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Post by Bozzy on Sept 24, 2014 2:05:41 GMT 1
Just wondered has anyone fitted them on a ypvs. Just wondered what effect it has?. Trying to sort current issue of bogging motor 5-6k after sustained high revs and then trying to ride through. Its fine when pottering about then giving it a hand full...its just when high revs drops down to say 4k behind car then change down to overtake and it splutters reving through. After that it fine again as though its getting too much fuel. No idea why its started this crap again.... might be temperture?
other ideas lightened flywheel and perhap another set of reeds as the yamaha racing reeds I have do sit flush and seal small gap not sure if this could be a cause. Was thinking stator but motor is ace everywere else.
Hope I am not chasing a non problem. Anyone with a K31 with aftermarket pipes would be interested to know if the same characteristics as I explianed above.
Bossy
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Post by midlifecrisisrd on Sept 24, 2014 8:33:19 GMT 1
You ain't got microns have you?
Try dropping the needle and see if it improves
Steve
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Post by Bozzy on Sept 24, 2014 21:05:38 GMT 1
No kennys just sure it's getting worse. When I got it on the dyno when I posted up here was advised to just jet up one as it was on the min at 4 to 6k which happened to be where this bad running is so it could be running a little rich. Trying to find out when temps drops dies the air get thicker and leans out or richen mixture? Just found the dyno chart it is showing the issue at 5.5 on the chart!  |
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Post by midlifecrisisrd on Sept 24, 2014 21:16:25 GMT 1
Colder air will lean out the mixture
Steve
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Post by Bozzy on Sept 24, 2014 21:46:16 GMT 1
I wonder if it actually running too lean.... Nearly went the wrong way before dyno ... Trying work out then based on thus why is this dip worse on the roadwhen coming down from high revs and accelerating through than when riding at low rev for a bit and it goes through really smooth.... Is that chart telling me it's rich upto 4.5k could this he it's running too lean and from high revs and cleared out its weak......most likely I am talking crap
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Post by bare on Sept 25, 2014 2:57:33 GMT 1
IMO Old Mikunis tend to stick their slides, when aged, as any in a Yama 350 Must be :-)
Mikunis need a Thorough Rebuild.. Every! year to help with this.
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Post by marsbar350 on Sept 25, 2014 10:09:57 GMT 1
have a look at my dyno graph aint much different than yours at 5k my stutter has gone  could it be something other than carb related  on the dyno sheet red was before and blue after  |
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Post by tsa on Sept 25, 2014 13:11:52 GMT 1
Id say drop the needle 1 clip and go up 1 more on the mains and try it. That is a rich dip at that point and its probably when he whacked the trottle open to fast and it ran really lean and was playing catchup on the dyno. Tell Kev to hold it at that point with the loaded drum and see if its still rich.
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Post by JOHN-DYNOSTAR on Sept 25, 2014 13:46:59 GMT 1
jetting up will make the problem worse I think. lower the needle one clip .
make sure you ride on the road and see how the bike cruises at 5k before and after doing any mods though. This
should indicate you are going the right way
edit; looking at the graph again you a/f goes from one extreme to another in the needle range which sort of indicates wrong shaped needles. but I could be wrong.
thinking about this some more .if you are paranoid about the bike running lean and doing Damage to the motor, you could lift the needle another clip and see if it makes your problem worse. you then at least know you are on he right track and if you need to go to the dyno again it will save you some time and money :-) |
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Post by Bozzy on Sept 25, 2014 21:54:27 GMT 1
Thank for advice. Think plan is I will remove carbs and just clean carbs out with carb cleaner to start as they gave not been apart for a good year.
I forgot to add I went up one jet after this run advised on here so it's running richer that this dyno result expect I could get away with dropping needle one notch. Worry is going the wrong way again nearly did first time until dyno.
