The RD400 drag bike

[AMCQ46]

I hope you were kidding on the 0.3 g difference.

I even ran 0.5 mm different size and brand pistons like Prox & Wiseco as a quick and dirty weekend repair on my YPVS. That makes up for maybe something like 10 g.
Guess what: it didn't vibrate more, just in slightly other rpm ranges. That was all.

Compensating deck height with different base gaskets is possible, but not smart for long term use. Imagine next rebuild in 5 years - will you remember which thickness goes where?
Better put on the list to machine both cylinders to the same height in order to have everything symmetrical.

Well spotted, 0.3g was a typo, should have read 3grams, but I also think that Harry is very exacting when he builds an engine, he had also weighed and matched the conrods before he assembled the crank.

He also etched the bottom of the barrels so I will always know which side needs the thicker base gasket.

[freeridenick]

Great read Al. I can't wait to hear how it goes at a meeting.

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[AMCQ46]

The time to test the beast is coming up.


I plan to do a Run What you run at Santapod on April 12th. book tickets here

and I have a dyno session is lined up on April 4th so I can
a) complete the running in of the new bores and pistons and
b) check the jetting and ignition with the new pipes.

anybody else want to come and laugh, you are more than welcome

[neil]

Good luck for your runs Al, hope it all goes well. Santa pod too far at moment for me. Maybe you'll get to Elvington or Melbourne sometime soon.

[sirch345]

I hope all goes to plan Al

Chris.

[Duffy1964]

Good luck Al hope you enjoy running it up the strip mate


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[fabiostar]

Kepp her lit Al

[AMCQ46]

The rebuilt engine is making the same 65bhp as before, but with the longer pipes it is now 2000rpm lower, so that is much more torque, and safer on the crank compared to the 10700rpm peak last time.


There were a few issues relating to an air leak on one side and the fact that the front tyre would hit the exhaust on heavy braking, but they are sorted now… so off to Santa pod tomorrow to hopefully have some fun in the sunshine. Wish me luck

[Kev L]

Hope all goes well mate

[Duffy1964]

Nice work Al, sounds like it will scream down the Santa pod strip. Enjoy your fun in the sunshine


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[haynesjones66]

i think we need to hear that! a video of one of your runs would be great

[alanfjones1411]

i think we need to hear that! a video of one of your runs would be great

Good luck Al.

[sirch345]

Good luck Al, I hope all is going well

Chris.

[AMCQ46]

Was a fun day out at santapod, but it was a little busy with the good weather bringing lots more people out to play on a variety of cars, bikes, go carts, jet cars, hot rods, the lot.

the bike was running well with only one hiccup when it refused to start after I left it in the formation que over the lunch break. The hotter 9 plugs had fouled because the engine had gone cold, so I put the 8s back in and it was fine.

The other bigger problem was the gearing, as i was in the redline in top way before the end of the 1/4 mile. This will be the side effect of bringing the peak power down from 10700rpm (which is too high for the crankshaft to be reliable) to 9000rpm by returning the expansion pipes to their original length.
By the time I got to 100mph, I was over revving so that was limiting my best run to 109mph and 12.7 seconds.

So I need a few more sprocket and a spreadsheet before I go back out again.

Rd waiting

Times

There one with no times was because I went too early and got a red light.



There was a firestorm there, doing kill switch backfires as we all do

Firestorm

A big $$$ Supercharged and carbon Busa

Supercharged Busa

A KTM engined sprint bike

KTM V2

Look at the size of that turbo

Big turbo

Classic American muscle car

Cool car

[sirch345]

Was a fun day out at santapod, but it was a little busy with the good weather bringing lots more people out to play on a variety of cars, bikes, go carts, jet cars, hot rods, the lot.

the bike was running well with only one hiccup when it refused to start after I left it in the formation que over the lunch break. The hotter 9 plugs had fouled because the engine had gone cold, so I put the 8s back in and it was fine.

The other bigger problem was the gearing, as i was in the redline in top way before the end of the 1/4 mile. This will be the side effect of bringing the peak power down from 10700rpm (which is too high for the crankshaft to be reliable) to 9000rpm by returning the expansion pipes to their original length.
By the time I got to 100mph, I was over revving so that was limiting my best run to 109mph and 12.7 seconds.

So I need a few more sprocket and a spreadsheet before I go back out again.

96392D46-A9A2-4D03-B4E0-A2C1E14205E2.jpeg
IMG_6070.jpeg
There one with no times was because I went too early and got a red light.

The first time out on a new to you bike, I'd say you did very well Al

If all you need for the next time is a few more sprockets and a spreadsheet that has to be a great result

Thanks for posting up the photo's

Chris.