The Big Day!

[Hawkinspickle]

So today was going to be the big day! The day I was firing up my 79 Special after months of sourcing parts in all areas of North America then putting it all together with a lot of help from you fine folks I might add. Fresh fuel in my nicely cleaned tank and all ready to go. Turned my rebuilt petcocks to on, pulled the choke and …. then seeing fuel pouring out of the air box!

Quickly shut off the petcocks and pulled the air box and drained the float bowls hoping no fuel found its way the crankcase, which I have heard from many of you is a super bad. I think I may have got lucky there but to make sure I immediately drained the fresh oil as a precaution and removed the plugs to see/smell for any hint of fuel in the combustion chamber. No smell of gas in oil or the chambers.

The carbs were just rebuilt by a local shop (not cheap) with new kits, one new float to replace the last brass one in it and with all new genuine Yamaha Mukuni pilot and main jets from Partzilla. While I will be going back to the shop to see what went wrong with the carbs, any suggestions or comments on all the above would be much appreciated. Also, is there anything else I could do as a precaution with respect to the fuel in crankcase issue or am I fretting too much?
Cheers, Dan

[bikerphil]

When initially filling the carbs, tap on the bowls with something, such as a screwdriver handle. The floats can get stuck in the down position and flood like you have described.

A few things that can cause the floats to bind are...

1. The gaskets are a bit too wide and need slight trimming on the sides so they don't interfere with the floats.
2. The float bulbs themselves need to be bent slightly inward to avoid contacting the bowl/gasket.
3. The drop tang on the float needs adjusting to keep the float from dropping too low when no fuel is present. The needle can become cocked in the seat if the float drops too low.

[Tonyxs11]

my 79 did the same thing on 2 carbs, I just replaced the float valves and the seats. all good now.

[jkorn]

I agree with above. Manual details how to adjust float bowls. It’s easy once they are off the bike. You only need to remove the bowls. Second issue could be the new fuel needles are not seating/sealing. I’ve had new rebuilt parts fail.

Also, I have had to tap the side of the bowls.

if all carbs seem to have been spewing fuel, I would guess floats are not adjusted correctly. It’s probably time to become intimately familiar with the carbs. I’ve had mine apart so many times I’ve lost count. For me hardest part is wrestling them off the bike.

during any work on the be sure and keep parts separate for each carb. Never intermix them.

Good luck. Jeff

[jkorn]

Like this example

[Hawkinspickle]

Thanks everyone for your insights. Jeff, if you were any closer, I just have you work on my carbs. Very few shops left in the Vancouver area that work on older bikes and in particular carburetors. Much like sourcing parts, the USA seems to have way more shops available. I believe there are only three, what I call, traditional shops left in my region where the rest appeared to have been wiped out by COVID. Most shops don't like to work on older bikes and only want to plug new bikes into Skynet. I will be taking all your comments to the mechanic who rebuilt the carbs. I forgot to mention that when attempting to drain the float bowls, the #4 drain screw was stripped. I couldn't drain that bowl at all and am hoping that this the screw is typical and readily available. As an example, I had to look all the way to Florida for a centre stand spring because no one in Canada had one! Nevertheless, I have to figure out how to get this screw out first. As for the fuel in oil, it makes me feel better that some of you dealt with the same overflow issue without damage to your engine.

[oldyam80sg]

Tapping on the float bowls usually frees up the stuck floats. You should really learn to take off the carbs and clean them yourself. Save you a lot of money and you are not waiting on anyone. Most shops by me wont even touch a bike this old.

[Hawkinspickle]

You guys are the best! You just don’t get this type of info from a manual. Yes, I am happy to say that a few lite taps on each carb bowl did the trick. Now to see how I can get that stripped drain screw out and if they are special order. If so, I’m leaving it lodged in for now. Thanks all….

[Hawkinspickle]

Tapping on the float bowls usually frees up the stuck floats. You should really learn to take off the carbs and clean them yourself. Save you a lot of money and you are not waiting on anyone. Most shops by me wont even touch a bike this old.

I hear ya! Next time I will, it's just that the carbs were a bit of a basket case, so I wanted it done right.

[oldyam80sg]

First time cleaning the carbs can be a bit overwhelming. I did it on a guys Kawasaki and charged him $75.00 to clean them as they sat on a bike for 20+ years. He complained to me that was too much, and then he wanted them done again when he ran the tank empty and got crap in the carbs again. Never did it for him as he didn't want to pay.

[jkorn]

The only shop my XS has ever been in is the garage. If the kid in the shop can do it, so can I. So much fun pulling those carbs off. Cleaning every little microscopic passageway with carb cleaner. Playing with the jets and the weights on the advance. In a very complex way it’s actually very simple. Fuel injection is for pussys. No computer on these bikes. It’s all about the main jets, needle position and advance. Look at the pipes. Too blue? Look at the plugs.

That’s what these machines are about. When I bought mine, it was the fastest production motorcycle on the market. Then Susikie came out with the 4 valve head. That day had past but it’s my XS. No other bike is like it. Period.

[bikerphil]

I would try them again, just tap the bowls when filling, if it floods again, then something wasn't done right and the re-builder is responsible.

Edit: I see you did try them with success this time. Awesome.

[Hawkinspickle]

First time cleaning the carbs can be a bit overwhelming. I did it on a guys Kawasaki and charged him $75.00 to clean them as they sat on a bike for 20+ years. He complained to me that was too much, and then he wanted them done again when he ran the tank empty and got crap in the carbs again. Never did it for him as he didn't want to pay.

In Canada, typical shop rate is $130 per hour. That's why knowing this has got to be something I need to do. And that's just labour....

[Tonyxs11]

talking of carbs, had a problem with my 79 running rich on number 2, just stripped them to find the threads on number 2 pilot jet are stripped in the carb body looks like i'll be after another set of carbs (or just number 2 if i can find one)

[Hawkinspickle]

UPDATE to the Big Day: Once the floats floated with the tap of a screwdriver, she fired right up!.... just in time to put her away for the coming winter. On that note I'm sure there's a forum for winterizing. The bike ran reasonably well on the simple bench sinc but will need a proper tune-up. The front brakes are spongy and started to drag. Not sure when the last time those were touched? Apart from that, I might get one day's ride in this year.