HRCA#1

It will be interesting to see how much if any info a pro like Roger Ditchfield will share. I will say he has responded to me several times via email and always gave me more info than I new to ask for.

8541Hawk

I am glad you guys are having good luck with Roger, I never did.
Maybe I just caught him on a bad day.

Anyways.... Back on topic....

I have 2 comments,
First I could have sworn the e-bay ad listed the carbs.....

Second, IMHO the HRC set up is a better all around or "steet" se t up, while the Moriwaki set up is a better "track only" set up.

To keep it short I will try to keep things as basic as I can and can give more details if you want.

So IMHO the main issues with the carbs, in the stock set up, are two things.
Lean on the bottom end and the front carb goes rich in the mid-range.

The 4 main ways of dealing with this are:
DynoJet- Speed the slide up and get the bike on the needles quickly.
FactoryPro- Run a rear emulsion tube in the front carb.
HRC & Moriwaki - Slow the slide down.

The difference is how they did it and how it works on a street bike,

HRC plugged a lift hole, as you guys know now. WHich slows down the slide in both directions.

Moriwaki used heavier springs, which slowed down the opening but speeds up the closing.

This changes the engine braking carateristics. This comes into play much more on an engine with a lightened flywheel &\or a STG1 or highr build.

The best way I can discribe it would be the HRC gives less engine braking with the slides closing slower so while you have more engine braking it's what I would call "soft" as it is very controllable.

With the Moriwaki set up you have what I would call "harsh and sudden" engine braking as she really slows down when the slides slam shut....

Besides that the Mori kit is pretty much a HRC "race" set up for running ram-air or no air filter (or open top with a K&N) of plugging the air bleeds and running smaller main jets.

So again, IMHO, the Mori set up is more peak power with maximum engine braking with no real concern of how the bike runs below 6K or so.

While the HRC set up is a little less max HP but a smoother powerband and softer engine braking.

So Mori-Track
HRC- Street\Track

Sorry to ramble on but that is short as I can keep it

HRCA#1

As John Wayne used to say " I like the way you talk pilgrim!". That's the best summation of the various approaches I've read or heard about.

MC Leather

My Bob Hayashida Moriwaki bike has a stock air box, stock air filter and 2 stock long velocity stacks. The jetting is close to the Factory stage 1 settings. I never checked the slides or the springs. Every so often I think about messing with fueling or adding a HRC CDI but then 3 things come to mind. The bike was built by a master that has passed on, if it ain't broke..., 131HP is plenty for me. Some day I'll take the whole bike apart and document all the changes, but not for a while.

Stephan

It would be great

Erik S.

I believe you. Roger has stated at least twice, that I have to modify the airbox. 125 HP will be more than enough for me.

RCVTR

Mike,
I would think that the engine braking characteristic is controlled far more with the throttle plates than slide position. The venturi opening created by the slides is many times larger than the tiny idle slit around the throttle plates. For less engine braking, turn up the idle speed and/or crack the throttle.

Another major factor in making the carbs work without an air filter is the needle profile. I believe this is the primary reason that people have trouble tuning for filter mods. The needles need to compensate for changes in mass airflow rate caused by the change of air filter. Otherwise the tune will work at some RPM ranges at the expense of others. HRC and Moriwaki most likely developed needles to tune to the airflow characteristics of the intake and exhaust systems.

8541Hawk

I agree it is but I also believe the slides play a part. The reason I say this is even with the throrrle plates in the "closed" position they are still open a bit for the idle setting.

With the slide open, you will still be feeding combustible mixture into the engine.

With the Moriwaki slide closing at least twice as fast as the HRC slide, I believe, this will cause a noticble difference in engine braking.

Once again I agree with you. I can't say for sure about the Moriwaki kit, as I only saw one and it was at least 10yrs ago but the HRC kit comes with 2 sets of needles.

One for an airbox with a filter and one for "ram-air" or no air filter.

Also, for these types of set ups they had you plug the airbleeds and run different mains.

