Author Topic: Robinson Precision Engines RPE equivalent (Read 10321 times)

mikeelem · « **Reply #25 on:** October 01, 2016, 05:20:55 pm »

As of now, the bike is getting a
Complete strip down, trying to get to its real beauty... Which looks prety far down the road...!

This ain't no big update... I know... But still, it's always worth the while having a pic to compare it to when done!

I'll try to get the engine out of there sometime this week and crack it open!

I'll be giving it a good wash, powder coat it and cook it while my wife is gone somewhere...

and then shaving all the rough castings in the casings to get it covered in glyptal...

It may not change a thing in the end... But as long as i believe it will Make the oil flow better, then be it...! And it's gives it a nice look... You can appreciate when it's all closed up!

This is the plan until the engine gets built

Things are going good as far as planning out the main components

Got a few questions on my mind as far as period correct for road racing...

First off... Those 31mm cr carbs that were used back in the 70s in the cr750 which were made out of magnesium... Are they acceptibly replaced by standard cr roundslides or flat slids in most racing associations?

What are good options still being period correct for suspension front and back. Do lots of racers go with the gl1000 front end to take advantage of the dual front brakes, maybe is there a better more efficient option.... Saw the ceriani i think it was... Any info on this would be nice

Last but not least... Swing arms. Upgrading it but staying in the same era! Ideas?

Feel free to talk about what ever you guys experienced over the years and worked out nicely.

I'll be posting pics of the internals once i split the cases!

Cheers!

Mike

MRieck · « **Reply #26 on:** October 01, 2016, 05:34:26 pm »

You need RS-34 carbs.....

mikeelem · « **Reply #27 on:** October 01, 2016, 05:54:22 pm »

I'm guessing not the new style flat slides but those on the gixxers in the 80s right? And by the way, mike i sent you a few emails, let me know if they went through... I've got a way of sending things out to the wrong people...

bwaller · « **Reply #28 on:** October 01, 2016, 06:01:35 pm »

So you plan to roadrace this? What ass'n?

mikeelem · « **Reply #29 on:** October 01, 2016, 06:23:54 pm »

Hey bwaller, i'm french... What ass'n... ?? I don't get it... Hahah... Sorry for my slang ignorance!!

mikeelem · « **Reply #30 on:** October 01, 2016, 06:25:47 pm »

But yeah... It's leaning towards the roadrace... Drag racing was an option... But opertunities will be greater in the road race association!

Bill/BentON Racing · « **Reply #31 on:** October 01, 2016, 08:12:01 pm »

What Mike said, just got through installing these today! Second set, best I've used on CB750's. Haven't used on a 836, but works so well on 915 and 1055cc engines so far! They go on so easy......not the first time! First time I recommend 2 people and a Samauto 2×4! Lol Bill

bear · « **Reply #32 on:** October 01, 2016, 09:50:50 pm »

Quote from: mikeelem on October 01, 2016, 06:25:47 pm

But yeah... It's leaning towards the roadrace... Drag racing was an option... But opertunities will be greater in the road race association!

If your serious about RR you need to get a copy of your rules before you start spending money.
Find the closest historic road racing club and make contact.

PeWe · « **Reply #33 on:** October 02, 2016, 12:20:16 am »

Quote from: MRieck on October 01, 2016, 05:34:26 pm

You need RS-34 carbs.....

RS-34 set is relatively cheap too! $725US at CycleX .(I paid $500US back in 1983 for Mikuni VM29 smoothbore. That was a lot then!)
Mikuni TMR32 cost almost double and the Yoshi version cost even more

http://www.ebay.co.uk/itm/Yoshimura-Mikuni-TMR-MJN32-Funnel-Carburettor-Kit-Honda-CB750-Four-1969-1977-4-/261740453643

bwaller · « **Reply #34 on:** October 02, 2016, 04:01:14 am »

http://www.vrra.ca/wp-content/uploads/2016/04/VRRA-Rules-and-Procedures-March-2016.pdf

Here is the VRRA rulebook, check page 29. A CB750 is a P2 but P2 heayweights are limited to 750cc's with allowance for a 5% overbore. Anything larger becomes a P3 and even then P3 heavy's are limited to 1100cc. So larger than 1100 and you're sunk....at least within this race association, same with USCRA. I expect AHMRA is also the same. Plus as an 1100 you'll be racing with TZ750's, Katana's, CB1100's some of those with original factory race kits and ten year further development in suspension & braking. This year there was a Quebec provincial race series that included a "vintage" middleweight class, still nothing you could enter.

