Topic: forgetfull Aussie drag racer

[sohc boy]

 Any other drag racers in AUS  ?I recently completed a rebuild on my k1 (later tank )which iv'e owned an raced since 1978 ,it's been off the track since 98,will run in Nostalgia racing here in OZ in the near future 

[Jim F]

Can you give us yanks some info on your build........
that is a cool bike  with all the RC stuff

Jim

[jweeks]

Before there was dragbike.com there was dragbike.au as I remember. Way back then the keeper of that race site offered to add almost anybody's drag bike to his web site. Yes, a couple of my Hondamatics were posted there. Not exactly an Aussie racer, but I was on the local web site. It got redesigned around the time that the dragbike.com site started up. I think that it got renamed and concentrated on Aussie race cars after that. You're on the right site to find us old school racers. Hope that some more local to you racers show up here.

                                                                 Jon Weeks

[Bill/BentON Racing]

Welcome,more info and pics please! Nice! Tell us more.Bill

[BLUE71TURBO]

 Welcome sohc boy !   Your ride is sweet !   Really dig the RC mag drive.  I'm running an A.R.D. CDM Magneto on my turbo bike.  We all will want to hear more about your ride.  We also have some real cool members here that are from down under.  You'll hear from them soon..........  

         

[sohc boy]

oooo...yea like that turbo bike ,ive been on aussie dragbike for a while ,but not much interest on there with   old stuff like this , have read an seen bit of stuff bout those hondamatics at the drags . The engine in it at the moment hsn't been run yet but it's 1123 cc, 900 crank ,alloy rods ,(1100 dimention) 73 mtc kawa pistons,12.1 comp, F2 engine,head gearbox ,cases , RC block , K/Harmond D grind cam , 1100 BOLD OR  CV carbs ,Sprint mag is new addition ,those ARD's are good mags ,used an older one for yrs with no trouble, on old eng , 836 f2 head ,std crank , 900 rod , Waggott cam (aus)  1100 bol d or cv's , petrol, best time 10.78@118, 5.5 slick 530 lbs 

[Sam Green Racing]

Have you any pictures of the frame mod without the tank on?

Sam.

[sohc boy]

not at the moment , but can do tmoro , frame is stock ,exept for top tubes cut , bent for head removal ,(bit ugly )done long time ago ,

[Retro Rocket]

Welcome sohc boy, tell us more about the Rolladoor  CV's please mate, what you have had to do to make them work on the Sohc....

[sohc boy]

 have used CR's an smoothbores, but for me  Honda CV's, work real good , had some mates that rode  Rolladoors  road racing using cv'srather than CR's so i tried em ,much easier to launch , 60FT'd better,lost a little top end power but picked some up all through the rev range  ,than CR's ....an cheap ! , they dont fit straight on , got to do lot of friggin around to fit em , got to narrow them up ,suit the cylinder spacing, an change all the linkages , an aDyna jet kit, i have a set iv'e made up off CX500 (39 mm ) i'm trying on this motor, on the bike are 37, i have used em on the street ,only 34"s , like i say real good throttle response   

[Retro Rocket]

Yeah, i've heard throttle response is better with the CV's. Terry {forum member Terry in Australia} just sold a 750/4 with CV's of a CBX750, same thing, needed lots of sorting out but they made the bike run smooth as a baby's bum and great response....

[sohc boy]

yea ... CBX750 ?,been umming an aring bout this frame for a long time ,has been hacked an modified a lot over the years, would like to lower it more , rake it slightly ,have aussie made sidewinder pipes to use ,so may use a fresh frame

[mick7504]

I like the design of that frame mod mate. 
Permanent and effective.
You've got my mind tickin' over now.

[sohc boy]

yea thanks Mick ,originally i had it bolted in ,with tabs on either ends of tube , but didn't  handle, real well ,how'd you end up with those piston mods an engine build you were doin ?

[Retro Rocket]

Looks similar to a boldor frame now....

[sohc boy]

yea similar , i did have my old motor in a boldor frame for awhile in the old days , but CAN'T REMEMBER (must be getting old like Sam. ) if i could get the head off? try n find photos.......found two

[mick7504]

yea thanks Mick ,originally i had it bolted in ,with tabs on either ends of tube , but didn't  handle, real well ,how'd you end up with those piston mods an engine build you were doin ?

That was all working out well and that Ivan Tighe cam was giving me a few headaches with piston to valve clearance which needs a bit more homework done in that area.
It was sapping up a lot of time so I've set it aside for the time being and finishing off a couple of other projects before I get back into it.

