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Post by chops on Mar 31, 2013 10:54:13 GMT -5
After finally fixing my last problem which was a kinked fuel pipe I have now got another issue. The bike was running great an showed no sign of any issues but this morning I have come to start the bike and it won't! It will turn over and over put nothing. I've checked and cleaned the carb out,refilled with fresh fuel,checked for kinks,it's getting a good spark! So I then checked to see if the fuel was getting "sucked" thru the carb by emptying the fuel filter and then turning it over and there lies my problem. There is no vacuum!! The petcock is fine because I can manually suck on the pipe and get fuel to come thru the filter. So I've taken the vacuum manifold off and noticed that there is a rubber washer half hanging inside the intake.  Then I take the black plastic spacer out to check the rubber washer and notice that a chunk of the plastic has came off it around where the rubber sits (hard to photo)  Now.. What affect would this have on the bike? And what will have happens to the piece of plastic that is no longer there. Also what is this part called so I can purchase a replacement to see if that is the cause. Ps..the bike is a 2012 jonway italia 50cc 139qmb with 1120kms on clock. |
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Post by Deleted on Mar 31, 2013 11:18:54 GMT -5
I've heard some people call them spacers or insulators. I think that they're meant to insulate the intake from the heat off the head. You can find them most anywhere.
I'm not running with one right now without any problem, but I would suggest replacing it to be safe.
I always manually draw a vacuum to prime the carb if I've had the carb off too, it saves on starter and kicking effort.
I'm little surprised it didn't give you a troubles before, with rough idle/ erratic behavior.
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Post by chops on Mar 31, 2013 11:22:46 GMT -5
[replyingto=hypocycle]hypocycle[/replyingto]ive now sorted the pics.
im just worried that the piece of plastic that has came off has obviosly gone into the engine somewhere, i know that it isnt much and hopefully wouldnt cause to much problem to a metal piston but just need some clarification
thanks
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Post by gatekeeper on Mar 31, 2013 11:28:40 GMT -5
Most likely that little piece of plastic is long gone and won't be a problem.
Now your intake must have vibrated loose and allowed the rubber o-ring to unseat. That will cause enough of an air leak to cause you to loose your vacuum. Replace the spacer and o-ring, snug the intake down tight and that should solve your vacuum problem.
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Post by chops on Mar 31, 2013 11:32:32 GMT -5
thats good to know and thanks for your help and reply.
just sheer coincidence that it drove home from work perfectly ok the day before, then the morning after it wouldnt start!!
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Post by gatekeeper on Mar 31, 2013 11:48:34 GMT -5
Possibly because once things were warmed up they expanded enough to minimize any air leaks.
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Post by chops on Apr 3, 2013 5:11:07 GMT -5
ive fitted the new manifold spacer and i still cant get it to start!
ive now noticed that it will actualy pull the fuel thru if i disconect the fuel "in" line on the carb and crank the bike over, there s loads of fuel coming thru but when i connect that fuel line back to the carb and crank it over, there is no fuel flowing into the carb!
so i dont think its a vacuum problem or a petcock problem... surely it has to be ANOTHER carb issue?
ive had the carb off again and thoroughly cleaned it and blew compressed air thru all jets and holes but still it wont fire up!
what part of the carb should i be looking at that pulls the fuel thru or should i be also looking elswhere?
need help asap please
thanks
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Post by imnts2 on Apr 3, 2013 7:38:29 GMT -5
Frankly, you did a great job of troubleshooting and looking thing over. How many time have we gone nuts trying to figure out what wrong and failed to see obvious things. A l;ot of mechancis is really just lookng at everything carefully. Of course it helps to have some idea how it should look.
Good work
lefty2
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Post by chops on Apr 3, 2013 7:45:22 GMT -5
Thanks for the praise pal but that doesn't really help. Lol.
It's just typical that I'm off work this week and all the testing equipment and tools are at work.
I'm gonna try a compression test just to rule that side of things out then if thats ok it will have to be ANOTHER new carb.
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Post by gatekeeper on Apr 3, 2013 12:45:38 GMT -5
Yes, check for compression. Also to see if it is a fuel issue take off the vacuum line at the intake manifold and spray a little carb cleaner into the nipple. Replace the vacuum line and crank it over and see if it fires.
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Post by chops on Apr 3, 2013 12:50:36 GMT -5
It HAS to be a carb issue because the fuel will flow freely and fast when the fuel line is disconnected from the carb and the bike is cranked over. I can see the fuel flowing thru the inline fuel filter and out into my catchment bottle,but once I put the fuel pipe back onto the carb and crank it over then no fuel is being pulled theu the carb!
So is this simply a carb issue or could other things cause this problem?
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Post by gatekeeper on Apr 3, 2013 13:43:53 GMT -5
With everything hooked up and working properly at idle the fuel flow rate may be so slow that it will be hard to see. Is there fuel in the carb bowl?
Try spraying carb cleaner directly in the vacuum nipple on the intake manifold and see if it will fire.
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Post by chops on Apr 3, 2013 13:46:02 GMT -5
Will need to double check tomoz now. Battery died so is now on charge.
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Post by alleyoop on Apr 3, 2013 14:18:43 GMT -5
If the carb bowl is full you will not see fuel flowing through the fuel filter. When the carb bowl is full the Float shuts off the fuel inlet until some fuel is used and then the Float drops and allows more fuel to come in.
Alleyoop
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Post by chops on Apr 3, 2013 14:26:47 GMT -5
So assuming that the carb bowl IS filling up but it's still
Not firing,what else can I be looking at?
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..BAD TO THE BONE..