My '59 Enfield /Indian 750cc Chief High Compression Build

[Scottie J]

You know guys, originally I wanted to boost this motor with an aftermarket EFI set up and push about 8-10 psi of boost but then I found out you can't use EFI in the vintage classes.  BUT then you guys are saying that my bike is actually considered a classic.  Should I still be looking into boosting my motor or are the same rules going to apply?  I could definitely create a lot more power boosting the motor and being able to program a fuel map.  My coworker/friend/engine guy specializes in building boosted Subaru motors.  He has a '04 Forrester and a '99 Impreza that both lay down 420 HP at the wheels and are daily drivers.  He knows his shit when it comes to turbos.

Scottie

[Stainless1]

ok, time to decide what you want to do... get a rulebook for running SCTA, while you wait, find the AMA rules on the Bub Website.  The organizations have some different classes and rules... they run different meets. 
You can build a boosted bike and run in either one, but learn the rules before you build.

[Briz]

Yeah, if you want to run in vintage, the cases & heads must be pre '56. They can be later as long as they're unchanged from a pre '56 model.

[Scottie J]

Okie Dokie!   

Downloaded both the SCTA Rookie Orientation Booklet and also the AMA BUB Rule Book.  After reading through the AMA BUB Rule Book it looks like I want to run either MPS-CBF or MPS-CF.  I'd really like to run MPS-CBF class but I can't find a record for that particular class code.  Does it actually exist and no one has attempted it or is it one of the chassis/engine combinations that is not allowed?

BTW  I really truly appreciate everyone giving me a hand at getting on my feet and getting this build underway.  Thanks Guys!   

Scottie

[SPARKY]

most likely means open record

[lsrjunkie]

Scottie, I'm not a bike guy by any means, but here's my advice. Get a rule book. Everyone says it, and they do for a reason. I can't imagine anything more terrible than spending tons of time and money, then getting to the salt and not being able to run.

Second, instead of going after a record, go after a good time. Everybody wants to break a record, but not everyone will. Go out there with a realistic number in your mind and if you run faster than that... Great! If you start out with 200mph in your head, then every time you don't run that fast you'll be upset and frustrated.

200mph is fast. It's real fast! My personal goal is to hit 200. This year? Nope. Next year? Probably not. But I'm darn sure not giving up till I get there!

Good luck with your buid and I hope to see ya on the Salt! 

[Koncretekid]

Okie Dokie!   

Downloaded both the SCTA Rookie Orientation Booklet and also the AMA BUB Rule Book.  After reading through the AMA BUB Rule Book it looks like I want to run either MPS-CBF or MPS-CF.  I'd really like to run MPS-CBF class but I can't find a record for that particular class code.  Does it actually exist and no one has attempted it or is it one of the chassis/engine combinations that is not allowed?

BTW  I really truly appreciate everyone giving me a hand at getting on my feet and getting this build underway.  Thanks Guys!   

Scottie

The Classic class  is new to BUB, having only been established a couple of years ago.  That is why you won't find many records.  It is a changing year class, 35 year old bikes, which means that in 2014, any bike made after 1979 is allowable.  So if you run in MPS-CBF 750 class, your competition could be 1979 blown 4 cylinder twin overhead cam Japanese  bikes.  Or you could run MPS-PBF (modified chassis, partially streamlined, pushrod motor, blown on fuel), which would exclude everything except pushrod motors, and the year does not matter.  Incidentally, there is no current record at BUB's in that class either, and the record at SCTA seems to be 158.462 mph.
Tom

[Scottie J]

The Classic class  is new to BUB, having only been established a couple of years ago.  That is why you won't find many records.  It is a changing year class, 35 year old bikes, which means that in 2014, any bike made after 1979 is allowable.  So if you run in MPS-CBF 750 class, your competition could be 1979 blown 4 cylinder twin overhead cam Japanese  bikes.  Or you could run MPS-PBF (modified chassis, partially streamlined, pushrod motor, blown on fuel), which would exclude everything except pushrod motors, and the year does not matter.  Incidentally, there is no current record at BUB's in that class either, and the record at SCTA seems to be 158.462 mph.
Tom
[/quote]

That is an excellent point!  I'd be much better off running MPS-CBF.  Is there any place to download rules regarding ignitions and fuel delivery?

