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oil level in a dry sump DR350

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This motor is becoming frustrating. The bike smokes real bad because the dry sump is filling with to much oil then it goes up the vent and into the carb intake thus causing exreme smoking. It does it cold and hot. If I drain the lower sump, the bike will run perfect for about 5 min. I have checked all of the basics and this doesn;t seem right for a low hour 350. The oil is clean and all components inside motor look good. What are the chances of a bad return oil pump? I took the line off and plenty of oil is coming out returning to the upper sump. Has anyone ever heard of this ? I searched the internet and seen this is a common problem with the DR350 but have not seen the fix.

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I have owned a DR350 for many years now and had several friends with them as well and never heard of an oil pump failure on one; but here's a few things I have heard of commonly:

Vacuum Petcock failure results in crankcase filling with fuel (causing too high oil level and smoking, and poor running)

Over filling the oil. Don't check the oil level cold; since the dipstick is on the oil chamber on the frame, if you check it cold it will always read low. Warm the engine up for several minutes, then let it sit 2 minutes and check the oil level with the dipstick just pushed against the opening in the frame (not screwed all the way back in). Alot of people overfill these bikes because the oil slowly drains down from the frame to the engine sump when not running.

Worn rings will pressurize the crankcase forcing oil into the airbox through the vent.

There is a screen at the bottom of the frame oil resevoir to filter out any large debris before pumping it through the motor. Drain the oil from the frame and unscrew the threaded plug at the bottom of the frame tube to check it and clean it, as it can keep oil from getting to the engine from the frame resevoir (although it sounds like you have the opposite problem from your description).

Those are all the common/easy things I can think of right off hand. You may have more luck checking the Suzuki DR forum here on thumpertalk, or search Maximum-Suzuki.com (lots of DR riders/experts on that site).

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I searched the internet and seen this is a common problem with the DR350 but have not seen the fix.

This is your clue. Whenever you see a "common" problem with no fix, it is likely there was no "problem" to begin with. I have seen this many times in many disciplines. No one posts the "fix" because either the problem mysteriously went away or the poster realized he made a simple mistake and chose not to tell anyone.

As others have said, overfilling the oil is not uncommon due to the not so intuitive oil level checking procedure. I can't conclude that is the issue with your bike, but I tend to think that's what happens to some DR350 owners. Fortunately for me, I carefully read the oil measuring procedure and have not had this problem on my low mileage 1990 DR350S.

The DR350 (particularly the older ones) are known to be very reliable. There really isn't much there to go wrong. It is entirely possible there is something seriously wrong with your bike, but the odds are against it. If you find a solution, please post it.

PS: I just realized you are also in MD. PM me if you need help.

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Hey, I'm having a similar issue with my 91 DR 350.

 

So here's the story. I bought a 91 dr 350 with just over 4k miles for 600$ score!. It had been sitting and didn't run when I bought it. I cleaned the carb, starts and runs fine. Before I even brought her out of the garage I emptied the clean looking oil out the case and frame, checked the filter and it seems very clean too. Then proceeded to not follow directions and put in about 2.5 liters of oil. Started it up oil and smoke everywhere; airbox, exhaust etc... Ran it for a minute and decided to read TT forums. Drained oil, replaced with 1700ML as specified.

 

About bike: running petcock on prime, bypassed diaphragm system. vacuum vent on carb plugged, using 10W40 castrol MC oil. 

 

Here's where I'm stuck. 

 

Started fresh with 1700 CC's of oil. Ran it for a couple minutes at idle burned off the oil that had gotten into the combustion chamber. Result- no dipstick reading. 

Ran it up and down a big hill for 2 minutes at high rpms, let idle for 2 minutes and shut off engine, still no dipstick reading.

Put in another 100CC of oil in the frame, ran it up and down the street a few times, let it sit and idle for 2 minutes, shut off -still no dipstick reading.

Added another 100 CC's of oil, ran 5 minutes, idled for 2 - STILL NO READING 

Another 100CC's totalling 2 full Liters, ran for 5min at high rpms, idled for 2- Still no reading! 

Added another 100CC's(2.1L total), started smoking out the exhaust again, and shut it off.

 

Drained oil and put in 1700cc again, ran the bike HARD for 5-10 Minutes, let it sit and idle but it died after about a minute of running. checked the dipstick and Still NO READING!!!!!

put in another 150 CC totalling 1850 Ran HARD, idled. NOTHING!

