354 exhausts low power
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    Junior Member
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    354 exhausts low power

    Hi all. I have a four into four exhaust pipe set fitted with no cross over or balance pipes in the system. I can wind the revs up to the red line when not moving, but the power just does not seem to be there when riding. Bike has standard carbs and points and I guarantee it is tuned precisely. Reckon I need to do something drastic to get over the sluggishness. Balance pipes, bigger jets? Had the bike years but never really used it so I am now just finding this out. Thanks all.
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    Senior Member R Powell's Avatar
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    Nice Bike! There is a mechanical advance and retard mechanism maybe this is stuck? What sort of speed does it go? I would think around 90 mph is about the mark. I would not have thought the pipes would make that much difference to the performance, are they standard?
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    Member Cosmo's Avatar
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    Quote Originally Posted by tony354 View Post
    Hi all. I have a four into four exhaust pipe set fitted with no cross over or balance pipes in the system. I can wind the revs up to the red line when not moving, but the power just does not seem to be there when riding. Bike has standard carbs and points and I guarantee it is tuned precisely. Reckon I need to do something drastic to get over the sluggishness. Balance pipes, bigger jets? Had the bike years but never really used it so I am now just finding this out. Thanks all.
    The standard exhausts should be open (and loud) Silentium 2-1's on each side with balance pipes between the inside headers at the silencer joint. The later 354 sport II's had more restrictive quieter pipes but of the similar design but black end caps, but it looks like you have new pattern italian "Quattro" pipes based on the earlier spoked wheel 350/500LS models anyway.
    In any event, the pipes shouldn't make that much difference, provided they are set up correctly, so check valve timings as well as carb jetting & needles and airbox/intakes. You are on your own with that set up as it is not standard for a sport. Remember the 354 is only a short stroke motor and power is only there right at the top of the rev range, but if the cams are off you won't get any real power at anything like the revs you need. The last one I had just about did a ton + on the flat tucked right in, but power was right at the top end - it likes revs!
    Back to basics I'm afraid! So check and check again.

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    Quote Originally Posted by Cosmo View Post
    The standard exhausts should be open (and loud) Silentium 2-1's on each side with balance pipes between the inside headers at the silencer joint. The later 354 sport II's had more restrictive quieter pipes but of the similar design but black end caps, but it looks like you have new pattern italian "Quattro" pipes based on the earlier spoked wheel 350/500LS models anyway.
    In any event, the pipes shouldn't make that much difference, provided they are set up correctly, so check valve timings as well as carb jetting & needles and airbox/intakes. You are on your own with that set up as it is not standard for a sport. Remember the 354 is only a short stroke motor and power is only there right at the top of the rev range, but if the cams are off you won't get any real power at anything like the revs you need. The last one I had just about did a ton + on the flat tucked right in, but power was right at the top end - it likes revs!
    Back to basics I'm afraid! So check and check again.
    Thanks. I ride big bikes and I am not too small either. Maybe I should thrash it more. I will look at settings but the carbs are well balanced and plugs good. I can only think valve timing, but they were set right. Maybe slip the cam around a bit on the cam chain. forwards or backwards? Hmmm. Don't think electronic ignition will do it - points are fine as they are. I will play - Thanks. Tony

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    Quote Originally Posted by R Powell View Post
    Nice Bike! There is a mechanical advance and retard mechanism maybe this is stuck? What sort of speed does it go? I would think around 90 mph is about the mark. I would not have thought the pipes would make that much difference to the performance, are they standard?
    Everything on the bike is fine. I can only get 70 on the clock. But it might be going faster as I keep up with traffic on the dual carriageway. It just feels reluctant around 4,500 to 8,000 revs - it won't pull through that band easily. Cheers, Tony.

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    Member Cosmo's Avatar
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    Yup, those symptoms do sound like the advance mechanism or the cam timing.
    It should do way more than 70 - even if you are a fellow of "larger" stature.

    With points, full advance is at about 4000 RPM and power will drop off massively if the bob weights don't "wake up" and aren't rotated at that point.

    Similarly if the ignition system check's out Ok on a strobe and statically, then you may have to pop the cam cover and followers off to check the cam timing properly with a timing plate protractor and dial gauge for TDC. Check the sprocket bolt holes line up exactly when the cam slot is level with the head. I have found a 654 engine with the cam sprocket needing to be removed and reversed on the chain just to get the bolts holes to line up exactly with the camchain/cam position and then to get the correct timing. It won't necessarily immediately look wrong unless you check properly, only a smidge out and it'll run, but no proper go.

    Note that despite the parts book and manual there are usually more than one pair of bolt holes on some of the sport models to allow for cam tuning.
    Retarding the cam timing usually gives more high RPM power but less at lower RPM. Standard timing is somewhere in the middle so that's probably where you should be. The original workshop manual is quite good and provides the info needed.
    I hope that helps and good luck!

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    Quote Originally Posted by Cosmo View Post
    Yup, those symptoms do sound like the advance mechanism or the cam timing.
    It should do way more than 70 - even if you are a fellow of "larger" stature.

    With points, full advance is at about 4000 RPM and power will drop off massively if the bob weights don't "wake up" and aren't rotated at that point.

    Similarly if the ignition system check's out Ok on a strobe and statically, then you may have to pop the cam cover and followers off to check the cam timing properly with a timing plate protractor and dial gauge for TDC. Check the sprocket bolt holes line up exactly when the cam slot is level with the head. I have found a 654 engine with the cam sprocket needing to be removed and reversed on the chain just to get the bolts holes to line up exactly with the camchain/cam position and then to get the correct timing. It won't necessarily immediately look wrong unless you check properly, only a smidge out and it'll run, but no proper go.

    Note that despite the parts book and manual there are usually more than one pair of bolt holes on some of the sport models to allow for cam tuning.
    Retarding the cam timing usually gives more high RPM power but less at lower RPM. Standard timing is somewhere in the middle so that's probably where you should be. The original workshop manual is quite good and provides the info needed.
    I hope that helps and good luck!
    Hi. I shall have a look at cam timing. everything else is definitely correct. I have owned so many bikes of all descriptions and when something is wrong - I usually find it. But this is a pain1 Cheers.

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