the rpm it is fine. But even as slow a 100kmph or 60mph it will go into the red zone. 60mph at 4000 rpm is I think way too high but I guess Yamaha doesn't think we actually use this bike for normal driving !

Could this be a carb sync problem or a jetting problem ? This is the only two things other than a plugged jet that could cause this.

I run regular gas
air filter is very clean - like new
stock plugs
water pump is working fine
stock pipes

I'm gonna have to take into the stealers anyway but I just wanted to ask you guys to see what ya think. I don't have gages nor the knowledge to fix it. But I don't want to look like a dumb ass when I go in there. Thanks Rob

 

[davidon]

Check the plugs for an indication if lean

 

[maleko89]

Check your temp gauge too. If the ground wire is loose or corroded then the reading will shoot up. The ground wire fastens to the coolant manifold, near the radiator cap.

It might be worth it to drain and change the coolant. When's the last time it was changed? Or, take the radiator cap and run w/o for several minutes. This allows any air in the system to bleed out.

Mark
#1098

 

[Robbarrie]

Let me give a little more info.

The bike has fresh coolant, I don't know it's total history. I bought it with stock pipes but was it ever jetted - not sure but don't think so.

I always thought you had to be in the rpm range to check a plug. I will have to take it out on the highway and get up to speed the pull in the clutch ( and hold ) and turn the run switch to off - come to a stop and check. Is this true ? I won't be able to do today but maybe this week.

I will check the wiring for temp gage. Never would have thought. It does shoot up pretty fast.

Thanks for the help.

 

[maleko89]

If it's a stock bike, you're jetting should be fine assuming nobody fooled with the jetting any.

Have you checked to make sure your fan kicks on? A stock bike will have the temp gauge push pretty close to redline. It nothing to worry about, just bakes the legs a little bit.

Mark

 

[Robbarrie]

I have a new thermostat on order and will see if that helps. However, it climbs in half way into the hot zone. This should not happen on a liquid cooled bike. I don't care how hard you ride or hot it is. It's not normal, I know I have a problem I'm just not 100% sure what it is. Just wanted to see if anyone had this happen only to find out it was a carb sync or jetting. I've been thinking on and off all day and decided that jetting isn't the problem ( your probably right )

Could a jet be plugged ? Could this cause this ?

If it isn't the thermostat I'll be looking in that direction...I figure.

 

[maleko89]

Did you test your fan switch? This keeps the temp from getting into the red zone. It doesn't cause the engine to cool any....just prevents the temperature from getting any higher.

Try this, turn your coolant drain valve to the drain position. Do this by ensuring the small metal ball shows through the top hole on the drain valve housing. What this will do is force the coolant to bypass the thermostat. If it's truly a thermostat problem then the temperature will go down. If not, the problem lies elsewhere.

Do you have access to a temperature gun? When I had the same problem I used that and the temperature read under 200 *F. I eventually found out it was a bad temp. gauge ground.

Mark

 

[maleko89]

Oh, about plugged jetting. I suppose an excessively lean mixture would cause the temperature to go up, but I would troubleshoot the cooling system first. How do your spark plugs look?

Mark

 

[Robbarrie]

The last time I checked the plugs when the bike got that hot they were fine. Nice tan color no white specks nor breakdown from the electrode. This bypass you were talking about - is this mentioned in the manual - to do this, as a check to test for thermostat operations.

I don't remember reading about this, then again I seem to forget a little more these days. :biglaugh:

I do have a temp gage ( inferred ) but I don't know what the temp should be at the point the needle hits the little red tick at the bottom of the red zone, anybody know what it should read?

I will check the plugs later today after I get up, check the wire, and do that test. Can you tell me - What's the big deal about running without the thermostat? I imagine the temp will spike around more but it shouldn't get hot at all (right?) it it was a faulty stat.

Thanks for your help, Rob

 

[maleko89]

If your plugs look like that I think your jetting is fine.

Here's how the thermostat works. When cold and in process of warming up the thermostat is closed and blocks off the radiator so coolant can't flow through it. This ensures a quicker engine warmup.

When it's closed, the bypass pipe that goes from the manifold to the thermostat housing is used. This hose bypasses the radiator and goes beneath the thermostatic valve. When warmed up to operating temp, the valve will open. This allows coolant to pass through the radiator for proper cooling and then uses the upper channel in the thermo housing. The thermostatic valve will be blocking the bypass pipe to the thermostat. But, if you open the drain valve....this allows coolant to flow through the radiator and if the valve is stuck closed will flow through the the lower bypass thermostatic channel. If your thermostat is operating correctly, you won't read a lower temperature because the lower bypass channel is blocked. The only thing you should notice if the drain valve is in the open position is the engine will take a bit longer to warmup since coolant is flowing through the radiator during initial start-up. So, thermostat closed bypasses radiator and uses lower thermostat coolant channel. If the thermostat is open then the radiator is used and the upper thermostat coolant channel is used.

The screw in the middle of your temp gauge is 205 *F.

Mark

 

[Robbarrie]

Thanks Mark;

Will you believe that I priced out a new one from the stealers at the new low price of $56.00 I nearly shit myself - for a fuc'n thermostat - this is totally nuts.
I didn't even ask if that came with a new gasket, I was so pissed off. WTF !:bang head:

 

[maleko89]

Try University Motors, everything is cheaper there.

Check with Morley too, he may have a spare lying around for sale.

Mark

 

[Robbarrie]

Mark I just checked the drain bypass valve. The little dimple was in the hole position. Is this open ?

If so, why was the bike still getting that hot ?

 

[maleko89]

The top hole is the drain position. If it's still getting hot then a stuck thermostat isn't the problem.

Mark

 

[Robbarrie]

Oh shit !

Thanks Mark

 

[TheFleshRocket]

The thermostat is the absolute first thing I would have thought.

I saw your other thread about where to buy a stat--but here's a quick fix if you don't want to spend any money and want to find out FOR SURE if it's the stat.

Simply remove the old stat. Top off the coolant and go for a test ride.

Assuming that's the problem, the bike will run cooler than normal and it won't get anywhere near the red zone. If that fixes it, buy a new stat. If it doesn't, put the old stat back in and look elsewhere in the cooling system.

I don't think jetting is responsible for the overheating. Even if the bike was jetted so lean it was practically unrideable, it would blow up the motor (think hole in piston) before the temp gauge would go up a significant amount. I've had my bike jetted stock and jetted way too rich, and it made no noticeable difference in the temp gauge. (Jetted rich usually results in the engine running a bit cooler.)

A long time ago, I had an '82 Monte Carlo and fried the ECU. The engine went into limp-home mode, meaning that it pulled ignition timing. The engine had no power (not that it had a lot to start with from the 229" V6) and the temp gauge DID climb into the low 200F range(had a 160F stat and ran 170-175F), but it didn't get close to overheating. Obviously that's a car, not a bike, but I'm just saying--I have a little experience with this sort of thing.