Mikuni choke problem

twinrock101 · Post by **twinrock101** » Sun Apr 09, 2017 7:16 pm

I got another dt200 which runs a 28mm mikuni same as tzr250 2ma.. anyway when you pull the choke on when warm and the engine races..i have checked the o ring , is there anywhere else it could suck air..?

jools · Post by **jools** » Mon Apr 10, 2017 9:16 am

More information required:
You say the revs rise when you put the choke on when warm: at tickover only? or with throttle opened?
Have you tuned the pilot jet/tickover screws to get the mixture right at tickover? Have you pulled down and thoroughly cleaned the carb? Checked if it has standard jet sizes?
Is the slide worn? etc etc...

Post by **hybrid** » Mon Apr 10, 2017 10:20 am

My 500 does it since I put the PWK's on it.
I've never thought anything of it.

twinrock101 · Post by **twinrock101** » Tue Apr 11, 2017 8:43 am

I have checked carb and set it all back to stock settings..the bike had the snorkle removed from air box and holes drilled, not by me. So a bigger idle jet was needed.. i qlso replaced crank seals . I came across the issue as it was running lean on the pilot..when i pulled the choke on it made it worse.. i rejetted pilot so it idles nicely..but the choke still has the same issue. Apart from this the bike runs fine..have not checked WOT.. slide is worn but no more than anyother carb i have seen from the 80s and 90s..
The bike will be heading to live in canberra..much colder so the use of a choke will prob be needed..

James W. · Post by **James W.** » Sat Apr 15, 2017 12:23 pm

TR, you do know that the Mikuni 'choke' is not actually a 'choke' as such, it is an extra fuel feed circuit...
..so while needed for cold starting, once the bike is moving, it shouldn't be left on, as some 4T's require..

You could swap the screw-in plunger 'choke' unit - from another compatible carb to check comparative function...

twinrock101 · Post by **twinrock101** » Sat Apr 15, 2017 10:08 pm

Yeah i know how it works..and im not having it on while running/riding but i also know that once warm when the choke is pulled on..the extra fuel should flood the mix and will bog the engine..however..mine is having the opposite effect. Racing..i dont have a spare plunger either..ill keep digging..its just very lean at idle..i have replaced both crank seals and carb manifold as well as bigger pilot and checked float height

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