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Raptor petcock problem

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I tried to replace my stock petcock on my '04 DRZ400s with a Yamaha Raptor petcock after reading some post on this site. Didnt seem to work for me. 

Haven't been able to ride for health reasons for about 4 years. Decided it was time to get back in the saddle. After sitting for so long had to do a little maintenance first. Changed oil, coolant, pulled carb and cleaned jets, attempted to change petcock to a manual Yamaha Raptor petcock after reading a few post on this forum. After getting everything back together bike wouldn't start. Pulled carb again to see if I could find a problem. All looked good. Put back together and still wouldn't start. Checked spark plug which looked great and had good fire. Crank the heck out of bike and would not start. It would sputter a little and actually ran for a little bit a couple times but would die after a few seconds. Took Raptor petcock off and put old one back on and it started an ran just fine. Not sure what I did wrong with Raptor petcock. Seemed like a simple install. I blocked off the vacuum nipple on carb with 1/4" vacuum cap from auto parts store. Had a nice fairly straight line from new petcock to stock carb. Must have had some sort of vacuum issue with new petcock because bike seems to run fine when I took Raptor petcock off and reinstalled stock petcock (removed vacuum nipple plug and put vacuum line back on carb and original petcock).  Any Ideas where I went wrong. Don't want to use old stock petcock because the in-tank screen broke and I cant find a replacement screen. Apparently you can buy just about any part for the stock carb except for the screens. Whats up with that?  Any aftermarket replacements available? Was thinking since I cant get a replacement screen that I would put in an in-line filter. Any suggestion on a small in-line filter that I could use in place of the in-tank screen?

Edited by llbaker2
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The raptor petcock is a free flow .model, no vacuum required only gravity.  Did you verify flow before you removed it?

Edited by Melkor
Damn autocorrect

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Silly question, but was there anything wrong with the OE one in the first place? Make sure lever is in the right position. Easy enough to check fuel flow. As mentioned, it is not a vacuum actuated petcock, so it should flow when turned on.

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Did you try the raptor petcock with the gas cap removed? If the gas cap is not venting correctly it would stop free flow.

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6 hours ago, Melkor said:

The raptor petcock is a free flow .model, no vacuum required only gravity.  Did you verify flow before you removed it?

I am aware the raptor petcock is free flow and that vacuum is not required. Thats why I capped off the vacuum nipple on the carb.

The float bowel was full of gas. 

Edited by llbaker2
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5 hours ago, Bandit0 said:

Silly question, but was there anything wrong with the OE one in the first place? Make sure lever is in the right position. Easy enough to check fuel flow. As mentioned, it is not a vacuum actuated petcock, so it should flow when turned on.

Couple issues with stock petcock: as I said in post the in-tank screen filter was very brittle and broke off (ethanol gas i suppose) and I cant find a replacement screen. Also wanted to replace because Ive read they are prone to failure and can allow gas to drain into oil which could cause seizure. As far as fuel flow I opened the drain on float bowel and gas was pouring out so guess its getting gas. 

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3 hours ago, sbmon said:

Did you try the raptor petcock with the gas cap removed? If the gas cap is not venting correctly it would stop free flow.

Just got a brand new cap. Tried it with and without cap on. Good idea though. Thanks for comment. Would either petcock work, raptor or stock, if venting were the issue?

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Couple things:

 

A bad petcock will not fill the crankcase with fuel unless the needle valve and/or seat seal is gone.

 

If you are sure fuel is getting into the bowl, but it is not getting to the cylinder, check the float height.

 

Strange that one works and the other doesn't.

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23 minutes ago, Bandit0 said:

A bad petcock will not fill the crankcase with fuel unless the needle valve and/or seat seal is gone.

Not entirely true. One of the failure modes of the vacuum petcock is the diaphragm fails and fuel moves through the vent line, flooding the carb and then the crankcase.

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6 minutes ago, Gary in NJ said:

Not entirely true. One of the failure modes of the vacuum petcock is the diaphragm fails and fuel moves through the vent line, flooding the carb and then the crankcase.

True. I have only seen that once or twice, but it is possible. This is usually found by a rich condition as the vacuum will suck fuel into the intake. 

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Im still working on this. Waiting on parts. Thinking something else is going on. Ordered a carb rebuild kit plus a few other o-rings, jets etc. Gonna try replacing (rather than just cleaning) all jets and o-rings. One of the o-rings was in pretty bad shape. Hoping that bad o-ring is the problem.

 

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Dont know what else to do. Guess I will take my DRZ400s to the shop. As I said above I have been unable to ride for a few years so my DRZ has sat for quite a while. Got new battery. No surprise bike would not start. Would turn over and hit a few licks and that was bout it. Figured carb was gummed up so pulled it and took apart and cleaned all the jets, put it back together and still would not start. Ordered a rebuild kit pulled carb again and replaced the following:

 pilot jet (23)

 main air jet (24)

main jet (14), main jet holder (12) and o-ring (13), needle jet (11)

pilot adjustment screw (36) and o-ring (33)

Diaphragm (15)

O-ring (37) 

Needle valve assimbly (18) including o-ring

My first time rebuilding a carb. Made a few mistakes no doubt. The one I know of was I didn't know about counting the turns until bottoming out on pilot adjustment screw so set it at 3 1/2 turns per Clymer manual. I measured the float bowl height at 13mm from gasket surface to highest point on float. Checked the throttle sensor resistance which is a little off. Closed it was 6270 ohms, open it was 5020 ohms or 80% of closed value. Manual said should be 78%. Don't know but hope that's close enough. 

Put it all back together and it fired right up and ran for several min. Turned ignition off and then started it back up several times and seemed to run and start well. 

Decided to take it for a short test drive down my 1/4 mile long driveway. Got to the end and it died and would not start back up. Would turn over and run for a sec or two and then die. Had to push it back to the house. Noticed that it was trying to backfire a little when trying to start it. 

Heck I dont know my problem may not even be the carb. Im not much of a mechanic. Pulled the plug and it looks great and has spark. Guess thats no surprise since it ran for while. 

Dang thing has done this to me several times. Put everything back together and it fires up and runs. I think COOL I finally got it. Come back later and it wont start. Will run for a sec or two and then die. 

Guess I should mention I also put a raptor petcock on bike and added an inline fuel filter. At one point I thought the new petcock might be causing problems so switched back to original stock petcock. After doing so once again the bike fired right up and ran for several min. I thought COOL, I got it now! Went back out next morning and it wouldnt start. This seems to be a recurring theme. Many times after I reinstall the carb it seems to start and run but then an hour or so later or the next morning it wont start. 

So what did I do wrong? Could it be something else rather than the carb. Could it be timing related? Did I miss something with the carb? Im out of ideas. Guess I will take it to the stealership. 

 

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