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  1. #1

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    Default Oil pressur on a 1970 Triumph 650

    Hi, I am new to this forum but not to the worls. I am looking at a 1970 Triumph 650 Chopper. The guy that owns it advised me that when he started it, it blew off the oil tank plug. What he did to prevent it was drill a small hole in a bung on the top of the tank. The problem is that you cannot tip the bike to the right or left without oil coming out of the hole he drilled. What would cause the plug to blow off in the first place? Any help would be appreciated. Thanks, Jim

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    Well the oil tank needs to be vented and also needs room to breathe in there. Sounds like a poorly designed oil tank.

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    The problem could be tank, vent system plumbing or crankcase pressure.

    Unless you're already very experienced and comfortable with vintage Britbikes, run away. They are delicate junk on a good day and killed their parent companies. They are OK fourth or fifth bikes. I'm not exaggerating and I have two Nortons and a Trident. I daily Evo FXRs for good reason. Romantics jacking off to their dead youth forget Britbikes require extreme dedication, can not possibly be made reliable by modern standards, and their "reliability" makes Ironheads look good. They vanished from the roads rapidly after better machines destroyed their sales.

    If ya want a chopper buy/build a five speed Evo Sportster. I just saved you serious pain. I'm happy to help those with Britbikes but the best thing I can do for someone considering one is warn them off.
    Last edited by farmall; 08-12-2019 at 2:51 PM.

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    Quote Originally Posted by farmall View Post
    If ya want a chopper buy/build a five speed Evo Sportster. I just saved you serious pain. I'm happy to help those with Britbikes but the best thing I can do for someone considering one is warn them off.
    Best advice around! I am into vintage British bikes and there was a LOT of changes over the years just on the unit 650s from 63-70, let alone the entire range of twins from the prewar twins to the demise in 1980s.

    As others have said, an oil bag NEEDS a vent, However there is other issues. I wrote up a very long and complicated tech post about the rocker box bypass on the return line as well as some bodgers who obstruct the oil return line in the oil tank itself. Triumph oiling, while a good, decent design, sure can use some mods and upgrades and thats a topic in itself. Want to start a war? Start discussing whats the best oil! Those have raged for years and pretty heated on some forums.

    When you get into Choppers, Heres something I learned when I opened a full time Brit bike shop. I initially assumed I would do 80% stock and restorations, a few customs and assorted rebuilds and parts/sales/service. I was wrong. The truth is, stock, restored or show bike British bikes usually add up mileage on & off the trailer and going to shows. They rarely break, need service or serious overhauls.

    However cafe, bobbers, choppers and customs in general tend to get ridden hard and put away wet. Some fool tries to race sportsters or a jap sport bike and blows up his scoot and wants it done before the weekend so he can do it again.

    Now heres where some will get their panties in a twist. Most people with a custom or start building one tend to have the least skills, knowledge or experience. I knew another well known shop/builder who said "Some fool gets out of jail or county lock up, reads about me in the horse and wants a chop and then when things go badly, starts threatening me, my shop or family."

    But, its not all bad, I know a number of people with really reliable British iron and either they learned along the way with some help and education, Or they brought enough skills to the situation they were up and running without too much help. But they are labor intensive and there is a LOT of tribal knowledge and learning how some of this stuff works, especially British designed. Once you learn it,, it makes sense and is pretty simple.

    But my point is, Someone elses Chopper is usually a time bomb, Not always, but usually very badly screwed up mods and mistakes. Tread carefully. Do some research and find someone knowledgeable to do a FPI (*First Person Inspection) That in itself can be tricky. I am in some vintage clubs and they are full of opinionated folks full of misinformation and urban myths.

    I consider any used, especially British or vintage HD, bike to be nothing but a core for a total rebuild. Only a few rare people I would say get on and ride it! But I have million stories of WTF? moments when I tear into a vintage bike of DPO (* Dreaded Previous Owner). In a few cases everything was surprisingly excellent condition and all I am out is gaskets, seals and my time.

    But after wrenching on stuff, I have a bad case of "Knockitis" Riding down the road I picture every squeak, creak, ting, ping and rattle of what it could be and what could happen. If I went thru it myself, I dont worry about it. Plan for the worst, hope for the best

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    From your profile, it looks like ya already got a '70 Triumph chopper, and a 750-4 Honda chop. Most Brit chops got a bad rap from 'builders' that didn't really know what they was doing, plus using worn out Amal carbs and sketchy Lucas electrics, combined with parts vibrating loose and falling off, and patch-together 'custom' wiring. Lack of knowledge about the engines and lack of much needed regular maintenance kept them from reaching anything close to reliable.

    But, Triumph did one thing well to those that were dedicated; turned ordinary men into mechanics.
    Click image for larger version. 

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    Here is a site which has an overload of info for the '69 Bonneville - just learn the few differences with your 1970 (such as crankcase venting through the primary), study intently and before you know it, combined with the proper tools, your Triumph will help you to become a mechanic too:

    The Bonnie Ref
    A Hyperlink Junkie's Illustrated Field Guide to the 1969 Triumph Bonneville
    http://www.hermit.cc/tmc/om/manual.htm

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    Tanks need expansion room/"ullage" ant they need the vent to be well above fluid level. Amateur tank fabbers often forget this but it's extremely basic.

    Vents should be located (inside the tank) away from return oil splash.

    Got a pic of the tank? If you're stuck with the bike might as well sort it out.

    Now heres where some will get their panties in a twist. Most people with a custom or start building one tend to have the least skills, knowledge or experience. I knew another well known shop/builder who said "Some fool gets out of jail or county lock up, reads about me in the horse and wants a chop and then when things go badly, starts threatening me, my shop or family."
    Deserves to be on a bronze plaque.

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    My 1st bike was a 67 tiger. I rebuilt the motor 3 times. I dont like babCOCK bearings, lost a oil pump on the way home from laconia , lost electrics a few times. Got smart put a ard mag in, i rode the shit outa that bike all over new england.
    You learn real quick how to work on them.
    Lota memories. I choped mine and had more pussy on that CJ king and queen.
    Paid 600 bucks the bike was 11 years old when i got it and it was falling apart.

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