Topic: Ultimate motor

[lordmoonpie]

How far away are you from firing that beast up mate? Have you got a video camera with sound? Ooooer!

Probably a couple of months sadly. The exhausts are being fabricated in May so I'll wait for those to be done so I don't upset the neighbours too much. They're very tolerant of me starting stuff up and revving the nuts off it but I don't want to test them too much too often 

I guess I'm not a million miles away from finishing really - got front fender to make, front brake lines, rear brake cable, all paint on the tins, carbs/cables to install, ignition to install and then tweak everything up. Will definitely get it all on video though in case it goes >BANG!< 

Think I'm all out of pictures too really - there's a few left of comparisons of bits and the cam cover after taking the metal out of the inside to fit over the hy-vo camchain but so far I haven't taken a picture of the motor in the frame....must get back down that garage.....after I've checked out Sam's Babe thread     

[Terry in Australia]

Yeah, I don't know about that babe thread mate, too many cross-eyed, hairy palmed old guys here doing some "one handed surfing" for my liking, ha ha!

If you've got the engine in the frame then I think it's only fair you take some pics and share them too, I'd like to see what you've done to the rest of the bike? Thanks mate! Cheers, Terry.

[Jim F]

Damn Terry
Its just too early in the morning on the east coast
to get a visual about hairy palms and old men

just Damn

[lordmoonpie]

Hairy palms or not - the motor is in the frame and waiting for exhausts. Although I have the headers, the factory replica megas take some time to make (not by me!!) so I'm polishing a round shiny object while I wait.

One observation though - the CR750 CR31 Keihin carbs are a complete #$%* to fit to the carb adaptors on the back of the engine....one week of hot water and shoving and they're on but I managed to pull a muscle in my shoulder in the process!

On top of all that I suppose some bright spark down under will want pics now 

[MRieck]

Hairy palms or not - the motor is in the frame and waiting for exhausts. Although I have the headers, the factory replica megas take some time to make (not by me!!) so I'm polishing a round shiny object while I wait.

One observation though - the CR750 CR31 Keihin carbs are a complete #$%* to fit to the carb adaptors on the back of the engine....one week of hot water and shoving and they're on but I managed to pull a muscle in my shoulder in the process!

On top of all that I suppose some bright spark down under will want pics now 

Have you had that set of CR's for a while LMP? Adaptors have been changed (I used to reduce the length and OD on older adaptors).

[lordmoonpie]

Mike, yes I guess I have had them for a while. I think the problem was though that my manifold rubber stubs were very old and cracked so I got a nice new set from Dave Silver. The problem was they were so new there was almost no give in them at all. A bit of boiling water and a long soak and they softened up a bit to be able to force them on and they clicked into place real nice. Don't want to try getting them off in a hurry though :-)

Back to my age old issue now and trying to fabricate the front fender brackets around that tight KR124 front tyre....been on that one for 8 months now!

[Terry in Australia]

Hairy palms or not - the motor is in the frame and waiting for exhausts. Although I have the headers, the factory replica megas take some time to make (not by me!!) so I'm polishing a round shiny object while I wait.

One observation though - the CR750 CR31 Keihin carbs are a complete #$%* to fit to the carb adaptors on the back of the engine....one week of hot water and shoving and they're on but I managed to pull a muscle in my shoulder in the process!

On top of all that I suppose some bright spark down under will want pics now 

Why don't you get some nice new soft rubber insulators, you tight arsed pommy prick? Oh, and some pics'd be nice, maaaaate! 

[bryanj]

Not wanting to throw a small moggy among the flying vermin but when i worked for Mead and Tomkinson in the 70's (try googling "nessie") I had two bikes that broke Hy-Vo cam chains---Both 250N's as i remember and both on relatively high, abused mileage

[lordmoonpie]

Why don't you get some nice new soft rubber insulators, you tight arsed pommy prick? Oh, and some pics'd be nice, maaaaate! 

Damn I've missed these thoughtful caring insights into my little motor - good to hear from You Terry!

I think that's where I went wrong thoug - these were brand spanking new rubbers - so new they had mld release agent all sliming over them....should stuck to those old crispy slightly perished ones I had I guess.

Oh yeah - pics! OK, got to install the throttle this weekend and then I promise a pic or two...what are you like with antici..........pation Terry? 

