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DRZ dies after running for a few minutes

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My bike starts and then runs for about 3 minutes and then dies. 

Performed the electrical tests in the FAQ, 12.8 volts when off, running is 13.5 and does not increase at 3000rpm. (I have a tt vapor). The bike has the free power mod done by the PO. The problem is the battery was new when installed about a month ago, so I'm not sure it is that. 

When I was riding the bike died and then wouldn't restart for a hour or so on the trickle charger. Restarted, when for a ride and it was fine. Now tried to ride to work today and it died within 3 minutes again. 

Tonight I plan to check if the tank is flowing gas by checking for pressure in the tank, what else should I do? Should I replace the battery?

Edited by FreddieMan

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Do you by chance still have a vacuum operated petcock? This can cause gas to leak into the cylinder and eventually into the oil. Once the oil heads sufficiently the gasoline will vaporize and essentially flood the bike with gas.... causing it to cut out after a few minutes of run time.

Thoughts? 

JM

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6 minutes ago, obisod said:

Do you by chance still have a vacuum operated petcock? This can cause gas to leak into the cylinder and eventually into the oil. Once the oil heads sufficiently the gasoline will vaporize and essentially flood the bike with gas.... causing it to cut out after a few minutes of run time.

Thoughts? 

JM

The bike has the FCR41, shouldn't it just flood out the hose if it's overfilling? Would it flood the crankcase? 

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4 minutes ago, obisod said:

I would remove the gas line between the carb and petcock to confirm a leak first before speculating more. Easy check.

I will do that tonight, thanks for the suggestion. 

Edited by FreddieMan
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11 hours ago, FreddieMan said:

The bike has the FCR41, shouldn't it just flood out the hose if it's overfilling? Would it flood the crankcase? 

Not 100% on the FCR, but I had the same exact issues as you when I got my bike at first.

Mine was NOT a bad petcock, but a dry rotted needle seat in the carb. This was letting what gas was in the fuel line leak past the needle and seat, over flows the float bowl and contaminated the oil. Over time that small amount was enough to shut me down just like you describe.

If your at the point where it's dead after just a few mins and starts after she's cooled down a bit - pull your dip and take a good sniff. Should be able to smell the sweet sweet smell of 93 wafting from your oil fill hole/dip.

If so - trouble shoot petcock and needle seat. Mind you this was on my BSR36 so your mileage may very. Good luck man!

Edited by RC_ichard
Typo

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The FCR has a better design and any free flow should go out the drain tube and not in the motor or air filter like it can with the Mikuni so that shouldn't be an issue. However a petcock that isn't flowing consistantly will stall the motor after a couple minutes and maybe work ok one day but not the next. First step would be to confirm the petcock is good and always flowing when it should and with enough volume . Then would be to see how the needle and seat are in the carb . Good way to check is to take a screwdriver with you on a ride and when it dies , very quickly open the float bowl drain screw and see if full flow comes out and enough to know the bowl was indeed full.

 

.

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Hello everyone. Thanks for all the comments. The petcock is not leaking, I checked that.

HOWEVER, I changed the oil and it was very milky and smelled hardcore of gas. I'm thinking in the process of attaching the throttle cable/trying to get to run I got a lot of gas in the oil from the accelerator pump, that's my only theory at least. 

 

It hasn't died on me since I changed it. I never knew gas in the oil could cause it to die. I did know it was really bad for the bearings if the oil gets thin enough. Hopefully I'm okay there. 

 

The idle however is still really uneven, it keeps sounding like it's about to die then springs back up to over 2000. Still playing with the screw to figure that out. 

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You should check the float height . It can be too high and be flooding the motor out.

Gas shouldn't turn the oil milky , only water does that . Gas mixes in and just thins it out where water doesn't readily mix so turns greenish white/milky. If you start the motor and shut it down after only a couple minutes or miles/very short trips frequently without running long enough to burn off the condensates it will turn the oil milky. I had a motor that I built from a box of parts and had a transmission spacer mixed up so I had only ridden to work and home 3 miles each way without letting it heat up fully  , after just 3 days when I took the side cover off to swap spacers it was covered in milky white-green sludge already from those short runs an no run time at full temp. Now I let my bikes idle a bit longer and take longer routes routinely or piddle around just to get more time for them to be hot and evaporate that water. The gas could have gotten in there also as you said when trying to start repeatedly .

 

.

Edited by jjktmrider

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