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Vacuum hose isn't kinked but...

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So I have searched a while on the forum but I am having trouble finding a answer. I just recently install a fcr-mx on my 2007 drz-sm over the winter. I got to take it for its first ride yesterday and it ran great for about 20

minutes and then it started to act like it was out of gas. It stalled out and finally got it going by putting it on prime. So the first thing i do when i get home is search and find that the vacuum hose is probably kinked. So I shorted it up and made sure there wasn't any kinks in the line last night. Today I get to take it for a ride 3 minutes into the ride its dies. I put back on prime and

it runs great. I believe I have everything hooked up right. The vacuum comes

off the petcock to the nipple in the header the lower bolt with copper washer. The gas to the carb. The other hoses don't looked kinked either. So I guess my real question is whats the next step to solving my problem? The carb is brand new and jetted for the stock pipe. Any help would be great. Thanks

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its not the carb.

you need to confirm fuel flows fromt he petcok with the engine running in the ON or RES position.

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Confirm vacuum at the petcock. Put it on prime. Pull the vacuum hose off the petcock. Start the bike. Is there vacuum at the loose end of the hose? If so you probably need a petcock. If not the hose may be blocked, check at the nipple.

Edit-So I type slow.

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Thanks guys I will check that tomorrow. I wasn't sure how to check so now I know and will get on it. Thanks again you guys are so fast!

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I suspect the problem is in the petcock. Maybe the vacuum diaphragm is not opening the valve or maybe there is crap in the filter or a passage. Disconnect the vacuum hose and the fuel hose. Run a fuel hose into a catch can. Connect a long hose to the petcock vacuum nipple that you can suck on with your mouth (or a vacuum pump but mouth works fine)

PRI - good flow?

ON - No flow? suck, good flow or poor flow?

RES - No flow? suck, good flow or poor flow?

How does ON and RES flow compare to PRI?

When you suck, do you get any gas thru the vacuum hose? If yes the diaphragm is bad.

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When you suck, do you get any gas thru the vacuum hose? If yes the diaphragm is bad.

I believe there are two diaphragms mechanically connected together with a vented space inbetween. A failure of either diaphragm won't result in fuel being pulled into the intake through the vacuum hose.

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I believe there are two diaphragms mechanically connected together with a vented space inbetween. A failure of either diaphragm won't result in fuel being pulled into the intake through the vacuum hose.

it is possible and happens all the time.

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Ok so I was able to test the bike after work today. So this is

what I did exactly. I started the bike and let it warm up next,

I pulled the vacuum hose off with the petcok on prime and it died.

Then I did it with it on res and on it died also. Next I kept the vacuum hose off the petcock and started the bike. The bike wouldn't start unless I had it chocked it and held in the clutch. Once it was running with out choke i felt the hose there was a lot of vacuum with it on prime. I switched the petcock to on and the hose still had vacuum. Then to res and it still had vacuum. Finally I pulled the gas line off and put it in a bottle and sucked one the vacuum hose coming from the petcock. When I sucked on the line gas came out both with the gas on and in res. Prime had a free flow just putting it to prime. I hope this helps. Thanks for the support guys.

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I just did the test with vacuum hose hooked up and cranking the engine. When I hit the starter gas came out of the line with the petcock set to on. An it did the same when set to res. Is it possible I just had shit clogging the filter of my petcock?

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I will take it for a ride tomorrow and see how it does. It never really has a hard time starting or idling with it set to on or res. Just when I ride it does this become a problem. I was wondering, if the boot around the carb wasn't a great seal if it would mess with the vacuum? Thanks again for the help Eddie.

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Ive been riding like this for about a year.(pri on all the time) I just fig it was something wrong with the vacuum. I'll try these suggestions also but will this effect the soon to come frc install?

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If you have a problem with the vacum or the valves in the tank ,it won't go away by switching carb.

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Well I was able to put some miles on the bike and everything ran great. With the petcock set to on. The FCR really pulls I can't believe the difference for stock. So now that I have the hp bug I need to decide what to get next. Any suggestions would be great.

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I am having a very similar problem with my 2002 DRZ. I can start and ride the bike without problems. After 3 miles or so the bike boggs then dies. It takes a bit to get it started usually need to have the choke on. I ride it a few hundred more yards or so the same problem bogs, no throttle response and the bike eventually dies.

I set the petcock to RES (reserve) and the problem went away, at least for two short tests. When I put it back to ON the problem came back.

The vacuum hose looks fine. Can the petcock be clogged or defective? Why would reserve seem to work?

Craig

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It could be the on intake which is clogged.

If you look at the fiche of the petcock ,the res position has another inlet .

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