Carbi problem

buzzawak · Post by **buzzawak** » Fri Sep 11, 2009 1:44 pm

See I told you the Yamaha Gods hate me.

I didn't notice it yesterday and I know I have read about the same problem in a thread some where.

Bike is starting and idling OK
Give it a bit of a rev and it only drops back down to 2k rpm
Adjust the throttle stop so its idling a 1k
Bit of a rev and again it only drops back to 2k
Occasionally is will drop back to 1k but seems to stick at 2k for a split second.

??????????

Post by **CMSMJ1** » Fri Sep 11, 2009 4:34 pm

Get a proper Honda... :scared:

Post by **Evilchicken0** » Fri Sep 11, 2009 6:12 pm

you've admitted to riding a honda ... so what do you expect ... the bike knows you are weak.

I think the adjuster wheel thing is worn so it's doing an either 2000 or 1000 rpm.
(Mine is usally at 1200 ish) when it fast idles try a little blip on the throttle. Just check the throttle returns to the stop and the cables go right back ... I think there's an adjuster there too

buzzawak · Post by **buzzawak** » Fri Sep 11, 2009 11:26 pm

CMSMJ1 wrote:Get a proper Honda...

buzzawak · Post by **buzzawak** » Fri Sep 11, 2009 11:43 pm

Evilchicken0 wrote:you've admitted to riding a honda ... so what do you expect ... the bike knows you are weak.

I think the adjuster wheel thing is worn so it's doing an either 2000 or 1000 rpm.
(Mine is usally at 1200 ish) when it fast idles try a little blip on the throttle. Just check the throttle returns to the stop and the cables go right back ... I think there's an adjuster there too

Hi Evil,
Its not the linkage, all fine there.
I wished I know more about how these carbies worked !
!

plodder · Post by **plodder** » Sat Sep 12, 2009 8:03 am

Either you've got a jammed butterfly or they are out of balance or it's lean

Post by **cagiva996** » Sat Sep 12, 2009 9:36 am

fluttering idle usually means an air leak somewhere in the intake be it airbox,carb rubbers or even a holed or loose downpipe.check that everything to do with carbs or airbox is tight and sealed that all carbs are sat in their rubbers(ooeer) and that the airbox is sat on the carbs properly.it may be a perished carb rubber allowing xtra air into the motor-give it a try!!

toosmooth · Post by **toosmooth** » Sat Sep 12, 2009 6:30 pm

it can also be a badly adjusted or knackered throttle cable - I've got the same issue on a little TTR125 of mine, if I adjust all the tension out of the cable then it has a mega low tickover but returns faithfully to tickover when revved.
If I adjust the cable to take up the slack and increase the tickover a tad, then it just revs and revs and dies down slowly. I am pretty sure I've stretched the cable (putting the bike in my estate car to get it home meant taking the throttle off the bars with it all in situ).
I'd rule out the cable before screwing up any settings on the carbs.

buzzawak · Post by **buzzawak** » Mon Sep 21, 2009 4:47 am

Ok the bike is now back on the road and better than before. It took a bit of reading, but now I have a good understanding on how these CV carbies work.

Remember I asked about the choke being very sensitive in another thread? Well this related to the current problem.

1) The starter enrichment valve is held in by two plastic barbs. I found that the plastic valve body would work its way out of the carbie by 1mm or 2mm which would open up the circuit, combined with the rubber seal around the valve shaft being worn and letting air to be drawn in. This caused the engine to run rich.

2) One of the needle valves wasn't seating properly causing higher that wanted fuel level, (but not flooding the carbi).

3) Poor connection on the primary input of the left coil.

Now all fixed (hopefully), I am a happy fizzer owner.

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