Author Topic: Fuel Filters ? (Read 5659 times)

rddcw · « **on:** December 19, 2015, 04:10:00 AM »

Rebuilding my 74' CB 750 K4 carbs. What type and size of fuel filters are you guys using ? I'm assuming 1/4" ? Thanks !

Stev-o · « **Reply #1 on:** December 19, 2015, 04:34:44 AM »

No filter on my K4, why do you think you need one? If there is an issue with your fuel tank, address it.

Your fuel line should be 5mm, 1/4" is too large.

rddcw · « **Reply #2 on:** December 19, 2015, 04:53:55 AM »

Tank Clean but nice to extra protection, so that's why I would like to have them.

strynboen · « **Reply #3 on:** December 19, 2015, 05:03:32 AM »

inline filters give a bad fuel flow..specily on 500/550..there is not heigh differens to give that ekstra pressure to press the fuel through the filter..and a light vaccum can easy give problems...if you have rustfree tank..there is no need for ekstra filters..more then that there is build inn the tank/ fuel tap. i have big problems doing the ton.it helped remove, the ekstra filter..(.fine rust can go through the filters and block the fuel..anyvay..)
.sorry for my bad english

Deltarider · « **Reply #4 on:** December 19, 2015, 08:53:28 AM »

Quote

inline filters give a bad fuel flow..specily on 500/550..there is not heigh differens to give that ekstra pressure to press the fuel through the filter..and a light vaccum can easy give problems...if you have rustfree tank..there is no need for ekstra filters..more then that there is build inn the tank/ fuel tap.

I agree. The inline filters I once had, brought nothing but trouble. The stock filter is excellent. No need for more.

flatlander · « **Reply #5 on:** December 19, 2015, 10:28:19 AM »

another vote for clean tank and OEM in-tank filter. nothing else needed, and everything else just gets in the way of flow.

BobbyR · « **Reply #6 on:** December 19, 2015, 11:16:09 AM »

I vote for a clean tank and a filter. The trick is using Tygon tubing which is more flexible. The trick to use a 90 degree filter. Have that line from the petcock at as steep and angle as you can to the filter inlet. Have the outlet of the filter basically be a straight drop. Been doing this for years on my K8 with no issues.

Kenzo · « **Reply #7 on:** December 19, 2015, 11:34:22 AM »

I've got two of those chrome & glass(huge & heavy) filters and two plastic inline filters(cheap) that have gone unused...just too cumbersome.

Cleaned the tank, got the rebuild kit for the petcock filter and I ain't look'n back.

IMO the in-tank petcock filter is the way to go.

Cheers

2wheels · « **Reply #8 on:** December 19, 2015, 07:38:18 PM »

I have been using the 1/4 inch fine mesh or sintered bronze for 40 years now, never had a problem.
Bike rarely sees wide open throttle or speeds over 70 mph. That could be a factor.

I had a tank empty onto the ground once because of crap in the float valve. Has never happened since I have used in line filters.

rddcw · « **Reply #9 on:** December 19, 2015, 09:15:41 PM »

Bobby, I'm assuming your using a 90 degree 1/4" fuel filter ? Are you using 2 ?

Don R · « **Reply #10 on:** December 19, 2015, 11:13:30 PM »

I had a problem with a filter once. I use them anyway.

seanbarney41 · « **Reply #11 on:** December 19, 2015, 11:36:35 PM »

Quote from: 2wheels on December 19, 2015, 07:38:18 PM

I have been using the 1/4 inch fine mesh or sintered bronze for 40 years now, never had a problem.
Bike rarely sees wide open throttle or speeds over 70 mph. That could be a factor.

I had a tank empty onto the ground once because of crap in the float valve. Has never happened since I have used in line filters.

this...wouldn't want to go over 70 now would we?

70CB750 · « **Reply #12 on:** December 20, 2015, 02:21:57 AM »

Petcock sediment bowl with filter is all thats needed, imho.

dhall57 · « **Reply #13 on:** December 20, 2015, 04:24:35 AM »

Don't run them on my KO or K6. No need to.

carnivorous chicken · « **Reply #14 on:** December 20, 2015, 07:35:00 AM »

I always run filters, and have never had fuel flow problems on 350Fs, 400Fs, 550s and 750s -- as well as other bikes.

Rumpelkrankshaft · « **Reply #15 on:** December 20, 2015, 12:38:02 PM »

Don't use them on the 550/4, had big trouble once on another bike which was result of in-line filter causing vapo(u)r lock.

PeWe · « **Reply #16 on:** December 20, 2015, 01:46:24 PM »

If never a problem with a fuel filter, it was not needed then, right? If a filter is needed due to particles follow the fuel, filter must be clogged and problem.

I got problems when I used a tank not properly rinsed after derust. Petock filter clogged after 15km ride and carbs got some too. Changed to my new tank and cleaned the carbs pilot circuit by spraying carb cleaner. A 250km long slow ride with constant low throtttle lift due to other Harley, Vincent riders finally cleaned the pilot circuits that got some dirt.