[lordmoonpie]

Not wanting to throw a small moggy among the flying vermin but when i worked for Mead and Tomkinson in the 70's (try googling "nessie") I had two bikes that broke Hy-Vo cam chains---Both 250N's as i remember and both on relatively high, abused mileage

I guess that's it isn't it - high mileage abused....mine's new as a new thing but then it's only mechanics isn't it - everything fails eventually

[Phxmark123]

Great motor tech info but I thought this was the ultimate motor...
[youtube=425,350]<object width="425" height="344"><param name="movie" value="

name="allowFullScreen" value="true"></param><embed src="

type="application/x-shockwave-flash" allowfullscreen="true" width="425" height="344"></embed></object>[/youtube]

[lordmoonpie]

Great motor tech info but I thought this was the ultimate motor...

Ha ha - it probably is in Texas, but over here we have corners! 

[bwaller]

Great motor tech info but I thought this was the ultimate motor...

Ha ha - it probably is in Texas, but over here we have corners! 

+1

[lordmoonpie]

Well with the motor in the frame it was finally time to tackle the double sided brakes. MAN! What a nightmare!   

The early 750 (K0/2) fork leg bottoms were installed and the forks into the yokes. Then begins a right saga to get it all into one functional piece and the main problem was the Dunlop KR124 front tyre. It is so wide at the shoulder, you can't put the wheel on with both caliper hangers installed first as it just won't clear them even with brute force and a flat tyre.

So, wheel placed between the fork legs with no discs installed and no spindle, raised up on a three inch wooden block. This gave me space enough to turn the fork legs out a quarter turn and bolt the caliper hanger/caliper assembly in place with correct length bolts. Turn them back in and bingo - brakes on and wheel in.

Next the disc was place in on the left side where the wheel hub mount is thickest and where the old speedo drive went. The right side disc then slots just up onto the shoulder of the hub and into the gap between the pads. Bolt them all up.

Finally, I had to reinstall the spindle and bolt up the fork leg spindle caps and voila! Job's a good 'un. Those discs look huge installed - well I suppose twin 290mm discs are pretty big for an old CB750. The only downside I can see is that the hangers and the fork legs don't align for the caliper tensioning spring and bolt. I know a lot of guys who race CB350 K4s junk this altogether and let the caliper arm swing free - any opinions on whether that's a good or bad thing?! 

Next job is to measure the brake lines and get them made up while work continues positively on the front fender brackets thanks to the great K0 patterns I had off this forum - thanks guys.

Ah - Terry will be wanting another picture no doubt...will really seriously try and do that soon to get the brakes in shot, the motor in the frame and the trick little bits like works replica foot levers and that ooh sooo deep sump! 

[rbmgf7]

why didn't i spot this thread before? lol. beautiful build moonpie.

so lemme recap...the reason why you went with the DOHC crank was for the hy-vo cam chain? i think i'm in luck with obtaining a hondamatic crank yet those still run on the roller chains for the cam. i figure i could roll with a Tsubaki cam chain with M3 tensioner. I sure using M3's tensioner over stock would prolong the chains life.

i find that hydraulic tensioner quite cool. i don't want to sound like a stickler, but how do you know the oil feed is sufficient enough in producing the right amount of pressure to tension the guide? if it works, Hey!, i'm game too. i'm actually stumped right now. looking at your underside pic of the tapped oiler and my lower F2 case, i have an opening while your appears blocked. or is that just the underside of the tensioner? it's been a while since i disassembled my case so i'm just lost. is that hose appart of the OEM plumbing or is that something you had to work up?

would've there been a way to spring load that slipper tensioner instead of hydraulics?

i know there was a debate a few pages back on running a hy-vo primary vs. a roller. IMO, just guessing, i figure the hy-vo would be stronger against shock loads than the roller. since the hy-vo may have a stronger tensile strenght, it could come in handy for drag racing. since roller chains are more efficient in power transfer, i figure those would be great for track race applications. again, this is just my opinion.

what primaries did RC use in that drag bike of his?

edited

[bwaller]

Have you reversed the legs so the calipers trail the forks? No matter, it is indeed a test of patience mounting the wheel. All these stock rotors? All the more reason to grind a couple mm off them, so as not to develop a hernia hefting that wheel in place!

