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Old 10-29-2012, 08:35 PM   #16
Bluethumb
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Pictures, pictures, pictures, and proof

I'd like to know the specifics on this build. Power wheelies at will? 135 mph? From a street airhead motor? I owned a Ducati Multistrada which put out an honest 85 hp at the wheel and I could only see an honest GPS verified 135 mph in perfect conditions, as in a long slight downhill with no head wind and it took everything for that motor to go a real 135. I'd bump up against 140 but very rarely. And I weigh 155 lbs. I owned a 916 that would lift the front wheel when I powered shifted into second. But an airhead is far from a Ducati 916.

I've owned some powerful airheads and might see an honest 120-125. The difference in pushing a bike from 120 to 135 is huge requiring exponentially more h.p.

Find someone you'll loan you a GoPro. Post some pictures.

But Supershaft, I'm calling bullshit until there's proof.
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Old 10-29-2012, 08:49 PM   #17
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I don't have a problem believing the power wheelies. I had low compression r100 pistons in my bike for a while and could do power wheelies in first gear. Man, they're hard to control! That was with low G/S gearing and the fact that my boxes hang behind my axle with that short monolever swingarm though.

Glad you're on your wheels, SS. Seems like you've got a fine 'build thread' right here to lay out your set-up so the rest of us don't have to spend 30 years figuring out how to do it. I give it 3 weeks before it gets sent to the basement
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Old 10-29-2012, 09:35 PM   #18
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I have had the same experience bgsoil with r80's with 1000cc cylinders on them! The main difference with my story is that I am running a 33/11 FD with a close ratio tranny. Big diff in first gear gearing!

BT, I had two friends back home with the same hotrod tricks done to their early '90's SS's. They were pulling around 88hp on their dyno. They hauled ass. They would power wheelie through first gear EVERY time you were hard into it and they have real tall first gears too. They would power wheelie through second half the time. I have ridden the new retro Ducati's that are suppose to have 85hp stock. I don't think they do and I know their midrange suffers big time for what little more they got on top over the older 900's. We'll see but I think my airhead will now out pull one.

My bike power wheelieing at will? It has done it ONCE! But I am tickled pink at that with my gearing. 135mph? I have never revved it up in top gear but if it will pull 8k rpm in top gear and I think it will and if pj's top speed/gearing chart is right, I think it will. It would easily rev to 8k rpm in fourth BEFORE I did a bunch more mods to it. According to my speedo that I know reads a little high and pj's chart, that's a 120 something mph right there. It will pull 8k in fourth now NO problem! Like I have said before, according to pj's chart, speed gun displays, and tickets I get, I don't think my speedo is that far off. I use to do machine and fab work on and help with a race airhead that would pull right around 155mph at Daytona lap after lap. Those are the ports I conservatively mimick when I did some port work on my bike this last rebuild. I think it helps!

Proof? That cracks me up bt. What can a photo prove? Just about nothing in my book. Same with dyno charts. We could race! I do think I am going to out run your Multistrada IF it is stock.
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Old 10-30-2012, 09:48 AM   #19
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Taking mph figures from a BMW speedo is a bit like relyin on (politician of your choice) to tell the truth
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Old 10-30-2012, 02:55 PM   #20
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That's why I have backed mine up with radar guns and gearing charts. That and accounting for some error. I realize my tach can be off too. Plus the fact that it tops out at 8k. It's the radar gun displays and tickets that tell me mine isn't that far off. That and, if you subtract a few MPH, it all lines up with pj's gearing chart.

I remembered last night that I passed a line of cars up a long hill with a at least piped and chipped Multistrada a year or so ago. (these guys spend MONEY on there bikes). We were side by side and we were both in a hurry catching up with one friend on a 1198 and the other on a gixxer 1000. He out pulled me a bit but my bike is running a lot stronger now. My friend on the 1198 also has a piped and chipped Multistrada. Hopefullly we will get the chance to do a quick from first gear roll on race up to 120 or so and see where we stand.

My main point is that airheads do not have to be tractor motors and boat anchors. They are really pretty easy to get running pretty strong very reliably. It's just that a lot of people go about it ass backwards IMO.

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Old 10-30-2012, 05:13 PM   #21
Bluethumb
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Build list?

Regardless if you can pull 125 mph or 135, it's sounds like one fast bike. Would really like to hear what you did to build it up. Would you list in detail what you did? Motor, suspension, carbs, FD?

