Clean the rust out of the gas tank.
Replace the fuel lines and fuel filter.
Disassemble and clean the carbs. Drop the bowl and at least unscrew the jets and blow them clean.

3/14/2012 3:55:31 PM

Replaced all the lines, got down to 2/4 carbs but the other 2 have screws that are rounded and I need to get them out somehow.

anyone know of a good way? the normal bit from lowes didnt work.

3/16/2012 4:38:51 PM

Happens all the time. Get some very small vice grips; grab the screws on the side of their heads.

To prevent this in the future: I always use the vice grips as well as a screwdriver to start each screw. An impact screwdriver(you hit it with a hammer) will also help, as long as the screw isn't damaged yet. Heating with a torch then cooling with computer duster upside down will help in extreme cases. Obviously the carbs need to be off the bike, drained and you need a very small torch to avoid melting all the gaskets.

PM me if you can't get the stripped ones. I might can weld something onto them.

I also like to replace phillips screws with allen or torx screws with a cylindrical head whenever possible. Burke Bros sells them.

[Edited on March 16, 2012 at 9:39 PM. Reason : .]

3/16/2012 9:33:49 PM

This week will be my first attempt at cleaning and rebuilding carbs. The rebuild kits arrive Monday and I picked up two cans of spray carb cleaner and a big pail of carb dip. Pulled the tank too, I'll pour in some of that rust removal stuff and BBs, and then replace the fuel lines an add an inline filter to be safe.

According to the guys on forums you're also supposed to check valve clearance while you're doing the carbs, but that might be a tad beyond my ability. We shall see.

3/17/2012 10:46:41 PM

Checking them is the easy part. Adjusting can get a little more complicated, but it depends on what adjustment system does the bike use. Screw types are easy, shim under bucket are a bit more of a project, and then you have PITA stuff like the desmodromic Ducati system

Quote :

"anyone know of a good way? the normal bit from lowes didnt work."

After soaking them with PB blaster and/or doing the heat/cool procedure (which i dont ever do unless i have all new gaskets), set a screwdriver on the edge of the screw head on the slight angle and beat on it with a hammer until it sinks into the metal and at the same time starts to rotate the screw. Many light blows work better than a few hard ones. Your screw will not be reuseable of course, but like SMC said you should probably replace them with a allen head anyhow.

3/17/2012 10:56:24 PM

You can also cut a nice new slot for a flathead screwdriver with a dremel tool.

When rebuilding the carbs, be sure to set the float height. Turn the carb upside down and measure the distance from the floats to the place where the bowl mounts. You'll need to find this spec in a manual, 25mm is a guess. You bend the metal tong on the floats to adjust them. Of course, if the bike is stock and the carbs are stock you shouldn't have to adjust them. Also be sure to remove the floats and shake them, listen for gasoline splashing around in them. Its presence means the floats have a pinhole leak. Once the carbs are back on the bike you can usually connect clear tubing the drain hole in the float bowl and hold the hose up so you can actually see the fuel level in the bowl. This level should be at the crack where the bowl mounts. So many carb problems can be traced to maladjusted floats.

Use a perfectly fitting flathead screwdriver to remove the jets...again, lots of penetrating lube and use great care...you do NOT want to strip the jets.

Check for play or leaks in the throttle shaft. Air leaking around the shaft usually means the carb is trash, but sometimes they have seals you can replace.

Check the vacuum slides by covering the air hole and ensuring they hold steady or at least fall slowly. If they fall fast the membrane is torn. The needle attached to the slide should not be bent or show signs of wear.

Before you put the carbs back on the bike, hold them up to the light and adjust the throttle plate screw so that you can see a crack of light around the butterfly. Adjust each carb the same. Once the bike is running you'll need to use a manometer(mercury sticks) to fine tune this adjustment.

If you remove the air box or change mufflers you'll need to switch to larger jets, failing to do so will melt a piston in no time. I usually work backwards...get the bike running, take it out with fresh spark plugs and cut the ignition during a full throttle run. You can use the spark plug color to adjust the mains. Then I more carefully adjust idle. Idle is dictated by the idle jet and your idle screw(more than 4 turns out means you should get a bigger idle jet). Cruise and midrange is controlled by the slide needle and the needle jet, sometimes they can be raised or lowered, or you can buy replacements with a more aggressive taper. The mains only come in at nearly full throttle. The amount of fuel at wide open throttle is of course a combination of all three circuits. Getting smooth power at all rpms and throttle positions is tricky and often takes lots of trial and error. Popping(especially on deceleration) generally means you're too lean, bogging and fouled plugs means too rich. When the bogging or popping happens will tell you which circuit to adjust. I like to draw marks on my handlebar to indicate throttle position.

