Topic: Thinking of putting on a genuine exhaust

[Scott]

G’day

I’ve never ridden this bike with a standard exhaust system on it and soon might be the time I do.

[Scott]

I got a set when I bought the bike and another set with another bike.

Is there any big difference?

[newday777]

I got a set when I bought the bike and another set with another bike.

Is there any big difference?

If one set(left?) is HM300 as apposed to HM341, then yes the 300 will be freer flowing so it has a little more power and a little louder than the 341 pipes give from more non removable baffling.

[Stev-o]

Check the numbers on the pipes, 341's would be correct, but both should work just fine.

I did the same to my K4 several years ago, and love the stock exhaust now.

[Don R]

 I had a really long muffler on a 4-1 header and it had crazy jet sizes compared to my no number yamiya (300) pipes. I'm really close to stock now even with a K&N in a stock airbox, 836, ported and a cam.
 My o2 sensor just confused things with erratic readings but the plugs are happy. I love the sound of the 300's especially when I take the baffles out.

[BenelliSEI]

What year is your K2? I’d suggest finding out what original pipe should be? I agree the HM300’s sound better (and louder), but since you have a choice……..

[MauiK3]

Im a fan of no number Yamiya exhaust. Great sound, easy tuning.

[ekpent]

What year is your K2? I’d suggest finding out what original pipe should be? I agree the HM300’s sound better (and louder), but since you have a choice……..

K2's here had HM341 pipes.

[Scott]

It's a 1972 model Australian delivered.

We're going on a trip early next year for a month and the guys I'm riding with will all be on bevel Ducatis, so it makes sense to throw a cool bike into the mix.

I see a lot more bevel Ducatis on the road than CB750s where I ride.

[Scott]

Sorry I thought I posted this before....Yes the ones on the left are HM300 pipes.

I pulled them down and started cleaning them up and the appear to be in great condition.  The small rubber tube that joins the mufflers near the end needs replacing, but that's about it.

I went to order that rubber x 2 and thought at the same time I will order the little clamp that goes around it.  Wow $31 for each little clamp means my old ones will be fine.

It's interesting though because I thought both bikes were 1972 models that I bought.

The gold bike is definitely a 1972 model and the other bike I was told 1972, but it had an engine that was painted black from the factory. (maybe that's earlier or later)  It's the slowest Rickman restoration project in the world.

[69cb750]

Yes the ones on the left are HM300 pipes.

The gold bike is definitely a 1972 model and the other bike I was told 1972, but it had an engine that was painted black from the factory. (maybe that's earlier or later)  It's the slowest Rickman restoration project in the world.

First year for black engines is 1977, K1 came with hm300 pipes, K2 came with hm341 pipes.
CB750 K1    77,157      July 1970 – Sep 1971    CB750-1044650 to CB750-1121806   
CB750 K2    63,500       Oct 1971 – Aug 1972    CB750-2000001 to CB750-2063500   Engine = frame + 7700

[Scott]

Thanks for the info.

I was looking at the parts I need to fit up the exhaust. Copper gaskets, spigots & bolts and the rubber tube between the upper & lower muffler.

At CMS it’s about $90 more than Vintage CB750.

Does anyone have experience with the quality of the cheaper option?

Thanks for any and all opinions.

[HondaMan]

Thanks for the info.

I was looking at the parts I need to fit up the exhaust. Copper gaskets, spigots & bolts and the rubber tube between the upper & lower muffler.

At CMS it’s about $90 more than Vintage CB750.

Does anyone have experience with the quality of the cheaper option?

Thanks for any and all opinions.

I do: Vintage CB750 has never let me down.

A word about the carb jetting and pipes:
If you go with the freer-flowing, open earlier pipes you will want to set the mainjet at #110 size and the needle in the slides at their center notch.
If you go with the quieter pipes, use a #105 mainjet and set the needles in the 4th slot position. This is needed because the low-midrange airflow thru the carbs drops a bit with those quieter pipes, so they had to have a slightly (1%) richer mix at the just-off-idle engine speed for a smooth takeoff.

Run lower-grade gasolines today, not premium. Premium today will foul the sparkplugs because the fuels burn slower and less hot in the engine.

[Scott]

Nice one mate, thanks for the heads up.

[Scott]

I'm making notes for my CB750 on paper.

Just so I don't make a mistake - is 4th slot on the needle from the pointy end?

Thanks
Scott

[HondaMan]

I'm making notes for my CB750 on paper.

Just so I don't make a mistake - is 4th slot on the needle from the pointy end?

Thanks
Scott

Nope, the slots are numbered from the blunt end, nearby. The top one is #1 (they use WHOLE numbers...   )

[Scott]

Excellent I can do that.

I've got to have a little think if I need any more parts for the bike at all before placing my order, they want nearly $100 Aussie for postage so I'll make the most of it.

[Shtonecb500]

I got a set when I bought the bike and another set with another bike.

Is there any big difference?

If one set(left?) is HM300 as apposed to HM341, then yes the 300 will be freer flowing so it has a little more power and a little louder than the 341 pipes give from more non removable baffling.

holy #$%*, I didnt know they sounded THIS GOOD.

hm300 pipes no baffle. This bike is gorgeous.

[newday777]

I got a set when I bought the bike and another set with another bike.

Is there any big difference?

If one set(left?) is HM300 as apposed to HM341, then yes the 300 will be freer flowing so it has a little more power and a little louder than the 341 pipes give from more non removable baffling.

holy #$%*, I didnt know they sounded THIS GOOD.

hm300 pipes no baffle. This bike is gorgeous.

The HM300 pipes have a removable baffle as compared to the 341 has the baffle welded in and just the cap comes off.