Most likely if yoru dealing with the corks, your dealing with the large thread size on the petcocks. It is like 3/8 pipe or bigger (forget the exact size). Several of the suppliers sell an adapter to go from large BSA to standard 1/4 pipe size petcocks. Good way to go on a rider. The corks do get to be a maintenance pain.
Did you polish the inside of the petcock cavities? I use a pice of 1/4" round bar that has the end split to put a piece of 400 grit sand paper in to polish the inside of the petcock. Makes a difference in life and sealing. You'll be surprised how much crud comes out on the sand paper. Corks also wear out, they get to the point, boiling in water will no longer work. They are also available from the various suppliers.
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Re: thread size for push/pull petcocks#1026 02/22/058:07 pm02/22/058:07 pm
I have fought the petcock wars for years. The push-pull BSA petcocks are leakers! The solution is to get an adapter and use the Triumph style petcocks with the flat sheet metal handle. They use internal O-rings and a circlip that you can see from the handle side. I just tell my favorite dealer to send me what I need and he knows whether it is the Japanese versions or the English version that don't leak. I honestly don't know but mine don't leak. He also will send, if asked, the washers that go with the petcocks that have bonded on rubber to better seal the tank/petcock/adapter junctions. If you want to try that approach give my guy a call and I am pretty sure he can set you up with adapters and petcocks that don't leak. Keith Moore at Moore's Cycle Center in Anaheim CA (714) 447-4402. Tell him I sent you and be sure you understand the sequence of assembly from the tank to the fuel line. Ask Keith for that info. He is always extremely helpful.
Re: thread size for push/pull petcocks#1027 02/22/059:24 pm02/22/059:24 pm
From a post not long ago, seems BSA used both 1/4"BSP (British Standard Pipe) and 3/8"BSP. If you measure the hole or the thread of a tap you've got and it comes out almost exactly 1/2"OD, it's 1/4"BSP (yes, I do mean that - 1/4"BSP = 1/2"OD :rolleyes: ). 3/8"BSP will obviously be commensurately bigger.
Triumph taps are 1/4"BSP: those ones on eBay - they're what's being supplied to the trade, probably from China - everyone's got 'em.
Re: thread size for push/pull petcocks#1029 02/23/052:56 am02/23/052:56 am
There are two sizes of fuel taps for BSAs, the earlier, larger diameter, and the later, smaller diameter which are more or less "standard" (that is, the same as Triumph fuel taps).
I could swear that by 1970 BSA was using the smaller fuel tap diameter. These are the ones that are refered to above as 1/4", but the actual diameter to the outer edge of the thread is 1/2".
The earlier BSA fuel taps were like 5/8" or 3/4" diameter (again, measured to the outer edge of the thread). As was mentioned above, adapters are available to convert the earlier setup to the smaller standard fuel tap size.
Let's see here. On one hand we have a $3000 to $6000 vintage BSA motorcycle with, in some cases, years of parts chasing and again, in some cases, years of work to complete. On the other hand we have a $70 set of fittings that will stop a gas leak. Gas leaks cause fires. Fires can cause the total loss of what's in the first hand. $70 against $3000 to $6000 dollars seems a bargain to me. Did I miss something?
Re: thread size for push/pull petcocks#1031 02/23/0512:52 pm02/23/0512:52 pm
LD, I didn't understand your post at all. Does it have to do with something I said?
All of the aftermarket fuel taps that I've seen are the smaller diameter (actual 1/2" to the outer edge of the thread). If you have an older BSA ('67 may have been the last year) with the larger diameter holes in the fuel tank, there are brass adapters to take the holes down to the smaller size, and this is what I recommend for those, with aftermarket 1/4-turn taps. I have a pair of those adapters for my '67 and they work fine. Once you get them inserted and properly sealed up, they never have to be disturbed.
However, I don't think the adapters are necessary on a 1970 model.
since i've owned this bike since '78, i'm quite aware of the tendancy of some parts suppliers of sticking it to us at times. it's happened to me and i don't rationalize it away to make me feel better. screw me once it's my fault, twice it's mine
mark, i don't think the jibe was aimed at you.
the inference is that i don't care for the bike and that i'm stupid and careless. i guess that's why i asked for advice.
well, it has over 50,000 miles on it and no rebuild: starts first kick and runs like hell. obviously, if i didn't care for it, it wd. be scrap. i paid 500 dollars for it in '78 and if i was worried about money it wd. be for sale.
i have 4 bikes and it takes money to keep them in good shape; a dollar saved here is a benifit there. it's bone stock except for tires and clutch and i ride it whenever the weather permits.
