TOPIC:

Kray-Z wrote:

Irish-Kawi wrote:

Kray-Z wrote: I'm finding this discussion very interesting. Unless you are an expert in tuning carbs and have a lot of time and gas to kill, for the best overall results, I would say stick with a properly maintained K&N filter in the stock air box and properly install and tune a Dyno-Jet kit. Most of my own stock CV's have Dyno-Jet kits in them now. It is relatively easy and works well enough. I don't drill out the stock slides unless I get an extra set first, just in case I ever want to return the carbs back to original. BTW, of all the CV carbs - I hate the BS34 Mikuni's the most - absolutely hate them!

I believe there is lots of things you can do with the intake side of the carbs (any carbs) that you can mess with to get more of whatever it is you want. One factory OEM example was the differences in the V65 Honda Sabre and Magna. The engines were nearly identical, yet the Sabre, with larger volumes in the exhaust and air box, made 4-5 hp and 2-3 Ft-lb. more torque than the Magna (cams were slightly different, too). So changing the air box can have some effect on performance if you try it. It might not be worth the effort, and you might end up not happy with what you get, though.

Other than maybe sort of looking like a racing engine should, and maybe making tuning access easier, I don't think pod filters are worth doing...(particularly on CV carbs) but are still better than open stacks or bells...that is crazy.

Hey Kray, curious why you have such a disdain for the BS34's? I am new to carbs for bikes and just starting to get my feet wet, but I have had very little issues if any with my BS34's, just wondering why the hate?

Brett

Hey Brett,

The BS34 hate-on is from those carbs being prone to rapid wear in the slides, fast idle (choke) plunger mechanism, and throttle plates / shafts. The wear is hard to visually detect, but it makes tuning these carbs an exercise in futility. They are known for this, especially if they are disused for long periods, or not kept clean and maintained. I have several medium to high-mileage sets of them on my shelves that worked somewhat o.k. while they were filthy / stained with oil, crud, and dried up fuel, but wouldn't work properly again after disassembling and cleaning. The crap and crud was actually contributing to sealing the shafts, slides, and butterflies. The lower mileage sets I have went through the cleaning and set up process much better and are on two of my stock engine bikes now (an 83 GPz1100 and an 81 CSR1000), but the others are all junk. I wasted a lot of time and money trying to get them to work. I also found them way more frustrating to set up and tune than the 6 carb sets of stock CV Keihins on my Honda CBX's. The opposite should be true. If Keihin FCR's weren't so expensive, I wouldn't have any Mikuni's at all.

More reason to get on board with jberger635's home brewed fuel injection / engine management system! If he gets it to work - i'll be the first one in line at his shop door...

Ahhh gotcha, yeah not an issue I have had with mine but will watch for it, thanks for the heads up

Brett

swest wrote: I just came back from Victorville. What a bunch of snooty riders. That's what. One guy kept "bean farting" in my ear till he turned off.
I like the pre AMF bikes.
Steve

Yeah, when I'm out on a jap bike, the Harley Snobbery is both insulting (always) and amusing (sometimes). I always think the SOB's should out to know I once owned one and have done custom and performance work on enough Harleys for my biker "brothers" over the years, and I know more about Harley history and tech than most of the "image is everything" bunch of SOB's so common these days. Next time ask one of those dicks if he even knows what an XR750 is!

But keep in mind - that is the dumb ass rider, not the bike.

Most are around my age and when I tell them I bought it new in 75 I Get the o; fish eye. They want nothing more with me. Now where's the posers here.
Steve

swest wrote: Most are around my age and when I tell them I bought it new in 75 I Get the o; fish eye. They want nothing more with me. Now where's the posers here.
Steve

99% (remember the 1% - er label?) of Harley owners today are newbie's trying to steal a piece of the bad-ass image. This I can't tolerate. I remember when I started street riding that maybe one in 50 bikes on the road was a "Hawg", and most of them didn't go very far from home (going to the local bar was their idea of "touring"). Many of the bad ass guys on Harleys I used to hang with back then secretly confided they thought my 79 CBX was cool, but didn't want any else to know that.

Now that 1 in 50 bikes isn't a Harley, I can understand how pissed off you must feel when surrounded by such stupidity...

Anyheeeeew...back to air-boxes and such....

