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Discussion in 'Your 250cc Projects' started by Murdo, Aug 17, 2016.
I had one of those... mine was a 1300cc - good for carrying the drum kit....
Look's like Ford Wild Violet ?
I sprayed a mate's ZX-6R that colour a few year's ago, he loved it
No, definately Mulberry Metalic. Was a popular colour for Fords back in the early 1970's.
Are you racing at Gunnedah this weekend?
No next weekend, if it doesn't rain.
My mistake. Hopefully weather holds off. Saw this car at the Winternats yesterday and I had a feeling it had raced at Gunnedah...look familiar?
Yep, Phil Penny from Kempsey.
1965 Honda S600, now fitted with 2JZ Toyota with huge turbo.
Cannot remember his times, but he runs 180mph on the 1/4.
Under 6 seconds on the 1/8th mile if I remember correctly
Took the little CBR to the Gunnedah 1/8th mile drag races. Weather cloudy and cool but no rain all weekend. If you have been reading this post you will know that the bike is mechanically stock, I have just removed all the bits not required for it to run. The 'ballast' on top is a bit on the heavy side too.
The first runs were all in the mid 11 second range with low 90's kmh, but by the finals on Sunday I had improved to 10.91 @ 99.7kmh, reaction time of 0.057 and 60ft of 2.43sec ,so happy with that. I found that leaving the line at around 8,000 rpm gave me better control of the clutch slip (I had tried at 12/13000 and the clutch was too 'grabby' to control, either wheel up or bogging) and changing up at 15,000 was slightly quicker than going right to redline. I was changing into fourth gear about 30 metres from the line (I tried holding third longer but it was slower) so I think the gearing is pretty close. I will start on the improvements now that I have a baseline to work from.
Have brought my spare engine (actually the one from this frame) in and started on a rebuild. The engine had done a lot of Kms and was an oil burner and had very little compression when I got it. I stripped the head and re-cut the valves and seats. Took the dremel and cleaned up the ports too.
First matched the head to the intake rubbers. You can see the 'step' that the gasses have to go around to get into the ports.
With the rubbers matched I removed the big casting lumps in the ports and smoothed the rest to help with the airflow.
There is a step at the back of the valve insert that I will grind out too.
The exhaust ports were choked with carbon (burnt oil, must have been like a two stroke to follow) and took some cleaning out. The amount in the ports would have reduced the amount of gas they could flow.
Ordered a set of +.50mm pistons to bring the bores back to correct clearances after a re-bore.
With all the head work I am planning to do I decided to build something to hold the head at a more comfortable angle in the vice. I scratched around in the scrap pile and found a piece of 38x38x5mm angle, a piece of 30mm square tube and an old broken Ford engine mount. Welded the mount to the square tube, drilled the angle for both sides of the head (and also to suit the FZR head used as a model) and found two 8mm SHCS to bolt the head to the angle. I cut a 3mm thick rubber washer to help hold the angle secure.
Held in the vice will allow adjustment to get the right height for comfortable working.
Now back to the 'good' CBR that I intend to register next year.
I took the carbs off to put the new Litetek seals in. The old rubbers (is that what they used to be, rubber?) were so hard that I had to use a tyre lever and block of wood on head to get the carbs off. Split or broke them all getting the carbs out, but have new ones ready to go.
After the carbs cleaned and sealed up, I did the valve clearances. About half were out and needed adjustment.
I went to check the thermostat and found this. I don't think it will work. The temp sender broke off when I tried to undo it too, so out with the left hand drills to get the remains out.
Blasted the thermo housing to clean all the years of crud off and went to Autobarn and found these. Fitted spot on and right heat range too.
Hooked up the car battery and did a compression test. I was hoping it would be good enough to get it started, but not to be as the highest pressure (even with oil in cylinder) was 60psi. It is stuffed, so will put this one aside and when the newly rebuilt engine goes into the purple drag bike will have a look at it then.
I feel your "no compression pain" Murdo, I have 2 mc22 engines here with no compression , parts for these old girls are getting pretty thin on the ground
Don't throw them out. Put them up the back if you're not going to rebuild them.
I will rebuild it, but I have three engines in bits at the moment (ZZR, CBR and Risky's FZR) so will have to get them finished first to get some room on the bench.
Today I got a bit of time to finish off the ports and get everything cleaned ready to assemble tomorrow.
Exhaust ports, one on left done, right still to go.
Both exhaust done up to valve guide. Still to finish the rest of port.
All cleaned and laid out ready for assembly. Buckets and shims in multi compartment box I bought at Bunnings.(note there are 18 valve seals, either somebody in China cannot count or they give you spares. )
I bought a second hand pipe from our favourite bike wrecker, some 2" tube from exhaust shop and a cheap little carbon/stainless muffler from fleabay. It is enough to take the bark off compared to open pipe and very light (about 1Kg). Ready for next drags now.
It really make's a difference cleaning up the port's and blending the valve seat's etc, a few of the car's and bike's i've done it's made them run so much smoother, rev cleaner and it's improved the torque.
So much so that they can get up hill's easy in a higher gear than they previously could
All the books I've read about valves/porting state that the last 1/2" before the valve seat is the most important bit, and if you can imagine the turbulance caused to flowing air by lumps and ridges then you will understand why smoothing the edges gives such a better running engine. They may only be little gains in airflow, but each little bit will add up to a better performing engine.
Goodo Murdo. I did the same with mine but never took many pics. Still have to seat the valves. This was before blast and paint of course.