I did never have any problems before. CB750K6 with single fuel pipe and nylon mesh around the petcok inlet insode the tank. Bike was stored outside some winters under a simple cover.
Now using a new tank with the old petcock type with 2 pipes and brass mesh. Tank that clogged has also the old petcock type, but new. The old style petcocks might be clogged easier due to the relatively small filter area inside the petcock?

I have no space left for fuel filters. Hoses routes especially to fit the Mikuni TMR32 carbs.
Clean tank is good.

carnivorous chicken · « **Reply #17 on:** December 20, 2015, 02:00:27 PM »

Quote from: PeWe on December 20, 2015, 01:46:24 PM

If never a problem with a fuel filter, it was not needed then, right?

Not necessarily. When I said I've never had problems, I meant I've never had fuel flow problems when using filters. The in-tank nylon filters can fall apart, petcock screens develop holes, and an in-line filter is simply one more way to ensure nothing makes it to your carbs. I've once had to change a filter because, after three or four years, it started to get clogged. But changing the in-line fuel filter was a hell of a lot easier than pulling my 350F carbs.

Some people run them, some don't, but all I am saying is it's never caused me problems.

jonda500 · « **Reply #18 on:** December 20, 2015, 05:35:15 PM »

I used to use two auto style fuel filters on my RZ250R - no problems unless I let it run out fully before switching to reserve- then it would take around twenty kicks to get it going again -I learned to fill it before it got to reserve and then had no further trouble.
I have never used any fuel filter on any SOHC/4 that I've owned - it's not hard to regularly clean the sediment bowl and occasionally drain out the float bowls

John

2wheels · « **Reply #19 on:** December 20, 2015, 06:22:36 PM »

Quote from: seanbarney41 on December 19, 2015, 11:36:35 PM

Quote from: 2wheels on December 19, 2015, 07:38:18 PM
I have been using the 1/4 inch fine mesh or sintered bronze for 40 years now, never had a problem.
Bike rarely sees wide open throttle or speeds over 70 mph. That could be a factor.

I had a tank empty onto the ground once because of crap in the float valve. Has never happened since I have used in line filters.
this...wouldn't want to go over 70 now would we?

Yeh I get it. Being a bit poky isn't cool, but some of us just were not ment to race. If you drive like these bike can a fuel filter in the line may cause poor gas flow. I just wanted the OP to know that if he is a WOT kind of guy extra filters may cause problems.

Deltarider · « **Reply #20 on:** December 20, 2015, 11:36:27 PM »

Quote

and an in-line filter is simply one more way to ensure nothing makes it to your carbs

Then... why not have 2, 3, 4?
After 35 years of experience I side with Strynboen. Specifically for the 500/550 best is to run the OEM filter, have the fuellines at standard length and in the right diameter (5,5 mm). Make it a habit to drain the carbbowls say every two months. That's it.
If, for a reason (that I don't understand) you must have an inline fuel filter, then choose the one with the paper filter inside. But for the 500/550, if you want troublefree, go without any extra filters.

carnivorous chicken · « **Reply #21 on:** December 21, 2015, 06:48:03 AM »

Quote from: Deltarider on December 20, 2015, 11:36:27 PM

Quote
and an in-line filter is simply one more way to ensure nothing makes it to your carbs
Then... why not have 2, 3, 4?

Now you're being ridiculous.

flybox1 · « **Reply #22 on:** December 21, 2015, 07:02:54 AM »

For any who have a horizontal petcock outlet, a 90deg Visu-filter works great.
You can even reverse the flow with some carb cleaner to rinse them out.

Henning · « **Reply #23 on:** December 21, 2015, 12:59:36 PM »

I have/have had two 750's. On the first one the inside of the tank was rusting badly, to the point it totally clogged the petcock filter and the bike wouldn't run. A five minute roadside repair and I was on my way again. On the current one the inside of the tank is good, apart from slight rust along the tank seams. The rust leaves a very fine dust in the petcock bowl and float bowls, which I know because I now have read the manual and know you're supposed to the clean the petcock filter for every 5000 k's.

Neither issue ever caused any problems with the carbs themselves, stuck float valves or blocked jets. Take it as a vote for not needing an inline filter.

BobbyR · « **Reply #24 on:** December 21, 2015, 01:05:44 PM »

Quote from: flybox1 on December 21, 2015, 07:02:54 AM

For any who have a horizontal petcock outlet, a 90deg Visu-filter works great.
You can even reverse the flow with some carb cleaner to rinse them out.

That is exactly the setup I have used for over 15 years with no issues WOT throttle whatever. Never had a problem and protects me from dirty gas some of these places pump if their tanks happen to be low or they just took a delivery and stirred up the bottom.

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Author Topic: Fuel Filters ? (Read 5659 times)