Topic: Rotten rusted CB750 aka The Red Rider OUT OF HIBERNATION

[MoMo]

Found a barb plumbing fitting that should do the trick.  Here was the problem,  small fitting bottom of the oil tank and large fitting lower crankcase.






And here is a photo of the fitting I found in the plumbing section of Home Depot



Have everything back together  but need to recharge the battery(some idiot left the key on) before I can test ride...Larry

thanks for the update Matt

[MoMo]

Well, the plumbing adapter seems to have worked just fine but the tach seal is leaking quite profusely.  I had a strange thing happen that I  had never seen before- that is afer the bike started and I went to check the oil level there was an audible whoosh to relieve pressure as I removed the dipstick.   Rode the bike around the block(don't want to ride too far due to the seal ) and when I came back and removed the dipstick again
no whoosh.  Is there some sort of intial circulation build up that would create pressure?  Photos to follow,  and leaving the key on ruined the new battery   ....Larry

[Terry in Australia]

I've never experienced that "whoosh" before Larry, but it could be that your oil filler cap has a better seal than mine? Ref the tach seal, I'm a slack bastard, so I just smear a little case sealant around the end of the cable, re-insert the cable, let it dry, and mine doesn't leak. Cheers, Terry.

[MoMo]

I've never experienced that "whoosh" before Larry, but it could be that your oil filler cap has a better seal than mine? Ref the tach seal, I'm a slack bastard, so I just smear a little case sealant around the end of the cable, re-insert the cable, let it dry, and mine doesn't leak. Cheers, Terry.

This is leaking badly, in less than a couple miles the front of the cylinder head is covered.  Thanks for the tip on sealant, might use it in conjunction with the new seal...Larry

[Terry in Australia]

If you're gonna go to the trouble of replacing the seal I don't think you'll need any sealant mate, I've only ever replaced one seal and after that it didn't leak at all, this is just the lazy, er. efficient way of doing it.

[MoMo]

Well, the whooshing sound has been figured out.  Some idiot connected the cam cover vent into the top oil tank vent causing it to be pressurized.  Fortuneately the bike wasn't ridden very far.  Since the vent problem was fixed a couple days ago I rode the bike to and from work experiencing somewhat poor performance, that was solved by repairing the yellow female end from the wire harness that connects to the right point set. It needed to be crimped down a bit.  I will post some photos of the final product as soon as I find my card reader(certainly not the tarot type)...Larry

[Terry in Australia]

Well done Larry, glad you fixed it. Cheers, Terry.

[MoMo]

Well done Larry, glad you fixed it. Cheers, Terry.

Thanks, Terry.

After nine months, selling a house, buying a house and starting to fix it up, and setting up shop in the barn The Red Rider is done.  New frame, swing arm bushings, wheel bearings, second hand 6K miles 750F motor, seat, battery, chain, steering head bearings.  It'll be for sale soon.


Here are a couple photos taken a couple days ago.   I intend to take more Weds morn if the weather permits...Larry








I do need to sand the side covers I got from Joe and install the emblems but for all purposes the bike is complete and runs well.

Anyone know for sure what brand the exhaust is?   Jardine?  No markings on it anywhere...Larry

[Stev-o]

Momo - was this the rusted bike that MrJack55 sold?

Nice job, looks good.

[MoMo]

Momo - was this the rusted bike that MrJack55 sold?

Nice job, looks good.

Yep,  I bought it from Jack along with a bunch of spare parts.  Thanks for the compliment, Stev-o...Larry

[mrjack55]

Well done Larry, you did the old girl proud.
I knew you were the man for the job.
I hope you get to enjoy a few rides before you sell her.

[MoMo]

Well done Larry, you did the old girl proud.
I knew you were the man for the job.
I hope you get to enjoy a few rides before you sell her.

Thanks, Jack.  I went for a fairly long ride today and intend to ride back and forth to work until I decide to sell(could always change my mind but I have two more 750s to finish plus a 400f).  Good to hear from you and thanks again...Larry

[MoMo]

Finished?  Not really, I finally had the time to take an extended test (more than the normal 5 mile commute to work) and experienced the fast idle when hot scenario-takes at least 15 to 20 miles before the problem rears its ugly head.   Idle shot up to 3k and would not idle at 1200 when I turned the knob back down.   Back to the shop and check for an air leak.   I still will post more photos of the "finished project" at some future point...Larry

[MoMo]

Fixed the high idle when hot problem--bike had some ill fitting hard rubbers    The intake manifold and air box boots had hardened even though I had soaked them in the xylene/wintergreen magic elixir.  I resoaked them which softened the rubber so both sets became useable.  If they harden again I guess I'll be looking for new ones.

