Topic: midget racer

[Don R]

Contrary to popular belief 3/4 midget racers are still using sohc hondas. I just scored a head, nos valves, stainless valves, starter, two head gaskets, misc gaskets and seals, trans gears, oil sumps, finned point cover, two dynos, clutch covers, a clutch basket 4 point plates and a few misc parts for a hundred. The sad part is there were at least 15 engines disassembled and parted out. I will remain in touch and see if I can pry loose some other parts. One head was sandcast but had been ported through the top into the cam area and epoxied up. Almost every thread was helicoiled, he says they are brittle.

[HondaMan]

Well, HOT DOG!

How many are missing their transmissions? Are any set up that way, with the oil pump being driven from the cam? They can sure be made to rev like the "Divine Wind" without their primary drive mass.

Brittle? 

How about "soft". You torque the sparkplugs and screws in with your fingers, not 3/4" drive ratchets....I do remember the Midget Racers of Southern Illinois going at their cars with 2-foot long torque wrenches....   

[754]

my 750 motors would be more brittle too, if I held them at 15,000 rpm as much as they do..

 Find out what they run for cams, ignitions, rods, pistons..

[Don R]

Cams are welded stock cores, web cams, they take off the dyno and run a 90 degree dual drive to turn a VW vertex magneto and a fuel pump for a hilborn injector, carillo rods, stock used bearings with stock oil pump, they turn down the crank weights. no cyl base gaskets, copper head gaskets, they are moving to parts from cycle X to get all their cars [in the shop] to match. They do cut off the transmission.
  His brittle opinion came from the sandcast head he had because almost every thread on it was helicoiled. Too bad it was ruined.
 I wonder if a guy could run the 90 degree dual drive and turn a vw distributor or mag and an ultra mini alternator?
 Lots of things to mull over. How about the vw mag on the left, plug the extra drive hole and an alternator belt driven off the right side like the old style magneto's?

[MRieck]

FJ heads used in Legend racing get soft from the extreme heat....all the cam cap threads pull out. What a great idea....take an air cooled engine that runs hot in the first place, enclose it and give it minimal cooling and then pin the throttle for 20 minutes straight.

[HondaMan]

A suggestion from the past: install a small flywheel on the unused output end (points end in those?) from a magneto bike, and add a couple of lighting coils to charge the battery (for starting, I'm presuming), with the other two coils to fire the ignition coils, using points and a transistor ignition from those points. Smooth the points cam ramps down to avoid an abrupt opening and closing ramp area, run a thin gap (about .008" was good back then) and condensors in the range of .022uF (14k RPM) to .018uf (16k RPM).

The stock Honda coils are good to 14,000 RPM. If the head is not hemi'ed (i.e., it is still configured as a swirl-charge engine), these coils' longer discharge time can be an improvement. If the ignition is some sort of high-current multi-spark type, though, or if the head is a hemi, none of this will work...you'll need more current, which will mean more HP used from the engine to drive the electrics...in any case, try to get a long spark, more than 1.0mS discharge time.

[Bill/BentON Racing]

I picked up one of these last year,cases are cut trans gone,was direct drive off left side crank,did have eternal oiling to rt side camshaft/cylinder head assembly,had 836 kit and Yosh alum rods,has h/p cam, valve springs etc,still got to take it apart.Bill Benton

[DaytonGuy]

Shouldn't we really be calling things things "Littple People" racers?  I mean really.  Where's the politically correctness??

[BLUE71TURBO]

How about MUNCHKIN RACERS from the LOLLYPOP GUILD ?  Oh crap !  Here comes the wicked witch !! 

[Don R]

I was looking into doing a little porting on the head I got and noticed the bias to one side. I figured that was to induce swirl. That is how I did my Jr. dragster engines. I am thinking just smoothing out the bumps and edges and not making any major changes. The [little car] racer just bought three heads to get one because it has angled [upward] intake nipples and ports, I am waiting to see the other two, they will be for sale.

[HB-1fan]

Yeah, Had an old friend named BUD here in Fl. that was from near Indy and lived that stuff from way back. I helped crew for them, he built engines for his sons car. It would do 100mph in a quater mile bowl, WOT for the whole race at 14-15k rpm on alchohol or methanol, don't remember which. I do remember the jets had about a 16th" hole through them. It was truly amazing to see what our beloved SOHC could do with no tranny holding it back. TQ was the class.

Rick

[HondaMan]

I was looking into doing a little porting on the head I got and noticed the bias to one side. I figured that was to induce swirl. That is how I did my Jr. dragster engines. I am thinking just smoothing out the bumps and edges and not making any major changes. The [little car] racer just bought three heads to get one because it has angled [upward] intake nipples and ports, I am waiting to see the other two, they will be for sale.

You're on the nose thare, Don: there is a lot more shrouding inside the chamber that continues to direct that swirling business. Sometimes (often, actually), the valves end up being shrouded because their seats are not even (recessed, mostly) with the head surfaces, and the in-chamber bumps that continue the swirl direction stuff end up becoming dams instead. You can usually lower the peaks of those ridges and reduce the bowls around the sides of the valves and get up to 15% more flow for the effort. The untimate is to hemi the head: search for my post about when I did that to my K2. It significantly increased the breathing, but ends up needing some other tuning attention afterward to get the whole peak improvement.   

[Don R]

The jr dragster was a 5 hp briggs which is of course a flathead, but I did work to unshroud the area around the intake valve and to continue the swirl. We found giving up compression to get flow was a good trade-off. We made out own billet head for a while and we cut the chamber with a ball mill wider than the head gasket to open up the valves. They were very fast for a small cc engine. Later we just got a blockzilla bored .210 and stroked .563  Now they run 3.5 bore and 3" stroke. Big$$$
 Thanks for the info I will look into the hemi. I just rode my 836 bike for the first time. I forgot how fast they are. Wow. Reminds me of the 900 ltd kawi.