Topic: Hondaman's HM341 Mod, any downside to it?

[DesertKyorugi]

My K1 came with a generic 4into1 and I managed to pick up a set of used HM341 in decent shape to put on. Since the K1s are supposed to have the free-breathing HM300s, I am thinking about the Hondaman mod of drilling out the baffle/chamber of the HM341 to match the HM300 airflow or at least come close to it. Is there a downside to the mod? Is there such a thing as too much airflow?
What about running it without the end cap diffusers? Will that be enough instead of drilling?

[my name is nobody]

you won't know how rusty inside they are till...............awwwww $H&t!!!!
maybe find some old trashed ones, repair them, and experiment with those before you take any chances on your good ones.
jmo...

[69cb750]

My K1 came with a generic 4into1 and I managed to pick up a set of used HM341 in decent shape to put on. Since the K1s are supposed to have the free-breathing HM300s, I am thinking about the Hondaman mod of drilling out the baffle/chamber of the HM341 to match the HM300 airflow or at least come close to it. Is there a downside to the mod? Is there such a thing as too much airflow?
What about running it without the end cap diffusers? Will that be enough instead of drilling?

Not necessary, 341's run fine with 115 or 120 main jets

[ekpent]

 You might find yourself surrounded by a group of 750 guys with pitchforks and light torches if you got caught guttin' out a nice set of HM341's.    Running without the mouse stopper end caps will make them sound a little throatier. Running some uncapped ones on K4 right now. I'm thinking of throwing a set of 341's on a K1 also so please report back how it works out for you.

[Don R]

 My experience taking old 341's apart included broken bolts and rusted baffles that wouldn't come out intact. I was trying to make one nice matched set out of two full sets and two ebay mufflers. If I had a nice set I'd just enjoy them as is for as long as possible.
 I plan to put a set of reproduction no number pipes on my brothers K4 when I sell my other bikes, it has a wonky 4-2 on it now.
 

[PeWe]

If the HM341 are in nice shape, do not drill into them.
Sell them to a K2 restorer that look for exact parts.
For the money buy new Yamiya no numbers HM300 replica.

[DesertKyorugi]

You might find yourself surrounded by a group of 750 guys with pitchforks and light torches if you got caught guttin' out a nice set of HM341's. 

Lol yeah, that's the downside that I was worried about 

If the HM341 are in nice shape, do not drill into them.
Sell them to a K2 restorer that look for exact parts.
For the money buy new Yamiya no numbers HM300 replica.

I have 2 sets for 2 K1s and out of 8 pipes, only 3 are hole-less.

I am not talking about gutting out the baffles, it will just be drilling additional holes or enlarging the holes that are already there.

Not necessary, 341's run fine with 115 or 120 main jets

I don't know what size mainjets it is running, this bike was purchased from the original owner who stored it in 1981. It came with 4 into 1 exhaust. It was running fine but a little rich with it. Haven't had a chance to ride it with the HM341 but after syncing the carbs it sounds wonderful

[DesertKyorugi]

What is the going price for a set of used HM341 with minimal small rust holes but good clean chrome overall?

[69cb750]

What is the going price for a set of used HM341 with minimal small rust holes but good clean chrome overall?

A nice used set of 300 or 341 pipes sell for $1200, they appear on ebay occasionally, pipes with holes, rust, dents are not worth much.

[DesertKyorugi]

What is the going price for a set of used HM341 with minimal small rust holes but good clean chrome overall?

A nice used set of 300 or 341 pipes sell for $1200, they appear on ebay occasionally, pipes with holes, rust, dents are not worth much.

This is the best set I have, two of the pipes have holes on the inside where you can't see. Definitely not in the $1200 range 

I figured if I am going to have it with me till it falls apart, why not make it flow as close to the HM300 as possible?

[69cb750]

I figured if I am going to have it with me till it falls apart, why not make it flow as close to the HM300 as possible?

Yamiya pipes are very nice and close to 300 pipes.

[DesertKyorugi]

I figured if I am going to have it with me till it falls apart, why not make it flow as close to the HM300 as possible?

Yamiya pipes are very nice and close to 300 pipes.

If I can sell the set I have, I would probably consider getting the Yamiya no number pipes 

[MauiK3]

+1 Yamiya no number pipes are great

[Stev-o]

I figured if I am going to have it with me till it falls apart, why not make it flow as close to the HM300 as possible?

Yamiya pipes are very nice and close to 300 pipes.

If I can sell the set I have, I would probably consider getting the Yamiya no number pipes 

You shouldnt have a problem selling them here on the forum but shipping can sometimes be a deal killer.  Expect around $300 for a real good pipe [1] and down to $100 for one that looks good but might have minor rust and/or a small hole.

[ekpent]

 My pitchfork comment was for minty pipes. If they have some holes starting then modding them probably is not going to destroy their value. Plus it is your bike.Be best to try and patch them up also at the same time. As for knowing what jets you have already its super easy to unsnap a float bowl and remove the emulsion tube with the main jet screwed in the end and read the number stamped on it. Have a little 8mm wrench at the ready.

[Don R]

 Give it a go, I'm just saying if they come apart when you try to pull the baffles don't blame us for encouraging you.  L0L!