usernameandpassword
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KH400 vs S3 exhaustYou know here's something funny I noticed. I've seen a few posts on how the KH400 exhaust was more restrictive than the S3 design. I've never opened up the two and did a '1 for 1' look to see what the differences are.
I purchased a set of KH400 exhaust for my S3 when I was restoring it. It was the only ones I could find that were in decent shape and were not too costly. I would like to put on the correct exhaust one day....maybe trade the KH400 exhaust for an S3 set. I've run this bike with the standard exhaust on it for more than 20 years but they were getting really rough, one pipe lost a plate, a baffle was broke off, chrome was in terrible shape from battery acid leaks, and one had a hairline crack at the bend under the brake pedal I could not get permanently fixed. I threw this KH exhaust on it and drove it around for the last two years.
Some people say there more restrictive but I could not tell the difference on my S3 from the standard S3 exhaust. Both sets cut the engine curve in at 5500 and there to 8500 was all band. It wanted to turn even higher than that with strong power. Low end torque was still pulling good at 3500 up and it has no problem getting out of the way. :-D Carb sync and setup was the same for both exhaust....jetting did not have to be changed. Both exhaust setups seemed to be pulling evenly.
Here's something I did notice recently. I pulled the baffles out to clean the packing and such and decided since they were a more restrictive design from what I was reading I would try them without the packings, to make them move gas more freely. On the test runs it appears that the curve now seems to roll in at 6K and still pulls strong. I didn't notice any real horse difference in the upper RPMs.
Question...Does anyone know for sure the differences between the two sets other than a guestimate? Has anyone actually cut the two open and looked where the stock baffle plates and cones are that can say for certain...this is the difference. Later this year I'm going to 'volume' the exhaust and see if there really is a difference in the amount of real estate inside these exhaust. I'm sure there is something.....hence the different DGM numbers but I'd really like to know what the real world differences are.
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nickt
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kh400 exuastshi i once owned a 400s3 myself,the difference between the the s3 and kh exhausts was a different design in the baffle plates.this was an attempt to reduce the emmissions slightly on the later bike,at this time the americans where trying to outlaw certain 2 strokes in the name of pollution.anyway there were also other differences,the carbs on some of the earlier models were larger and had larger jets the airbox was also less restrictive.these same differences also existed between the s1 and the kh250 (the s1 was quicker than the kh250)while fitting these pipes to to your bike wont do any harm you would not benefit from any power gain unless the other differences were addressed also.triple exhausts need a regular clean inside to keep them clear,what happens is where the pipes kick up shortly after the downpipe union unburnt fuel and 2stroke oil collect.ive had them block that badly that the bike wouldnt do over 40mph.
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usernameandpassword
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Re: kh400 exuasts | nickt wrote: | | ...while fitting these pipes to to your bike wont do any harm you would not benefit from any power gain unless the other differences were addressed also. |
Thanks for the reply Nick however I do have a 75 S3 with the bigger carb jets and less restrictive airbox. You'd think fitting the KH pipes would have toned it down a little but actually it didn't, the bike ran the same with either exhaust.
Just by fitting less or more restrictive pipes, I also would have thought that a jetting change may be required but that was not the case either.
I did see where the KH baffle runs a different part number. Since I have both exhaust, I will take a look and see if any real considerable differences exist. I definitely want to do a volume test when I get it in for the winter, to see if the inside chamber did change with the volume it can hold. I have to install a new exhaust gasket anyway.
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dandare
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A good mod was to cut about 4 inches of the end of the KH baffle, that helped.
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ThreePipesSmokin
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Triple Ed told me that the KH500 pipes were dimensionally the same as the H1E/F but were coated inside with a coumpound to reduce noise. Maybe the KH400 pipes are the same as the S3 with the coating and different baffles? :smt102
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netbikes
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Re: kh400 exuasts | nickt wrote: | | .triple exhausts need a regular clean inside to keep them clear,what happens is where the pipes kick up shortly after the downpipe union unburnt fuel and 2stroke oil collect.ive had them block that badly that the bike wouldnt do over 40mph. |
If your not worried about a little oil on the floor drill a small hole at that point.
The unburnt excess oil will leak out which should solve the problem.
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husson73
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For sure S3 are better cause less restrictive.
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ThreePipesSmokin
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Re: kh400 exuasts | netbikes wrote: | | nickt wrote: | | .triple exhausts need a regular clean inside to keep them clear,what happens is where the pipes kick up shortly after the downpipe union unburnt fuel and 2stroke oil collect.ive had them block that badly that the bike wouldnt do over 40mph. |
If your not worried about a little oil on the floor drill a small hole at that point.
The unburnt excess oil will leak out which should solve the problem. |
Just keep the front wheel in the air long enough and often enough to keep the oil drained out of the pipes! :thumright:
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