I think I see a new motor build coming....

[dirtdigger]

I just made a deal on some RC parts and bottom end. Will get some pictures once I have the parts in hand. Didn't really need to spend the money right now but couldn't pass it up. Might build a new motor for the hardtail so I will do a build thread once I get parts rounded up and find some money to do it. The things we do for more power....

 

[Travis]

Are those RC golden rods that you picked up months ago going in that motor?

 

[dirtdigger]

No, I happen to run across a guy that has a RC bottom end....cases to cylinder. No head. RC crank, golden rods, and a RC cylinder block. Cant wait to see what else is in there. Now I have a set of RC rods to hang on the wall I guess lol

 

[Travis]

There you go... I think I remember you saying something about them being art! Or you could sell them to recoup some of your cost for this engine...

Are those the cylinders with about 5 big fins on them?

 

[dirtdigger]

Are those the cylinders with about 5 big fins on them?[/QUOTE]

Yup thats the one. Everything should show up tomorrow so I will see what other goodies are in there.

 

[dirtdigger]

Got my new toys today...thank you UPS. I cant believe how good the crank, rods and pistons look. Bearings look almost new as do the piston. First time I have had an actual RC big block in my hands, hone the cylinders and new set of rings and the bottom end would be good to go. Will have to see how the winter goes as far as money before I decide what to do. If I built this I would have to have a good head built so I will have to start saving my pennies.

 

[K2750tracy]

What kind of hp can you get out of a setup like that?

 

[dirtdigger]

Hard to really say for sure. According to RC back in the day from there literature they rated them at 100+ hp to the REAR wheel with the 1000cc Cobra motor. My dad had one back when they built these, his was in a stock 750 frame but he said he broke rear spokes and bent teeth on the countershaft sprocket when he would drag race. I saw one of the sprockets, hooked teeth on a sprocket look kind of funny lol. The real key to making big power from big displacement is a good cylinder head and carburation. There is a lot of potential in these old motors.

 

[joe p]

When I ran small countershaft sprocket I had that problem too. So I ran a 19t sprocket front and larger rear sprocket. I'm still kicking myself for getting rid of all my Cobra stuff. Back when I raced that motor, the best time I ran was 10.65/120 mph. But that is a great find! I met a guy in Oklahoma who said he had a shop full of all those Cobra parts, but he planned on keeping them.
Joe p

 

[joe p]

Can't seem to post this picture......

 

[dirtdigger]

I have chatted with Russ Collins Jr through emails about running the big block on the street because I had concerns about heating with the lack of fins. He said he used to run them all the time back in the day and it never was a problem. He is going to talk to his dad about it but said it should be fine. So I am leaning towards building the motor with the big block. The parts cost too much just to leave sitting around so I want to use them if I can. Now I need to find some rings for the pistons.

 

[joe p]

I ran a 1000cc on the street but I put 10.5:1 pistons in it with a smaller cam. To run those pistons,you are going to have to get a lot of head work done and it ain't cheap:blue:. I have a GPZ head on my KZ that I have invested about $3000 in.

 

[joe p]

Check this out. www.cyclexchange.net/Cycle X Honda Drag Bike.htm

 

[dirtdigger]

I won't have to have much done to the head. They are 12:1 pistons so I wont have to open the chambers up too much. I will have bigger valves installed and I will do the rest of the work(opening the chamber and some port work). $1000 will get you a really good head for a 750 honda with big valves and porting. I have a flow bench so I do my own porting.

I've been following that drag bike built for sometime. They have been working on it off and on for several years. I use a lot of there parts.

 

[joe p]

Doing your own work can really help on the budget. When I worked at a machine shop, I did all my own work on my engines. But now I have to send all my machine work out. If I could just win the lottery, I'd get a lathe, milling machine, heliarc, etc, etc...

 

[dirtdigger]

Well just traded my RC block too, well I'm not allowed to say, for newly sleeved stock block and partial payment for new 970 pistons. After talking to couple of guys (RCjr and Jay at Ape)about running the RC block on the street I decided against it in favor of using a stock block. They can be run on the street if carefull but I want to be able to run around town and in traffic and Sturgis traffic is crazy during the ralley. They do run hot in low airflow circumstances so of to a new home it goes. Now my next biggest issue is going to be getting a cylinder head built to flow enough airflow for the 970, just gotta come up with some money

 

[joe p]

Back in the day I traded one of my big blocks to Brent Adams in Austin for a stock block with 1000cc sleeves and a set of pistons to go with it. The stock blocks do work better on the street. I guess it was a good deal for both of us.

 

[dirtdigger]

I would have kept the block just for the coolness factor but I was able to do a trade and get going on my build so I had to say goodbye.

 

[dirtdigger]

Cylinder off to be sleeved and new 970 pistons from Cycle x ordered! Now to find some more money to buy more stuff!

 

[dirtdigger]

Still waiting for the big bore to show up, it will be a late xmas present I guess! Jay at Ape says the Cycle X pistons look really nice, will post pictures once everything shows up.