Author Topic: Goober in the Carb  (Read 3190 times)

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Offline Bruin

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Goober in the Carb
« on: October 02, 2014, 12:25:55 PM »
It has been a month + since I ran Bonneville motorcycle speed trials and I finally got around to pulling the Mikuni carb. There was a teaspoon of powdery granules in the float bowl. What the what? Granted, I run a non-filtered velocity stack but how does anything get down the needle tube into the sealed bowl? I did use gas from the fuel truck but that was filtered before getting to the carb. The brass fittings (prime pump & idle screw) were nearly fused in place. Salt oxidation? And there was a little thin white deposit in the bowl, salt? Granted it was a very wet event this year but I only had a chance to run the 82 XR 500 a couple of runs. I've never had this much goober in the bowl and how any gets in there is mysterious to me. Anyone else get this much bowl deposit? Explanation?
STD; Speed Team Doo
'82 Honda 500 APS-AF
'70 Triumph 250 MPS-PG
'71 Triumph 250 APS-PF
'70 Triumph 250 M-PG

Offline rouse

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Re: Goober in the Carb
« Reply #1 on: October 02, 2014, 02:07:03 PM »
Was you running GAS or methanol ??

What was in your gas if you were running gas??

Methanol will do that to aluminum parts (like float bowls), if it sets for any time at all, even a week.

Rouse
Johnnie Rouse
Bike 4680 P-PP2000 SCTA record 153.325    A-PF3000 182.920
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Offline wobblywalrus

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Re: Goober in the Carb
« Reply #2 on: October 02, 2014, 09:54:06 PM »
Folks see this in their combustion chambers, according to this forum.

Offline Bruin

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Re: Goober in the Carb
« Reply #3 on: October 03, 2014, 12:19:28 AM »
I ran the 110 octane from the gas truck. I drained the tank today and it was clean. I pulled the head, the cylinder and piston looked normal in every way. I did talk to an engineer and he explained that the brass to aluminum adhesion in the carb was a galvanic reaction precipitated by the salt (electrolyte). But he had no explanation for the volume of granules in the float bowl.
STD; Speed Team Doo
'82 Honda 500 APS-AF
'70 Triumph 250 MPS-PG
'71 Triumph 250 APS-PF
'70 Triumph 250 M-PG

Offline wobblywalrus

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Re: Goober in the Carb
« Reply #4 on: October 03, 2014, 12:33:14 AM »
Sending a sample to a lab for analysis can answer your question.  Often it is not as expensive as as one thinks it will be.

Offline manta22

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Re: Goober in the Carb
« Reply #5 on: October 03, 2014, 01:49:01 AM »
Copper fuel line & fittings are not recommended for fuel lines. Copper acts as a catalyst to degrade the fuel. I suppose the alloyed copper in brass fittings would do the same.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Bruin

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Re: Goober in the Carb
« Reply #6 on: October 03, 2014, 05:41:01 PM »
I pulled the Mikuni carb on my wife's bike. It has air and fuel filters and thanks to a petcock that seeps a little, the float bowl stayed full of gas. Amazingly, it too harbored salt crystals. (See Picture) I'm thinking the only access to her bowl was through the gas line. I theorize that there was salt in the race gas we purchased from the truck. As the gas evaporated and refilled the bowl, it became concentrated and formed crystals. The same thing happening in two different bikes with one source of fuel. I'm going to post this in the BMST page to see if anyone else had this happen.
STD; Speed Team Doo
'82 Honda 500 APS-AF
'70 Triumph 250 MPS-PG
'71 Triumph 250 APS-PF
'70 Triumph 250 M-PG

Offline wobblywalrus

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Re: Goober in the Carb
« Reply #7 on: October 03, 2014, 10:08:56 PM »
There are brass fuel line fittings on my bike and the float valve and jets are brass.  No corrosion problems observed during the use of many types of gasoline. 

Offline Bruin

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Re: Goober in the Carb
« Reply #8 on: October 05, 2014, 11:40:26 PM »
Clue: I have drained and inspected both gas tanks, neither show any sign of salt like deposits. So the gas may not be contaminated. It is looking more and more like they are forming when the saline heavy air meets the gas. But I am still astounded by how much formed in both carb float bowls, it's not like there is an air scoop directing air into the float bowl.
STD; Speed Team Doo
'82 Honda 500 APS-AF
'70 Triumph 250 MPS-PG
'71 Triumph 250 APS-PF
'70 Triumph 250 M-PG