big red runs, kinda

[BigReds Forever]

I found parts to fix the carb this morning and got the red running again. Only problem is with jetting, wasnt sure if i should post this in the jetting sticky or not, but hear it goes. Well, it starts really hard cold but its always done that. Once it warms up it runs pretty good. Only problem is that if you stab the throttle really hard it dies out. Is that normal, i havent been able to drive it around and try it under load cus doesnt have tires on it. Will it quit that when im actually take it out and drive it or do i need to adjust something. Its stock except an aftermarket exhaust, it has a larger head pipe but i dont think the mufferler flows anymore. The carb is set up stock with the pilot out 3 rounds. thinking mabey a biger main or moving the clip down a notch, what do you guys think?

[bigreddaddy]

Only problem is that if you stab the throttle really hard it dies out.


When you stab the throttle do you just do it for a second and let off or do you keep holding it at full throttle?
What parts did you get to fix your carb? What was wrong with the carb?

[BigReds Forever]

i took it appart to rebuild it becaues it sat forever with gas in it. While i was cleaning it a screw head striped out and the drain tube broke out of the float bowl, i got a new screw and some 1/8" brass to fix it. When i stab it, if i hold it, it will accutaly die, if i just hit it and let off it will stutter and return to idle.

[chris200x]

Hard starting and bogging usually can be cured by going up a size or two on the slow jet.

I added a K&N air filter and a supertrapp exhuast to my 250sx (250ES BR has the same motor) I ended up having to go up one size on both the slow and main jet and also had to lower the clip on the needle one notch.

This may helpful to you... but i see your in Minnesota... which is most likely alot colder and higher in elevation.

[bigreddaddy]

Have you checked your plug after running it? Is it black? Do you have a clean air filter?

[traxxasx]

My best bet is you installed a clogged jet. You have 2 jets one for idle 25% throttle(little jet) Then you have the main jet 75%throttle. Take your carb appart Take out both jets blow threw both so no gas in them (if you can even blow threw them) now hold them both to the light. You should be able to see a tiny tiny bit of light threw them if you can there good, if you cant its clogged. Best thing ive dont to unclog jets are some carb cleaner and one single strand from a bike brake or throttle line, you get the idea i hope.

[TravEX]

Will it still stutter and die if you took the air box lid off? If so, your jetting is rich (with lid on). Up a pilot is always a good idea for winter temps, and out 1/2 on screw.

Travis

[BigReds Forever]

Ive rebuilt many carbs, none of the jets are cloged. Air filter is good but i havent tried it without the airbox lid. Ill do that today and get back to you. Already turned the pilot screw out .5 for a total of 3. What do you guys think about up a size of slow jet?

[BigReds Forever]

its an '85 250

[chris200x]

Yeah, that's the same carb as I have on my SX. Try the bigger pilot and see if that helps. You have a stock air filer as well?

Sometimes these BR's ans SX can be a pain in the rear to get started when it's cold. I know my buddy huffa's SX is hard to start if it's been sitting a while. Bigger jets should help....

[conig]

i have had the same issue for almost two years now. i have rebuilt the carfb several times and I can still not figure this out. im subscribing hoping you figure something out, I think its a cam chain issue as I have some tapping. ive gone up and down on jets drastically no air box, air box etc. plug actually tends to look ok, ive also changed heat ranges several times.

hopefully this will give you some idea's/ help.

[BigReds Forever]

thanks for your input but im pretty sure mine has issues due to jetting. Ive just recently been through the topend, clutches ect on this thing and it is still having issues (rebuild was for other reasons) One thing i do know is that the 85's had lots of cold start issues, infact honda changed small things on the carb 3 times throughtout the 85 model, and then in 86 added something called a "starter" jet. Not sure exactly what it does but i would guess it ritchens the mix when starting. They also came out with a "cold start kit" which is basicaly a different vent tube configuration (I have done this) didnt seam to do much. I gonna try the pilot and slow jet and ill let you guys know what happens.

[TravEX]

What is the different vent tube configuration? I have re-done all my tubes and hoses. This next weekend will tell me how it starts in cold weather, supposed to get down to 20 degrees. I've started it in 30 degree weather easily. I expected that the 'cold start' kit was just a richer pilot.

[conig]

please let me know what you find, if I don't figure this out soon, I will most likly sell the bike. in parts or not, which I hate to do as ive owned it since new.

[BigReds Forever]

Im not sure exactly what this does but i have an original honda microfiltch and this is what it shows. Its hard to describe so i drew it. If anyone has more info on this let me know.

picture is from the front, black is vent lines, red is T's, i couldnt find the fancy T that honda used so i just used 2 of them as shown to the right.

[TravEX]

I'll try to get pics of what I did on mine. Maybe this afternoon.

[conig]

is that routing important, as thats what is not correct with mine. ive moddied all those lines with check valves(installed correctly) or snorkels for water protection.

[chris200x]

is that routing important, as thats what is not correct with mine. ive moddied all those lines with check valves(installed correctly) or snorkels for water protection.

What are these check valves you speak of? Is there something to put on the vent hoses to let air out but not let water in? :idea: Where can these be bought?
got pics?

[TravEX]

On mine, I got a 5 way plastic "T" for 3/16" vacuum lines. I ran the 2 float overflow hoses, and the bowl drain hose the the "T" that I placed behind the carb. I hooked those 3 lines up, then ran a hose up to under the tank by the intake holes in the frame, and ran another down under the frame by the crankcase breather tube. So the carb is always 'vented' or 'drained' if needed. I also put a 1 way valve (off a 300 fourtrax) on the drain tube, so no water can come up the tube, only drain out. I got this idea from the crankcase breather hose, it's runs up and down, to vent or drain, whichever is needed. I'm gonna run long hoses up from the crankcase breather when ever I can get the hose (what size is it?), either that or put a PCV valve on top and bottom of the hose to keep water out.

Mine starts great in cold weather, started right up on a 28 degree morning after I trailored it at 65 mph for 35 miles. Started the best out of everything in my sig.

Travis

[mike84bigred]

My machine did that to. Once i got the carb. jetted and cleaned out, its been flawless. no hesitation or bogging out at all. it will kinda crappy until it warms up tho.. depending on the temp., mine could take up to 15 min. to finally run perfect.