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Thread: Will Inline Paper Fuel Filter Starve Gravity Fed SC28 under high RPM? Reply to Thread
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  Topic Review (Newest First)
08-12-2019 11:10 PM
dualheadlamps
Re: Will Inline Paper Fuel Filter Starve Gravity Fed SC28 under high RPM?

Quote:
Originally Posted by IanDoohan View Post
The petcock is not “vacuum assisted”, when Honda had the SC28 with the fuel pump they put the in line filter in it after the pump to catch debris the pump may create. The SC28 petcock was just an on/off/reserve, in that if you left it “on” all the time, the pump would stop the gravity feed of fuel from overflowing the bowls.

When Honda went to the SC33 and deleted the pump, there was now a need to “automatically” stop the fuel flow once the bike was off so you didn’t have to turn the petcock off after each use, so they incorporated a “vacuum operated petcock”, so when the engine is running and creates vacuum it allows fuel to flow. When the engine stops running and no vacuum is present it stops fuel flow. So both the SC28 and SC33 petcocks flow the same amount of fuel, but the SC33 uses vacuum to stop it once the engine shuts off.

I used the OEM Honda fuel filter from the 93 in my 99.
I just assumed they were vacuum assisted on the S33 since it had a vacuum line going to it.

In that case I'll run my SC28 petcock for now with an OEM fuel filter in line and manually turn the petcock off.

Thanks for clarifying why Honda put the filter there in the pump operated bike, makes sense, never thought of the debris that can come out of a pump going kaput.
08-12-2019 10:58 PM
IanDoohan
Re: Will Inline Paper Fuel Filter Starve Gravity Fed SC28 under high RPM?

Quote:
Originally Posted by dualheadlamps View Post
I would just run the strainer with no filter as Honda designed the SC33 that way, but I'm in a bit of a pickle as my strainer is damaged. Just need the bike running now till I get the parts in, don't want to run with zero fuel filtering.

Is your 99 petcock just a gravity supply or vaccuum assisted? Problem is I just have the regular gravity petcock from the stock SC28.

Curious, what brand/type of in line filter do you run?
The petcock is not “vacuum assisted”, when Honda had the SC28 with the fuel pump they put the in line filter in it after the pump to catch debris the pump may create. The SC28 petcock was just an on/off/reserve, in that if you left it “on” all the time, the pump would stop the gravity feed of fuel from overflowing the bowls.

When Honda went to the SC33 and deleted the pump, there was now a need to “automatically” stop the fuel flow once the bike was off so you didn’t have to turn the petcock off after each use, so they incorporated a “vacuum operated petcock”, so when the engine is running and creates vacuum it allows fuel to flow. When the engine stops running and no vacuum is present it stops fuel flow. So both the SC28 and SC33 petcocks flow the same amount of fuel, but the SC33 uses vacuum to stop it once the engine shuts off.

I used the OEM Honda fuel filter from the 93 in my 99.
08-12-2019 10:23 PM
dualheadlamps
Re: Will Inline Paper Fuel Filter Starve Gravity Fed SC28 under high RPM?

Quote:
Originally Posted by IanDoohan View Post
I have one in line on my 99 track in addition to the strainer. No issues. I would surmize tht your SC28 wont have any issues either. I just run the strainer on my 93, no added filter.
I would just run the strainer with no filter as Honda designed the SC33 that way, but I'm in a bit of a pickle as my strainer is damaged. Just need the bike running now till I get the parts in, don't want to run with zero fuel filtering.

Is your 99 petcock just a gravity supply or vaccuum assisted? Problem is I just have the regular gravity petcock from the stock SC28.

Curious, what brand/type of in line filter do you run?
08-12-2019 9:13 PM
IanDoohan
Re: Will Inline Paper Fuel Filter Starve Gravity Fed SC28 under high RPM?

Quote:
Originally Posted by dualheadlamps View Post
The in tank petcock strainer on my SC28 is bad and needs replacing, currently removed. I don't want to run the bike with zero fuel filtering and wanted to know if running an in-line paper fuel filter between the petcock and the carbs would be okay while being gravity fed? Right now the bike is equipped with the stock non-vacuum operated petcock plumbed to bypass the pump and gravity feed the carbs.

I don't want the bike to run lean at high RPMs. Would it be okay? Also, any filter recommendations?


Cheers,

dualheadlamps
I have one in line on my 99 track in addition to the strainer. No issues. I would surmize tht your SC28 wont have any issues either. I just run the strainer on my 93, no added filter.
08-12-2019 2:22 PM
dualheadlamps
Will Inline Paper Fuel Filter Starve Gravity Fed SC28 under high RPM?

The in tank petcock strainer on my SC28 is bad and needs replacing, currently removed. I don't want to run the bike with zero fuel filtering and wanted to know if running an in-line paper fuel filter between the petcock and the carbs would be okay while being gravity fed? Right now the bike is equipped with the stock non-vacuum operated petcock plumbed to bypass the pump and gravity feed the carbs.

I don't want the bike to run lean at high RPMs. Would it be okay? Also, any filter recommendations?


Cheers,

dualheadlamps

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