250 Big Red Choke problem

[ThinktwiceZ71]

I got a 85 big red 250 , runs good , no problems there , I did the cold start jet drilling and it starts a lot easier for sure. problem is , even before I did the cold jet drilling was if I used any choke at all it wont start , and if I do use the choke at all after it starts it just about dies immediately. what would cause this ? is something wrong with the choke circuit ? or maybe the cable ?

just looking for a place to start , cause usually a choke will richen it up a little bit and help it out some when cold , but my choke make it worse and kill it. ( and im talking any choke at all , not full or half):wondering

thanks a lot - Art

[barnett468]

does your carb have just a plunger or a butterfly plate in the carb for the choke.

if it has a plunger it is not a choke, meaning there is no butterfly in the carb venturi and it is simply a fuel enrichment circuit for starting.

are you saying it started fairly easy with no choke before and then you drilled the jet and it starts even easier now with no choke?

all bikes should either run bad or die if the choke is applied once the engine is warm like after 3 minutes.

[ThinktwiceZ71]

my carb has the plunger on the cable that is hooked to the handlebar (stock)

it didn't start worth a crap before I did the jet drilling , now it starts a lot easier

what im saying is that as soon as I fire it up within a few seconds if I put a little choke to it , it bogs it down like its gonna die , not idle it up like I thought it would do

[ThinktwiceZ71]

so , is my carb actually too rich ?

[dougspcs]

did you clean the carb while you're at it? blow it out with compressed air to ensure none of your drill filings settled into any internal ports?

my form answer these days is 'send it to Jim(FlyingW)..'

For a really reasonable fee he's make that carb work and look better than new!

I don't waste my time doing them anymore..

[ThinktwiceZ71]

I removed the starter jet , drilled it out of the carb , cleaned the carb and reinstalled the jet , I didn't drill it in the carb.

[tri again]

hmmmm....just to clarify, I've had that 85 es cold start on a couple machines.
The 'choke' is kinda magical when it works right.
Seems like it has the first bit of slide, say 1/4", and is nice to help it warm up but just for a minute or 2. Almost seems like a high idle effect.
When slid more left (on) they seem to have 2 clicks, one for full choke, say 1/2 and then that higher idle.
My favorite part is that they will actually turn themselves off if you take off and forget to turn the choke off.

As Barnett said, it's an enrichment circuit, the piston moves and a blunt needle allows gas or air or both.
Seems complicated to me and I'd love to see a colored flow chart but they work like a dream when they work right.
I wish I had some useful info more than another cleaning but that's what usually works.
I do agree, a little choke should do something other than kill it when warm.
Should make it run rough.
But you say it starts without? choke?
An obvious guess is that it's rich already and the enrichment is simply too much fuel.


How does it run?
What color is the plug?
After fighting with my first cold start ES for almost a year and buying another trike for winter, this topic fascinates me.

[Flyingw]

Great conversation guys. The choke valve has a needle on the end of it. When the choke is off, the needle sets in the hole at the bottom of the choke valve hole blocking the passage. When the choke is set to ON whether its half or full choke, the needle rises out of the hole unblocking the passage partially or fully allowing an extra amount of fuel for cold start. Under normal operation, the choke is set to full choke allowing for maximum enrichment but once the motor fires, the lever should be set to half for a couple of minutes or so until the motor has reached a warm condition then the choke should be placed back in the OFF position.

