Topic: A Bike Is Born....750/1000cc

[dragracer]

The pistons i've got coming are high compression- kicking starting it will not be easy. I think i will pursue an onboard electric starter if i can work out the starter clutch issue. I will get Paul Cashio to build me one of his hi torque super starters and crank the bike with 24 volts.

[MRieck]

Paul is a great guy....had several conversations with him just a little while ago.

[Bill/BentON Racing]

Well,let's do it!!! First 750A crank with Hy Vo chain,stock.

Hey,this better!!

We can do it!!

Clearance on main bearing 5,4

Mains 3

Now the fun begins! Mains on 4 ,what clearance?

Better chain on,rubs barely the rubber block

This one.(J.Weeks said it would!)

This is top case half,just getting started. Called me Honda boys yesterday,2 primary chains,one in Ontario,I got it coming,sang our saga went from 156.00 to 118.00 plus shipping!K Other one for Frank,waiting on reply to see if they'd match price.Somewhere in the States! Jerry,those others were replacement chains ,not OEM. We both want a Honda new one to start with. A pic from the top side soon.

[dragracer]

Thanks for looking out for me on the  chain Bill. Per our conversation, did you measure the 900 rods versus the stock length 750 rods??? I think Jon Weeks or someone said the 750 rods were 4mm longer than the DOHC rods. And are the 1100F rods the same length as the 900 rods??

Big Jay, if you're out there reading this thread, how much can you safely stroke a 900 crank? Just giving this some thought. If we got 6mm more from a stock stroke 900 crank, i wonder if we can fudge more out of one stroked and still have the rotating parts fit the cases and not interfer with the bottom of the sleeves. One limitation to keep in mind is we don't want an oversquare (stroke bigger than bore) engine.

[jweeks]

Frank,
     I've already asked Jay at Valdosta if APE would stroke a 900F crank. He said that they could. Bear and I have discussed more stroke than +6 mm. Cases vary some, so you should measure for the case clearances. You can go between 2 and 3 more mm of stroke than what the 900F crank offers. Generally, you can go 73 mm bore without risking pulling out cylinder studs. Bear has had fun trying to get 74 mm bores to last as the cylinder studs don't have enough meat around them to stay put with an insert sleeve wall that is consistent top to bottom. So, it depends on how big of a bore you want to run. Going 1200 cc + requires compromises. 

                                                           Jon Weeks

[jweeks]

750 DOHC rods 1.5 mm shorter than our stock SOHC 750 rods. The 900F and 1100F rods are 1.5 mm longer than our stock rods. The 900F uses 15 mm pins; the 1100F rods use 17 mm pins.

http://www.satanicmechanic.org/conrods.shtml

                                                               Jon Weeks

[MRieck]

Would it be easier to move the pin height with custom pistons if you further stroke that 900 crank?

[jweeks]

     Add 9  mm stroke and 1.5 mm longer rods requires up to a 6 mm spacer and/or higher piston pin location to offset it. Moving the pin location up would help prevent longer cam chains and longer cylinder studs.
     Feeding big cubic inches requires more air going through the cylinder heads to make it worth the investment. Kenny (Cycle X) is using raised straight ports, bigger valves, etc. to get that. Everything seems to make the engine taller reducing clearances to stock frames. I don't know the valve cover to frame rail clearances for a clutch cb750. I know that it's tighter than the automatics. More things to check the wilder you build it.

                           73 mm bore by 72 mm stroke is 1206 cc.

     Would love to see one being built. If I hit the lottery, maybe.....

                                                                       Jon Weeks

[MRieck]

For conversation/compromise purposes (and far less money) how about an F2 head with 5mm stems and a 35mm intake? I have ordered the 5mm F2 valves in 34 before. The program is already in place at Kibblewhite. I would change the keeper groove height (easy) from what exists now but that is it. If you were making the custom pistons you could fool around with the crown to get some compression (good luck getting a lot). You could get enough to make it fun.

[Bill/BentON Racing]

Mike,I been thinking something more than Stage III I got now,have F2 head or heads,holding two for Bear! I like the 35 mm inlet,,got some 34 CV's from Bear a while back,so 34 or 35 be ok I think.5.5 mm valve conversion also.What you need I got I can trade?lol, 900F rods just arrived!!,as Jon said,longer!K. Probably use Jay's 1000cc kit,already got it.900F crank and rods,Kenny lighten and balance crank,coatings on pistons,maybe elsewhere,shot peen rods,Mike Rieck Stage? F2 head,295 's worked the best so far,so it initially,better brakes etc,my 125/75 will be there if needed! More pics later,Bill

[bear]

The pin height with the both pistons I mentioned earlier are closer to crown by around 3mm. They use 17mm pins though. I'm heading out to the shed shortly, I will run the verniers over them and report back.
Mike and I have discussed valve size previously on a different thread.
We use the F2 heads with 35mm Mitsubishi inlet valves and exhausts machined down 1/2mm from std to provide enough clearance.
Mike has rightly pointed out that these valves are a little heavy, but they are cheap and they do the job.
Another point I should mention is that we use cast guides rather than the bronze ones.
While the cast units are no where near as effective with regard to heat dispersion we found that the bronze guides wore excessively and caused some valve train problems.
Probably due to their weight.
With regard to compression, varying the base plate thickness allowed us to tune our CR to some degree.

Cheers,
Brian

By the by, Both of our motors are running a CR of 13 to 1.

[Bill/BentON Racing]

13 to 1 sounds good! Heres some more pics.

