Float Bowl Issues - My First Journey Into Carb Territory

As some of you know, I bought my XJ as a project bike, something to get my hands dirty (literally and figuratively) with motorcycle maintenance and repair. To those ends, I have been in a 10 week workshop class devoted to the art of motorcycle maintenance.

I'm quite certain my carbs are a bit of a mess. The idle is all over the place. It runs smoothly at speed, but it is lacking power down low. From measuring the temps of the headers, clearly not all cylinders are firing the same.

So... I bought a rebuild kit (basically a new float needle assembly and gasket) and we pulled the carbs yesterday. Not that hard, just get those cables out of the way. Harder, as you know, putting that sucker back in. It helps to have strong fingers. Also helps to get those brackets properly oriented BEFORE you try and reinstall. . Learning curve.

Drained the unit, and first thing I noticed was the amount of rust in the gasoline. I have GOT to get an inline fuel filter. I will be trying the reverse electroplating technique outlined on this website.

The bottom of the carbs weren't as bad as I thought. A couple of the pilot jets had minor blockage, easily dislodged by blowing on it. The float needle did have some minor scoring and was replaced. Old gaskets were replaced.

I should point out the class is only supposed to last for three hours, and I have to ride the bike home. I'll do the thorough cleaning at home.

Fussed and fussed, got the unit back on the bike, checked the throttle and choke cables for smooth operation. Fifteen minutes left in the class, time to fire it up. Turn to petcock to "prime"... and that's where the fun began! Gas bubbled out of the boots, on to the floor. All four cylinders flooded. Crap.

Float needle, right? Maybe. We had checked float level, everything within spec, as per Haynes. Here is the (K&L) rebuild kit I got from Bike Bandit:




(note - pictures lie. It only had a gasket, float needle assembly and pilot screw cap)

So, with the eternal patience of the workshop leader, we pulled the carbs again. Much faster this time... learning curve! It looked like that float needle, while fitting the same as the old one, wasn't quite the same. The springy button on the bottom was a bit smaller, and the spring action was lighter. Also, the float assembly itself didn't come with that little mesh filter, nor did it have indents to install one, and it had a fabric (teflon?) washer instead of a copper one.

Not sure of the relevance of all that. The needle popped up and down ok, so the fit was fine. So obviously the float level was WAY out of whack with the replacement needle. Being that it was already over one hour past the end of the class, and it was getting late, we put the old float assembly back in. Did an on-bench test by funneling fuel through the hose to see if it stopped intake when the bowls filled... and it did.

Put the carbs back on the bike, again much easier the second time. Pulled the spark plugs and turned it over a few times to blow out the flooded cylinders and dried the plugs. This time... no flooding at "prime", and the bike started fine.

So it had to be that new float assembly. I can't understand why they wouldn't include instructions on a new float height. Or maybe it had something to do with the cheap washer. For $20, you'd think they would have made it copper.

What do you guys think of the above? Sound right? Since the old needles do need replacing, can anyone recommend a set they KNOW to fit and work properly? Anything I/we did wrong so I know for next time?

I don't mind the extra effort and time this took. I don't even mind that I didn't accomplish what I wanted out of it, and the frustration of having to do everything twice. I learned a bit, so it was worth it.

 

If you had gas pouring out onto the floor, there's a good chance some of it got into the crankcase. Gas in the oil can thin it out to the point where it won't provide proper lubrication, and you'll eat up crankshaft bearings and such.

You might want to change your oil immediately.

 

K&L kits do not have the correct float needles for our carbs. I tried a set on my XJ 650 Seca, and ended up cleaning the stock needles and replacing them. I also noted that the needle seats were not drilled clean. There was actually a bit of flash left on the seat base that left the needles open. I was a bit miffed that for $20 all i could replace were the gaskets. Since then I have not had any problems with sealing or poeration, other than "doh" moments, like not tightening a needle seat and having it back out or not tightening a pilot jet, then spending one of the last weeks of good riding weather chasing a cold cylinder/misfire problem. Best bet would be to clean the carbs totally, using jet cleaning wires and compressed air, then resetting everything and syncing the carbs. cruzerjd

 

Geometry and Finish.

Check the Geometry of the NEW Needle as it slides into the Float Valve Body.
Sometimes the Kit Needles are cockeyed and you have to put the wire clip on opposite of the way you had it to get the vertical alignment.

Finish

The aftermarket Valve Body is not as well "Finished" as the OEM's.
Roll-up some 1200 Finishing Paper to a diameter that will fit the Valve Body nice and tight.
Turn the rolled-up finishing paper in the Valve Body applying a nice shine to the Inside Diameter of that New Valve Body.
Test the Needle for movement.
"Shine" the quadrant ends of the Needles.
Get as much of a frictionless surface as you can.

