After riding this bike for 1 day there are a few things I need to address. This being my first EVER liquid cooled bike, I'm not sure where to start.
Issue Number 1
Bike appears to be running lean when cold and warm. Rev won't come down quickly especially when shifting. On my air cooled bikes I would just adjust the air screw and it would help. However on this bike I don't see any air adjustment screws on the carbs. Is there something else I should be looking for? If not I may just need to clean the carbs out.
Issue Number 2
Bike overheated a bit today. First place to start would probably be the thermostat. Right? I imagine it hasn't been replaced in a really long time, if ever.
Although these can be "generic" questions, for better results, please indicate year, model, mileage of the vehicle. Are you referring to the XS850 in your profile or ???
Sorry about that. I forgot I hadn't updated my signature.
Bike is a 1984 VF750F with around 37k miles on it.
It didn't shut down, it just puked coolant. It was running between half and 3/4 temp on the gauge when I shut it down. Then it spit coolant from the reservoir.
Didn't have a chance to get to the t-stat last night, but I did replace the spark plugs. Made a fair difference in how the bike runs. Don't know when they were last replaced, but the ones I pulled were ugly.
I'll probably get to the t-stat this weekend.
What do you guys think about the lean symptoms? Basically when I shift, the RPM's are slow to drop. They stay about where I revved to until I complete the shift. In my 70's bikes I'd adjust the air mixture screw, and if that didn't do I'd clean and consider rejetting the carbs. On this bike it appears that there isn't a air screw. So should I just pull the carbs, or is there something else I should be looking at?
Can't help on the lean condition, if that is the problem.
Back to your coolant though, might consider getting a new rad cap too. Not expensive and could help. Also double check and see if there is an air bubble in the coolant system. Burp if need be.
Can't help on the lean condition, if that is the problem.
Back to your coolant though, might consider getting a new rad cap too. Not expensive and could help. Also double check and see if there is an air bubble in the coolant system. Burp if need be.
To show how new I am to liquid cooled bikes, I'm going to have to tell you that I do not know what a rad cap is, or how to burp a coolant system.
Catching on to your lingo... rad cap = radiator cap. Burp the system by leaving the cap off running it till it's warm?
Burp: run up to temp with the bike on the SIDE stand (forces air to the cap/high point) & the radiator cap off. Blip the throttle a few time while doing this, adding coolant as the level drops. Once it's hot, cap it & let cool completely. Check again when cool & top off if necessary.
Don't forget to put some in the overflow container on the left side~
Didn't have a chance to get to the t-stat last night, but I did replace the spark plugs. Made a fair difference in how the bike runs. Don't know when they were last replaced, but the ones I pulled were ugly.
I'll probably get to the t-stat this weekend.
What do you guys think about the lean symptoms? Basically when I shift, the RPM's are slow to drop. They stay about where I revved to until I complete the shift. In my 70's bikes I'd adjust the air mixture screw, and if that didn't do I'd clean and consider rejetting the carbs. On this bike it appears that there isn't a air screw. So should I just pull the carbs, or is there something else I should be looking at?
Treitz, this is what I would suggest you try,
If your carbs ain't synced then one or two will keep pulling a fast idle.
First check your carb-engine rubber boots for tightness and cracks with some solvent like carb cleaner.
Then see if there are any gas leaking near the carb needle covers (some residue on mine suggested the diaphram wasn't sealed tight and gas was leaking out).
Then sync the carbs to the #4 carb (the one you can't adjust). The three screws for the carbs are tricky to reach ( I use a 7mm long crescent wrench).
The idle adjust screw is between the front two carbs. (reaching in between the hot engine and carbs is a real pain in the ... hand.) Turn down idle speed after synced.
Then start removing things if you feel the problem is internal somewhere.
Didn't have a chance to get to the t-stat last night, but I did replace the spark plugs. Made a fair difference in how the bike runs. Don't know when they were last replaced, but the ones I pulled were ugly.
I'll probably get to the t-stat this weekend.
What do you guys think about the lean symptoms? Basically when I shift, the RPM's are slow to drop. They stay about where I revved to until I complete the shift. In my 70's bikes I'd adjust the air mixture screw, and if that didn't do I'd clean and consider rejetting the carbs. On this bike it appears that there isn't a air screw. So should I just pull the carbs, or is there something else I should be looking at?
Treitz, this is what I would suggest you try,
If your carbs ain't synced then one or two will keep pulling a fast idle.
First check your carb-engine rubber boots for tightness and cracks with some solvent like carb cleaner.
Then see if there are any gas leaking near the carb needle covers (some residue on mine suggested the diaphram wasn't sealed tight and gas was leaking out).
Then sync the carbs to the #4 carb (the one you can't adjust). The three screws for the carbs are tricky to reach ( I use a 7mm long crescent wrench).
The idle adjust screw is between the front two carbs. (reaching in between the hot engine and carbs is a real pain in the ... hand.) Turn down idle speed after synced.
Then start removing things if you feel the problem is internal somewhere.
Good advice. I will do all of the above. Sometimes with a unfamiliar bike you forget all of the things that you know how to do that will translate directly from one bike to the other.
I have a carb syncing tool, so I have no reason not to sync them. I imagine they have vacuum nipples somewhere near the top so I have to remove the tank first?
Yep. Syncing is relatively easy. So sitting on the bike, front two cylinders (left-right) are 2-4, and back two are 1-3, if I recall correctly.