Scottie

[panic]

The mains are 1.875", not metric.
The crank is nodular cast-iron, and I don't want to be in the same state when it turns 9,000 RPM.
The original rods are aluminum alloy very much like those used by Triumph, Ariel, BSA, Norton twins for 50 years.

200 is going to need at least 1 of the following:
1. second engine
2. turbo or blower
3. large dose of nitrous or nitromethane

I note with alarm the recent trend to invoke the "dynamic compression ratio". It makes wonderful bar stool conversation, but has very little application in LSR.
It also requires you to know, prior to the calculation:
1. static CR
2. stroke length
3. rod length
4. intake valve closing point
Doing some numbers very quickly, an IVC about 55° ABDC will drop the DCR to 13.5

16:1 is going to require a really tall dome, and (if possible) a second plug location.
The valve reliefs will probably need to be hand-fitted as closely as possible to the actual valve curtain "footprint" at its point of tangency to the dome.
Examine your head bolt pattern very closely, and google about this - I think I remember extra bolts added to prevent gasket failure.

A bigger rocker will take some work, but space typically isn't the problem, because the new rocker will be smaller in stature. The ratio is raised by shortening the distance from the pushrod adjuster to central shaft. You may also wish to re-clock the lever angles to prep the geometry once your lift is known.

[edinlr]

If you are serious about trying to get that antique to run 200 you need to be sure to study everything Tom Mellor has done with his Triumph triple.  Yes it is a ten year newer design, but it is still a British pushrod design.  Tom doesn't make Hayabusa type horsepower, but he does have a very slippery bike that just cheats the wind.

[panic]

An afterthought on CR vs. IVC:
Unless the ICL is weird, closing at 55° ABDC probably isn't enough intake duration for peak power; something closer to 70° will be better.
Yes, that will drop the DCR significantly but IMHO the trade-off is a net gain.
I can't find anything about single vs. dual pattern, I would pose this specific question to your head porter: what's the intake:exhaust flow proportion over the lift range you'll be using?

For exhaust I suggest reverse-cone megaphones, partially because they're easy to modify after construction (a 2>1 is a nightmare).

IIRC these engines have a sump in the crankcase. This is going to need some work as if it were an automotive (wet) pan re: windage, scraper, pickup location instead of following best practice for a Triumph etc. with remote oil.

[wobblywalrus]

Are the Royal Enfields dry sump with the oil held in a separate reservoir in the crank cases?  At least that is what I remember.  It was a lot of years ago.

[Scottie J]

I'm more worried about not getting enough lift out of the valves and not even hitting 9000 rpms than I am about the crankshaft grenading.  I'm going to balance the rotating assembly to at least 10,000 rpms so if it's going to go it will most likely happen during balancing.  But I have to disagree about DC not being important.  Now I'll admit I'm brand new to LSR, but how can anyone expect to get max HP out of a motor without blueprinting out?  Fyi the cams I'm using the intake closes at at 77° and the exhaust open at 75°.  Intake lift is .328 exhaust is .344.  My head guy is keeping in close contact with me and we are blueprinting the motor together.

Are the Royal Enfields dry sump with the oil held in a separate reservoir in the crank cases?  At least that is what I remember.  It was a lot of years ago.

Correct it is a dry sump motor, 2 oil pumps.

And another question.  I see it is not required to runfront brakes.  Do any of you guys run a front brake?

Scottie

[fredvance]

no

[panic]

I think you need to read up on balancing.
Who did your CR > DCR calculation?