I have had precisely what you describe happen to me on Carbs that Members sent-in with Kits happen during the Float Height Test.
The Carbs overflowed.

After applying a mirror finish to the Inside Diameter of the Float Valve Body they were fine.

 

Thanks, that makes me feel a bit better. It's not my fault.

Is this something to be expected with all aftermarket stuff? I am thinking Bike Bandit et al should be informed that those needles just plain don't work without careful finishing.

Are there any aftermarket needles that work out of the box? The OEM version is $50 - as always, way too expensive.

 

I used the same kits on the last 650 I worked on. I felt lucky to find even those sub standard kits for those Hitichi carbs. I had to clean up the finish as stated above and also used the old washers. That was the only way I could get the float levels to come even close to spec. The kit washers for under the valve body are way to thin.

 

Actually, there are two different styles of aftermarket float valve needle-seat kits available for the Hitachi carbs:

(1) One style has a taller float needle, but has a seat that DOES have the filter screen:

fs2) Aftermarket Hitachi Carb Lower End Deluxe Rebuild Kit---contains the float needle with retainer clip, float valve brass screw-in seat, a metal seat washer, and a factory bowl gasket. The float needle seat DOES include the filter screen. NOTE: the float Needle that comes with this set is approximately 1mm taller than the factory Yamaha needle, and will require that you re-adjust the float level height after installation.


For all XJ650 (except Turbo), all XJ750, and all XJ700 (except "X") models:

HCP2776 aftermarket Hitachi Carb Lower End Rebuild Kit, single:
$ 23.00

HCP2776SET4 aftermarket Hitachi Carb Lower End Rebuild Kit, set of 4:
$ 82.00



(2) the other style has a float needle with the same height as the stock one, but the seat that comes with it has no filter screen (and no provision for a filter screen, either):

nn) Aftermarket Hitachi Carb Lower End Standard Rebuild Kit---contains the float needle with retainer clip, float valve brass screw-in seat, a fiber seat washer, idle mixture screw block-off cap, and an aftermarket bowl gasket. The float needle seat does NOT include the filter screen. NOTE: the float Needle that comes with this set is approximately the same height as a factory Yamaha needle, and it may not be necessary to re-adjust the float level height after installation.


For all XJ650 (except Turbo), all XJ750, and all XJ700 (except "X") models:

HCP1 aftermarket Hitachi Carb Lower End Rebuild Kit, single:
$ 19.00

HCP1SET4 aftermarket Hitachi Carb Lower End Rebuild Kit, set of 4:
$ 69.00



(3) You can also buy just the float Needle, or the Needle/Seat Kit, both of which contain the needle that is 1mm taller than the factory needle:

fs3) Aftermarket Hitachi float valve Needle Only (includes the retainer clip)...for those who wish to do an extreme-budget rebuild, you can buy the rubber-tipped float valve NEEDLE by itself (without its brass seat). Needle includes its hanger/retainer arm clip. NOTE: this Needle is approximately 1mm taller than a factory Yamaha needle, and will require that you re-adjust the float level height after installation. For use on all XJ650 (except Turbo) models, all XJ700 non-X models, and all XJ750 models.

HCP870 Hitachi float valve Needle with clip, each:
$ 7.50

HCP870SET4 Hitachi float valve Needle with clip, set of 4:
$ 28.00


jj) Aftermarket Hitachi Float Needle Valve Assembly---contains the float valve Needle with retainer clip, float valve needle brass screw-in Seat, and the metal seat Washer. The seat DOES include the filter screen, but this kit does NOT include the idle mixture screw block-off cap. NOTE: the float Needle that comes with this set is approximately 1mm taller than a factory Yamaha needle, and will require that you re-adjust the float level height after installation.

For all XJ650 (except Turbo), all XJ750, and all XJ700 (except "X") models:

HCP872 Aftermarket Hitachi Float Needle Valve Assembly, single:
$ 11.00

HCP872SET4 Aftermarket Hitachi Float Needle Valve Assembly, set of 4:
$ 39.00



(4) Note that neither style aftermarket float seat accepts the factory "domed" filter screen; the boss on the float seat (where the filter attaches) is the wrong size in the HCP872 and HCP2776 kits (but those kits do come with a newer version "flat" filter) and the HCP1 seat does not have a provision for mounting any style of screen on the needle seat, aftermarket or original.


(5) Finally, in taking apart quite a number of these Hitachi carbs, I have discovered that there are actually 3 different styles of float seats/needle used, with various dimensional differences:

HCP1 kit comes w/o a screen but the float seat has a 5.10mm screen mtg. boss.

