Bellmouth intake shapes

[slracer]

John, The attached pic is from Speed Week at Bonneville this August: a blown Honda 305 Dream! He used an air pump from a Porsche 928(?) as the blower and fabricated his bell mouth from fiberglass. Thought you might find it interesting, even if "old" style bell with sharp edges! -- Doug

PS - He called the bike "Bad Dream" and went 76.020 mph for his record. Anybody got a "Dream" they want to race?

[106-1194218389]

Bruce,
Sometimes when we did a large cut using a radius cutter it would get chatter. We could sometime resolve this by wrapping a heavy rubber bungi cord around the outside of the piece that was being machined. (Just in case you run into this) Also if you used a tracer it would probably be easier to do multiple sizes if you were asked to do so - hint hint :;):
John

[106-1194218389]

Doug,
Thanks for the picture. From what I read in the article from Prof. Blair on the bell mouths there was not a lot of difference in the shapes as far as hp. But if you are trying to get every last bit then it would be worth it. That "Dream" could switch to the elliptical bellmouth now and come back and set another record next year.

John

[49-1183904562]

[color=#000000]Bruce;

The key to making good air horns is Metal Spinning, there are some great sites and videos on the web on this subject. I have done some really crude tests on my lathe and I think it is very doable. Your lathe will wok fine you will need so bar stock to make up some spoons and some harbor freight wood lathe chisels to make your plug from. The key is to make a really good plug

[slracer]

John, When I talked to the guy, as he was disassembling his engine for verification, he had never had it that far apart before and it was not only stock, but old stock. The unblown records are 20 years old at 139 & 140 with a Yamaha. The attached pic shows the (very clean) blower installation. He should have a lot more in the bike when he builds a motor. The only other blown engine was a Harley (Aermacchi?) pushrod which went 72 mph with the blower and 108 without! There has to be a story there? I'm offline for about 3 weeks so save some good stuff for me! -- Doug

[106-1194218389]

I have found a video on You Tube that shows a gentleman spinning some aluminum. He makes it look easy. and here's another and then a third one - They sure make it look easy and fast

John

[106-1194218389]

Here is the web site for the gentleman in the first video Seems to be a pretty good web site.

John

[106-1194218389]

Here is one of the things he is making on his DVD - look familiar

[106-1194218389]

Here is the link for a cheap lathe that should do the job
Well I guess I don't have an excuse anymore
John

[slracer]

I've been keeping an incomplete old Craftsman lathe in the shop, wondering what to do with it. Maybe now I have an answer? -- Doug

[49-1183904562]

Sorry Guy's I wasn't trying to get you to spend more money . I have been interested in this for a while and it really looks like a good DIY Project.

John those are the videos I was speaking of I ripped them for my archives "You can just watch them over and over festinating.



Rick

PS. Doug you could spin a bullet nose cone to streamline your headlight :p

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[bruce]

Ok, who ran me up on the lathe manual tracer attachment on eBay? ???

I won it anyways!!

I stumbled into a discussion on a machine shop forum I go to daily talking about manual tracer attachments for a lathe, I thought I'd check eBay and there was one up for auction this past week. I bid on it and got outbid in the last hour so I figureout what was in my paypal account and let another bid fly . . . I'm happy to say it's on it's way to my shop now

I found a guy who has a webpage talking about his attachment:



Looks like it should do what I need it to do with my velocity stacks on my carbs. Looks like another project, UGH!

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Bruce,
did you notice that guy's project that he made the bell for? Wow, that was cool. My wife is going to kill me.

John

[slracer]

Rick & John, Sorry for the delayed response, but we left the US on 10/1 and I stumbled across the questions today while trying to get caught up with missed posts. Now that I have been "relieved" of the pressure of defending my record, :O I will be changing classes (but staying with the 100cc pushrod motor). Until now, a bullet shaped headlight (or anything else) was not legal so John you can put your camera away (for now). I'll have to find the photo (post card) of a BMW in the 30's with the rider wearing cones instead of bullets, but placed as suggested (I hope you did mean external with the placement!). :p It set a record so they may have helped!

With a new head (the bike's, not mine) being ported by one forum member, a fuel injection unit being put together (with eBay parts), and a blower being built (with parts donated by another forum member) maybe I should call the new toy the "Flowbench Special"? I can't find my original design from 1998, but have been trying to recreate it the last month or so. It will be radical, but if a 100cc pushrod motor with blown fuel injection and burning Nitro doesn't make you smile, you have no sense of humor! I'll keep everyone in touch! -- Doug