CB500/4,CB750/4,CB900F/4....Used to think the reason I could spin the little 550 to 13,000+,never a rod problem,eas due to shorter length.Well,yes,but look @ 500 rod,so much better,even has a lower pin hole on small end.A lot like the 900F,Honda learned in the 2 years before 500 came out!!

Well,if the piston won't fit,the sleeve got no chance!!!

Looking Good!

I think you can tell which side I been working on.

When that little blk mark gone,we'll be done on that side!Was all the way across.
1100F rods not out ther rt now,ebay today.I can get the 250 pistons(ain't telling which ones,you guys bought all the 1100 rods!)Bear ,not .050 available,but .025 are.Can get them,cost plus 10% for @ $300.00,don't mind bit need the rods for 17mm pin.I like the pin height 3mm up! ;)Back to filing.Guys,Thanks,Bill

[Jerry Rxman Griffin aka MuthaF'er]

Bill, answer yer damn phone! Call me. (1-NOS-RC-1080)

[scottly]

Back to filing.Guys,Thanks,Bill

Hey Bill, it looks like you are removing material across the entire face of the main bearing web, even where it is not interfering with the crank. Why not use a burr, and only remove the minimum material required for clearance?   

[Bill/BentON Racing]

  Getting ready to get my dremel ,burr etc. out!  Well,Scottly,you might be right,but looks can be deceiving! ;)Really not much to remove,.040 or less....But,I hear you! Bill

[dragracer]

This is getting better by the second.

I need to finish up my other projects so i can contribute on my end. Bill has been doing all the work as usual.


Thanks Bear for all the detailed info and Jon Weeks for sharing your knowledge.

No doubt the head will be the limitation of any SOHC big cc build. Going with the 5.5mm valve conversion does give the option of installing lighter titanium valves when going oversize- yes, they are expensive. I would also think sinking the valves back in the head should help somewhat in limiting valve to valve clearance issues. I'm sure Mike has experimented already with that concept.

[Bill/BentON Racing]

Working,well maybe,enjoy,pics how it got here tomorrow!

another

Time for bed! Frank,you rt,getting pumped!! ,Bill
Spins over nicely!!!! ::)Scottly,you were rt also!

[dragracer]

750 DOHC rods 1.5 mm shorter than our stock SOHC 750 rods. The 900F and 1100F rods are 1.5 mm longer than our stock rods. The 900F uses 15 mm pins; the 1100F rods use 17 mm pins.

http://www.satanicmechanic.org/conrods.shtml

                                                               Jon Weeks

Any issues in putting bushings in the 1100 DOHC rods  to bring it down to 15mm?? We've done that to GPZ Kaw rods to go from 18mm to 17mm to use KZ pistons- greater variety in those. Of course in an ideal, money is no object world we would have custom pistons made to move the pin location up.

[bear]

750 DOHC rods 1.5 mm shorter than our stock SOHC 750 rods. The 900F and 1100F rods are 1.5 mm longer than our stock rods. The 900F uses 15 mm pins; the 1100F rods use 17 mm pins.

http://www.satanicmechanic.org/conrods.shtml

                                                               Jon Weeks

Any issues in putting bushings in the 1100 DOHC rods  to bring it down to 15mm?? We've done that to GPZ Kaw rods to go from 18mm to 17mm to use KZ pistons- greater variety in those. Of course in an ideal, money is no object world we would have custom pistons made to move the pin location up.

I can't see a problem with that Frank.
Rod length and strength is one thing but I don't think that pin DIA is really going to be an issue.

Cheers,
Brian

[jweeks]

Frank,
    Why would you convert an 1100F rod into a 900F rod via bushings? Do you have some aftermarket 1100F rods? Are the 1100F rod bolts stronger than the 900F ones? I don't know that answer ... anyone?
     Am I the only one sleeping after midnight here? 

                                                          Jon Weeks

[Bill/BentON Racing]

Frank,I got a nice set of 900F rods.Looking for 1100F rods! Bill

[Greggo]

13 to 1 sounds good! Heres some more pics.

CB500/4,CB750/4,CB900F/4....Used to think the reason I could spin the little 550 to 13,000+,never a rod problem,eas due to shorter length.Well,yes,but look @ 500 rod,so much better,even has a lower pin hole on small end.A lot like the 900F,Honda learned in the 2 years before 500 came out!!

I concur!  People knock the 500/4, but what amazing little screamers they were straight from the factory, taking many lessons learned from the 750, and feedback from buyers...I hear they're even better with a turbo

[Bill/BentON Racing]

Mike,I been thinking something more than Stage III I got now,have F2 head or heads,holding two for Bear! I like the 35 mm inlet,,got some 34 CV's from Bear a while back,so 34 or 35 be ok I think.5.5 mm valve conversion also.What you need I got I can trade?lol, 900F rods just arrived!!,as Jon said,longer!K. Probably use Jay's 1000cc kit,already got it.900F crank and rods,Kenny lighten and balance crank,coatings on pistons,maybe elsewhere,shot peen rods,Mike Rieck Stage? F2 head,295 's worked the best so far,so it initially,better brakes etc,my 125/75 will be there if needed! More pics later,Bill

Forgot about CV's need 38mm or something close.Any such animal on a street bike, flat slides be good! Thanks Bill

[754]

How about pin bushing with heavy interference fit, then OFFSET bored ...way cheaper than pistobs getting made..

[Bill/BentON Racing]

Frank, the pistons have the pin 3mm higher.Bill