Topic: Project "Evolution" 78' CB750K... the morphing continues...

[madmtnmotors]

We have a runner! Fired right up, short warm up then settled into a 950rpm idle. Synced the carbs, dynamic check of timing, went for a ride...

Then spent all weekend trying to figure out why it would pull hard up to 5500 rpm then fall flat on its face. Cranking the throttle to wide open would bring upon sputtering and surging, but below 5000 rpm it would run perfect. Turns out the increase to 836cc did not require such a drastic increase in main jets from 110 to 125. Reverting back to 110 mains settled everything down and now runs more like it should all the way to 8500 rpm. I'll put down as many break in miles as I can this week and then off to the local track for test-n-tune next weekend!

[Stev-o]

Good news!

[Retro Rocket]

Good news!

+1   

[Desert-SOHC]

Great!

[SOHC4 Cafe Racer Fan]

Excellent!

[scottly]

Turns out the increase to 836cc did not require such a drastic increase in main jets from 110 to 125. Reverting back to 110 mains settled everything down and now runs more like it should all the way to 8500 rpm.

Yup, an increase in air-flow generates more "pull" on the main jets. That's how carburetors work...

[madmtnmotors]

Have you tried contacting webcam for an answer yet? In my experience, their customer service has been good. Especially since you have these pictures. Did you buy direct from them, or a distributor? (I looked through the thread and didn't see)

Waiting on a response from the distributor before I weigh in on their customer service...

I have also reached out to Jim French, our resident microwelder, about a potential repair if the warranty efforts fall through.

Update:

    Ken at Cycle X has convinced WebCam to replace the defective CX-1 cam. Woo-Hoo! Thanks Ken! I figured it would be covered due to the improperly drilled flange. Should ship out any day now.

    I will reach out to any cam supplier in the future, prior to installing a cam that has any visible defects, just to be on the safe side.

[Davez134]

Awesome! Glad to hear they did the right thing.

[SOHC4 Cafe Racer Fan]

Great news. I like it when manufacturers stand behind their products - especially specialty items like performance engine parts.

[Desert-SOHC]

that's awesome!

[BPellerine]

a little harder to keep the front end down with the new cam?haha bill

[Restoration Fan]

Good news but don't get caught up in the 'go faster' mentality quite yet.  Keep doing what you're doing at getting good at running consistent times to win Street ET.

It's easy to try to shoot for 11's then 10's then 9's etc on these bikes but Frank keeps proving that consistency wins these races, not speed.  And as we already know, the 78's are the fastest already anyways! 

Congrats on a great job down in Valdosta, Wilbur!  Keep showing these boys what a SOHC bike can do.

[RandyBMC]

That must be a great feeling hearing it run!  I can't even imagine what it would be like to ride it!

Congrats 

[madmtnmotors]

Update: Front end has been lowered and preloaded by 1-1/2". At rest there is no compression of the fork springs now, so there is no extension of the forks upon launch off the starting line. This has helped reduce the wheelies. I still managed to pull the front wheel a couple of times at "The Rock" last month, but they were more subdued. The flamed fuel tank that was caved in on the way to Memphis (broken tie down strap... dammit!) has been replaced with a straight tank sporting original paint. Flat drag handlebars along with a 1/4 turn throttle round out the bulk of the mods to date.

The only other mod so far has been the addition of a rev limiter that I just finished up yesterday. A quick 30 mile "shakedown" today to "get-er-dialed" and I've got the rev limiter coming on around 9500 right now. Special shout out to POPS for cutting me a great deal on the Dyna 200DRL! I would have installed it sooner, but I lost the friggin box that I put it in and spent the last three months looking for it!

The only thing left to do for the near future is the addition of a shift light. Picts to follow... stay tuned! 

[Restoration Fan]

Good luck with it in Valdosta, Wilbur!

Ron

[Stev-o]

 Picts to follow... stay tuned! 

Holy crap, Wilbur! How long do we need to stay tuned??!

[madmtnmotors]

 Picts to follow... stay tuned! 

Holy crap, Wilbur! How long do we need to stay tuned??!

Until now...


New (to me) Dyna DRL-200 safely stowed in the tool rev limiter tray:




All wired up:




Safely snuggled in some high density foam:




 

[madmtnmotors]

Dropped the oil pan today and found the rest of the wayward friction material from the friction disks that failed during test-n-tune two weeks ago:








Also addressed the weak link that reared its ugly head in the form of a failed glass fuse before half track in round three last weekend:







That's right, you are not seeing things. I added another 15A circuit dedicated strictly to igniting the fuel/air mixture. While I was at it I added a couple relays to take the load off the ignition switch. EZPZ 

No more failed glass fuses for me! 

[Stev-o]

Hey Wilbur...looks good.  Debating switching fuse blacks too, where did you source them, Hondaman?

Whens the next race?

[Rnobx67]

Want to keep an eye on your post. Amazing job done

[madmtnmotors]

The fuse block I used from here:

http://www.wiringproducts.com/4-circuit-raised-ato-atc-fuse-block.html

It uses 1/4" male spade connections on the backside. I had a melted fusebox in the parts bin that I harvested the harness pigtail from. New Vintage Connections connectors for the fusebox connections on the freshly trimmed wires and the other end plugs right in to the stock harness. The holes are almost exactly the same as the stock fusebox if you orient it horizontally. This stuck out a little far for my taste so I made a bracket to recess it in about 3/8" which uses the stock mounting holes and orients the new fuse block vertically as well.


Next race in Valdosta in April... coming soon! 

[SOHC4 Cafe Racer Fan]

Same company supplies a 6-fuse block.  http://www.wiringproducts.com/6-circuit-ato-atc-fuse-block.html

It's a good idea in that it allows you to carry 2 spare fuses (just in case).

[madmtnmotors]

Same company supplies a 6-fuse block.  http://www.wiringproducts.com/6-circuit-ato-atc-fuse-block.html

It's a good idea in that it allows you to carry 2 spare fuses (just in case).

I ordered a couple of those as well, but the side connections make this a rather large assembly when wired up. It can be done, just requires more real estate.

[Stev-o]

The fuse block I used from here:

http://www.wiringproducts.com/4-circuit-raised-ato-atc-fuse-block.html

It uses 1/4" male spade connections on the backside. I had a melted fusebox in the parts bin that I harvested the harness pigtail from. New Vintage Connections connectors for the fusebox connections on the freshly trimmed wires and the other end plugs right in to the stock harness. The holes are almost exactly the same as the stock fusebox if you orient it horizontally. This stuck out a little far for my taste so I made a bracket to recess it in about 3/8" which uses the stock mounting holes and orients the new fuse block vertically as well.


Next race in Valdosta in April... coming soon! 

Good info...thanks

[madmtnmotors]

The fuse block I used from here:

http://www.wiringproducts.com/4-circuit-raised-ato-atc-fuse-block.html

It uses 1/4" male spade connections on the backside. I had a melted fusebox in the parts bin that I harvested the harness pigtail from. New Vintage Connections connectors for the fusebox connections on the freshly trimmed wires and the other end plugs right in to the stock harness. The holes are almost exactly the same as the stock fusebox if you orient it horizontally. This stuck out a little far for my taste so I made a bracket to recess it in about 3/8" which uses the stock mounting holes and orients the new fuse block vertically as well.


Next race in Valdosta in April... coming soon! 

Good info...thanks

If you use the same (or similar) fuse block, I can post a pdf pattern for the bracket if you like.