And when are we going see a picture?
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Old 10-30-2012, 05:54 PM   #22
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Sure: The bike is a naked '92 R100RT with all the pollution crap removed and Staintune Sport mufflers.

I started with a close ratio gear set. I swapped the intermediate shaft helical gear for the later pressure face angle and at the same time put a beefier input shaft and cush drive. The CR first gear got into the much larger cush drive so we had to machine it back down just a RCH. I kept the stock 33/11 FD. Love it!

Then I put a sport cam in, titanium spring retainers, and cleaned up the ports a bit. Loved it. Big diff right off the bat. 32mm carbs stayed stock except for much leaner 262 needle jets. (Increased reversion really richened up idle and just off idle.)

Then a friend gave me some 38mm PHM rubber mounted Dell's with no choke bodies. I filed about a third of the velocity stack threads off so the airbox snorlels fit right on the carbs like a 32mm Bing. Real clean looking IMO and it works! I started with R90S jetting and leaned it WAY out for a LOT more power. I disconnected the pumps and ended up with 130 mains among many other changes. All that got me around 30% more power from stock with great power all the way through the rev range to up above 8k rpm. Over the 32mm Bings, way more mostly midrange and top end. Not as big of a difference as just the cam but I love it!

Then 70,000 miles later with 101,000 total, my exhaust guides were toasted. New guides. 42 to 44mm intake valves and a LOT of port work. My ports were badly mismatched. I took out a LOT of meat matching them up. Redid my intake valve to seat ID ratio by hand. Took .025 off the heads. Put new cylinders and 9.5:1 pistons in. (I had one compression ring groove wearing like they do so I sprung for all new.) New titanium retainers. Mine were hammered! Manton 4130 pushrods. Dual plugged it with the stock bean can and two .7 ohm Dyna's. Remapped the ignition curve from 6 to 32 degrees to 6 to 28. That's it engine wise. I have yet to do some airbox experiements with the new setup.

Chassis: Fox twin clicker. Preloaded stock fork springs. Forks are on backwards. Headlight and handle bar windshield are frame mounted via a modified RT/RS front fairing/headlight mount. /6 style ignition switch. EBC organic pads. Steel braided brake line. K1 bars. San Jose top tree. A whole bunch of worthless IMO crap taken off including the side covers and their mounts. It's a whole big box worth of crap. That's about it. I will hopefully have some pictures in a month or so. I forgot to add that I cut weight by running a 19 amp battery too. I have better luck with them than the bigger batteries. They weight a lot less and they don't make your bike look like thay have a boat battery in them.

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Old 10-31-2012, 07:57 AM   #23
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Shaft, I know you are a proponent of leaner and leaner mains, but that didn't work in my case with Mikunis and twin-plugs. Different bike, carbs, etc., but going to 195's from 170's got me four more mph on the top end and I had to back off.

I started at 150's then moved my way up. The 160's would rev cleanly to redline buy I'd get a surge (only on a cold day, was absent when 80 degrees) when backing off from WOT as flow transitioned to the richer needle/needle jet. I went up 2 sizes to 170 and thought all seemed well. After discussing my jetting with someone who is very familiar with Mikuni/Airhead setups, I plugged in my 195's and instantly noticed more power. I still have some more testing to do with some other mains, but I'm running out of good weather here in MI.