 

Right after running with 1850 cc I took off the frame plug and like 2 drops of oil came out. let it run with no frame plug for a second and little spurts of 1-2cc with air were being sprayed out.

 

 

I took off the banjo bolt to the line that feeds back into the frame at the frame and kicked it over with the decomp lever depressed and it spurts out oil. And took off the oil filter and did the same, I saw oil drawn up. 

Then I have proceeded to remove ALL the oil lines except the one from the valve cover to airbox and the case to the airbox. I blew through them with my mouth, and caped on end. no leaks that I can tell. and no obstructions. Every oil passage in the engine looks clean. no leaks anywhere. 

 

Any suggestions are much appreciated, no suggestion is a bad suggestion, idea's, oil diagrams, clymer manual pdfs? 

 

Please help. This bike is driving me crazy!

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My recently acquired 99 DR350SE would run for about 30 seconds then die.

Engine was blowing fluid through crankcase breather hose into airbox and flooding the carbs.

Problem was caused by the petcock steadily dripping fuel which eventually found its way into the engine oil. When I drained the oil there was a full gallon of fluid in there (over twice the normal volume).

Fixing the petcock fixed the problem.

This is just an FYI for current readers of an old topic. Thought it might be helpful to someone.

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Hey, I'm having a similar issue with my 91 DR 350.

 

So here's the story. I bought a 91 dr 350 with just over 4k miles for 600$ score!. It had been sitting and didn't run when I bought it. I cleaned the carb, starts and runs fine. Before I even brought her out of the garage I emptied the clean looking oil out the case and frame, checked the filter and it seems very clean too. Then proceeded to not follow directions and put in about 2.5 liters of oil. Started it up oil and smoke everywhere; airbox, exhaust etc... Ran it for a minute and decided to read TT forums. Drained oil, replaced with 1700ML as specified.

 

About bike: running petcock on prime, bypassed diaphragm system. vacuum vent on carb plugged, using 10W40 castrol MC oil. 

 

Here's where I'm stuck. 

 

Started fresh with 1700 CC's of oil. Ran it for a couple minutes at idle burned off the oil that had gotten into the combustion chamber. Result- no dipstick reading. 

Ran it up and down a big hill for 2 minutes at high rpms, let idle for 2 minutes and shut off engine, still no dipstick reading.

Put in another 100CC of oil in the frame, ran it up and down the street a few times, let it sit and idle for 2 minutes, shut off -still no dipstick reading.

Added another 100 CC's of oil, ran 5 minutes, idled for 2 - STILL NO READING 

Another 100CC's totalling 2 full Liters, ran for 5min at high rpms, idled for 2- Still no reading! 

Added another 100CC's(2.1L total), started smoking out the exhaust again, and shut it off.

 

Drained oil and put in 1700cc again, ran the bike HARD for 5-10 Minutes, let it sit and idle but it died after about a minute of running. checked the dipstick and Still NO READING!!!!!

put in another 150 CC totalling 1850 Ran HARD, idled. NOTHING!

 

Right after running with 1850 cc I took off the frame plug and like 2 drops of oil came out. let it run with no frame plug for a second and little spurts of 1-2cc with air were being sprayed out.

 

 

I took off the banjo bolt to the line that feeds back into the frame at the frame and kicked it over with the decomp lever depressed and it spurts out oil. And took off the oil filter and did the same, I saw oil drawn up. 

Then I have proceeded to remove ALL the oil lines except the one from the valve cover to airbox and the case to the airbox. I blew through them with my mouth, and caped on end. no leaks that I can tell. and no obstructions. Every oil passage in the engine looks clean. no leaks anywhere. 

 

Any suggestions are much appreciated, no suggestion is a bad suggestion, idea's, oil diagrams, clymer manual pdfs? 

 

Please help. This bike is driving me crazy!

why would you run on prime & bypass the vacuum port?

when you check the oil, are you straddling the bike so that its upright?

also, insert the stick without threading in.

if no reading on dipstick, pull the case bolt to check for case oil level.

i dont know about 1700 anything, i always put in 2.0 quarts.

i always check the oil with motor hot from riding, about a minute or 2 after killing it.

Edited by plugeye

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