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in-line fuel filter?? why isn't there one?

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Guest

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Noob question:

it appears, the petcock is the only device that filters fuel before the carbs. That seems odd. What am I missing here? Why do most Gasoline engines have a dedicated filter before fuel dispersion? What makes my ultra sensitive quad carb config immune to needing a dedicated filter. I am at a loss.

P-
 
There is a pretty substantial filter screen attached to the petcock up inside the tank. Google: Suzuki petcock images.
 
I have a brand new petcock I will be installing on my "T". There is a screen in there as mentioned but I also have a fuel filter on as well.


Ed
 
Inline filters tend to actually slow fuel flow to the carbs. Especially if you use the kind intended for systems with fuel pumps. If youn tanks clean and the in tank filter is clean and not damaged you should never need added on stuff.
 
The float valves on the CV carbs have a small screen as well as the screen in the petcock. A lot of people don't do maintenance and if there was a more substantial filter I'd be willing to bet a lot of folks would be riding around with the carbs starving of fuel because of a clogged filter.
 
bonanzadave said:
There is a pretty substantial filter screen attached to the petcock up inside the tank. Google: Suzuki petcock images.
Click to expand...

That was my initial concern. What prompted this was, i recently went out to the shed to check the bike, give it a quick start, make sure battery was charged, that all was well. I noticed a gas smell. Last time I checked the bike and smelled gas was when I left the petcock on prime, filling the crankcase with fuel. So of course i got nervous. This time the petcock was in standard running position and there was some residue of fuel on the front sprocket cover. Bike was on the side stand, so it was fairly tipped over. No excessive fuel was visible, just the residue, and odor.

I took it out, and attempted to start it. I got some backfiring, and some air shooting sideways from what appeared to be the head gasket area, but i was unsure as to exactly where the blast of air came from. after a few more attempts, the bike started. I've driven it, it runs perfectly. And now starts properly, and has shown no gas leak ( at least not in a straight up position, its back in the shed on the sidestand , so we'll see what happens) . It shows no sign of a head gasket leak, or other rogue exhaust leaks. But it was unsettling when the puff of air blew onto my pant leg.

I know if the head gasket does leak I'm running a risk of damaging the bike. But there is no evidence there's a leak. It runs perfectly now, with all pipes getting hot, and idle and on road behavior as normal.

I never removed/checked the petcock when I got the bike, but the inside of the tank is really clean, and there's been no evidence of fuel contamination, but i was concerned after the backfiring. ( thus the reason for the fuel filter question.

I'm assuming my next move is to pull, check and replace the petcock if needed? and check the compression of course. Also, chef rebuilt the carbs but they haven't been vacuum synched yet...which may have an effect here....

( Oh boy... I'm gonna get some kinda motorcycle mechanic cert before this I finish fixing every neglected item on this bike, Im sure...gotta love it when the ad says " runs perfect....needs nothing" READ: I haven't ever maintained this pretty 1982 motorcycle......aauugh)
 
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You already have FIVE filters there, why do you think you need more? :-k

As others have mentioned, the primary filter is on the petcock, then there is another one inside the carb, just before the inlet valve.

.
 
Pb9717 said:
Oh boy... I'm gonna get some kinda motorcycle mechanic cert before this I finish fixing every neglected item on this bike, Im sure...gotta love it when the ad says " runs perfect....needs nothing" READ: I haven't ever maintained this pretty 1982 motorcycle......aauugh)
Click to expand...

Hey, did that seller ever live in Colorado. Sounds crazy familiar!
 
Burque73 said:
Hey, did that seller ever live in Colorado. Sounds crazy familiar!
Click to expand...

Nope....bike was from Wisconsin...one owner for 34 years. Said he drove it about 500 Miles a year. The way its been needing so much TLC, appears after 500 miles he would just put it away, and prayed it would run better the next year....
 
Steve said:
You already have FIVE filters there, why do you think you need more? :-k

As others have mentioned, the primary filter is on the petcock, then there is another one inside the carb, just before the inlet valve.

.
Click to expand...