I can tell you very seriously that some P2750 Hondas (usually 762cc) are bloody fast in good hands. We have several forum members here racing these now. In the RR game, it's far better to have a proper package design first (suspension, handling, brakes) These large CB750 vids you see from CycleX & Australia racing against more modern motorcycles may be exciting but these are very talented riders with unusual results! As Bear mentioned these big engines have a limited life expectancy. Lot's of time, and deep pockets needed!

As Bear also states, if you're building a bike to roadrace don't spend a cent until you investigate the rulebooks.... If you go drag racing it's a different story.

You should contact Roger Belanger from Quebec City. Roger races a Katana in the VRRA. He's a good guy, Francophone and can answer anything you need to know. If you're interested let me know & I'll get you in contact.

I'm sorry for being Debbie Downer but I'm just trying to help shed some facts. And your English is tremendous!

mikeelem · « **Reply #35 on:** October 02, 2016, 07:07:31 am »

Bill, thanks for the pics and feedback on the carbs, i allready tried mikunies on a cb400 and loved them. I'll take you on the 2 x 4 if ever it comes to that...

Pewe, the price range is nice ... Which it didn't look like in 1983...!!

Bwaller, i spoke to Dominic who is the vice president of the VRRA, he prety much said the same thing as you as far as p3 heavyweight leaders being a cb900 and katana 1100. He also said the guys drive good bikes, but have been racing since de 80's which accounts for a lot of their success. The class is limited to pre 1982 bikes

As far as displacement goes, 1100 + 5% brings the absolute maximum to 1155cc...

P2 has 1972 year production limits...

Don't worry about the downer stuff, this is what it's all about, giving and getting advice. I appreciate it and you guys are right about everything that has been sent here... I just like being drastic in what i do. So let's see where all of this will take me!

Using same era technology probably means i can get a pretty decent suspension, braking system fitted on the bike... It's just a tad more complicated then using what was initially concieved for that specific bike during producion...

Keep the ideas coming... If you have any thaughts , everything is welcome!!

Thanks guys!

Mike

Bill/BentON Racing · « **Reply #36 on:** October 02, 2016, 10:28:33 am »

A 73mm kit and 1/4 stroker puts you at 1155!

, Bill

mikeelem · « **Reply #37 on:** October 02, 2016, 01:45:17 pm »

It's all about labor cost!! Strokers aren't given and are quite undertaking... Boring to the extreme also is!! I'm looking into this bill and will let you know!

PeWe · « **Reply #38 on:** October 04, 2016, 11:44:30 am »

Quote from: mikeelem on October 02, 2016, 07:07:31 am

Pewe, the price range is nice ... Which it didn't look like in 1983...!!

Forgot to mention that the price was like that in Sweden with the additional VAT, US price likely closer to 400

MRieck · « **Reply #39 on:** October 04, 2016, 06:40:30 pm »

Welded stroker cranks always break....eventually. You can't pour that heat into it and expect it to live. Now a Marine billet crank would be great.

kmb69 · « **Reply #40 on:** October 04, 2016, 07:55:08 pm »

Quote from: MRieck on October 04, 2016, 06:40:30 pm

Welded stroker cranks always break....eventually. You can't pour that heat into it and expect it to live. Now a Marine billet crank would be great.

Marine is probably the best. RPE has pictures on their website of a billet crank, I'm guessing a stroker, being machined in their shop.

scottly · « **Reply #41 on:** October 04, 2016, 08:24:39 pm »

Quote from: MRieck on October 04, 2016, 06:40:30 pm

Now a Marine billet crank would be great.