These QA series carbs don't use a traditional choke circuit but as Barnett said, its an enrichment circuit instead meaning the butterfly works independently of the choke circuit. There is a tiny hole forward of the butterfly in the venture and this is where the fuel comes from at idle when the butterfly is closed. With all this said, the one thing to need to check is the synchronization adjustment. This adjustment synchronizes the slide and butterfly so the actuate at the same time. Over time, the tab that is under the cable cover gets bent and the synchronization is off meaning the slide and butterfly don't move at the same time. This is a very important adjustment to make. Post #31 of my tutorial shows you how to do this adjustment. Check this and report back. When I do my operational check of the carbs, after the motor has fired even when cold, I throw the choke to full and the motor should stumble and die. This tells me the carb is being enriched and the choke circuit is working.

http://www.3wheelerworld.com/showthread.php/161746-ES-SX-350X-Carb-rebuild-Tutoral/page3

[ThinktwiceZ71]

Ok I will check that tommorow and report back , thanks a lot

[Big G]

Hey FlyingW, can this adjustment be done without taking the carb off?
I also have the cold start issue on my 85 ES, and now that winter's upon us it drives me bonkers to try and start the thing when cold. I was going to do the 'drill out the jet fix', but then I thought this might save me taking the carb off and muckin around with things if I can do this simple adjustment with the carb still on?

[ThinktwiceZ71]

This is how my 85 250es turned out , drilled it to .081 , it refused to start in the cold before . https://www.youtube.com/watch?v=80Ual_JKnXs&feature=youtube_gdata_player

It was 21 degrees today

[Flyingw]

Yes Big G, it can. Just be sure to back the idle knob all the way off so the slide and butterfly are all the way down and closed. Take the throttle cable off. If the tab is bent up, just bend it back down and adjust the split linkage then reset your idle.

[Flyingw]

It seems to idle pretty good.

[tri again]

This is how my 85 250es turned out , drilled it to .081 , it refused to start in the cold before . https://www.youtube.com/watch?v=80Ual_JKnXs&feature=youtube_gdata_player

It was 21 degrees today

.081 mm or thousandths?
I know there's a thread on this but I can never remember.
Sounds good but battery sounds ccccold.
Congratulations.

[Flyingw]

.081mm. I've been drilling them with a .080mm drill but its all good.

[tri again]

Before I heard about the cold start recall and bought another trike for winter,
I'd keep a spark plug on my woodstove so it would be HoT and put that in the 85es when I wanted to ride.
A lightbulb under the carb seemed safer than a hairdryer or I'd aim a hairdryer at the thing for a while.
I'd also get on the trike and rock it side to side as violently as I could to get some gas to slosh inside the carb.
Yesterday, it was minus 6F and I wish I knew how to post youtube....full choke and easily less than 1/2 second on the starter...off to half choke after 15 seconds, half choke for another 10-15 sec, then barely cracked for 1/2 min and then no choke and gentle idle for a few minutes to warm the oil before a ride.
They are soooooooooo nice when they work right.
Definitely worth the aggravation of r&r and smelling like gas for a day.

[barnett468]

I wish I knew how to post youtube.If you mean you want to know how to post a youtube link here you can just post the video on youtube, click on the video to view it then copy the url and paste it on the page here.

If you want to know how to download a video to youtube you can send me a pm or just ask any neighborhood kid that is around 8 years old or more.

That's what I do when I need help with a "smart" phone or computers etc., then I just pay them 5 bucks to not to tell anyone how stupid I am.

[ThinktwiceZ71]

182250182251ok im confused , If I take my digital caliper to .080mm , there isn't even a damn gap on in the thing , but .080 " looks right to me . does your "mm" mean mini micro , or milli meter ?

sorry if this is a dumb question , cause I drilled mine to .080" not .080mm and it runs a lot better and sure starts a lot better.

here are 2 pictures to see what I mean....one is set to .08mm , and one is set to .080 "


if im wrong , oops my bad

[ThinktwiceZ71]

another thing I noticed back to the choke problem.....I noticed my choke plunger doesn't have a oring on it , but my buddy's machine does and so does his parts plunger . would that cause my choke problem I am having ?

[Flyingw]

The 85 carbs did not have an oring. The 86/87 carbs did. Either will work in any of the carbs.

[Flyingw]

.080mm is correct. Yes it is a tiny hole. If you drilled it to .080in then the hole is WAY too big. This accounts for why the motor does what it does when you choke it. Send me your address and I'll send you a drilled startup jet.