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Message started by Slowlane on 02/23/21 at 07:46:47

Title: Running 65mph...motor quit and wont start
Post by Slowlane on 02/23/21 at 07:46:47

2009 S40 1233miles.  I have been working on this bike for 3 solid months.  I have a clean gas tank, clean carb (3 times) clean non-eth gas.  It has been running perfectly for the last few weeks but yesterday after about 20 miles....I was doing 65mph and running beautifully and all of a sudden it just quits.  Wont start.  Plenty of battery.  So, loaded it on my truck and brought it home.  Tried to start several times but no fire.  Then some seemingly intermittent fireing but still not cranking.  Charged battery 13.3v and tried cranking again this am.  No crank, no fire.  The bike is practically new 1233miles and everything is stock except for a new battery and new Raptor (oem)petcock.  I stuck a clear tube on the bottom of the carb and loosened the drain screw and clean gas came flowing out.   Any help appreciated.  Thanks  Slowlane

Title: Re: Running 65mph...motor quit and wont start
Post by Gary_in_NJ on 02/23/21 at 08:14:21

You are going to have to take a systematic approach to trouble shooting this.

- Confirm spark. Remove the spark plug and ground the electrode to the engine case. Crank over the engine and observe a blue spark. If it is red or missing, you have an ignition problem (could be a fouled plug, a bad lead or a coil failure). Please advise.

- Confirm compression. The best method is a leak-down test because the results point to the potential problem for the loss of compression. But at this stage, a simple compression test is needed. Advise test results (psi).

- Confirm fuel flow. You checked the float bowl had fuel, good. But how much? Using that same tube measure the height of the fuel in the float bowl by getting the end of the hose above the carb and opening the drain. Advise the height of the fuel (or distance between the fuel height and the spot there the carb body and body meet).

- Confirm Air. Check the filter to ensure it is clean and not obstructing flow. Check the carb inlet boot for FOD.

Let us know what doesn't check out, and we can guide you through a remedy.

You mention that the engine doesn't crank. Check your battery connections to make sure they haven't come loose. Confirm there isn't any corrosion. Make sure the ground is secure to the engine case (towards the rear of the engine) and that the positive is tight at the starter solenoid. Also do know that a failure mode of a motorcycle battery with a cracked plate is to show normal voltage unloaded, however the voltage will go to zero under load. So check your voltage in a static condition and then while cranking (or attempting to) the engine over. This type of failure commonly turns the bike off like a switch and is difficult to identify unless you know what you are looking for. Now you know.

Also, while it may seem obvious - but sometimes it's not, make sure that the switch on the right control is in the "RUN" position.

Title: Re: Running 65mph...motor quit and wont start
Post by Slowlane on 02/23/21 at 08:53:10

Took off the seat and the rt side cover....shot some starting fluid in and it stumbled and stumbled and started and ran but it ran badly.  Backed off the throttle and it quit and smoked up the garage.....gotta be that f'ing carb again.  Thinking about getting Lancer's carb.

Title: Re: Running 65mph...motor quit and wont start
Post by Slowlane on 02/23/21 at 14:20:58

Gary...looped the clear tubing from the drain upward with drain screw open.  the fuel level stayed just about even with the bottom of the bowl.

Removed the plug and it was black and wet.  cleaned it....spark was regular and blue/white.

Title: Re: Running 65mph...motor quit and wont start
Post by Gary_in_NJ on 02/23/21 at 14:44:26

Do you still have the OEM petcock? Try it again with the fuel petcock set to prime.

Title: Re: Running 65mph...motor quit and wont start
Post by Slowlane on 02/23/21 at 15:01:18

Starting work on putting the oem petcock back in and running oem hose back to the vent.   The Yamaha Raptor I put in was barcoded from Yamaha via Amazon $44.00.

Got OEM petcock back in and the OEM vent hose.  Put it on Prime...checked the fuel level with the clear hose with drain screw open...same...comes right to the bottom of the bowl.   Bike cranks and runs now but really ragged...lot of black smoke and dies at idle.



Air filter clean and air box clean and dry.

Title: Re: Running 65mph...motor quit and wont start
Post by Gary_in_NJ on 02/23/21 at 17:21:00

Ok, good info. It would appear that the float height is not set at the correct height. The carb needn’t come off the bike to adjust the float height, but I find it much easier and precise to make the adjustment on a work bench. Read the FAQ in the technical section on adjusting the tab on the float and measuring with the carb at the right angle (the tab on the float should touch the needle valve, but not compress it). Once adjusted, perform the test with the clear tube again.

While you have the tank off, put that Raptor petcock back on.

