Bottom end dead spot

[skiracer]

Hey Ted,
Here is a brief history of the last couple of months; The bike was running great with the standard 36 mm Bing.  I went to a 36 mm Mikuni for better response on the bottom end.  After some small jetting refinements, the bike was running great until I noticed the main seal on the mag side was leaking.  I changed the seal, and the bike sat for almost a month while I rode my modern 200 in a couple of enduros.  I went out to get the bike prepared for the ISDTRR, and discovered the "new" problem of the dead spot on the very bottom end.  Raising the neddle all the was has helped out a lot, but I am not there yet.  I am going to check the size of the neddle jet today so I know what size I need.  Now, I am not sure how the numbering works on the neddle jets; do I go with a larger number for richer, or a smaller number?  Thanks for your help!  James

quote:Originally posted by t20sl

Did it ever run fine?  Reread your answer and still not clear.  Was changing seal trying to fix the dead spot or did it run ok before seal change?  If it never ran fine then go with larger slow (pilot jet) first.  Don't change main.  Main effects 1/2 throttle barely and really doesn't have major effect until 3/4 to full.  Pilot effects idle transtion to 1/4.
If my memory serves me correct I read somewhere you can remove needle completely from a Mikuni and it should start and take a little throttle.  If it doesn't and falls flat (lean) then go with bigger slow jet.  Then reinstall needle.  I have never tried that method tjhough.  Ted

[skiracer]

Okay, here are my jetting sizes on the carb.

Neddle jet:   159  Q-5
Main jet:     290
Pilot jet:     30

So, if I need to make the bike richer with the neddle jet, do I get a larger number from the "159?"  And, what does the "Q-5" stand for?

Thanks, James

[Lew Mayer]

I believe the Q-5 is the jet size. I'll have to dig out an old book to see whats richer.

Q-6 is the next richest needle jet I see listed in my book.

Lew Mayer

[skiracer]

Hey Lew,

If the "Q" number is the sizing number, what is the "159?"  Is that part of the model type?  Thanks for your help.  James

quote:Originally posted by Lew Mayer

I believe the Q-5 is the jet size. I'll have to dig out an old book to see whats richer.

Q-6 is the next richest needle jet I see listed in my book.

Lew Mayer