Adjusting the valves isn't too hard if they have adjusting screws. Be sure to adjust the cam chain tension before you start. Remove all the spark plugs and use a dowel rod down the spark plug hole to feel the top of the piston and visually check that the cam lobes are facing away to ensure you've got the correct cylinder up to top dead center.

[Edited on March 18, 2012 at 12:52 AM. Reason : .]

3/18/2012 12:37:14 AM

Quote :

"If you remove the air box or change mufflers you'll need to switch to larger jets, failing to do so will melt a piston in no time."

Hrm, the air box on this bike was already removed (well, cut out of the way) when I got the bike . . . . I wonder if the previous owner did that? Is there a good way to tell? My carb rebuild kits actually came in yesterday, and I already have the carb rack pulled off the bike (but not disassembled yet).

3/18/2012 3:42:23 PM

Take a look at the spark plugs...the tips shouldn't be bone white or melted, but instead a light tan color or darker. There's much much more to reading plugs, but that's the basics.

But while you have the carbs apart, you'll find the jet sizes printed on the jet. Find out what the stock sizes were for your model...these sometimes changed each year. If the airbox is the only modification, you can likely keep the stock idle jet and just turn the idle screw out a bit. Mains may have to go up one size. Each bike responds differently though, so there is always going to be some trial and error. I wouldn't worry too much about jets until you get the carbs clean and can actually test them on the bike. Air temperature and ethanol content will also affect jet sizing.

3/18/2012 5:53:32 PM

Guess I'll just get it all clean and then see what happens, heh. Getting the screws off really is a bitch, I'll replace them all with nice allen-heads when I put it back together.

3/18/2012 10:48:47 PM

3/19/2012 8:12:29 PM

Anyone here hang out with the NCSportsbikes.com crew here in Raleigh?

3/22/2012 8:37:25 PM

I ride with them on the track very regularly. I don't ride on the street any more so I don't meet up with them on thursday any more. They used to do saturday/sunday group rides that were a lot of fun (that's when I got in that picture on the homepage)

3/23/2012 12:46:55 AM

Completely disassembled all four carbs and removed all the jets, etc today. Intermediate picture. Definitely a new experience but not as bad as I thought, and after doing so I can understand why the bike wouldn't run. Mostly an exercise in finding the right screwdriver size to remove brass screws without stripping them, or to apply enough force to remove one someone has already partially stripped being a dumbass.

Because apparently someone had tried to disassemble and clean the carbs already. They did a good job for the most part. Everything was fairly clean and nothing was missing, but the floats were stuck and wouldn't move. Instead of removing the float pins with a punch they pried them loose and then yanked them out with vice grips (the indentations were visible) . . . . and bent them slightly. So the floats couldn't move freely.


Explains why I got the bike so cheap. Hopefully after I replace those pins everything will be good to go. I have all the jets and other small parts sitting overnight in a pail of carb dip, just for the sake of being thorough even though they looked clean.

3/24/2012 1:51:24 AM

Remember to check the floats...if there is fuel sloshing inside them they have a pinhole leak. Try to find the correct spec for the float height and measure it with a ruler now...wrong float height will screw everything up.

Set each idle circuit fuel mixture screw to 2 turns out...precisely

To get them back into their rubber intake boots, smear a little silicon based lube on the boots. Tighten the shit out of those intake boot clamps, air leaks suck. Once back on the bike, turn the fuel petcock to the "prime" setting(The "on" position only flows fuel when the engine is running via engine vacuum). Sometimes the float valves stick open and gas will run out the carb. Try tapping it gently with a screwdriver to free up the valve, otherwise pull it back off and check for trash/replace float valve.

Set bike level on center stand. Now attach 12 inches of clear tubing to each of the little spigots on the carb bowls. Turn the end of the tubing up and open the bowl to see how full each carb bowl is. The correct level is right at the seam between the carb and the bowl, plus or minus 1mm. If incorrect, take the bowl/carb back off and bend the tang on the float to make it right.

To start the bike, you'll likely have to put your palm over each carb opening to block it off and force engine vacuum to pull fuel through all the carb circuits while you crank the motor. If it backfires your hand will sting a little...OK, more than a little...maybe use a rubber dish lid instead. Do this for each carb. You know the carb is working when you get fuel mist on the palm of your hand.

Once the bike runs, start to reduce the idle speed screw(the one that holds all four butterflies open). When it stumbles, turn the idle back up. You want a low idle below 2000rpms so that you can hear small changes. Put your hand over the tailpipes and feel for warm, even pulses to insure that all cylinders are firing.