HCP872 and HCP2776 kits comes with a screen and the float seat has a
4.53mm screen mtg. boss

There is a third style of seat and it uses a "domed" style screen. The mounting boss for the screen on the seat is 7.25mm OD and it is "stepped".

It is difficult to be sure, but I would wager that the "third style" seat listed above is the real "factory original" style seat, and is not available as an aftermarket replacement. Of course, the factory may have sourced seats from different suppliers when new, and/or changed suppliers or design specs during production of these carbs, so it's really hard to tell----25+ years later----which are truly "original" and which aren't......


(6) In all cases, I would strongly recommend adjusting the float heights after your carb rebuild is done, even if you re-use your original float needle/seat unit!

 

Adjustment of the float level after any needle valve and or seat replacement is a given. The K&L kits I bought must have been the lower end units you discribed as the quility of the parts was just that, lower end. I was able to make them work but it should not have taken that kind of effort and the manufacturer could have provided better information to the suppliers who I'm sure would have passed it along to the consumer. Thanks for the great information on the Hitichi parts and the part numbers for the kits. If you have sourceing information you could post all of us would be in your debt. Next time I'm in a set of Hitichis I'll know what to go looking for.

 

To add a cherry to yesterday's long day:

Leaving the workshop, it was dark out. Hitting the on ramp to the freeway was done literally. Apparently there was about a three foot patch of something very slippery. Down I went. Luckily my gear protected me, and the engine guard protected the bike. New Mac's took a bit of a scrape too. Nothing that can't be painted out.

There I was huffing and puffing trying to right the bike and get it out of the intersection. Ever try doing that on an oil slick? Quite the challenge, let me tell you. Then I had to restart a flooded engine again. And the neighborhood I was in is, shall we say, "marginal".

I drove by there again this afternoon. Sure enough, a big, black and very shiny patch right at the start of the on ramp. Easy to see in daylight.

 

BTW:

Your fuel level should be 3mm +/- 1mm from the lip on the surface where the bowl mounts to the carb body.

 

Glad to hear you are ok and nothing is broken beyond minor repair. Oil slick at night, thats the stuff nightmares are made of

 

http://www.xjbikes.com/Forums/viewtopic ... rt=45.html

 

its a good thing to hear the gear helped.
the bones, thats the worst parts to replace

 

Chacal thanks for the link. I have bookmaked it. Wish I had found it during my research would have saved me lots of time.

 

I must have lucked out. When I went through and cleaned my carbs, number three had been overflowing. Sure enought there was a groove in the rubber tip of the float needle. I ordered just the needle from CRC2Online (Cycle ReCycle). It looked just like the old one, without the groove of course, and worked fine with no modification. The float level even stayed dead nuts on.

Wow, I never think of myself as lucky....maybe I just didn't know it! 8O

 

ive just changrd my fork oil seals, could anyone tell me the amount of oil i need to put in each fork? thanks

 

And the year and model of your bike is: _____________________

 

Len is our local parts Guru - check his link - great prices and fast shipping.

 

fork oil for a 1985 xj 700 maxim x.

 

FORK OIL:

Unlike motor oil or gear oil, fork oil's major purpose is not lubrication.....rather, it acts as part of the suspension system, providing both damping and rebound control functions. The different "weight" or viscosity of fork oils allows you to modify the ride and handling characteristics of your bike in a fairly simple way.

And yes, it IS a lubricant also!

Although many people----including, unbelievably, Yamaha itself----recommends the use of engine motor oil as a substitute for fork oil, this is not a very good idea. Engine oils (or any multi-viscosity oil) uses additives and detergents that, while wonderful in for their intended purposes inside an engine block, tranny case, or rear drive unit, are not such a good idea inside forks. Forks operate at a much lower temperature and temperature RANGE than engine and drivetrains do, and thus do not need all those additives. And fork oil also tends to contain higher percentages of molybdenum disulfide and anti-foaming agents than engine or gear oil, both of which are very important to proper fork operation.

As a small example.......most motor oils are of a multi-viscosity nature (such as 10W30) which change their viscosity in relation to their temperature (thin when cool, thicker as they warm). A very necessary and useful feature for an engine, where you do not want your oil thinning out as the engine warms up. Not such a good idea for your suspension----unless for some reason you WANT your handling characteristics to change (get stiffer) as the forks heat up!


Proper fork oil levels and scheduled change intervals are important for fork performance and fork part longevity.....water contamination, as well as particulate wear will accumulate in fork oil, and since there is no oil filtering mechanism within your forks, the only way to get the grit and gunk out (before it chews up your oil seals and slider bearings!) is to change your fork fluid regularly. Yamaha recommends a fork fluid change every 10,000 miles or 24 months (all models except 700's), or every 16,000 miles or 24 months (all 700's). If you just bought a used bike, we recommend you do a fluid change as soon as possible, because just like other routine maintenance tasks (besides engine oil changes), this is one that has very likely been ignored for the last 10-12 years!


