Yet another Carb Virgin. Questions follow!

Hey Guys,
I have recently undertaken the task of cleaning my carbs. Now I am not a mechanic by any means, I am a tradesman so I have decent mechanical apptitude but definatly not much in the way of mechanics. So after reading HOARDS of carb article's and write ups and manual how-to's I decided it was time. I took the rack off the bike fairly easily. broke up the rack easily enough. dun dun dun, it was time. So I have got my first carb apart. I am gonna do one at a time just to ensure I don't mix things up. After messing around with the carb a bit, i got it apart, its cleaned. It was actually pretty clean when I got it apart, which is a bit of a bummer because I probably didn't need to do this haha, oh well at least I know its done now. Anyway, I purchased most of my parts from chacal, however I did purchase a carb repair kit off ebay first. Now the float needle valve that was already in my carb had a little screen on it (which i crushed trying to remove, BAH) however my carb repair kid never had a screen on it. and the little "knob" that the screen attaches to is a different size on the valve that came in the kit. Is this the proper kit? The screen would not have fit on the new valve anyway so.... where should I go from here? Thanks

Colin

 

Hey Colin,

There are a number of different float valve brass seats (the piece that the screen fits onto), and they do differ in design and in which screen will fit them. Here's the cheat-sheet:

HITACHI FUEL INLET "FLOAT" VALVES:

Original and aftermarket FUEL INLET "FLOAT" VALVE UNITS and KITS are a critical item to replace when performing a carb rebuild. Worn or damaged float valve seats or needles will cause bowl overflow and carb "flooding", making it impossible to set the fuel levels and float heights correctly, and leading to dangerous and damaging fuel overflow issues.

NOTE1 on fuel inlet/float valve Seats, Filter Screens, and Needles:

- original fuel inlet - float valve brass seats had a fuel inlet boss (where the inlet filter screen sits) of either 5.10mm (and thus uses the HCP9855 flat screen) or a 6.57mm boss with a 7.30mm "capture lip" (and this style float valve seat uses the HCP869 domed screen).

- The HCP10 (OEM) kit comes with a flat screen and the float valve seat has a 5.10mm screen mounting boss. The float valve seat washer is made of copper as original.

- The HCP1 kit (aftermarket) comes without a screen but the float valve seat has a 5.10mm screen mounting boss, so the HCP9855 FLAT screen can be used with these kits. The needle is the same length as the OEM needle and is rubber-tipped just like the original.

- The HCP18210 kits (aftermarket) comes with a screen . The needle is the same length as the OEM needle and is rubber-tipped just like the original. The float valve seat washer is made of aluminum rather than copper.

- The HCP17176 kits comes without a screen and the float seat has a 6.57mm screen mounting boss. The needle is slightly longer than the OEM needle and is metal-tipped (rather than rubber-tipped like the original needle). The float valve seat washer is made of aluminum rather than copper. These metal-tipped needles are a desirable option for people who live in an area where there is a significant amount of E-85 (alcohol) fuel blended with the gasoline. Ethanol tends to soften and attack rubber products, including the rubber tip of the original style float needles, which can then cause the float valve unit to stick (closed) or leak fuel even when in the closed position.


NOTE2: on all of the float needles that use a retaining clip, please note that the clip can be installed in two different ways (orientations). User experience indicates that the clip should be positioned so that the "open" area of the clip (that part of the clip that snaps over the ridge on the top of the needle) should be oriented towards the "back" of the carbs; in other words, the open area of the clip should be towards the airbox.

NOTE3: on all of the float needles that use a central, spring-loaded "plunger" at the float end, please note that this plunger is designed to act as a "shock absorber" and is not normally depressed in normal operation, and the float heights and fuel levels should not be set with this plunger depressed. Doing so will result in a vastly incorrect fuel level setting and will lead to carb flooding.



QUESTION: does it matter which style fuel inlet - float valve seat/needle/etc. is used in your carbs?

ANSWER: Not really, although it's probably best (but not absolutely necessary) to make sure that all 4 carbs use the same style set-up. The installation of any replacement fuel inlet - float valve seats and needles will require checking and re-adjustment of the fuel level and float heights after installation.. You should ALWAYS check and adjust your float levels anytime you go into your carbs----and periodically even if you don't! I know, it's a pain-in-the-tail light to adjust the float levels----but correct float levels really will insure that your bike performs at its best and will also prevent problems with carb flooding.


HELPFUL HINT: in many cases, a float valve brass seat may get small scars, burrs, or other deformities in the area where the rubber needle tip contacts the seat opening, and thus preventing the fuel flow from being completely shut off even when the bowl is full. Such minor flaws can sometimes be polished out with some very fine (600-grit or higher) polishing paper rolled up into a very tight "cigarette" and then moved back-and-forth thru the opening. Likewise, any flaws on the internal bore of the seat......where the needle slides.....can sometimes be polished away. You should inspect the seat and needle very carefully, under good light and with strong magnification, in order to inspect these crucial parts during any rebuild process, or if carb flooding is indicated.



NOTE: screens are not interchangeable between different style seats, since the style and diameter of the screen seat boss is different between each type of seat. Make sure that you properly identify which style seat you have before ordering replacement filters.