Bike is running  lean as the carbs were fitted with 105 main jets. I have another set of carbs with three 115 and one 120 main jets.  I am pretty sure 115's will cure the lean  problem.  So I need one 115 main jet,  anyone reading this have one spare 115 main?  Bike has 4 into 1 exhaust with K&N air filter...Larry

Still intend to post more photos whenever I get some time.

[lucky]

Fixed the high idle when hot problem--bike had some ill fitting hard rubbers    The intake manifold and air box boots had hardened even though I had soaked them in the xylene/wintergreen magic elixir.  I resoaked them which softened the rubber so both sets became useable.  If they harden again I guess I'll be looking for new ones.

Bike is running  lean as the carbs were fitted with 105 main jets. I have another set of carbs with three 115 and one 120 main jets.  I am pretty sure 115's will cure the lean  problem.  So I need one 115 main jet,  anyone reading this have one spare 115 main?  Bike has 4 into 1 exhaust with K&N air filter...Larry

Still intend to post more photos whenever I get some time.

Just move the needle clips down one notch and that will richen 1/4-3/4 throttle .
No need to change the main jet. You do not run at WOT that much anyway.

[MoMo]

Finally found time to install the three 115 main jets along with a 112 I found in a bin of miscellaneous parts.  Still need another 115 but the bike runs soooooo much better with the 115/112 combo and the K&N filter along with whatever brand the exhaust is.  Easier to start, smooth throughout the entire power band.  Hedging on the thought of selling it ....Larry

[MoMo]

At work the other day I was talking with a customer and the conversation turned to motorcycles.  He mentioned he had a 1969 1/2 (his phrase) Honda CB750 for sale.  Thinking he would be asking 2 to 5K I hesitantly asked how much?  Answer, $1000.  Me,, does it have a clear title?  Answer, yes.  Me, I'll take it.   He asked me to come look before committing, which I did, then shook hands to confirm sale.  Went back last night with money and trailer,bike is now at MoMo's Shop.  I'll be going out to take some photos to post up...Larry

[70CB750]

Congratulations!

Actually, NO!  I am bloody jealous 

[MoMo]

Congratulations!

Actually, NO!  I am bloody jealous 

Thanks, it was a deal that I could not pass up.  Fortunately, I had the funds, but if I didn't I would have begged, borrowed or stole to raise the money. I just checked the engine serial numbers and found that it starts with 250 so it is a later (75? motor).  Still worth the money though...Larry

[Terry in Australia]

Geez Larry, that's exciting and slightly disappointing, all rolled into one. So the engine is a 1975, what's the frame number? Sandcast or diecast? Anyway, post some pics mate! Cheers, Terry.

[MoMo]

A couple photos that I am able to post while there is some time before work...Larry









Terry, it sure is a dichotomy of emotion.  Here are the frame and motor number photos.  Build date was 1970 so it is not sandcast.  More photos to follow...Larry


frame photo will not copy from photobucket.             s/n 1029342

[70CB750]

My frame is 10296xx

But for a 1000, good catch!

[MoMo]

My frame is 10296xx

But for a 1000, good catch!

It was hard to pass on.  Motor s/n 2503055.   thanks...Larry

[Terry in Australia]

Nice one Larry, I guess the original engine crapped out (chain damage, perhaps?) so they just installed another engine, "back in the day"? It goes without saying that I want it, I've got a late 1969 diecast engine sitting here (in pieces) that's look just right in that bike!

[MoMo]

Nice one Larry, I guess the original engine crapped out (chain damage, perhaps?) so they just installed another engine, "back in the day"? It goes without saying that I want it, I've got a late 1969 diecast engine sitting here (in pieces) that's look just right in that bike!

I have 4 motors laying around, maybe one might be appropriate to the year.  Am I right in assuming that motor number is a 75?  Take care...Larry