THE HONDA CR 750 Web Site Page 5

Reader's Write

From: "Andrea Servante-Freeman"
To: "Murray Barnard"
Subject: Re: honda cr 750
Date: Thu, 1 Jan 1998 21:32:36 +1300

Have surfed your site and taken copies of the pages.
Do you havefurther details on modifications as I have built a post
classic for racing in New Zealand.

Sadly on its first outing it pushed oil out of the oil tank top and spat
me down the road. (Wanganui Cemetry Circuit Boxing Day , New Zealand)
There are some other guys that would be interested in your feedback as post classic racing is still in its infancy down here.
Any details on how to get in contact on the net with other post classic
racers would be appreciated

Regards

Dave Freeman

From: Murray Barnard
To: [email protected]
Subject: Re: honda cr 750
Date: Sunday, 4 January 1998 14:03

Sorry, but I don't have anymore info than that published on my website.
I have found it difficult to get info on the CR750 though I'm sure that
many people out there have a heap of Honda Four knowledge.

MY Honda is basically standard, I have worked on the frame and race parts
but left the motor stock for reliability at the moment.

Time doesn't permit me to do much either.
Why did your bike spit its oil out?

cheers
Murray

From: "Andrea Servante-Freeman"
To: "Murray Barnard"
Subject: Re: honda cr 750
Date: Thu, 8 Jan 1998 21:32:36 +1300
X-MSMail-Priority: Normal

Murray,
Thank you for your reply.

You mention that your Honda is basically standard except for frame bracing.
Do you use it as a road bike or post classic?

I totally rebuilt mine and the performance parts were 836 12:1 kit, APE cam
and valve springs and 31mm CR smoothbores. We got 71 hp at the rear wheel
on our local Dynotech dyno. (This was not jetted 100% and the motor was
still tight.) Ignition was via std points using total loss. Crank and rods
at this stage are std.

I suspect there will be more power available if I increased the inlet
valve size and the inlet tract diameter.

I have also laced 2.5 x 18 and 2.15 x 18 rims into front and back. Double
disks are on the front with std calipers. Frame has been braced.

Due to time constraints I did not get the chance to test the bike on a
circuit prior to the Boxing Day street races at Wanganui. (Have you heard
of this race)

The first practice showed a jetting and clutch problem which we were able
to fix. In the next practice I started to push the bike harder and it was
during this it put a mist of oil onto the rear wheel and put me down the
road. It came out of the oil tank cap. I'm a bit mistified as with the new
motor I know I don't have a blow by problem. The filler cap system is a bit
simplistic and seems to have a spring/pressure releif valve integral in the
cap. Perhaps I need to adapt a screw top in. Have you any ideas? I see that
the CR 750's used a different oil tank.

I also see that from your web site that the CR 750's had a cam chain
reliability problem. One of the guys (Vince Sharpe) over here has exactly
the same problem. (Especially on long circuits). Any ideas??

If you have any contacts in the post classic fraternity over there I would
be nice to make e mail contact.

Regards
Dave Freeman

Can anyone help? I know that a fair number of hot Honda Fours are running over in the Eastern States of Australia eg Wolfenden's, but I don't have details of their modifications. Can anyone help with details or photos?

Murray

At 04:47 PM 15-12-97 +0100, you wrote:
Hi, my name is wannes
I'm only the 8th visitor of your page, but I think it's very cool I also have some Honda's, and I want to convert it to a CR is that possible? are their CR kits avaiable (for CB550four)? I'm looking especially for an alloy long petrol tank, a fairing and a seat.... are their replica's of these parts?V if you know more about it, please let me know...

regards
wannes tollenaere
[email protected]
koning albertlaan 165
tel +32 9 243 93 10
fax +32 9 243 93 11

Hello there Wannes,

I don't know who makes alloy tanks for the CR but there is a mob in the USA who makes fibreglass replicas... see...

Airtech

Check the British Classic magazines there are some CR replica manufacturers there who make tanks out of alloy, I'm sure.

cheers
Murray

From: "Andrea"
Subject: Building a CR750 Tips
Date: Tue, 26 May 1998

I'm in the middle of building a cr750 for use on the street, (not enough dosh for racing) and I've gleened quite a bit of information from an ex-racer. If you want to keep from having camchain trouble go for longer duration instead of lift, use the valve spring kit from R/D and port,port,port those heads. This is just an opinion since I've only seen seven or eight heads, but, Honda has some pretty messy in/ex ports!