Now start to turn each mixture screw in quarter turn increments. The goal is to optimize the fuel mixture, which will increase rpms slightly...you can then reduce the rpms back down with the big idle speed screw. So make small adjustments to the idle mixture screw...listen...and watch the tach. If rpms increase, continue turning the mixture screw in that direction. As you go too rich the rpms will fall again. Turn backwards to the middle of the range with the best RPMS. Once you have achieved the best RPMS, turn the big idle speed screw down so you hear the motor better again. As you do this for each carb you should be able to reduce the idle from 2000rpms to 1200 or so.

If you hear lots of popping and backfiring you are too lean, you might have an air leak. Also, if you rev the bike and it seems to "hang" at high rpm you might have an air leak. You can spray starting fluid around the carb boots to check for this...listen for a surge or a stumble or some reaction from the starter fluid being sucked in.

Once you have the bike idling, borrow or buy some mercury sticks. You connect these to each carb to measure air flow(indirectly by measuring vacuum at each carb boot). You use these to adjust("sync") the butterflies of each carb for identical airflow at idle. Once synced you can probably drop the idle speed even more and repeat the mixture screw setting process just to be sure.

All this will get the bike to idle, but tuning the bike running down the road is a whole other story. Looking good, report back.



[Edited on March 24, 2012 at 10:53 PM. Reason : .]

3/24/2012 10:35:07 PM

The fuel tee is cracked and leaks (not to mention doesn't fit snugly). Whoever cleaned it previously had just slathered RTV on and hoped for the best. So it looks like I have to order and wait for a new one.

After submerging the carb bodies overnight in a pail of carb parts dip the difference is amazing. Especially on the springs and screws that were all rusted and nasty . . . . they came out looking literally brand new.

3/25/2012 7:13:13 AM

new (for me bike)



considering I have only ridden my cb400t before it was certainly a step up in weight/power which made the first mile or two...interesting. i got the hang of it though for the 70 mile trip home.

3/25/2012 8:35:34 PM

what's the big orange thing?

3/25/2012 9:05:59 PM

got it from a dealer. was a makeshift pricetag.

3/25/2012 9:07:58 PM

That's awesome! Beautiful bike! Congrats

3/25/2012 10:01:49 PM

Quote :

"Anyone here hang out with the NCSportsbikes.com crew here in Raleigh?"

I have in the past year, not so much over the winter. Since the group rides are starting back up, I'll be out there doing those most weekends.

3/28/2012 8:59:39 AM

I should have taken more before pictures so it would be clear just how amazing of a change this is. The carb bodies, screws and springs and hardware . . . everything was corroded and rusted and filthy, especially the caps. After a two day soak in carb dip, a lot of elbow grease with a wire brush, and liberal spraying with carb cleaner (I think I went through 6 cans, mostly on the internal passages) . . . . the difference is amazing.

Threw me in a loop for a bit that two of the caps were chromed and two weren't. Apparently Yamaha only bothered to chrome the outer caps that are more visible, heh. Before cleaning I couldn't tell the difference!


Today I install the rack and try to fire up the engine for the first time. Hopefully it goes well! The gas tank is cleaned and de-rusted and freshly filled (plus some Seafoam, can't hurt) and I have new fuel tubing and an extra inline filter just in case.

4/1/2012 3:05:20 AM

I would do your initial testing and tuning without the Seafoam. You just cleaned the carbs, so it's not really doing much. if you want to clean the intakes, just pull some in through the vac lines while it's running.

4/1/2012 7:52:02 AM

finished getting the bike ready and took it out for the first ride of the year today.

4/1/2012 7:22:16 PM

http://youtu.be/yJRWSs_XWlo


OH

FUCK

YEAH!




It catches instantly with the first push of the button, runs and idles properly, doesn't cough or miss or smoke. And I haven't even ADJUSTED anything yet! Definitely exceeded all of the expectations I had of what to expect on the first start.

4/1/2012 8:35:04 PM

Front brake master cylinder and caliper rebuild kits ordered, along with new brake pads and a new metal line. The front brake right now does nothing, so definitely the first order of business before I can take the bike out and see how it rides.

Definitely a lot of small things and cleaning/etc remaining before I'll be on the road, but the end is in sight. The way the engine runs just blows me away, it starts easier and idles better than anything I've ridden before, despite being almost 30 years old. Guess they really knew how to make bikes back then!



So who wants to come riding with me on my maiden voyage?

4/2/2012 4:51:05 AM

^i would be up for a ride, dont know where you are but i usually ride around north wake county

4/2/2012 7:25:59 AM

^^ I'm free now until sundown tonight... Located near crossroads.

4/2/2012 2:05:13 PM

^Like I said, while it runs now it'll still be a bit before my bike is safe to actually take on the road. Call it a week or so, the new parts need to arrive so I can rebuild the front brakes at the very least.

