Sudden starting issues with 1990 DR350S

I just bought a 1990 DR350S 5 days ago with 10k miles on it. It's in great shape and the previous owner seemed very competent with bikes (he had several others and was offloading this one because he replaced it with a newer DR400). The problem is, this is my first motorcycle and I'm still trying to learn all about the engine and everything. He cold started it for me when I saw it and for the first 3 days I had no trouble doing the same. He showed me the trick I've read on here a few times with the whole "petcock set at "on," hold the decompression lever and give it a 5-10 warm up kicks, then full choke, slowly kick it until the lever pops back out, then give it a good kick and it fires up" ...that worked like a charm for my first 3 days and I was able to get out on the road and everything was running great, no hiccups or shifting issues or idle problems at all.

Now, yesterday and today, I have been having trouble getting it to fire up. I was able to get it up yesterday twice but it wouldn't idle and eventually stalled out and I couldn't get it again. Same thing once today, eventually stalling out. Now I can't get it at all. I tried a few roll starts and got close twice, but it never went (could be the wet driveway since it's been raining for 2 days straight).

I'm not super mechanically inclined, but I have a few resources I can talk to and ask for help, but I want to give them some direction so they aren't starting from scratch.

So, I've read (but don't know how to do it) cleaning the carb, spark plugs, throttle adjustments, etc.,(i saw that stuff here http://www.thumpertalk.com/forum/showthread.php?t=964093) but I don't get why it would change over 18 hours and I don't know if one of those are really the issue. My friend did stall the bike once, but it started up after that and then the next day I had trouble. I'm totally lost and really really anxious to get riding again since I'm now fully inspected and registered. Any pointers? Sorry for the long message... Thanks to everyone.

I just bought a 1990 DR350S 5 days ago with 10k miles on it. It's in great shape and the previous owner seemed very competent with bikes (he had several others and was offloading this one because he replaced it with a newer DR400). The problem is, this is my first motorcycle and I'm still trying to learn all about the engine and everything. He cold started it for me when I saw it and for the first 3 days I had no trouble doing the same. He showed me the trick I've read on here a few times with the whole "petcock set at "on," hold the decompression lever and give it a 5-10 warm up kicks, then full choke, slowly kick it until the lever pops back out, then give it a good kick and it fires up" ...that worked like a charm for my first 3 days and I was able to get out on the road and everything was running great, no hiccups or shifting issues or idle problems at all.

Now, yesterday and today, I have been having trouble getting it to fire up. I was able to get it up yesterday twice but it wouldn't idle and eventually stalled out and I couldn't get it again. Same thing once today, eventually stalling out. Now I can't get it at all. I tried a few roll starts and got close twice, but it never went (could be the wet driveway since it's been raining for 2 days straight).

I'm not super mechanically inclined, but I have a few resources I can talk to and ask for help, but I want to give them some direction so they aren't starting from scratch.

So, I've read (but don't know how to do it) cleaning the carb, spark plugs, throttle adjustments, etc.,(i saw that stuff here http://www.thumpertalk.com/forum/showthread.php?t=964093) but I don't get why it would change over 18 hours and I don't know if one of those are really the issue. My friend did stall the bike once, but it started up after that and then the next day I had trouble. I'm totally lost and really really anxious to get riding again since I'm now fully inspected and registered. Any pointers? Sorry for the long message... Thanks to everyone.

Captain Obvious here... how's the fuel level?

3 days sounds like just enough time to run out of gas... try it on RES or PRI.

Failing that, pull the plug and check for spark.

Thanks for the response, and I thought that was it after the first day, so I filled it up, so the gas isn't stale either. This morning I drained the float bowl and it refilled when I went to PRI so that was good. I'm going to check the plug after work today and maybe just replace it depending on how it looks.

If you have the original stock petcock, it may be shot:

http://dr350.wikia.com/wiki/Vacuum_petcock

Check the two hoses from the petcock to the carb, one is the fuel line, the other is the vacuum line.

Both hoses are good, and I guess it could be the petcock, even though PRI worked well to refill the float, maybe the ON setting is actually leaking through. So if I drain the float and then leave it at ON without trying to start it and I check the release later and there is gas there, then I have an issue. Is that right? Strange though since it was working the day before just fine...

Also, I've seen that the '01-'05 Yamaha Raptor 660 petcocks are a suitable replacement for my 1990 DR350S. Can anyone confirm that? I found one for a decent price if that's the route I end up having to go.

The Raptor 660 petcock works great with the stock tank. ON/OFF/RESERVE .... no more vacuum crap to worry about.

Be sure to check your oil level properly so you're certain it's not overfilled because of gasoline leaking from the vacuum line into the cylinder then to the crank case. :smirk:

Strange though since it was working the day before just fine...

Probably just about everyone here with a vacuum petcock has had a problem with it. It's hard to tell when it will go bad, maybe three days ago, maybe next year. It does seem strange, but it is known to happen.

Be sure to check your oil level properly so you're certain it's not overfilled because of gasoline leaking from the vacuum line into the cylinder then to the crank case. :smirk:

:smirk:

I would go one step further and drain/change the oil. If it's watery and/or smells of gas, you have a problem. Also, you have no idea how well the PO maintained the bike. When did he last change the oil? Oil and a new filter is cheap insurance. You might invest in a magnetic drain plug while you are at it. I have the one from ProCycle:

http://www.procycle.us/bikepages/dr350.html

Report back what you find, it will help others.

So as it turns out it was the tube running from the petcock to the carb. I'm not totally sure what was wrong with it and I couldn't find a complete leak or crack in it, so I'm guessing it was just that it didn't really fit well so the vacuum wasn't strong. Replaced it and it roared right up and I haven't had any issues since. Thanks for the replies, hope no one else gets stumped by something so simple.

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