Agreed....my concern is the prior owner has never done anything to ensure the petcock is filtering well. I'm assuming I have to remove and inspect it. Just to make sure its in good working order....
 
Pb9717 said:
Agreed....my concern is the prior owner has never done anything to ensure the petcock is filtering well. I'm assuming I have to remove and inspect it. Just to make sure its in good working order....
Click to expand...

I ran one of those small lawnmower inline filters (clear paper element) and never had an issue. That said; I did have to increase the flow because the stock petcock would starve the engine. Pingle with paper element in line and the 1166 ran fine.
 
Pb9717 said:
I'm assuming I have to remove and inspect it. Just to make sure its in good working order....
Click to expand...
That would be correct. Why not be prepared before you remove it, have the gasket ready AND the two sealing washers for the bolts that hold it to the tank. They have a rubber sealing area, so are not just 'standard' washers. You might find them at a GOOD hardware store, but they are somewhat rare.



posplayr said:
I ran one of those small lawnmower inline filters (clear paper element) and never had an issue.
Click to expand...
If you feel you MUST run an external filter, that is the proper one to use. Most don't bother to look for a lawn mower filter, they just grab a cheap one at the local auto parts store. The problem there is that an automotive filter is designed for a system with a pump, which will force fuel through a rather restrictive filter. The only 'pump' that we have is gravity, which is not nearly as powerful, so a filter designed for a gravity-fed system works best.

.
 
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Steve said:
You already have FIVE filters there, why do you think you need more? :-k

As others have mentioned, the primary filter is on the petcock, then there is another one inside the carb, just before the inlet valve.

.
Click to expand...

Where are the other three filters? If be inclined to run an in line filter figuring I can tend to that easier than the peacock screen and the carb bowl fuel valve (if my new to me '77 750b & '79 1000e have them). I have in lines (I think paper element automotive) in my old cb750 and xj550 without issue (not that many miles on either but they don't starve). And aren't the sintered lawnmower filters small for the fuel line? Lastly, I think on the xjforever forum I read to not use sintered general purpose filters as they break down with motorcycle vibration..
 
garyS-NJ said:
Where are the other three filters? If be inclined to run an in line filter figuring I can tend to that easier than the peacock screen and the carb bowl fuel valve (if my new to me '77 750b & '79 1000e have them). I have in lines (I think paper element automotive) in my old cb750 and xj550 without issue (not that many miles on either but they don't starve). And aren't the sintered lawnmower filters small for the fuel line? Lastly, I think on the xjforever forum I read to not use sintered general purpose filters as they break down with motorcycle vibration..
Click to expand...

I believe there are small screens inside the carbs just before the float valves.

Personally I use Emgo inline motorcycle filters... and I must admit that even with all that filtering (petcock, inline, in carb screens) I still find a little rusty looking debris in my bowls, but it doesn't seem to hurt anything.
 

Petcock picture --
Old & New from this years change on my GS850
You can see the screen filter material

IMG_20160512_111453106_HDR_zpsy9qnkaxg.jpg
 
garyS-NJ said:
Where are the other three filters? If be inclined to run an in line filter figuring I can tend to that easier than the peacock screen and the carb bowl fuel valve (if my new to me '77 750b & '79 1000e have them).
Click to expand...
Seeing that you have VM carbs, you only have ONE filter.

In the BS carbs, there is the petcock filter and one filter in each carb at the inlet valve (some call it the float valve), but your carbs do not have one.

.
 
The way I figure this is if you get anything in the carb, you have lost the battle and must pull the carbs.

If that little filter on the petcocks is the only thing to filter out krud, then you better keep it fresh.

Nothing is going to get through that paper filter, and you can see exactly what if anything it traps. No longer have this single point failure available to you.

The inline filter is cheap and since most are clear you can actually see if there is gas flowing.

You don't even need clamps becuase there is just no pressure.

And as mentioned, get the ones for a lawnmower and there will be no flow issues.

https://www.summitracing.com/parts/...1KPfDX8m0Ukn3Tqbeni3vouYqb_etK8kGYaAilE8P8HAQ
 
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