Title: Re: Running 65mph...motor quit and wont start
Post by Slowlane on 02/23/21 at 17:27:26

Gary....It's gotta have something with the carb and I'll doo all those things tomorow or the next day.  I was doing 65 about 20 miles out on a pleasant ride when it was just like someone turned off the ignition.  Now after all these trys...It is running but very badly.  Thanks for hanging with me.  Slowlane

Title: Re: Running 65mph...motor quit and wont start
Post by Gary_in_NJ on 02/23/21 at 18:08:37

If the float is set such that the carb bowl doesn’t fill, you will consume all of the fuel especially at a large throttle opening to maintain cruise speed - and that will stop the engine. With that said, once the fuel refills the bowl the bike will usually start. This may not be THE problem, but it is one to correct.

Title: Re: Running 65mph...motor quit and wont start
Post by ckahleer on 02/23/21 at 19:14:04

Verify the kill switch is 100%
With the bike running, jiggle the switch a bit. Not enough to go to the off position, but within the on area.

Title: Re: Running 65mph...motor quit and wont start
Post by Dave on 02/24/21 at 04:53:18

Carb issues seldom show up "instantly" while the engine is running.  Most of the time a carb issue will onset gradually....with lean surges and erratic acceleration if the problem is a lack of fuel, and sluggishness and smoke if the issue is too much fuel.

You describe the issue as occurring quickly - and that sound more like an electrical or ignition issue to me.  Have you changed your spark plug?  Have you checked the battery voltage?

The kickstand safety switch is a known "problem child" - it is down where it gets a lot of water and grit thrown at it and when it fails it can cause problems (but generally only when the bike is in gear).  You can take the connector apart on the frame just above the drive pulley and put a jumper wire on the connector to bypass the switch and confirm it is not the cause of the problem.

Title: Re: Running 65mph...motor quit and wont start
Post by oldNslow on 02/24/21 at 07:22:06

Slowlane,

Take the float bowl off. See if either the main jet or the pilot jet are laying in the bottom of the bowl. If either of them came loose and fell out that could cause a "sudden" carb issue like what you are experiencing.

You said in your first post that you've cleaned the carb 3 times. Maybe the last time you did that  you didn't get one of the jets screwed in tight.

Title: Re: Running 65mph...motor quit and wont start
Post by justin_o_guy2 on 02/24/21 at 09:33:47

I use ether.

If It runs on ether,
Well, you get the idea

Title: Re: Running 65mph...motor quit and wont start
Post by Slowlane on 02/24/21 at 19:29:33

FOUND IT!!!  Pulled the carb and found a piece of Bounty paper towel stuck to the main jet.  Put it back together and it runs perfect.  Embarrassing to say the least.  Thank all of you.  Slowlanehttp://[img]https://i.postimg.cc/wMKQTw93/Bounty-1.jpg (https://postimg.cc/ftK98jth)[/img]

Title: Re: Running 65mph...motor quit and wont start
Post by Dave on 02/25/21 at 03:06:55

Sound like "The Quicker Picker Upper" was all that was necessary to slow you down!

I am surprised that the bike wouldn't idle normally - as it doesn't look like the pilot jet was blocked.

Title: Re: Running 65mph...motor quit and wont start
Post by LANCER on 02/25/21 at 04:51:44

Putting a paper towel inside the carb is a heck of a way to clean the passageways in the carb body ! [ch128540]

Title: Re: Running 65mph...motor quit and wont start
Post by Slowlane on 02/25/21 at 06:56:38


0D363B2C3D312A2C373F322D5E0 wrote:
Sound like "The Quicker Picker Upper" was all that was necessary to slow you down!

I am surprised that the bike wouldn't idle normally - as it doesn't look like the pilot jet was blocked.


Oh you sly fox you caught me.  It was embarrassing enough to find a piece of paper towel in there.  The idle jet just fell out in my hand too.  I think I must have blindly got my screwdriver blade on the outside of the jet and thought that it was tight.
Anyway, its running great now.  

Title: Re: Running 65mph...motor quit and wont start
Post by LANCER on 02/25/21 at 09:58:33

Eh, it happens.  [ch128526][ch127949]

Title: Re: Running 65mph...motor quit and wont start
Post by LANCER on 02/25/21 at 10:05:23

Always double check your jets.

Title: Re: Running 65mph...motor quit and wont start
Post by Dave on 02/25/21 at 13:34:09

Congratulations on your perseverance and success.

You stuck with it until you found the problem and it was resolved.

You are well on your way to becoming a good mechanic!

Title: Re: Running 65mph...motor quit and wont start
Post by justin_o_guy2 on 02/25/21 at 13:36:55

One thing for sure, you will Never sew up a patient with hemostats in his gut.

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