Carb rebuild!! Losing my sh#$%.

Restoring an 81 550 Seca and I just spent the last 8 hours trying to rebuild the carbs and I'm only half done!!!! To be fair to me, when I bought the bike the guy gave me a an extra full set of never used set disassembled carbs with all original 37 year old parts...so I'm actually rebuilding two sets. I'm trying to make a whole new set from the bottom up using all the 37 year old parts. I saw a few vids on bench synching them. I've been studying up on carb cleans for the last month or so and finally got the courage to go for it and it's freaking me out right now. I mean, I think I'm okay but it I'm really afraid of messing this up. Any words of warning???

 

One item on the Mikuni carbs the butterfly scores are peened on the back side these can be difficult to remove you have to file down to remove , replace with new screws and a dab of blue lock tight .

 

My advise is to buy new seals and washers. If you use the old stuff you were given you are prone to leaks. Buying new will be a lil pricey but then you know it will work right.

Rebuilding carbs arent that difficult if you label everything you take off. Since you are building a second set from scratch my advice is to start with the one thats already put together, so you can see how it comes apart and goes back together. Once you are comfortable then build from scratch.

 

It's OK if you mess up.
We'll help you un-mess it.

 

Day two and the rebuilt carbs are done!!!! Wow. That felt kind of intense. I just had to get it done before I forgot. I hope I did everything alright. Anyway, the challenge is still on. I still have to get the carbs back in!!!! Ugh. Does anybody have any tips how to get the rear carburetor boots back on. Those things are a bitch. They're right at that place where they're hard but still malleable. So, trying to save a buck and get these guys back on. And it's hard. Again, any videos or advice. Please let me know.

 

Thanks man. Don't have much of a fan base over here.

 

A heat gun is your best friend

 

get a welding rod or a stiff coat hanger, bend a 90 about 3/4 inch on the end and a handle about 5 inches away.
make it nice and smooth on the tip of the 90, then use it to work the boot to where it needs to be. a old philips screwdriver ground round and smooth
helps too when your fingers get tired

 

Thanks, I'll give it a try. I'll try anything. I'm at this bike's mercy.

 

Does anybody know how many turns the pilot screw should have. My manual says it's preset. Guess they didn't think these things would still be around. Anyway, on my old set of carbs I only got two out. The other two were stripped. I counted 1 3/4 turns on one and 2 1/4 turn on the other. So, I currently have all of the pilot screws on the new set of carbs turned to two full revolutionary turns each. Am I on the right track here or am I just way off base? Also, I went with the factory recommended 112.5 jets instead of the 115's that were currently on the bike. I'm just curious on that one.

 

Right. Don't have one.

 

Hairdryer.....

 

I've been using the el cheapo harbor freight one for about 10yrs now--- hasn't burned out yet

 

If all else fails on the carbs I have a nice set of US spec carbs I can sell you nice and clean inside and no stripped screws

 

Hair dryer worked great. Still can't get the carbs in.

 

Help!!!!!!! I can't get the carbs back in the bike. It's impossible. Does anybody live in the Los Angeles area and can help me out. I'll buy you dinner or lunch or whatever. I need help!!!!

 

When you say new seals are you referring to the intake manifolds and the airbox boots or are you referring to O-rings, or both? I took off the intake manifolds and noticed there were no gaskets. So, I ordered a new set. The air box boots are a little hard but usable. Once I warm them up with the hair dryer they become very soft and extremely easy to work with.

 

Are the carbs not going onto the engine side ‘tubes’ or the air box side?

(On a 650Maxim)
For the engine side make sure bores are clean smear a little bit of oil on them, line up carbs and make grunting noises as you are straddled over bike pushing in a left/right/up/down manner until they get started then use a hammer handle/ chunk of wood to pry them into position.

For the air box side, loosen the air box, it doesn’t move much but that little bit of forward movement can make a big difference in getting them to seat proper.

 

2 1/2 turns is baseline You'll adjust from there. They are preset and sealed due to federal emissions legislation. Yamaha and Hitachi expected the machines to last for a very long time.

 

To get the carbs back into the bike, I've read to use a ratchet strap or big f clamps. I've tried both and I think I'd vote ratchet strap for overall ease. I put a little silicone spray on the inside of the boot, and make sure everything is lined up and that the carbs are actually in the boot holes before tightening. I found it impossible to do without the straps or clamps.