Well the story continues... cleaned out the carbs today and got the bike running. It started right up once it got some gas, which I was very happy to see -so definitely making progress.

However, I never did get it up to temp as it started tospew gas from the breather/overflow pipes on the 1&2 carbs.I had hoped that the stuck float needle that I had came across when cleaning this afternoon was going to address that issue- not so lucky. Hoping that 'll have time tomorrow morning to get back at it,check to see if the valve is stuck on one of those two carbs again or if any of thefloatshave gas in them - I tested them earlier to see that they floated (as was suggested), but maybe I should have left them sit for a while before concluding they were good (appearance looks very good as well).

The other thing I wanted to do earlier but just wasn't understanding,was how to take the measurement and set the float heights. I've read the procedure, it's justnot clear to me - seems like you need three hands to do it... Is it difficult to set ? Maybe it'll come to me tomorrow.

Thanks for all of the help,

 

Like I said, my first guess is a crack in one of your floats. If you did the "bowl of gas" thing, you should have seen both sides of each float would, well, "float." You should be able to tell right away. My bad one sunk right to the bottom instantly. Just one side of it, but that's enough to make it not work.

Next, you should try to make sure that the flat tab on the float is smooth and clean. You could even scotch-brite or fine sand the top of the tab so the little wire for the float needle slides smoothly on it. Also clean the sides of the float-needle and the needle-seat (the part it slides into) really well, because maybe the float-needle is sticking in there.

Next? Take off all 4 float bowls, and leave everything else in there and assembled. If you hold the whole carb assembly in the air so the floats are "hanging" in mid-air, you shouild be able to move it around and see all 4 floats move smoothly and seat in the carb. If some of them are sticky or hang even when they should fall up into the carb, maybe more cleaning.

If that goes well, then get a small length of fuel hose (Not entirely necessary,) and hook it where you would hook the gas line up in the middle of the assembly. Do the "tip the carb" trick and blow into the hose (not too hard) at the same time. When all 4 floats "seat" into the carb assembly, you shouldn't be able to hear ANY AIR AT ALL leaking through the float needles and seats. If so - you guessed it - more cleaning, mostly on the black ends of the float needles.

If your float needles aren't seating perfect, you can buy new ones (maybe $20 each, inclides the washer, new needle, wire-spring,seat, and the little plastic filter that's under the seat).

You can also find a drill bit that has the same profile of the end of the float needle and put it in the needle-seat and turn it VERY LIGHTLY to de-burr and clean the seat.

Again, you're having the exact same problem I did and I'm just so happy I got it to work that just want to share.

 

FLOAT HEIGHT:

Float height is the amount the float travels into the bowl before the float needle becomes unseated. Or, when it's on the bike, the amount of gas that gets into the bowl before the needle closes and cuts off the gas. Same thing.

Anyway, a "two hands" way I found to check float height is so: Hold the carb upside down so the needle is seated. Get a tiny screwdriver or something and hold the needle in it's seat with some light pressure. Then tilt the carb so the float moves as far as it can out of the body of the carb. The "float height" is the distance from the flat outer surface of the carb to the very bottom of the float, and should be 8mm if you have a 87-89, 9mm on a '90. The OEM floats I bought came at 9mm, and IMO that's fine, but whatever.

If your height is off, you need to bend the little tab on the float VERY SLIGHTLY in the right direction to make it better. Unless someone really messed with it, it's probably fine.

If the little tab is in a parallel plane to the plastic of the float, it's probably really close.

 

I think your right that one of thefloat needles isnot working smoothly - likely the one that I foundoriginallystuck.I did clean it and when re-assembling, play with a bit because It seemed to get hung-up in the seat bore when hangin the float, so I cleaned it a bit more... I guess I didn't do a good job I did float tests, but I did them in water (I'll redo them since the density is different) - I reread your post afterwards and realized that I goofed up there... but the floats look in really good shape.

The float tabs were all nice and shiny and straight, so I didn't mess with them thinking that they most likely were ok. I'll try-out your procedure for measuring the height - think I've got it.

Anyhow, the good think is that I now know how take the carbs off and apart... and after a few more times will be quite proficient Off to go get some more carb cleaner.

Thanks for your help Gogar,

 

Cool.

Yeah, water doesn't count.

 

Success!I spent some time cleaning the float needlesagain, but I have to chalk it up to the float heights, they were way off on 3 of the 4 (like 40-50 degrees).Ran it for quite some time and no more puking outgas - sounds fierce! It was idling high though (2k). I'll have to read up on that and sync'ing the carbs and look at ordering a tool -what's a good buy?

Next-up, check the antifreeze and test the rad fan. The fan hadn'tkicked in whenIhad it running and it was getting into mid scale on the temperature gauge.. might be ok, but better check.I'd also like to run a bit of gas with some carb cleaner through itto help clean out the carb internals a bit better (the bike had sat all of last year from what I was told).. And I guess, I better then get some gas stabilizer for the winter so I'm not having to tear it apart again in the spring.

Thanks again,
Jaime

 

I have a thread called "synced my carbs" or something where I bough a Motion Pro Mercury tool for like $65. It was pretty easy and fun.

https://cbrforum.com/m_426441/tm.htm

Congratulations! It's really cool the first time you hear it and it sounds good.

I don't think the fan will turn on until you get waaaay up almost to the H. Mine's never turned on. You can check to see if the fan itself works, though. With the key on, pull the faston connector off the fitting on the lower left part of the radiator. Stick a flathead screwdriver in the faston and then ground it to the shiny part of the fitting. The fan should turn on.