All good stuff for top end power but not so great if you ride the bike on the street as the bottom end suffers badly.

Once again, this is all just my opinion......

Kind of like my opinion on MC Leather's post.... good info but I also believe Bob would have run the billet stacks if they were as easy to get as they are now. Back when they were Mori unobtainium bits it was not worth the time or $$ to hunt them down but for $130 or whatever they are a good investment, but of course the carbs set up would be a little different.

Anyways, again IMHO, you can tune the new STG1 engine one of 2 ways. (or any VTR for that matter) Max peak power or big fat torque curve with a little less max HP.

For a street ridden bike, I like the second option and that is how I set up bike when I do them.

7moore7

Maybe that explains the weird gearing! People are probably wanting to cruise at 8krpm to make use of all that top end power, lol!

HRCA#1

Mike, My HRC Carb kit only came with one set of needles, do I need to file a grievance? Also how do I know which ones I have.

Erik S.

I thought about this while looking at the pics of the Stg 3 bike, that Roger sent me. Does your bike have the Ram air? If so that would explain why the airbox is still stock.

twist

This is something I haven't heard before, "Factory stock auto tensioners.... They actually do work well if taken care of".

How does one take care of them to make them last? Why can't the springs simply be replaced by better springs? (Sorry for the newb question)

RCVTR

Bob Hayashidas is a stage 2 engine, meaning that it has stage 2 cams, Carrillo Rods, extensive crankshaft work, in order to run a higher redline, as well as an unobtanium close-ratio kit transmission. Different torque curve than a stage 1 engine, but a stage 1 engine doesn't make 130 HP.

RCVTR

Also...
Bob ran a stock airbox and air filter, with a Moriwaki superbike exhaust system (speaking of unobtainium). At 130 HP, the heavily braced VTR chassis wiggled all over the place. He had to lay on the tank and just let the ***-end shake all over.

He got much more serious, with a stage 3 engine in his RC51 and won the AFM open twins championship (ridden by Rich Thorwaldsen)

Erik S.

The stage 1 only makes 125 at the rear wheel. Roger has stated that the frame will not need bracing. It would be a riot to ride the stage 2 or stage 3 bike.

I want that big fat torque curve.

MC Leather

The bike does move around a lot at speed but I blame some of that on the current street fighter bar setup. I'm also ridding the bike slower than it wants me to.

I also think this bike had a bunch more power when it was raced. I got a 131 HP on 93oct pump gas. I bet with good race gas, better jetting and in a fresher state it put out 140hp or so.

RCVTR, I always love to read your posts about the bike, it reminds how trick it is and how little I know about it.

RCVTR

Yes, I believe it was over 140 HP.

One engine had wrist pins that were heat-treated wrong and too brittle. One of them let go on the back straight, at T-Hill. The connecting rod almost cut the case in half, by the time he got it stopped.

YETI

You are one lucky chap ,
I have the same spec engine and its a scream !!
mine is running with stage 1 zero moriwaki exhaust , moriwaki carbs and moriwaki velosity staks and its making 128 bhp .
I popped in manual tensioners ( just incase )

ENJOY !!!

YETI..

smokinjoe73

Wow, quite a monumentous purchase. You gotta keep the reading world of the forum posted. Sounds like it will be a real fire breathing ripstomping bike. You should write to a motomag & have them do an article.

Erik S.

Thanks Yeti and Smokin.

I'm hoping it will be fun.

I'll be on the lookout for an exhaust header soon.

The good news is, I passed my physicals yesterday and got the job offer. So it's full speed ahead on the engine.

Revelation

Great... just found this topic! Wow a real moriwaki engine!

Last year I sent a tuned up engine over to Roger for an overhaul... but it was so far gone that I opted for another (stock) engine.
He was reasonable with the costs and friendly throughout the whole process.
Indeed when you exchange emails with him you get more answers than questions!
As soon as my streetfighter runs I will pay him a visit!

cybercarl