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weak idle
by: smtpajw - May 27, 2013 21:57:54 GMT -5
Post by smtpajw on May 27, 2013 21:57:54 GMT -5
Long story but I'll start from the beginning..
So i bought a roketa fiji 150 4-5 weeks ago, i drove it for about a week no problem. about 55mph top speed. So, i did an oil change and replaced the spark plug. Immediately started it up afterwards and its idling really rough, but i thought whatever and wrapped up for the night.
The following morning i start up to do a full test and its still idling rough. So its a little weak but runs fine on throttle. I get to WOT to about 52mph and then suddenly dies. Refuses to restart and when it diss, any throttle kills it. After digging around i found that the e.clip on the carb needle was broken. Fix that and it runs again. But now i have a few new issues.
Now when the scooter is started up any throttle will kill it unless i leave it idling for a few minutes. When its cold out it'll take multiple start ups to keep it from dieing.
From I'd say 15% to 30% throttle the engine will start to bog and lose power & rpms, but if i twist further it'll jump out of it and take off..
Maximum mph has dropped to anywhere between 45 to 50mph with WOT. Won't go over 7000rpms. While holding WOT you can kind of feel the bike hesitating almost like it pulls back real hard but then pushes again.
What could possibly cause such a change? Is the carb messed up? Could it be the spark plug? I've already tried messing with the idle adjust screw with no luck. Any ideas?
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weak idle
by: skuttadawg - May 28, 2013 1:09:43 GMT -5
Post by skuttadawg on May 28, 2013 1:09:43 GMT -5
Did it start with plug change ? What plug did you have and what is the new one ? Still have the old one to test ? When it is cold the choke should have the idle higher for a minute or so then the idle speed will lower . Did you adjust the idle when it was hot or at least warm ? Was the diagram torn ? I have had water in the gas from getting from a shady place rather than a trusted source while riding in the country . It ran just fine coming ho,e but the next day no start at all . I was mad since it was new and ran perfect so far . I called my scooter dealer to ask if they have heard of this happening to my model of scooter . He told me they had a scooter in the shop with the same issue as mine and it puzzled them . They drained the gas tank and bowl on the carb then refilled with good gas , and tada it started up as did mine after I did the same procedure
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weak idle
by: carpespasm - May 28, 2013 9:37:07 GMT -5
Post by carpespasm on May 28, 2013 9:37:07 GMT -5
Just tossing my 2 bits in, I had a scooter that had a similarly fluttery problem that just seemed to occur out of the blue and turned out to be a tight exhaust valve. The torn carb diaphragm does sound like a possible culprit, but if what skuttadawg suggested doesn't work maybe check the valves. Couldn't hoit.  |
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weak idle
by: jerseyboy - May 28, 2013 17:33:07 GMT -5
Post by jerseyboy on May 28, 2013 17:33:07 GMT -5
Do a plug chop,,sounds like its starving for fuel,,does it pop pop pop when you let the throttle off?
Try to go up a size on the main jet if your plug is light in color.
Good luck!!!
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weak idle
by: smtpajw - May 28, 2013 20:10:36 GMT -5
Post by smtpajw on May 28, 2013 20:10:36 GMT -5
Yes, it started with the plug change. Tried the old one and it still does.the same thing.
Not a fuel issue, gone through 5 tanks.
Diaphragm as far as i can tell has no holes. I've already looked while fixing the e clip.
Idle was adjusted while hot.
Engine pops/backfires only if i let go of the throttle instantly instead of slowly revving down..
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weak idle
by: alleyoop - May 28, 2013 20:36:09 GMT -5
Post by alleyoop on May 28, 2013 20:36:09 GMT -5
Since you were messing with the Carb CHECK the VACUUM hose going to the ACV valve on the throttle cable side you may not have connected the Vacuum hose to the ACV valve. Alleyoop  |
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weak idle
by: smtpajw - May 28, 2013 20:57:51 GMT -5
Post by smtpajw on May 28, 2013 20:57:51 GMT -5
everything on the carb is connected. A little hard to tell in this pic, but its there... Attachments:
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weak idle
by: alleyoop - May 28, 2013 21:28:17 GMT -5
Post by alleyoop on May 28, 2013 21:28:17 GMT -5
Yes the ACV VACUUM is connected. If it backfires when you let go of the throttle quickly it is running LEAN on De-celeration. Check for Leak or missing nuts on the Header Pipe where it connects to the motor, that is a common cause of backfires when you let go of the throttle quickly. Also if the idle is set to LOW, the butterfly covers almost all of the tiny fuel outlets when it closes and the cannot get enough fuel from the ACV.
Alleyoop
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weak idle
by: smtpajw - May 29, 2013 10:18:22 GMT -5
Post by smtpajw on May 29, 2013 10:18:22 GMT -5
Yes, there is an exhaust leak where the pipe connects to the motor. I have the round gasket in there between the motor and the pipe, so I'm not sure why it leaks.
As for idle, its set to be at about 1900rpm while hot
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weak idle
by: scootnwinn - May 29, 2013 11:10:47 GMT -5
Post by scootnwinn on May 29, 2013 11:10:47 GMT -5
If you installed a new clip on the needle there is a chance it is in the wrong slot. You seem to be a bit lean so try moving the clip down one slot. If that makes it worse move it up one slot from the original position. Get that exhaust leak fixed...
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weak idle
by: smtpajw - May 29, 2013 17:07:51 GMT -5
Post by smtpajw on May 29, 2013 17:07:51 GMT -5
As far as i can tell there is only 2 slots for the clip on the needle. I have it on the lower one.
As far as the exhaust leak, how would i fix it..? I have the gasket in place and the nuts are as.tight as they'll get..
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weak idle
by: smtpajw - May 31, 2013 19:20:44 GMT -5
Post by smtpajw on May 31, 2013 19:20:44 GMT -5
Any ideas on this?
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weak idle
by: alleyoop - May 31, 2013 19:32:18 GMT -5
Post by alleyoop on May 31, 2013 19:32:18 GMT -5
Usually what people do is put the gasket in the grove in the head and then put the flange on the studs and tighten one nut down then the other. That is the wrong way to do it , what happens is when you tighten on side down it pushs the gasket off to the other side and you will have a leak. You need to put the gasket in the grove and put the flange on and bring the nuts up evenly so the gasket gets smashed evenly and not get pushed off to one side.
So bring up the nuts up evenly then snuge each one like you would a head CRISS CROSS and not tighten one down then another etc..
That is your problem if it backfires when letting go of the throttle, if you ease off little by little if its not to bad it will not backfire, but a sudden closing of the throttle it will.
Alleyoop
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weak idle
by: smtpajw - May 31, 2013 19:44:09 GMT -5
Post by smtpajw on May 31, 2013 19:44:09 GMT -5
Yea, thats exactly what its doing... Guess I'll have to try and make some time and redo it. Last time i tried to take the pipe back off it was stuck on there pretty good..
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weak idle
by: alleyoop - May 31, 2013 19:56:57 GMT -5
Post by alleyoop on May 31, 2013 19:56:57 GMT -5
What helps do this correct is loosen the bolts holding the muffler so that you have a little play do it does not put pressure on the pipe. Then once you get the Flange on the motor tighten down you can then tighten the muffler down.
Alleyoop
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..BAD TO THE BONE..
