Topic: HM300 pipes - Holes in Exhaust!!!

[andy750]

I had noticed a slight increase in noise from my HM300 pipes in the last week or so and today I happened to check the end of the exhausts - in both upper pipes I have a very small hole approx. in the same place as indicated by photos....anyone know if I can repair these successfully and if so whats the best way???

And to think I saw a left side set on Ebay last week go for cheap! 

Thanks in advance,
Andy

[736cc]

Take the baffles out which will relieve the back-pressure on the rot holes, otherwise they will blow-out even more. As a bonus, it will make THE BEST SOUND

[Jerry Rxman Griffin aka MuthaF'er]

Going back to Japan anytime soon?

[andy750]

No 

[paulages]

there's no cheap and good way, once you consider that the chrome will be ruined as soon as you weld it shut, and that's if the metal isn't too thin and rusted to weld at all. if they were mine, i'd try a dab of jb weld, with the baffles out, so that it can be applied from the inside as well, making it a more effective plug. this would be after brushing some rust mort or something similar on from the inside.

[rbmgf7]

take it to a chrome shop, strip it, patch it up, and rechrome it. it'll probably cost less than a hundred to strip, repairing depends on who's doing it - you or them, and rechrome may cost a few hundred.

I'm astonished to see original 4-4 sets which are dented, rusted out, etc. sell for so much on ebay. I figured thats what they were doing and either using or reselling them.

I've seen just one 4-4 pipe sell for over $100, depending on the condition.

[Raul CB750K1]

First thing, I'm surprised that the hole is in the top side; they are generally in the bottom side, where condensation water collects.

I'm going to start using 2-stroke oil as prevention. As I removed my pipes to replace the swingarm, I removed the baffles too and today I did a first run without baffles. Man, that is good sound!!!


You got original HM300 pipes available from Honda for about 200 euro each. So you can

a) Pay $150-$200 and have a repaired pipe
b) Pay $300 and have a new pipe and an old one to run the heck out of it.


You decide.

[bwaller]

Bummer Andy.

I'm going to include a pic but not sure if it'll show up well. Talking about bummer, I was removing some of the baffling from this NOS #341 pipe and wasn't careful enough when prying out a support piece for the end cap and it popped open a small hole where it was spot welded. I'll leave out the obvious language that came next!

I first blocked the small hole on the inside, then using a heated soldering iron filled the hole with solder from the outside. When I was happy the patch would hold well I ground away the solder until it was almost flat with the pipe surface leaving a fairly thin patch. Then just applied a dab of heat resistant silicone to the inside of the wound.

The picture makes it look worse than it is, although it is evident upon close inspection. It has held for three summers so I quess it'll last. It was the best fix I could think of.

[andy750]

Thanks guys - great advice and especially the last photo - so thanks for that Bwaller! That was exactly what I was looking for! I think your repair looks very good.

My only "problem" now is that today when I went to remove the baffle the 10 mm screw holding it, simply snapped when turned with little force  .....so first step is to get this screw out somehow!!

Cheers
Andy

[736cc]

Oh yeah, I forgot to mention those bolts usually shear off when removing the baffles. Bang the baffle out using a long flat screwdriver and hammer. Or grab the vertical bar w/ a visegrips and persuade it. Then ez-out or use a reverse drill bit on the busted bolt.
New HM300 baffles available $25 each last time I bought them a year ago.

[andy750]

Thanks Andy Ill try that. I checked DSS and he has then for $25 (he also has new HM300 pipes but the exchange rate is killing me - $245/pipe and thats not including shipping  ) - anyway one step at a time...much appreciated!

cheers
Andy