Anyone that use HM300 pipes on a modified engine?
836, ported head, moderate cam, Mikuni VM29.
Too restrictive even with no baffels? Or is a 4-1 much better?
I like the OEM 4-4 design that will take my bike back to the glory CB750 era.
The HM300’s will be just fine and I also prefer them for their classic looks and sound for street engines up to 836. Much of the HM300 old vs. new sound difference comes from the baffle packing material. The original baffle had a thin, fluffy fiberglass wrap secured by wire which required regular re-packing to maintain the sound level. The new style baffle packing has a thick, pressed style fiberglass wrap which lasts a long time, but reduces the sound level.
The solution here is to wrap the baffles just as Honda originally did. Pick up some aftermarket packing and wire them up to restore the original HM300 sound. This setup will take your 836 back to the early glory days with it’s ear-pleasing exhaust note. Running the baffles without any packing or doing a baffle delete for more exhaust noise will compromise the sound quality that the original HM300’s were known for, but that can be subjective.
Dream, in the pics you posted, the original has from what I can see ( correct me if I'm wrong ) NO holes in the tube from the end of the baffle to the packing, I would then assume the end of the hole is free? The ones I got from Yamiya with the no number exhaust look like the bottom ones in your post, the end is blocked and the exhaust has to go out through those small holes so this is also effecting the note greatly, they are completely different baffles. I took off the 4/4s and put my 4/2s back on, I prefer the look. Both systems sound very similar with the 4/4 being a little quieter.
PeWe, if it wasn't for shipping cost you could have these 4/4s for a good price but I'll hang onto them for now, never know, I might get my money back on them one day.
Keep the 4-4, I'm sure you'll change your mind in the future. 4-4 on these bikes look really good.
About baffles... I have seen NOS baffles for sale if they differ from new shipped with No number from Yamiya
