Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: sprinta on December 30, 2021, 10:32:10 AM
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I have just bought a new set of Yamiya no number 300's and would like to know if any of you have found a treatment or process to protect/preserve, as best one can, the inside of the pipes before use to hopefully prolong their use by stopping/slowing down internal rust/corrosion?
Even from new, as a result of all the various chemicals used during the chroming process, there will be some that will not have been flushed out due to the internal structures trapping some and as a result there will enviably be some rust/corrosion already present.
I know that some recommend an annual filling and draining of old/new engine oil, but this is a far too messy and time consuming procedure for me to do on an annual basics and whilst happy to do whilst before they have been used for the first time is this the best procedure for what would hopefully be a first time and once only process?
I know that short journeys and blocked drain holes are the killer for these pipes and I never do a ride of less than 30 miles and always ensure that the drain holes are clear, but even so the ends of the pipes rarely get more than warm.
Have any of you found alternative treatment/processes?
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My 500 pipes are now 30yrs old,
Before you fit them, pour oil into them, and try to coat all the nooks and crannies are immersed,
But your doing the right thing, very few short journeys,
Make sure you get the pipes hot,
Riding up a long hill at 8,000rpm in 4th,
Burn any debris out,
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For different reasons Sprinta, I add 2 stroke oil to all my bikes; at 150:1 or so, and primarily to prolong the tank life. I’ll assume it can only help wrt exhaust life too, and am now keen to learn what the experts in the field have to say …… ?
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Just run the bike a tad on the rich side, rather than leaner.
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I'm a fan of adding low dose of 2T oil every four tank fulls or so.
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I used to pour 2T oil in my pipes, seems to work on two stroke exhausts so why not 4 strokes.
Cheers
Dennis
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For different reasons Sprinta, I add 2 stroke oil to all my bikes; at 150:1 or so, and primarily to prolong the tank life. I’ll assume it can only help wrt exhaust life too, and am now keen to learn what the experts in the field have to say …… ?
I see that the same and feel it's beneficial to these exhaust considered how much a replacement is going to cost.
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Just run the bike a tad on the rich side, rather than leaner.
I've the opposite view of combustion julie, the leaner running gives less unburnt content to get the exhaust dryer and less likely to corrode.
You can see it to an extent in cars, years ago with them generally running much richer and prior to more concise mixture control, gave atrocious outflow to exhaust systems with replacement being fairly routine.
With more lean and concisely monitored running conditions it has helped many system run almost indefinitely in relative sense.
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My brother bought a repro set for his Z1 what he did was buy a tin of hamerite paint poured it into each pipe swirled it around to coat all the inside then hung them up for 2-3 days to let eccess drain out he tells me no smell of paint and been on bike 6 years now
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Graham's 750 K6 is still on the original pipes at 42k miles, with just a couple of very, very small weld repairs on the underside of the bottom right silencer ( the usual place for them to rot) . The previous owner of the bike used it as his daily hack for years and years. I've no idea if the modern versions last this long without rotting out totally though.
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I periodically put some 2 stroke oil in the petrol,
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Thanks for all the replies and suggestions.
I removed the detachable end baffles and popped a bore camera inside, so this is what the new unused exhausts look like even before they have been used!
Last one is via the downpipe looking at the end baffle basket.
Might pour some rust converter inside to kill(?) the existing rust/corrosion and then pour in some: Oil, ACF-50 or what?
Has anybody had any experience of the Frost internal Exhaust Coating: https://www.frost.co.uk/ew-hi-temp-internal-exhaust-coating/
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Welding oxidizes the steel during manufacturing with that locally sited (along the weld sites) being fairly typical.
Saying that, they look particularly clean for the reality of the production process, and quite impressive from those shots of the quality of manufacturing. You can see that the welding heat has travelled quite short distances from weld site, showing a decent competency of weld process.
Just an aside to any "treatment" liquids etc, check them on something else chromed first to avoid any impairment of the finish.
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Wrt adding 2T to the petrol, no one’s yet commented upon the life expectancy of the bigger two-stroke bike exhausts. All those RD400 / GT550 owners - how do your exhausts fare / look internally?
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I have a 1973 RD125,
the exhausts seem perfect (https://uploads.tapatalk-cdn.com/20211231/443c9eb1f3d899298bf8788d884dc8d5.jpg)
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Blimey John; if those exhausts are the originals & 49yo then it’s a fair advert for 2T. (assuming the bike has done a fair mileage)
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26,000 when I got it (https://uploads.tapatalk-cdn.com/20220101/ac0ee2361e9261cf1513c843b7254d2d.jpg)
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