Oil cooler problems?

[CLYNT BEASTWOOD]

So, I have a question, my 89 750 runs extremely hot in my opinion. I don't think it is cooling properly. Is there any way to check to see if it is working? Could the lines be plugged in some manner?

[92xjunker]

Hot running engine is a lean carb problem or jetting problem. Now, if your riding in 100* weather and stop and go traffic, the bike will run hot.

[CLYNT BEASTWOOD]

All of my spark plugs look good, in the morning the bike runs amazing then in the afternoon it runs progressively more horrible. The other day it started spewing fuel and died. It starts out acting like it is starving for something from a stop but clears up and runs fine until the next stop where it happens all over. The other day it just got really bad, now it's parked.

[92xjunker]

Do you have an after market exhaust, a jet kit installed and the A/F screws at 2.5 turns out?

[CLYNT BEASTWOOD]

My bike is stock as far as all that goes. I just recently synced the carbs so they are not all exactly 2.5 turns out

[92xjunker]

A/F and the sync screws are completely different setting screws. The A/F screws are under the carb on the engine side. They should be set to 2.5 turns out, the factory sets them all over the place. 2.5 will help the engin run better.

[CLYNT BEASTWOOD]

I've never checked the A/F screws. Quite honestly, I didn't know they were under there. I guess I'll have to take the carbs off and check

This whole time, like an idiot, I thought the A/F screws were the ones I adjusted to sync the carbs. I learn something new everyday

[92xjunker]

. There may be caps over them. Use care in removing them.

[CLYNT BEASTWOOD]

Ok, thanks junker

[shpielers]

If it's an idle issue from running too hot/lean, the bike will tend to idle higher than normal.

Carefully drill out the caps covering the A/F screws, and carefully pry them out. Turn the screws all the way in until lightly seated, then turn out 2.5 turns. From the factory, I've heard ranging from .5 to 3+. Mine were all around 1.25-1.5.

Sync the carbs after you adjust the A/F screws. You'll need to. Bike should start easier, and run better when the engine gets toasty.

If you have some other issue...this won't fix it. But it will help once you find/fix the other issue.

[CLYNT BEASTWOOD]

Thank you guys, I'll be working on it Monday

[Kreylyn]

Cold engines run better when the fuel air mix going into the engine is richer.

Hot engines run better when the fuel air mix going into the engine is leaner.

Running well in morning (cold, sat over night, lower ambient temps) but not so well (recently ran, hotter ambient temp, sun exposure) in the afternoon, suggests you have an issue with the bike running rich.


You mentioned the bike was spitting gas.

Excessive gas would enrich the fuel air mix. Another finger being pointed at running rich.

So... lets assume that the bike is running rich.

The most likely cause of rich running on a kat is going to be fuel in the oil. Fuel in the oil is caused by a carb(s) float needle not stopping the flow of fuel to fill the bowl, so it over flows and drains into the crank case mixing with the oil.

You mentioned "spitting fuel"... so that would be commonly caused by the flooding issue from the not working properly float needle.

Lets assume that is the case.

Check your oil, smell for fuel. If it has any kind of fuel smell at all, that's bad... and will cause the bike to run poorly when hot.

Steps to fix it...

Pull and clean the carbs, check / adjust the float needles and float levels to make sure they are properly seating and set. Use this time to make any other adjustments and cleaning like the a/f screws and so on. Once you have them cleaned and fully assembled, think your ready to put them back on?...

Bench test the carb float needles work correctly before putting them back on the bike. While off the bike, and on the work bench, you can use water if you want but flow liquid into the bowls and make sure they do not leak and each bowl has the exact same amount of fuel in them.

Do this by...

Set the carbs upright on the work bench.
Use a container for the liquid that can be attached to the fuel line into the carbs.
Using the container, fill them via the fuel line with liquid.
No fuel should leak out of the carbs anywhere.

Once you have confirmed the bowls are full, and nothing is leaking... blow on the fuel line. If you hear bubbles, that's a problem... track down which needle(s) is letting the air by... those are a leaking issue.

If you have the bowls full, no liquid is leaking, and you can't blow air through them, then...

Drain each bowl individually into a measuring cup or 4 clear cups so you can compare the amount of liquid in each. Those should match. If not, that's a problem.

Once you have confirmed the bowls do not leak, the fuel level is equal in all 4, and you can't blow air past when the bowls are full... open the bowls and drain the water out and allow to dry/blow out lightly with air.

Put them back together and install on bike with air box and filter.

Now... check your petcock works correctly.

No leaking when in the "on" or "res" positions. That's arrow down or towards the front of the bike.

"Pri" will flow fuel so don't turn it to that position unless your ready for fuel to come out. Never leave the petcock in "pri" position unless your specifically wanting fuel to flow to fill the carbs with the bike not running, or your testing another issue and want to make sure fuel is flowing.

Very important... Drain the oil, replace with new. No need to replace the filter unless it's time (needed to do a oil change and filler replace anyways). Fuel doesn't hurt the filter, you just want to get it out of the crank case and put pure oil back in. The minute amount left once you drain the crank case does not need to be "flushed" out so don't worry about running new oil and changing again quickly. What little is left will dissipate through the crank case vent /air box system when run normally, and isn't enough to cause running issues.

You had the carbs off the bike... Sync them. This is always the case. You may not need to make any adjustments, but always check.

If you really want to dial the carbs in, with the bike running... tune the a/f screws. The drop down method is the pain the arse but no expensive tools / gas analyzer needed to do process to tune them in.

If your bike is a US model, 2.5 turns out on the a/f screws is the best starting point, and probably very close to the final point anyways that if you don't do a final tuning on them, it will probably still run very well.

Krey

[CLYNT BEASTWOOD]

Thank you Krey for the great information, I appreciate it.