HCP2644 Aftermarket Hitachi fuel inlet - float valve needle seat FLAT FILTER SCREEN, use one per carb, for use with float valve seats that have a 4.53mm screen boss (used on some original and aftermarket seats). This style screen pushes straight onto the brass seat screen boss. Each:

HCP9855 Aftermarket Hitachi fuel inlet - float valve needle seat FLAT FILTER SCREEN, use one per carb, for use with float valve seats that have a 5.10mm screen boss (used on some original seats, and on the HCP1 aftermarket and the HCP10 oem seat assemblies). This style screen pushes straight onto the brass seat screen boss. Each:
$ 6.95

HCP869 Aftermarket Hitachi fuel inlet - float valve needle seat DOMED FILTER SCREEN, use one per carb, for use with float valve seats that have a a 6.57mm boss with a 7.30mm "capture lip" (used on many original seats). This style screen "snaps" onto the capture lip of the brass seat screen boss. Each:

 

Hi Colin,
I did exactly the same thing squashed it flat. I thought it was some kind of lizard egg that had been layed in the fule line? & was puzzled as to how I could repair the screen, while looking through my tool box i came across a 5mm allen key (a long one with a knob on the end) and used that to gently push the screen back into shape, worked a treat hope this helps you out

myles

 

i could definatly push it back into shape but i wasnt sure if it would work properly if the screen wasnt aboslutly perfect again.

 

One of mine was squished when I did my carbs too. I just ended up tossing them and running with no screens. I read on here somewhere awhile back that it doesn't effect performance at all but it's basically the last line of defense from little particles getting into the fuel circuits. You can ditch them but you definitely want to have a clean tank and a good in-line fuel filter.

 

Add an inline fuel filter (w/NEW hose) and you can run without the "beenie screens"

While you are in the carbs - make DURN sure you clean the Pilot passages from the Pilot jet to the little, tiny holes at the butterflies.

 

I have found that 3 out of 4 of my jets are random sizes. somebody has obviously been in here before. i was a bit hesitant because the bike ran what seems ok before I did this project so the jets obviously worked. but i figure i should make it proper, correct? SO. for the jets, i am at an elevation of 3400' I have read about rejetting. So if my main fuel is supposed to be a #110 (81xj650 canada) that means I should subtract 2 sizes per 2000' feet. so should i go to a #107? Pilot fuel, should i leave the same as I am not 6000' above sealevel and am not increasing my main fuel at all? and do i do anything to my main air jet? my pilot air jet was the only one that was correct.

 

any info guys? i wanna order the jets up so I can get the carb project rolling.

 

right now i have a 45 on the pilot fuel and a 55 on the main air.

 

100% agree with TimeTR....no need for the screens if you put an inline filter on. No screens on any of my bikes.

>Dun Dun Dun-- You referring to Captain Chaos?

Dave F

 

will be be ok to put in these jets? #45 and 55 instead of 40 and 50?

 

If you have the stock airbox, complete exhaust, and "paper-type" air filter, you should re-jet to "stock specs" even at 3,400' unless you plan on ROUTINELY riding up to 6,000' .

Adjusting the "air jet" is the LAST bit of tuning you would try - once everything else doesn't work right.

Start "stock" and let your plug color be your guide.

If your bike is modified, or you want to "go rich" for some odd reason, tell us now.

 

its not modified at all, those were the jets that were in the carbs so I wasnt sure if I should leave them or not.

 

well guys, project is coming along nicely. should be putting last carb together tomorrow night, then comes the tuning and tinkering. question, to check to valves clearances, im gonna need a new gasket arnt I?

 

Not necessarily.
You might get lucky and be able to reuse the one you have.

If it was oiled before going together, last time, you should be good.

If you DO install a New Gasket use Elmers Glue or Gasket Sealant to hold the Ridge in the Mounting Channel.
Lube the Mating Surfaces.
Use a Artist Brush and "Paint" on a sheen of Oil so the Gasket Mates and "Squishes-down" tight.

Now is the time to replace the Rubber Donuts that are under the Collars of the Cam Cover fasteners.

 

you think eh? this carb project is sure way more expensive than you orignally might think haha. is it necessary to change these donuts?

 

If they haven't been changed, then they are compressed and hardened. That means that they won't give you the correct pressure on the valve cover when you re-install it. THAT means that you will probably end up with a valve cover that constantly leaks around the gasket no matter what you try to do.

Dave F

 

Those "donuts" are actually more important than the gasket itself, for the reasons Dave stated. While you've got a 50~50 shot that you can re-use the gasket, you'll certainly need new donuts.

If the gasket is hard, crispy or cracked/split anywhere, then replace it as well.

Once gasket and donuts have been replaced, they're good for many more 5000-mile valve clearance checks.

 

thaks for all the help guys, so stoked to get this baby back on the road this summer. got a few other plans for it too before this summer so gotta get this done! anybody know any website for mirrors?

 

Update your signature with your bike info as well as your location, makes it a lot easier to help ya!

Not sure what bike you're looking for mirrors for