If that stutter was all the time through the revs I would understand it only pops from low rev use through that part. But from sustained high revs down to 4 then open up it really splutters bad, let it rev through shoots off clean 6 to 10. If I then ride about at say 4 k for a bit it cleanly runs through.......bloody weird
Cannot work out if it's over fuel from high revs and chokes or it opposite and leaning out too much...if I feather the throttle I've. Don't give too much handful it feels and rounds better
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Post by 4l04ever on Sept 26, 2014 19:13:26 GMT 1
jetting up will make the problem worse I think. lower the needle one clip .
make sure you ride on the road and see how the bike cruises at 5k before and after doing any mods though. This
should indicate you are going the right way
edit; looking at the graph again you a/f goes from one extreme to another in the needle range which sort of indicates wrong shaped needles. but I could be wrong.
thinking about this some more .if you are paranoid about the bike running lean and doing Damage to the motor, you could lift the needle another clip and see if it makes your problem worse. you then at least know you are on he right track and if you need to go to the dyno again it will save you some time and money :-) Kev will have run the bike with full throttle in 4th gear on the power run, so the needle is not being used with that throttle setting. |
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Post by midlifecrisisrd on Sept 26, 2014 19:17:41 GMT 1
jetting up will make the problem worse I think. lower the needle one clip .
make sure you ride on the road and see how the bike cruises at 5k before and after doing any mods though. This
should indicate you are going the right way
edit; looking at the graph again you a/f goes from one extreme to another in the needle range which sort of indicates wrong shaped needles. but I could be wrong.
thinking about this some more .if you are paranoid about the bike running lean and doing Damage to the motor, you could lift the needle another clip and see if it makes your problem worse. you then at least know you are on he right track and if you need to go to the dyno again it will save you some time and money :-) Kev will have run the bike with full throttle in 4th gear on the power run, so the needle is not being used with that throttle setting. On a slightly different point you said he will have done the power run in 4th. Does this make a big difference as mine was done in 6th. They even did a run showing power against speed to show it was in top Steve |
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Post by JOHN-DYNOSTAR on Sept 27, 2014 9:05:15 GMT 1
The result would be the same in a different gear. It would just be a longer graph and possibly if there was a rich/lean area it would show up more, due to the extra load of the higher gear been used.
(:)unless he uses different load on the dyno for different gears of course ) |
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Post by midlifecrisisrd on Sept 27, 2014 10:13:37 GMT 1
The result would be the same in a different gear. It would just be a longer graph and possibly if there was a rich/lean area it would show up more, due to the extra load of the higher gear been used.
(:)unless he uses different load on the dyno for different gears of course ) Would it not affect the peak he due to the greater acceleration Steve |
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Post by JOHN-DYNOSTAR on Sept 27, 2014 10:42:42 GMT 1
The result would be the same in a different gear. It would just be a longer graph and possibly if there was a rich/lean area it would show up more, due to the extra load of the higher gear been used.
(:)unless he uses different load on the dyno for different gears of course ) Would it not affect the peak he due to the greater acceleration Steve marginally (possibly a couple of HP ) . that would depend on the dyno .(we have recorded 0.6 of a hp difference from 4th gear to 6th in one test on daves turbo bike.) the torque would definitely be different
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Post by Bozzy on Sept 27, 2014 22:39:41 GMT 1
Update-- removed carbs sprayed carb cleaner through jets and generally around carbs. . Put the boost bottle back on bike removing original and tried today.. Def improvement it still has a little pop/minor flat spot 5to 6 when coming down from high revs then revving through.....it also feels like it misses/hunts a little if I ride at the 5.5k spot....but it was way better today and was no way a problem like before... It's perfect everywhere else in the rev range
So not sure if it either 1) cleaned carbs 2) boost bottle 3) fact it was a little warmer today and not the cool wind as last ride....
Alternative is I never rev past 6k and it's 100% smooth but that would not be fun:-)
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Post by botty on Sept 27, 2014 23:20:05 GMT 1
It's the pipes Bossy. You really need to go back to standard.
I'll take the Kenny pipes off your hands. Just to help you out. LOL
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Post by gibba1008 on Sept 28, 2014 11:03:48 GMT 1
I have this same hole on mine, its made much worse once the carbs become even just a hair out of sinc..... if I lower the needle totally disappears but it then feels a tad weak. I rather have it a little rich even if the four stroking at 4.5-5k is a little annoying....
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Post by Bozzy on Oct 1, 2014 21:57:05 GMT 1
Thanks mate nice to know it's just knowing that it's not something going wrong you know what it's like I can now just ride it and not keep trying to find that spot... Perhaps it was better due to cleaning carbs out I and was not temp.
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