Juddering/spluttering between 6-8k rpm (Full Version)

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Juddering/spluttering between 6-8k rpm

  

kingo -> Juddering/spluttering between 6-8k rpm (5/13/2008 5:56:55 AM)

hi folks,
hopefully someone can help, I have an M reg 600f and have found over the past year between 6k-8k rpm it seems like there is a momentary fuel starvation or blockage. I've ran some radex through on 3 full tanks but still no joy- still juddering in any gear. For long periods of a ride I also cant get over 9k rpm either :(

Any ideas??

cheers

  
rrasco -> RE: Juddering/spluttering between 6-8k rpm (5/13/2008 7:22:24 AM)

Sounds like its bogging/choking then it picks back up at about 8K and takes off, right?  I have this same problem, but I do know my carbs and idle need to be adjusted.

kingo -> RE: Juddering/spluttering between 6-8k rpm (5/13/2008 7:53:49 AM)

yup, same issue...... hmmmmmmm

Gogar -> RE: Juddering/spluttering between 6-8k rpm (5/13/2008 8:05:36 AM)

It's possible your main jet size is a little too big. 6-8k rpm is the spot where the main jet comes into play, and when it starts pouring a little bit too much gas into the engine, you get that temporary bog and then it catches and continues to the top.

If your bike has Dynojet needles or something, it's also possible that the clips are a position or two too low, and the slide pulls the needle up out of the way of the main jet too early, and you're too rich in the beginning of the main jet curve.

Has the bike ever run right for you?


rrasco -> RE: Juddering/spluttering between 6-8k rpm (5/13/2008 9:07:26 AM)

I've always had minor bogging issues.  Nothing that makes it un-ridable, just normally better if you shift before 6K for commuting anyhow.  When you need it, just throttle up.

dalex -> RE: Juddering/spluttering between 6-8k rpm (5/13/2008 9:22:35 AM)

I used to have the same issue. Can't pinpoint exactly what fixed it but cleaning the carbs, re-adjusting the pilot screws, a small dose of seafom, blocking the brass tubes next to the intake boots on the carbs and blocking half of each air-intake holes on the frame completely eliminated the bugging. In my case, part of the issue was caused by main jets being too small (hence covering half the air-intake). I now have larger mainjets ready to be installed but will only replace them once I'm ready to do a sync as well.

I would start by cleaning the carbs and take a reading on your spark plugs as well. In the process you can see what jets/needles you have now. It will give you a better idea on which way to go from there.

kingo -> RE: Juddering/spluttering between 6-8k rpm (5/13/2008 5:20:20 PM)

WOW- thx guys..

Guess what I'm doing this weekend :)

I'll let you know how it goes :)

rrasco -> RE: Juddering/spluttering between 6-8k rpm (5/14/2008 7:11:39 AM)

Just to add, I was paying closer attention to when the boggin occurs and it seems to be about 5,500-6,000RPM.  A little smaller window than yours Kingo, but in the same range.

drakito -> RE: Juddering/spluttering between 6-8k rpm (5/22/2008 12:53:35 AM)

I had this as well, but a good cleaning, rejeting, and synching fixed it up nice. I also had it p-n-p at the same time, made for a fun ride. However it has started to come back lately. The tuning was done almost 9 years ago, so I'm sure something has slipped, degraded or fallen apart between now and then.

  

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