Fork oil capacities and recommended weights are as follows. The amounts listed are per fork tube:


XJ550 Maxim: 272cc or 9.20 fluid ounces. 10W fork oil.

XJ550 Seca: 230cc or 7.78 fluid ounces. 10W fork oil.

1980-81 XJ650 Maxim and Midnight Maxim: 262cc or 8.86 fluid ounces. 10W fork oil.

1982-84 XJ650 Maxim: 278cc or 9.40 fluid ounces. 10W fork oil.

1982 XJ650RJ Seca: 236cc or 7.98 fluid ounces. 10W fork oil. Fork oil level is specified as 400mm (15.75") below the top of the tube without the spring installed, forks fully collapsed.

1982 XJ650LJ Turbo: 238cc or 8.04 fluid ounces. 10W fork oil. Fork oil level is specified as 180mm (7.09") below the top of the tube without the spring installed, forks fully collapsed.

1983 XJ650LK Turbo: unknown.

1985-86 XJ700 non-X: 383cc or 12.96 fluid ounces. 10W fork oil.

1985-86 XJ700-X: 389cc or 13.16 fluid ounces. 10W fork oil.

1982 XJ750 Maxim: 257cc or 8.69 fluid ounces. 10W fork oil.

1983 XJ750 Maxim and Midnight Maxim: 257cc or 8.69 fluid ounces. 10W fork oil. NOTE: owner's manual states that the fork oil capacity is 278cc (9.40 fluid ounces). It is unknown which measurement is correct.

1981-83 XJ750 Seca: 309cc or 10.45 fluid ounces. 20W fork oil.

1983 XJ750 E-II Seca or 1984 XJ750RL Seca: 286cc or 9.67 fluid ounces. 5W fork oil. Fork oil level is specified as 168mm (6.61") below the top of the tube without the spring installed, forks fully collapsed.

1983 XJ900RK Seca: 286cc or 9.67 fluid ounces. 5W fork oil. Fork oil level is specified as 164mm (6.46") below the top of the tube without the spring installed, forks fully collapsed.

1982-84 XJ1100 Maxim and Midnight Maxim: 210cc or 7.10 fluid ounces. 10W fork oil. Fork oil level is specified as 210mm (8.27") below the top of the tube without the spring installed, forks fully collapsed.


IMPORTANT NOTE: the above fork oil VOLUMES are for use only when using the stock fork springs. The use of aftermarket performance front fork coil springs will change those volumes, since aftermarket springs are thicker than stock----and thus displace more oil. Using the stock oil fluid VOLUME with aftermarket fork springs is a sure way to OVERFILL your forks, with the very real possibility of blowing out fork seals.


Unlike with your engine oil, where a bit too much or too little oil volume in the crankcase is not really a significant concern, with fork oil, too much or too little can cause real problems (too much oil can result in blown oil seals and a stiff, harsh ride, while too little oil volume results in excessive foaming, a soft mushy ride with possible bottoming, and erratic fork performance and lots of front end "dive" upon braking).

A better way to determine the amount of fork oil that is needed and necessary is via the measurement of the fork oil LEVEL within the tubes.....sort of like measuring the oil level with a dipstick. Yamaha does not specify this level for all models; and in any case, if using aftermarket springs, the factory oil level recommendation is not always useful. The maximum oil level should be 5-1/2" (140mm) below the top of the inner fork tube, measured with all internal fork tube components installed EXCEPT FOR THE SPRINGS, and with the inner fork tube fully collapsed into the lower (outer) tube.


In order to be as accurate as possible, we recommend the use of a suitable measuring device, such as the HCP1728 oil level syringe listed further below.


And finally, the fork oil viscosity can be changed from the factory recommendations to give a softer or firmer ride.......the lower the viscosity, the thinner the oil, and the softer the ride (i.e. 5W oil is thinner than 10W which is thinner than 20W, etc.) In this regard, you would certainly be correct in thinking of fork oil as a suspension "tuning tool"! Note that a thicker oil viscosity will have much more effect on the fork "rebound" characteristics than it will on the fork compression dampening function.

 

thanks for the info on the fork oil and the amounts. can anyone help me with a problem i,m getting, my 85 maximx seems to be running on 3 cylinders num 2,3,and 4. if i take the vacume pipe off whilst engine is running then num 1 cylinder starts working. why is this and how can i solve this problem? many thanks, nige - Nottingham, England.