You can just hang the calipers/hangers unmounted, clamp the wheel with rotors in place, then install the calipers down over the rotors and bolt up the hangers last.

Maybe yours are the earlier brackets, but I'm not sure why you're tensioner holes don't align, mine is a K3 and they do so I use the adjusters, but as you said there are those who do not. I can't imagine it would be terrible without, but if roadracing it's best to do all you can to quarantee a good handful of front brake when you need it!   

Terry's not the only one.....pics are always good.

[MRieck]

what primaries did RC use in that drag bike of his?

edited

I know the man that had the fastest normally aspirated CB in the USA in the mid 70"s (9 low teens....almost 8's). As I mentioned before he used CR primary chains with no problems. That was a delicate engine with a very complex top end....especially at the end of its use. I don't know what RC used.

[lordmoonpie]

why didn't i spot this thread before? lol. beautiful build moonpie.

so lemme recap...the reason why you went with the DOHC crank was for the hy-vo cam chain? i think i'm in luck with obtaining a hondamatic crank yet those still run on the roller chains for the cam. i figure i could roll with a Tsubaki cam chain with M3 tensioner. I sure using M3's tensioner over stock would prolong the chains life.

i find that hydraulic tensioner quite cool. i don't want to sound like a stickler, but how do you know the oil feed is sufficient enough in producing the right amount of pressure to tension the guide? looking at your underside pic of the tapped oiler and my lower F2 case, i have an opening while your appears blocked. or is that just the underside of the tensioner?  is that hose appart of the OEM plumbing or is that something you had to work up?

would've there been a way to spring load that slipper tensioner instead of hydraulics?

The reason I went for the DOHC crank was to get the hy-vo camchain, just in case I get to Daytona LOL!

It was simply an exercise to see if I could do it - a puzzle or a challenge I don't know really?! Bottom line is that M3 use the A crank and race camchains and there's not much better racing out there than Mark's bikes in standard CR trim.

Ah the hy-vo tensioner is a combination tensioner. It uses a spring inside the tensioner cylinder to push up as well. The kit tensioner apparently used a stronger spring but I use a standard one pre-loaded with a couple of washers - works just nicely. The oil is there to add a bit of dynamic tension but it would probably run fine without it. The oil feed is also used to create a bit of a spray for the hy-vo chain but again it's probably quite wel lubed just with splashing around in the cases.

Not sure how the F2 oiler differs from my old K2 - F2 is a bit modern for me  The plumbing is all home developed though with cues from Mark at M3.

I don't know yet whether the hy-vo chains will sap horsepower or I'll be able to rev higher with confidence in their strength - but it was great fun building it!

[rbmgf7]

ok, i get it  . thanks for the explination. this is truely an awesome build. 

[lordmoonpie]

Oooo - the excitement is killing me! Tomorrow I get the bike back with it's works replica four into four megas.

They are brand new fabrications BUT they are patterned directly off a set of original works exhausts so can't wait to see them in the flesh....might even break out the camera 

[voxonda]

My sweet lord, please bring out the camera!

Cheers, Rob

[bwaller]

I'm glad you're doing your part to keep the economy going LMP.   

This will be good, drum roll please...............

[Terry in Australia]

C'mon pie-man, where the fck are those pics mate?

[lordmoonpie]

Here they are! The exhausts are off the bike already as I'l be sending them away for their usual reatment - sprayed with molten aluminium and then painted with VHT paint. It gives a durable rust proof finish that last for years.

So - these are copied from a set of genuine works CR750 pipes. They are very very good with the only differences being the extra depth in my middle two pipes to get around the deep sump and the seam of the weld on the top pipe which is apparently very hard to recreate without the budget capacity of Honda. Having said that he's even managed to create the rolled over lip on the reverse cones just like the factory items. Superb job imho!

See what you guys think!

Oh I guess I haven't posted any pics for a long while have I....better get some more done soon so you can see how the build is going. Basially I've just got loads of niggly jobs left - clutch and tacho cable, ignition, paint, steering damper mount, clutch lever etc. I reckon I should be able to fire her up for the summer! 

[bwaller]

Nicely done. Folks should be able to hear you work your way around!