70 dollars is about 2% of what the bike is worth... for fuel taps. the leaking is not external, which could indeed start a fire.
maybe ld sells parts?
mark, thanks for your help.
i better go out and see if my bike's on fire.
"the empty sky, how it tricks men." john berryman
Re: thread size for push/pull petcocks#1033 02/23/052:28 pm02/23/052:28 pm
Cat: Maybe you've already changed those corks sometime. If not, its pretty easy. Last ones I replaced don't leak after maybe a year and a half. And I have some spare corks put aside. Since these taps are one of the BSA "features" I love, I also risk burning down my bike I guess.
Re: thread size for push/pull petcocks#1034 02/23/052:42 pm02/23/052:42 pm
Cat: I thought of something else to tell you about. Baxter's is my favorite bike shop of all, and has been since the first time I walked in there. If I lived as close as you do, I'd be over there every week. Anyway, one time Randy took the time to explain to me that, generally speaking, the price he puts on stuff like that is just based on what he had to give for it. This would be obvious to a business man, I guess, but I had never really thought about it.
So I've learned that if any dealer seems really high on a specific item, they might make it up to you on the very next piece you want.
Re: thread size for push/pull petcocks#1035 02/23/0511:54 pm02/23/0511:54 pm
CAT was complaining about the $70 for a petcock set with adapters. My point was safety for your vintage bike investment is certainly worth more than $70. Complaining about the price of something as important as a petcock doesn't make sense to me. Getting the right fittings and petcocks that work and a petcock system that doesn't leak is priceless!
Re: thread size for push/pull petcocks#1036 02/24/0512:47 am02/24/0512:47 am
CAT , I've been all over this one for quite a while myself . I like the look of the push pull , but I have tried everything from new corks to NOS taps ( outrageously expensive , but pretty ) and they all leak , sometimes not at first , but eventually theu will , and sudden temperature changes seem to increase this .Anyway , that wasnt your question ...... I have a '70 Lightning tank that has the arlier style large holes for the taps , I have seen others , butthe smaller standard Triumph size seems to be the most common , so I guess you will have to measure what you have .If you do have the larger size bungs in your tank (that always sounds funny , doent it ??) that isnt an issue , as others have mentioned , there are readily avaialble adapters to reduce down to the required size.Keep in mind that when checking a petcock for tap size , you are usually looking for the I.D. of the pipe , where as when looking for standard hardware taps you are looking atthe O.D. of the bolt m so obviously a 1/4" tap for a bolt would pretty much fit inside a 1/4" pipe that would be tapped with a 1/4" pipe tap , if that helps you visualize things ???? obviously , the 1/4" pipe tap would be much larger than a 1/4-20 SAE tap .
Getting back to quality/$$ , I am a firm believer in spending $$ when/where necessary , and this may well be one of the places it is neccessary. I have tried the taps you show , theytend to leak internally after a season or so , I have tried the latest and greatest high $$ pre unit Triumph knockoffs , not a lot better , I have a set of NOS pre unit Triumph petcocks I havent tried them yet , hoping they are well made , but I did get a set last summer that cost quite a bit but I think they come with a guarantee, kinda pricey , kinda ugly(they appear to be machined from billet aluminum) but if they work I will use them on everything I won from now on . I had good luck with a company called Pingel on my "other" bike , I have been thinking about looking into them , they may have something for Britbikes?they were nearly $100 each last I looked , butthey worked .... just didnt look very British...If anyone has the answer , the taps that really work, speak up ...... -BONZO
I have 7 taps with adapters that I got from Keith Moore and not one leaks, ever. You can shop around and try several different cheaper ones or fool with the stock push-pull BSA petcocks trying to get them to stop leaking or you can call Mr Moore up and probably get the right fix the first time. You choose.
Re: thread size for push/pull petcocks#1040 02/25/051:23 pm02/25/051:23 pm
The all-metal, 1/4-turn petcocks I got from Walridge Motors don't leak, but they do bind a bit, especially when hot. Once in a while I take them apart (a snap ring holds the plunger in), clean and lap them with grinding compound.
Last year I broke one of the petcocks on my boss' '77 T140V. He insisted on the stock replacement tap, mainly because of aesthetics, but I have to admit they are good; they don't leak and they don't bind.
Cat, I hate the push pull taps.... I think the pitch is 3/8 BSP. Try on these BSA part #'s Part # 27-8443 Filter, this will also be a bushing to adapt down to a smaller, more common sized tap. Part # 65-8085 Tap Part # 68-8085 Transfer line, if your using a single carb. This is the set up I'm going with on my '65 L/R They were used on the MK II, according to my spares book. Good luck.
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