TOPIC:

After cleaning the BS34 for my 650, I tried them on the bike today, and got it to fire up, after a few minutes of trying. At first I couldn't keep it running, so I had to hold down on the starter, and choke it. She finally sparked a few and started running, but it popped, and popped, but the pops came from inside the carb. it smelt like the gas was not being burned all the way, like it was running really rich. Weird enough, they had no filters on them during the startup. I stopped the engine, and plugged in my colortune, and watched the flame, and saw that it was a yellow flame, with a few blue flames when it would pop. Then all of sudden it would start racing, up to about 5-6K and would not go down. These carbs are using stock jets, and exhaust. I ordered new jets, and needle jet spacer just incase put they are not in.

1. Does anyone know what the issue may be or where i can start searching for a problem?

C:\fakepath\BS34 Assembly.bmp

Make certain that the carbs have been assembled correctly as per diagram.

The mixture screws are Out (counter clockwise) Richer, In (clockwise) Leaner.

Make certain to adjust the idle screw so that a small crack of light is visible at the bottom of all four carb bores ( .5 mm ) Increase if necessary.

You must install the airbox/filters, in order to restore proper vacuum in the carb, and apropriate air mixture for starting. - The enrichener/choke only works the way it was intended to be assembled.

Good luck.

WOW. I'm nut sure why it did that...

Here:


Also... BS34's are really big for a 650. You may have some flat spots/slow speed issues with that big a carb. The colortune is an excellent tool, but your carbs need to be close to utilise it.

The colors you were getting seem to indicate multiple problems. It must be running with the choke closed. Make sure absolutely no air leaks and filter/s installed tight.

Also,as its running,spray the carb boots with carb cleaner..if the idle changes,means boot was effected by you working carbs...I had that problem with mine.Boots got hard and porus from old age ,and were letting in air,causing rich running..Took alot of curse words to figure what was up..

Your carbs will run lean if you try to start the bike without the air box or air filters. I thought your original post mentioned that the filters were not connected when you tried to start the bike.

yes i ran them without filter, i dont know what I was thinking, and also speaking of vacuum. You know there are vacuum ports on the carbs for the petcock. on one of the carbs there are two vacuum ports, and i dont know where it goes too so there is one leak there!

Darkangel wrote: yes i ran them without filter, i dont know what I was thinking, and also speaking of vacuum. You know there are vacuum ports on the carbs for the petcock. on one of the carbs there are two vacuum ports, and i dont know where it goes too so there is one leak there!

You can cap all your vacuum ports and turn your petcock to prime, or on (if it dont have prime), whichever flows gas freely.

Dont forget that there are supposed to be bowl vents to atmosphere.

Ok, I will buy some vacuum port covers, and try to seal those guys up. Now which is the bowl vent? Also my pods will be here soon, and i can throw them on the carbs. If that does not calm the carbs down, then I need to readjust the air mixture jet?

Darkangel wrote: Ok, I will buy some vacuum port covers, and try to seal those guys up. Now which is the bowl vent? Also my pods will be here soon, and i can throw them on the carbs. If that does not calm the carbs down, then I need to readjust the air mixture jet?

You can use just about anything that is airtight and fits as a vacuum caps.

Sorry, there are bowl vents, but they are inside the intake tract and you dont need to vent or cap them - so no worries.

The carbs should deffinately be checked for proper fuel height, and jet as close as possible before deciding to change the air jets. You should be able to get them running well as is.

Goodluck.

ok becuase I bout new jets as it was....but these weekend i will work on them...and see where i get.

Ok so last night i put the filters on, and I'll you this.
1. it has real trouble starting , and the plugs are not fouled up.
2. when she does run, if I hit the throttle, off turn of the choke she dies?

Finally i got her to run, and took her out riding a lil, and the same thing..when i hit the gas she died.
So i got her back home, and put on a needle jet spacer, and it ran better, but still real tough time starting. so I added another, and 100 mains, and the bike would not start at all..., i switched back to the stock jets, and still nothing?
Im at a loss for what to do. never had this much trouble with carbs

Any body?