Buy or borrow a cheap handheld GPS to get an instant and reliable reading so you don't have to rely on radar guns and charts.
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Old 10-31-2012, 01:13 PM   #24
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Not if you read between the lines. What I am a proponent of is running them as lean as you can versus as rich as you can. There is a lot of hp free for the taking between the two setups. The way my bike was set up, it ran fine with 155's in it but it ran WAY better with 130's. I have seen the same thing play out at shop dyno days time after time on all sorts of bikes. Like I have always warned about, most of it has to do with port velocity. Higher velocity, smaller jets. Whether or not your bike is a big port of a small port makes a big diff. So does the airbox setup. The airbox setup really effects just off idle jetting. Now that I raised my compression from 8.5:1 to a guestimated 10.0:1, put bigger intake valves in, and really hogged out my ports, I might see bigger mains in my future. I have got to tune on my new setup some yet. Airbox setups that use to just kill my midrange now barely effect it. I am going to test freer flowing airbox setups and exhuast and see what happens. Even if I end up running 170 mains with my new set up, I bet it would sound just as good minus three or four (or five!) hp with 190's in it. Typically speaking, that is the nature of jetting. THAT is what I am a proponent of!
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Old 11-01-2012, 02:58 PM   #25
Uncle Pollo
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Super is uknowingly guiding me into tunning happiness. I
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Old 11-01-2012, 06:02 PM   #26
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Originally Posted by Uncle Pollo View Post
Super is uknowingly guiding me into tunning happiness. I
I really do hope I am helping somebody. Yes, sometimes things do start off too lean on the mains (setups very often start off too lean just off idle but that is another story) but most of the time it's the other way around. So many peole think of jetting as putting the biggest jets in there that will still work. Wrong! It's all about putting the smallest jets in there that still work. If your butt dyno can't tell the difference a real one will!
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Old 11-02-2012, 04:05 AM   #27
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Quote:
Originally Posted by supershaft View Post
I really do hope I am helping somebody. Yes, sometimes things do start off too lean on the mains (setups very often start off too lean just off idle but that is another story) but most of the time it's the other way around. So many peole think of jetting as putting the biggest jets in there that will still work. Wrong! It's all about putting the smallest jets in there that still work. If your butt dyno can't tell the difference a real one will!
i was too lwan on main but too fat on the pilot and nj
changed the needle and upped the main and got better but a big hiccup
went down 2 steps on nj and back to the 6f4 and rides better.

in a couple days i will step back to 140 main and see

my riding is from 5000 to 10000 feet so i have to ride on the lean side of things

if i was going down i would tune on the rich side

i love being able to deccide a change, visualize it, predict the outcome, and be right!
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Old 11-03-2012, 10:47 PM   #28
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Something about my Dell's that I forgot: If they are too rich just off idle they surge. I am running a few tuning experiments. I think I am making ground. I am going to run it like I have it know for a while and see what I think. The jetting is all the same but I am now running 165 mains all because of airbox mods. Basically no airbox top and I shortened my velocity stacks by about three inches. It just barely effects my low rpm power versus killing it before the port work and higher CR. Now it is pulling a lot stronger at 8k rpm. The intake is noisy now! My valves definitely are not floating with those pushrods which are almost three times as heavy as the stock ones but that is what the big money pushrod guys are doing so I am giving it a try. Does it help? I don't know other than it has to be helping a least just a bit since those stock rods flex a lot. I do know that it is running good as it is! I am still running stock springs with no preload. I was thinking about preloading them just a bit but my stack height was already a bit short according to spec so I didn't. I don't think it is hurting me at all. In my experience, more spring pressure takes a lot of longevity out of the setup so I try to not go there.

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Old 11-05-2012, 01:08 PM   #29
supershaft OP
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My shortened rubber velocity stacks are coming loose. Rats! I can't figure a good way to do it. First off I am going to go back to stock length and make sure it is worth the trouble (I think they will be but I am not absolutely sure just yet) and then I am going to find some aluminum tubing to machine on for the snorkel/box junction and clamp some after market ones on the inside of the box. I will probably end up with about the exact setup that was on a race bike I worked on that RAN. My bike is semi regularly lifting the front wheel at around 5k rpm in first with no bumps or anything but smooth pavement involved. I think that is around 45mph! I have raised the compression on enough bikes to think that a lot of my performance gains are from my port work. I was a bit worried because they where so far mismatched I took a lot of meat out matching them up. I usually follow Smokey's advise and leave the port floor pretty much alone but I had one raised floor a lot higher than the other so I took the high one down and matched them up. I raised the roof a lot on the other to match that up but that almost always works. That and the top sides. That always works too if you do it right. Same story all over again with the exhausts minus the top sides of the exhaust are just like the bottom sides.

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Old 11-05-2012, 11:12 PM   #30
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Well, now that I have my airbox setup dialed in, I am going to recheck some even bigger mains and some K2 jet needles. I think it might need to be richer up above 7k rpm and not any richer down lower. K2's are thicker all the way down from my K9's I am running now. A couple of more tests and then I will be set up!

My poor landlord thinks his CRF450 is going to out run my airhead now that he has it geared to go 100mph. When he had it geared to go 85, he could barely out pull me until I shifted to second at around 65mph (meanwhile he had gone through at least three gears) and then I would leave him behind (as far as the engines are concerned!). He had five gears inside of two of mine. Now its three since I shift into fourth around 105. Now I am going to smoke him from the get go!

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