nofacemonster

Thanks a lot for all your help friends. i think i got it fixed. Today in the morning i removed the carburetor. Change the slow jet back to 45 which is the standard according to the Japanese website i found. The previous owner of the bike has done some serious crappy adjustments to the carb in thought of increasing the fuel economy ( which never will work in my opinion ). He has changed the main jet from 162.5 to 102.5 which is really bad. So i don't have 162.5 and spare parts are not easily accessible in where i live. Even though i never had a problem with the main jet i changed it to what i had. 140 size, which is still much larger than the 102.5. The float settings were screwed up too. So i found these information in the Japanese website saying it should be 12.5mm ~ 13.5mm so i set it according to the website. Phew! now it runs way better than what it was. Idle seems 90% OK as far as i see. I ran about 5KM ride, slow and fast and checked the spark plug and color seems to be pretty ok. But i'll have to check it again after a at least 25 to 30km ride. So i am not 100% sure on that.

i have my SR 400 carburetor cleaned, slow jet was kind of too big, so i re-jet the carburetor with 40 Size pilot jet. I checked everything, the Needle was set to middle. Pilot screw is now set to 1 1/2 turns. Floater is properly adjusted so it won't overflow. Bike runs well, spark plug looks cleaner now. New air filter etc as well. I did all above because few reasons. 1.) Bad fuel economy, failed the green test (now passed) 2.) The IDL RPM goes up and down in a weird way and if i accelerate suddenly it stops, drop dead. Not a big issue while riding but i wanted to get rid of it. First problem i think is solved now because spark plug looks pretty good. Second problem still remains. I made a video for you so it will be really clear. The RPM goes up and down without doing anything with the throttle, and when i throttle suddenly it comes back down and stops. What causes this?. For your info * Pilot screw is 1 1/2 turns * New float needle ( So checked for any leaks, so far no ) * Pilot jet down from 45 - > 40 * Main jet is still what it was, 102.5 ( looks pretty small for a SR4 but i don't know the standard size * Carb is BST34 Mikuni * Exhaust wasn't there when i bought the bike, some stupid custom made pipe loud as hell, so i couldn't find the stock original exhaust. I added a honda GB500 Clubman exhaust. * air cleaner was shit, so i made one using air cleaner material, something similar to stock air filter. everything else seems pretty normal to me. please take a look at the video. http://youtu.be/xeysGZr5Z38

I believe it to be 1996. The problem is i never gotten any document regards to my bike with it. So it's very difficult to figure out which year etc. Most of the information on the internet regards to yamaha SR400 is in japanese, so that's another bad situation because finding it is the difficult part.

Hi everybody, i am from Sri lanka, a tropical island lost in the indian ocean. I currently ride a Yamaha SR 400, and in the process of getting it in to good shape. I hope ya'll doing great.....

Hi friends, i am in the process of getting my bike in good shape , i need the main & pilot jet sizes for my bikes carburetor. it has Mikuni BST34 (diaphragm Carburetor). I believe the model of my bike is somewhere in 90's to have this carburetor. If you guys know this, please let me know, i searched everywhere, finding a manual is not easy either . Also if you know correct float height settings let me know, thanks a million.