How Do I I.d. An Exhaust?

Discussion in 'Bonneville' started by MartyWilson, Aug 23, 2020.

  1. MartyWilson

    MartyWilson Guest

    Not my area of expertise so I'm hoping someone can help. Got my third Bonnie last week (2001 790cc model) and she has peashooters but they don't have any markings on them to say what they are. I am guessing that they aren't Triumph as all the OEM ones I have seen have part no's etc. stamped on them and I don't think they are Norman Hyde Togas as I have those on my other 2001 Bonnie and the Togas are shorter and squatter where these are, if anything, marginally longer than stock. They aren't nearly as loud as the Togas either. Any ideas on what they are or how to find out?
     
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  2. Don the Don

    Don the Don Bigger Than The Average Bear

    Nov 5, 2019
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    Got a pic of them it might help in sorting them for you
     
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  3. Samsgrandad

    Samsgrandad Senior Member

    Dec 15, 2019
    605
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    Somerset
    Pictures would help but you might like to have a look on www.classicbikeshop.co.uk they do a variety of different silencers for the Bonnevilles, one of which is a pea shooter style
     
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  4. MartyWilson

    MartyWilson Guest

    When it stops raining I'll get her out and take a pic or two of the exhausts.
     
  5. Ducatitotriumph

    Ducatitotriumph Crème de la Crème

    Apr 25, 2019
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    #5 Ducatitotriumph, Aug 23, 2020
    Last edited: Aug 23, 2020
    I THINK the rules are that of it says "not for road use" then end of argument .
    But, if there's nothing, then thats ok.
    Also, if there's nothing on them, how are you to know that they’re not for road use and too loud Mr officer?
    Decent reasoning I think ?
    Hey, it's not my licence.....!!!!!
     
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  6. MartyWilson

    MartyWilson Guest

    Well I found the answer while taking some pics to put on here. I stuck my phone under the exhaust where I couldn't see myself without lying on the ground and, lo and behold!, printed on the underside of the exhaust is the details of the exhaust - Triumph A9600401 NOT FOR ROAD USE

    I am shocked and horrified, how on God's green did this pass the beady eyes of that nice MOT man? :grinning: Now all I have to do is figure why the bloody bike is spluttering badly at low revs and when cold and I will be happy.
     
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  7. MadMrB

    MadMrB Elite Member

    Dec 24, 2018
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    Northamptonshire, UK
    Removing the snorkel and fitting a vortex bellmouth (already had K&N filter) really improved the cold start on my 790, now it starts really easily from cold and maintains consistent idle rpm.

    https://www.squaredeals-ltd.co.uk/b...stack-bellmouth--air-intake-scoop-28063-p.asp
     
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  8. MartyWilson

    MartyWilson Guest

    Thanks for that advice @MadMrB You know I haven't actually looked under the side cover yet. The original snorkel is actually in one of the Givi panniers that came with the bike so I have assumed that a mod has been made but I have to add that there is a Triumph Twin Power Bellmouth (still in box) and a DNA filter that looks brand new in box also in the pannier.

    The problem I am having is that, if you crack the throttle too quickly while at a standstill the engine will die and needs to be gently revved and also, if I let the revs drop too low on the road the engine will stutter and bog down when I try to accelerate. This is worse when cold. I suspect that this is a fuel system problem but I am so rusty I could use a few pointers.
     
  9. MadMrB

    MadMrB Elite Member

    Dec 24, 2018
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    My mechanical abilities don't go beyond very basic tasks, but I agree it does sound like a fueling issue. Do you know if the jets have been changed to match the TORS?

    You probably already have these, but attached are two versions of the Jenks Bonneville Tuning Guide which suggests what carb configuration (jets etc) you should use for the various levels of modification (filter type, silencers, etc).
     

    Attached Files:

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  10. MadMrB

    MadMrB Elite Member

    Dec 24, 2018
    3,562
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    Northamptonshire, UK
  11. MartyWilson

    MartyWilson Guest

    @MadMrB I suspect that, given that the Air Injection has been removed and blanked off and the presence of the Triumph Twin Power Bellmouth and DNA filter in the pannier, that the previous owner had bought the TTP 'Stage 1 Torque Induction kit' so hopefully that means that he fitted the suitable TTP jets for a Triumph TORS exhaust. I am desperately trying to remember my 'how carbs work and how to adjust them 101' but I'm drawing a blank at the moment. I am wondering if it might be mixture related either getting too much or too little fuel when coming off the pilot jets onto the main jets but that is a stab in the dark. Need to consult the text books or an expert.
     
  12. Don the Don

    Don the Don Bigger Than The Average Bear

    Nov 5, 2019
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    Do a spark plug check the colour of those will tell you how it's running
     
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  13. Kinjane

    Kinjane Active Member

    Oct 15, 2017
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    Bristol, Land of Enger
    For less than a cup of boutique coffee a marine supplies store should be able to sell you a small bottle of Star Tron to put in the tank which will dissolve any ethanol deposits/gum in the jets that might be responsible for your bad fuelling before you start looking to change things elsewhere ;)
     
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  14. MartyWilson

    MartyWilson Guest

  15. Kinjane

    Kinjane Active Member

    Oct 15, 2017
    242
    43
    Bristol, Land of Enger
    That's the stuff, but my local boatyard chandlery sells it for just over £2 for a small bottle.
    Cleaned the secondary injectors on the car within half a mile.
     
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  16. MartyWilson

    MartyWilson Guest

    250ml bottle of Star Tron ordered from ebay. Unfortunately, although I live on a sea loch with yachts and a small marina I doubt anyone locally would have any Star Tron and it's a sixty mile round trip to the nearest chandlers I know of so would cost me more in petrol that I would save. Hopefully it will sort things out. Certainly the bike had done little more that sixty or so miles a year over the last ten years before I bought her (I suspect it was to the MOT station and back) and so there is every chance her carbs are a bit gummed up. She is not lacking at all in power in the higher rev ranges in all gears and it seems to be around about 1500 to 3000 revs, depending on gear, that she suffers a stutter and bogs down.
     
  17. Hobnail

    Hobnail Senior Member

    Jan 4, 2020
    1,245
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    USA
    Take a look at this for tuning assistance.
     

    Attached Files:

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  18. MartyWilson

    MartyWilson Guest

    Well interesting news... I got some Star Tron and put it in and there was a little improvement but she was still pretty much suffering the same stutter and dying when I twisted the throttle any more than gently and would choke at low revs on the road.

    Next step was to have a go at the pilot screws before taking a deep breath and overhauling the carbs. Guess what! The mixture screw on the left-hand carb was at exactly zero turns out and the right-hand one was at about 3/4 of a turn out. Not having a pilot screw driver in the toolbox I had to guesstimate the number of turns I wound them out but making them the roughly three/three and a quarter turns that my other '01 Bonnie has noted in her history as the pilot screw settings the problem vanished on the spot and she was roaring like a good 'un. In my other Bonnie's history notes it is noted that the mixture screws were set to this to cure a 'hesitation' at 2,000 rpm. This bike was definitely a bargain and I am guessing that part of that was because she was being off-loaded as a rough runner!
     
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  19. swampy61

    swampy61 Well-Known Member

    Mar 29, 2020
    125
    93
    Shropshire
    I had TORS exhaust on my sprint rs with not for road use discretely stamped on it. It passed every Mot since 2006 with it on.
     
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