I'm keeping my generator kit so I can run a head/tail light, but, having your generator rotor turned down helps the motor rev quicker, provided you balance your rods and crank. Speaking of motors...I'm not terribly impressed with the race results I've seen from 750's with the 836 kit. The reliability seems to suffer, stock bore and it's associated piston sizes develop nice horse power, more is achived by porting,valve timing, carb work and careful tuning. (for about the same price of the bore kit alone!)

The Honda 750 four, in my experience, is a pretty darn easy way to get into vintage roadracing, or at least get the feel of the 70's four. In fact, the 500 four and its slightly bigger sister the 550 are also alot of fun (I've got 5 of the buggers) and if the 750 seems too heavy and hard to handle try a 500 or 550 (the 550 unfortunatly falls into a nasty class for racing compeating with machines that out strip it in raw horsepower, for racing use a 500)

Here are the companies I've used so far... Airtech - replica fiberglass body work , good stuff for the price Megacycle - Cams and rocker arms - GREAT stuff! R/D - valve springs K&N - good stock valve sizes, cheaper and better than the ones from Honda (sorry Sochiro) Olins - good shocks are available, they don't look right though... Dyna - ignition kit and coils (use 3ohm) that kick bottom.

Thanks Dave, see the message from Wayne below about oil blowing out of the oil-tank, re your previous message
Murray

Date: Fri, 08 Jan 1999
From: "iwc.net ALL Numbers"
Reply-To: [email protected]
To: [email protected]
Subject: Dave Freeman's Oil tank blow by

Howdy Murray!
Just surfing tonight for Honda bike info.
Just bought an '85 VF1000R, and missing our CB750 SOHC that's been apart now for 20 years! How the time flies, my dad was right that the time goes faster the older you get.

Nice page on the CR750's. We recently visited the American Motorcyclist Association's Motorcycle Heritage Museum in Columbus, OH and the internal display was all Honda's Lots of our history there, and five of our six Honda's.

Saw my first CR750 in person, there, thus the interest in your page when I saw a link. Nice images, quiet a history.

Read messages from Dave (Andrea Servante-Freeman) about losing oil out of his oil tank and crashing and being at a loss as to why. In a previous life, I was a Honda Dealer mechanic for a while.

I'm not familiar with the oiling system on the CR750. But I am with the early CB750 from which it came, and there can't be a big difference in function. I may be the only dealer mechanic who had a 750 come in blowing oil out of the street bike's oil tank vent, and I'm sorry to say it took several visits before we found the cause.

The 750's dry sump system had two or three vent hoses for crankcase pressure. I'm looking at the parts book for the K0 and K1 and I'm foggy. What we found on the offending bike, was the vent tube from the engine's valve cover was pinched between the engine cases and the swing arm. Pinched fully closed off.

Seems the guy had installed a new endless chain and did a sloppy job of putting the swing arm back on, pinching the crank vent hose. There is a place on back of the crankcase that is recessed for the carb drain tubes, and the crank vent tube so they will all pass freely between the cases and the swing arm. He had the vent hose pinched next to that.

Only at higher RPM's, there is enough crank pressure even in a tight engine, to require that crank pressure venting from the engine. Without that, the excess crankcase pressure forces the return oil probably to foam enough to overflow the tank level, forcing liquid oil out past the baffled oil tank breather.

I was stabbing in the dark after having the oil tank off cleaning it's vent baffle to no avail. I disconnected the crank breather tube from the valve cover, hooked a test tube to the valve cover nipple and blew on it to verify the cover baffling was clear. It was. Then for the hell of it I blew into the top of the breather hose. Eureka! It was fully blocked! Rerouted the hose and the problem was gone.

Had performed the good troubleshooter's questioning to the customer about had he done anything to the bike just before the symptom presented itself. He insisted no. He was embarrased when I called him and told him about the new chain installer's mistake!

I would have Dave make sure all his crank vent TUBES are clear and NOT PINCHED IN ROUTING, and that he can blow through a known clear hose into the various nipples to which they are connected proving the system to be open.

I bet that stops his oil blowing. Tell him to pass it on, too! If you can't forward this, let me know, and I'll see if I can pass it on.

From a fellow Honda fan. Wife and I have 350 twin, 350 Four, 750 four, CX650TD, GL1000, and just purchased a clean VF1000R at age 49...... Hopeless!

Have a good one, Murray.

Wayne & Belle Hager
PO Box 431
Grayslake, IL 60030 US
847 223 3003, fax 847 223 7074

Thanks Wayne, much appreciated
Murray


1997 Murray Barnard