At the moment, I'm putting an 836 together with JE pistons, Cyclex Super Rods, HD primary chains, 125/75 Megacycle cam and a Mike Rieck Stage 4 head.
I want to see how these Pamco Ignitions and coils run as well.

People will say that I'm mad (but I already know that) and I'm going to bolt a set RS34 Mikunis onto it and see how that all goes with the S/4 Head.
It can always be backed off if it's too much.

[sohc boy]

sounds like a good thing , if RS 34,s dont work ,can allways change em

[BLUE71TURBO]

sounds like a good thing , if RS 34,s dont work ,can allways change em

     Hell mate,  If they don't work you can always try this....................     

                 

                 

                 

[Sam Green Racing]

yea thanks Mick ,originally i had it bolted in ,with tabs on either ends of tube , but didn't  handle, real well ,how'd you end up with those piston mods an engine build you were doin ?

Take a closer look at the top rails on Blue71turbo.  Jon has no handling problems.

Sam.

[CR750]

Hey SOHC boy,

Nice bike.
What's interesting you're using velocity stacks with the CV's.
Word on the cb1100f.net is they will never handle as good with those stacks as the stock/modified airbox.
Some 'knowledgeable' ( you never know on the www) guys over there ( also drag/racers, at least they claim ) say it got to do with the back pressure needed for the CV's to properly function.
But it seems you have no issues with yours ? any thoughts on this ? Any special mods ?

The stock carbs work just fine as long as the airbox and paper filter are in place. You can use any exhaust you want. You can use 750 carbs on an 1100 motor. The stock jetting in the carbs will work just fine. Now as soon as you do anything they stop working, flat spots, poor acceleration, and always inconsistant."

What happens is the heavy piston labrynth type SU CV carb plain does not work that well. Was not good on 50's era British motorcycles or sports cars and Japanese were not much better.

The diaphram type CV carb works so much better. The slide was much lighter and more important the diaphram did not leak. The only seal is a labrynth,ie grooves cut on the OD of a close fitting piston on these,so does not have the differential pressure to lift the slide. This is why the stock airbox is so critical.

The diaphram type work so much better,maybe even with velocity stacks,and not need filters at all. At least the slide movement is good enough to actually "jet" the carbs.

All regular bike carb rules. Idle is idle only,slide and needle is 1/4 to 3/4,and main jet is 3/4 to full throttle. There is some overlap in these ranges,but by and large you can leave the main jet out and not tell until attempt to get near full and would then be overrich.

[jweeks]

Cr750 - 77 pages of Sam's Hondamatic build in the High Performance and Racing Forum section (this one that we're in). CV carbs used on a cb750A motor. A bracket drag racing bike. Videos of it running. You can tune a set of CV carbs to fit your motor with or without an airbox. Jet kits are available to refine the carbs for more modified situations. We've even got charts of fuel/air ratios on a rear wheel dyno run. We've recently discussed the effects of stacks on CV carbs on the drag strip. Different transmissions don't affect what carbs are used. The Hondamatics just spend a lot of time pulling through the midrange compaired to the clutch versions. The clutch CB750's would be less sensitive to midrange needles and more sensitive to the main jets controlling the top end than the Hondamatics need. I've got 20 years of drag racing Hondamatics with CV carbs. Never run with an air box. I've gotten down into the high 10 second quarter mile range with some back room help from Dyna Jet. Too many misconceptions out there on CV carbs. What keeps them from being used more on our bikes is the differences in cylinder spacing that requires rework to fit onto a CB750. (Except for some Seca 32mm CV carbs and some Canadian Nighthawk 750 34mm CV carbs that are supposed to be a direct fit.) Just get adjustable needles and a selection of main jets, put it on a rear wheel dyno, sniff the exhaust and tune from there. Often the idle circuits need a little leaning down to keep the idle smooth. It's a lot cheaper way to get some bigger carbs onto any cb750. The information is out there.

                                                                             Hondamatic

[sohc boy]

Thanks CR 750, im still in love with this bike after 33 yr's,just ask my two ex wives !   I use to, an still get a lot of comments(an laugh's) bout these CV's, like why are you using those stupid things for ? yea they dont work in stock form if you just remove the air box ,the slide flutters up n down eratickly , some guys i knew who road raced boldor's did a air passage mod ,,using an english air kit ,dont remember the name of it , they block off one passage , install a jet in the mouth of the carb for the air pass,put a spacer under the slide,install larger primary jet, (main jet to suit your needs ) can take some pics if you like

[orkid1989]

beautiful bike

[NitroHunter]

Bike looks great - love that mag.