What a discussion! lots to think about there.Interesting to hear about the BS34s.I didnt know that.
Anyway,if I remember the actual first post,it was about getting more oomph from the bike by opening up the airbox a bit. From what I understand, this, if it works at all,will give a minimal increase in power? How would you go about measuring that increase? assuming youre not going to dyno the bike? Would it just be from feel?
If thats the case , and Im just thinking outside the (air)box here. Would it not be a lot easier and cheaper,to just pull the airbox off the bike completely,fly up and down the road and see how much increase in horsey power you can feel? At least then you would know you have a chance of achieving something other than a mess by drilling holes in your airbox.

P.S. Im not a purest and have nothing against drilling holes in airboxes or any other parts of bikes,just seems like a lot of effort for what?

davido wrote: What a discussion! lots to think about there.Interesting to hear about the BS34s.I didnt know that.
Anyway,if I remember the actual first post,it was about getting more oomph from the bike by opening up the airbox a bit. From what I understand, this, if it works at all,will give a minimal increase in power? How would you go about measuring that increase? assuming youre not going to dyno the bike? Would it just be from feel?
If thats the case , and Im just thinking outside the (air)box here. Would it not be a lot easier and cheaper,to just pull the airbox off the bike completely,fly up and down the road and see how much increase in horsey power you can feel? At least then you would know you have a chance of achieving something other than a mess by drilling holes in your airbox.

P.S. Im not a purest and have nothing against drilling holes in airboxes or any other parts of bikes,just seems like a lot of effort for what?

Definitely a dyno thing to be done properly. If you get any increase in peak power, don't count on much more than 1-2%. The seat of your pants is a notorious liar...and it seems to respond best to / with un-muffled, loud, and obnoxious noises!

Taking off the stock air box and running the engine without serious effort re-jetting and tuning the carbs is going to prove one thing - the engine runs like a bag of crap that way...

I'm happy with my result. I very much doubt I'm going to go any further.

My boss is cussing the day he bought his fat boy and got rid off his Vulcan. He's trying desperately to get the thing running, he can't get gas to flow into the carb, so he can sell it. His second Harley the first was a 78 in 79-80, a real nightmare. His only solace is he also has a Bonneville American. He can't wait to get another Vulcan or Suzuki or maybe a Star.

If it needs more juice then it should deliver more power like pods or a 4/1.
Steve

davido wrote: ................ If thats the case , and Im just thinking outside the (air)box here. Would it not be a lot easier and cheaper,to just pull the airbox off the bike completely,fly up and down the road and see how much increase in horsey power you can feel? At least then you would know you have a chance of achieving something other than a mess by drilling holes in your airbox.

P.S. Im not a purest and have nothing against drilling holes in airboxes or any other parts of bikes,just seems like a lot of effort for what?

Agree. In fact, the easiest way to temporarily see the affect would be to just remove the airbox cap and the air filter. That would only take a minute to do and could very easily be reversed once it is discovered that more air doesn't mean more power - just more noise. I'm quite sure a dyno test would prove this to be the case even if the seat of the pants-o-meter (which is often affected by how loud a machine is) fools one into thinking more power has been found. Ed

GPzMOD750 wrote: I'm happy with my result. I very much doubt I'm going to go any further.

My boss is cussing the day he bought his fat boy and got rid off his Vulcan. He's trying desperately to get the thing running, he can't get gas to flow into the carb, so he can sell it. His second Harley the first was a 78 in 79-80, a real nightmare. His only solace is he also has a Bonneville American. He can't wait to get another Vulcan or Suzuki or maybe a Star.

It was far worse before. The worst I've ever had to deal with were the late AMF Harleys, 79 - 82. Assembled new with wrong or missing parts (like missing transmission thrust washers), parts not completely machined (transmission and engine cases) or machined so badly that a 15 year old could have done better with an angle grinder, warped gasket faces, porous or improperly filled castings covered up with body filler and paint, partially machined threads, off center holes...what nightmares those were. And that electric starter mechanism!!!! I would say that was a joke, but not the funny kind. The word "Shovelhead" strikes fear into my heart even now...

I'm following the thread ...but I think the thing you'll notice is that the induction system sounds a little different, very slightly louder or a pitch change... But you'll feel virtually no difference in real performance.
Time will tell and I've been proven wrong before. LOL!

I'm just voicing my opinion in this thread just like everyone else.
I would like to see a dyno comparison of a stock airbox vs. a modified
airbox vs. individual filters. [ K&N or UN with a DynoJet kit ]


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