Said the man with the million dollar CB....

mikeelem · « **Reply #42 on:** October 10, 2016, 04:31:59 pm »

I've had a bit more time to put on this bike... while i was unscrewing all the bolts on one side, the kids were screwing them back in on the other... talk about being productive!!

The engine came out without much hassle... no broken or jammed bolts and nuts even if they seemed kind of rusted in!

The bike is registered as a K model but engine looks to me as an f one... correct me if i am wrong!

So i still have the lower end to split but that will be the next time story!

Thanks for watching

Mike

Jerry Rxman Griffin aka MuthaF'er · « **Reply #43 on:** October 10, 2016, 06:45:21 pm »

What year?
'392' on the top fin #3 intake side?
Serial number?
Number on piston by the pin? 300, 392??

My initial thought is K7 or K8 but I'm not sure about the serial number block being sideways... K8's have 392 heads like the early F. Late F's have a '410' head

kmb69 · « **Reply #44 on:** October 10, 2016, 07:51:11 pm »

Quote from: Jerry Rxman Griffin aka MuthaF'er on October 10, 2016, 06:45:21 pm

What year?
'392' on the top fin #3 intake side?
Serial number?
Number on piston by the pin? 300, 392??

My initial thought is K7 or K8 but I'm not sure about the serial number block being sideways... K8's have 392 heads like the early F. Late F's have a '410' head

Late K8's and pretty sure all F2's had the sideways engine number pad.
Crankcase and camshaft look like F2 to me. 410 head casting number would confirm.

Bill/BentON Racing · « **Reply #45 on:** October 10, 2016, 08:03:35 pm »

Yep, only late K8's and F2 had serial number perpindicular to cylinder. All others parallel.

754 · « **Reply #46 on:** October 10, 2016, 08:07:06 pm »

In the first pic where you sprocket cover is. The motormount there appear to be btoken.. Do you have the piece.?

mikeelem · « **Reply #47 on:** October 11, 2016, 04:26:24 pm »

Well looks like the engine is a k8!
Cam lift looks kind of high as even when unscrewing the adjusting screws on the rocker arms it couldn't relieve the valve springs to free the cam lobe... but maybe this is just normal...
Any markings on aftermarket hot cams??

And as far as motormount goes... you are right... it broke or was broken... i probably will try to weld it up or use another top case...

Recieved the glyptal from eastwood along with cast aluminium powder for the engine...

Keep looking..!!

Thanks guys!

kmb69 · « **Reply #48 on:** October 11, 2016, 04:41:41 pm »

Quote from: mikeelem on October 11, 2016, 04:26:24 pm

.....
And as far as motormount goes... you are right... it broke or was broken... i probably will try to weld it up or use another top case...
.....

Honda machined cases as sets with bearing surfaces line-bored. Not advisable to replace just the top.
Need to weld it if you can. Clean the pieces thoroughly and put an engine mount bolt through them to hold in place while welding.
Those cases with the number pad perpendicular to the cylinders are purportedly the strongest SOHC cases Honda made.

mikeelem · « **Reply #49 on:** October 11, 2016, 05:06:09 pm »

Well that is nice to know kmb69! Thanks for the advice! Will do! I'm still working on the main frame being the engine, but will be coming up soon with the building plan!
The engine part is quite of a mock up but i will soon elaborate the plan.

I will keep updates as far ad preperation goes!

Utility will be road racing

Maximum displacement limitation is 1155 cc

And i intend on bringing it spot on

I know i could get an fzr with probably the same figures for 1/3 of the price...

But hey... in my mind... nothing sounds and feels as hot and bad ass as a modified vintage bike.... even if tech upgrades will be my main competitor!

Keep this as a background thread if it suits you guys... ideas come faster then money;)

Cheers!

Mike

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Author Topic: Robinson Precision Engines RPE equivalent (Read 10321 times)