The #3 vacuum port screw is behind the thermostat housing. You can reach the screw with a long screw driver, and need a longish sync extension tube to get to it. I made my own, but I think there are ones for sale that are long enough. The rest are easy to get to, and no tank/fairing removal is required.
Yep. Syncing is relatively easy. So sitting on the bike, front two cylinders (left-right) are 2-4, and back two are 1-3, if I recall correctly.
The #3 vacuum port screw is behind the thermostat housing. You can reach the screw with a long screw driver, and need a longish sync extension tube to get to it. I made my own, but I think there are ones for sale that are long enough. The rest are easy to get to, and no tank/fairing removal is required.
It is well explained in the factory manual.
Right on. I need to track down a factory manual for it.
You're saying you can actually sync it with the tank on!?
Yep. You can see the phillips screw heads near the bottom of each carb. There is a washer on each screw. Use medium Locktite to secure. I will see if I have an electronic version of the manual to send you.
Yep. You can see the phillips screw heads near the bottom of each carb. There is a washer on each screw. Use medium Locktite to secure. I will see if I have an electronic version of the manual to send you.
After riding this bike for 1 day there are a few things I need to address. This being my first EVER liquid cooled bike, I'm not sure where to start.
Issue Number 1
Bike appears to be running lean when cold and warm. Rev won't come down quickly especially when shifting. On my air cooled bikes I would just adjust the air screw and it would help. However on this bike I don't see any air adjustment screws on the carbs. Is there something else I should be looking for? If not I may just need to clean the carbs out.
Issue Number 2
Bike overheated a bit today. First place to start would probably be the thermostat. Right? I imagine it hasn't been replaced in a really long time, if ever.
After thinking about it, I think it may be a air leak in the carb boots actually because it changes how it acts based on the RPM. At higher RPM it is slower to come down. At lower RPM, like 3K or lower it drops much faster. Making me think that the higher pressure at higher RPM is bring in more air, leaning the system out.
Tried burping the system and I think there could be 2 issues. Themrostat &/OR fans.
I ran the bike to running temp with the cap off. Once the coolant level dropped I added more coolant. Did this successfully about 3 times. Then the bike kept getting hotter, and hotter until it just started pouring all of the coolant out of the radiator (open cap). Bike was at about 50% on the gauge.
You can short the fan to ground to test if it works. Otherwise I'd guess a bad temp sensor.
Considering the burping was working until it overheated, would it be safe to assume that the t-stat actually does not need replaced? I would assume it was opening because as the engine got warmer the fluid would go down. My guess is the lack of fan made the engine heat up too fast for the t-stat to keep up?
And for giggles I shake my bike side to side on the center stand . Its helps get the bubbles to the top of the rad.
All of this with the bike running and the cap off?
No I wait after warning it up and then I turn off the bike and stand it on the center stand and then shake it side to side . Then open the cap and refill.
You can short the fan to ground to test if it works. Otherwise I'd guess a bad temp sensor.
Considering the burping was working until it overheated, would it be safe to assume that the t-stat actually does not need replaced? I would assume it was opening because as the engine got warmer the fluid would go down. My guess is the lack of fan made the engine heat up too fast for the t-stat to keep up?
Okay. So I did the process again with the same results. The t-stat opened up about 2 times before it started to get too warm. The fans never came on.
I looked into the wiring and didn't find anything disconnected, and the fuses are good. So one would assume a bad sensor?
I read a forum where someone had fan issues and just wired up a toggle switch to switch the fan on and off. Would this be done by connecting the black and blue wires from the fan to a toggle switch that connects them when the switch is "on"?
Continuous engine temps above 220ºF or 104ºC are a problem and the proper order of items to trouble shoot are:
1)Faulty radiator cap... system should hold 1.1 pressure ratio... 2)Insufficient coolant... 3)Passages blocked in the radiator, hose or water jacket... 4)Air in the system... 5)Thermostat stuck closed... 6)Faulty temp meter or thermo sensor... 7)Faulty fan... 8)Faulty fan switch...
Continuous engine temps above 220ºF or 104ºC are a problem and the proper
order of items to trouble shoot are:
1)Faulty radiator cap... system should hold 1.1 pressure ratio...
2)Insufficient coolant...
3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system...
5)Thermostat stuck closed...
6)Faulty temp meter or thermo sensor...
7)Faulty fan...
8)Faulty fan switch...
I don't understand why any of the top 5 items would keep the fans from turning on? As I mentioned in earlier posts, the thermostat will open and close a few times once the bike is at running temp. I can see this with the cap on as the fluid rises and falls. But the fans never kick on, is gradually overheats when sitting still. Note that this is also taking place in 100+ degree temps.
My bike overheats if idling around town too. So I added a switch as some suggested and turn it on when I see the temperature climb. It was easier than finding a thermo switch with a lower temperature range. The thermo switch actually turns on just before it overheats.
Did you get a chance to do a cooling system flush, to remove any junk that may have built up inside? Could be restricted passages.
Okay, I got the ground test to work, so I know the fans do in fact work. I think I will go with the external switch option rather than replacing the stock fan switch mechanism.
Fan switch installed. We'll see how she does around town in the 100 degree days. I'll still replace the rad cap soon anyway as the one on it doesn't appear to be in the best shape.
Thanks everyone for the help so far.
Next up trying to track down the lean running issue. A carb sync is in order, just haven't had time to do it yet.