4/2/2012 2:17:41 PM

you doing stainless lines in the front?

4/2/2012 6:01:53 PM

You know, I do my best to park my bike away from other cars. I really like my motorcycle. I love it even. So it really grinds my gears that despite consistently parking away from other people, within the last few days someone has knocked my bike over. There's a couple scratches on the engine guard and one on the end of the handle bar. Luckily that's it. Looks like there's a tire mark on the engine cover itself. I guess I should be fortunate that was all that happened when it fell. But I mean, seriously? WTF. I washed and waxed the bike last week so I know it was fine then. I rode it a couple times to run errands a few days ago. Today I was working on the bike and that's how I noticed the scratches. I feel so violated



[Edited on April 3, 2012 at 7:54 PM. Reason : .]

4/3/2012 7:53:08 PM

Sorry to hear that bro . Did you by any chance park it in front of a red s2000? (too soon??)

4/3/2012 8:18:16 PM

man, what kind of motherless fuck knocks someone's bike over and doesn't leave a note?

4/3/2012 8:19:55 PM

^^ LOL. At first I thought I was going to murder someone. Then I thought, "Oh hellllll no. everyone is gonna think I'm a squid tryin' to make up a bs story "

^I know right? someone bumps into the mazda trying to parallel park off hillsboro st and leaves me a note. There wasn't even a scratch! At least they picked my bike back up instead of just leaving it on the ground...


[Edited on April 3, 2012 at 8:24 PM. Reason : .]

4/3/2012 8:22:44 PM

I might be hopping ship back to kawi power. Steve Rapp's old bike is up for sale.. 128hp on pump gas

4/4/2012 12:37:03 AM

^^ That doesn't make it one bit better. That means they knew damn well they fucked up your bike, and made conscious decision to not make it right. Fuck them.

4/4/2012 12:59:38 AM

Any camera's in said parking lot by chance that would have caught the action / possible plates?

4/4/2012 9:05:30 AM

people have knocked your bike over? more than once?? holy shit man I would flip my lid over that

Yeah, definitely check for cameras. Not that you'd get anything useful (enhance...enhance...enhance...), but maybe something recognizable in case you run into them at the same store again. Any insurance? I've got full coverage with progressive and they've been stellar...I could fart and rip my seat and they'd pay for a new one.

[Edited on April 4, 2012 at 12:43 PM. Reason : not that i'd file a claim for that but you know what i mean]

4/4/2012 12:41:57 PM

lol.. no... Bike was only dropped once. I have progressive too. It's just engine guards and the handle bar end cap, nothing major. A little bit of black paint and unless you are staring at it 2 feet away looking for it, no one will be able to notice. I "could" go in and investigate, but i doubt it'd be worth my time. I look at my receipts, find time and location spent at various locations, try to pull surveillance, if any, find culprit, match description with store purchase time stamp, review transaction of said customer, contact their financial institution for customer/client contact information in regards to hit and run investigation via police department, prosecute. I guess that would roughly be the process in catching them, but at this point it's more trouble than worth over a couple scratches on an engine guard.

[Edited on April 4, 2012 at 1:00 PM. Reason : .]

4/4/2012 12:55:33 PM

do it...FOR GREAT JUSTICE.

4/4/2012 1:03:42 PM

Ive got an old beater bike that the fairings are cracked in places and I still get pissed when my roomates get close enough to bump it in the parking lot.

id be hella pissed

4/4/2012 3:30:26 PM

so my one of my best friends / old roommates from my hometown just sent me a text saying he just got home from a week stay at the hospital and no longer has his spleen.

broke some ribs and is on oxygen still...

he was riding his 'busa and a car cut into his lane

be careful out there.

4/5/2012 10:58:06 PM

^ Fuckers. 80% of the people on the road are flat-out dangerous and shouldn't be driving.

Quote :

"but at this point it's more trouble than worth over a couple scratches on an engine guard."

It's not about your scratched engine guard. Hunt that motherfucker down to the ends of the earth.

4/5/2012 11:03:38 PM

Thanks for the tip ray. I will now ride safe!!

4/6/2012 10:36:04 AM

we're not invincible, k

4/6/2012 10:37:06 AM

guardrail to leg after a truck forced him off the road.

4/6/2012 10:52:00 AM

Look what you started ray!

4/6/2012 12:41:54 PM

big shout out to smc for helping me get those screws off on the bike.
cleaned it all out.

runs sooooo much better now. Amazing what the right tools do.

4/6/2012 1:10:09 PM

my bad

4/6/2012 1:17:16 PM

That's justin mccormicks leg

4/6/2012 3:47:37 PM

Where's a good place locally to get new tires? Any suggestions?

4/6/2012 7:04:53 PM