Topic: My first complete build 72 CB750 - completed for now...

[algophobe]

Don: Gotta look at it with a silver lining or else i'll pull my hair out.
PeWe: Thanks for info.

Im thinking that since I have to take apart the top end, I might just send it off the head to have the valve guides rechecked. I bought the valve guides off of ebay, not knowing any better at the beginning when I first got into this, they stated they were Kibblewhites and had a local machine shop put them in, in addition to putting new valves and cutting the seats. What do you think about a port job while I'm at it? According to Satanic Mechanic's website, he says no point in putting CR31's in of you're not doing a port job. Any recommendations where I can send them to? I read in passing of a name or two on this site but can't seem to track them links down.

[SOHC4 Cafe Racer Fan]

Don: Gotta look at it with a silver lining or else i'll pull my hair out.
PeWe: Thanks for info.

Im thinking that since I have to take apart the top end, I might just send it off the head to have the valve guides rechecked. I bought the valve guides off of ebay, not knowing any better at the beginning when I first got into this, they stated they were Kibblewhites and had a local machine shop put them in, in addition to putting new valves and cutting the seats. What do you think about a port job while I'm at it? According to Satanic Mechanic's website, he says no point in putting CR31's in of you're not doing a port job. Any recommendations where I can send them to? I read in passing of a name or two on this site but can't seem to track them links down.

CR31s are a waste without a high-compression piston kit, porting and a performance cam.  CR29s work REALLY well with a Wiseco 836cc kit, CX-7 cam and JMR (Mike Rieck) Stage 4 port job.  If you are including all of those ingredients or a larger big bore kit with port work and a cam, then consider CR31s.

Mike's email is jmrieck2@gmail.com  He's located in Ashland, outside of Boston, MA.
His work is not cheap.  It is pretty much THE BEST and worth every penny if you are building a performance CB engine.

If you want to see what a Stage 4 CB750 port job looks like, Jay at Lossa Engineering has one at his shop.

[algophobe]

Well this is one time that i am glad i dont hang around you Don, cuz you probably would get me to spend a lot of money!

[Byron Norton]

The guys are right: you can't mix cases...easily...to do so, you MUST have the crank holes align-bored, and this usually results (best case scenario) with using the Black (thickest) bearing shells, followed by turning down the crankshaft journals to get the clearance needed. Often, they are far enough different that this won't work, but I have seen it done, once. Only once...successfully.

It is much cheaper to fix the cracked case, and it usually works OK. just make sure the case mating face is flat above the new weld, or else have it welded up and have a machine shop touch it back flat to match the sealing surface. This is much more commonly done than you might think!

My engine boss, is cracked, right lower front & rear lower back boss. I’ve seen welded cases before, but these two are structural.

[algophobe]

so after a long hiatus, i'm finally able to get back to working on the bike again. i've decided to cut the frame and pull the engine to work on the malfunctioning 4th cylinder. i'm thinking of using the Gordon frame it but having a little trouble locating one. any leads?

[RAFster122s]

Scottly offers one.

[algophobe]

Unfortunately I'm looking for the weld on type of frame kit. Cyclex isn't making them right now and I can't seem to get a hold of RRR Solutions for the Gordon type.

[Terry in Australia]

Have you tried calling them mate? (864) 710-7964 Hopefully Covid-19 hasn't killed them off.

[algophobe]

Have you tried calling them mate? (864) 710-7964 Hopefully Covid-19 hasn't killed them off.

yes, tried. that's what i'm thinking. figured somebody on here would know them

[Terry in Australia]

What a shame, this Covid-19 thing is slowing everything and killing off small businesses everywhere. I've been waiting 6 weeks for a couple of small parts from APE, but received confirmation (after they ignored my first two emails) that the items have now been sent by UPS, and the tracking indicates I'll receive them next week.

My favourite Australian Motorcycle magazine has gone broke (just after I paid another 12 month subscription, which I don't imagine I'll see returned) and even my local "Fish and Chip" shop has closed down, which sucks. It'll be interesting to see what businesses come back/start up again after the virus has been wiped off the face of the earth.  

[algophobe]

What a shame, this Covid-19 thing is slowing everything and killing off small businesses everywhere. I've been waiting 6 weeks for a couple of small parts from APE, but received confirmation (after they ignored my first two emails) that the items have now been sent by UPS, and the tracking indicates I'll receive them next week.

My favourite Australian Motorcycle magazine has gone broke (just after I paid another 12 month subscription, which I don't imagine I'll see returned) and even my local "Fish and Chip" shop has closed down, which sucks. It'll be interesting to see what businesses come back/start up again after the virus has been wiped off the face of the earth.

the motorcycle magazine industry has been dying for years along with local newspapers, my subscription had changed hands 3 times during the same subscription from Sports Rider mag to cycle world to Motorcyclist. fortunately here in the states we've seen rise in purchases of riding gear as people have more time on their hand, distribution is slow but i think its partly due to increase demand as well as slow supply. i went to our local bike shops and the shelves were nearly empty but they were able to have the gear drop shipped to my house when i purchased it in store. i recently got my dream bike (Ducati Hypermotard 950 SP), it was the last they had in SoCal warehouse. Italy is slowly ramping up their production but focusing on the more popular Panigale and monsters. but i think covid was overall a good thing in the long run, we've been gluttonous for decades and its forcing us to focus on the simple things though at great costs.

[algophobe]

What a shame, this Covid-19 thing is slowing everything and killing off small businesses everywhere. I've been waiting 6 weeks for a couple of small parts from APE, but received confirmation (after they ignored my first two emails) that the items have now been sent by UPS, and the tracking indicates I'll receive them next week.

My favourite Australian Motorcycle magazine has gone broke (just after I paid another 12 month subscription, which I don't imagine I'll see returned) and even my local "Fish and Chip" shop has closed down, which sucks. It'll be interesting to see what businesses come back/start up again after the virus has been wiped off the face of the earth.

the motorcycle magazine industry has been dying for years along with local newspapers, my subscription had changed hands 3 times during the same subscription from Sports Rider mag to cycle world to Motorcyclist. fortunately here in the states we've seen rise in purchases of riding gear as people have more time on their hand, distribution is slow but supply is limitted i think is partly due to increase demand as well as slow supply. i went to our local bike shops and the shelves were nearly empty but they were able to have the gear drop shipped to my house when i purchased it in store. i recently got my dream bike (Ducati Hypermotard 950 SP), it was the last they had in SoCal warehouse. Italy is slowly ramping up their production but focusing on the more popular Panigale and monsters. but i think covid was overall a good thing in the long run, we've been gluttonous for decades and its forcing us to focus on the simple things though at great costs. its exposed true personalities and weaknesses of people and society as a whoel that we've long ignored with a false grin.

[SOHC4 Cafe Racer Fan]

Don’t know if you saw the news but Cycle World will be leaving print, too, next month!

https://www.asphaltandrubber.com/news/octane-acquires-bonnier-motorcycle-group/

[Terry in Australia]

Yep that sucks, as much as the internet is the new media, I like to read my bike mags in the crapper, and looking at my iphone feels just weird. Give me a magazine with glossy pages anytime, when times are tough it's hard to wipe yer arse on an iphone...........

[algophobe]

Yep that sucks, as much as the internet is the new media, I like to read my bike mags in the crapper, and looking at my iphone feels just weird. Give me a magazine with glossy pages anytime, when times are tough it's hard to wipe yer arse on an iphone...........

i agree, there's something to be said about tangible magazine, i still have copies from the 90's of cycle world with great repair tips etc. the print copies of vintage magazines are prized possessions for some.

[PeWe]

What a shame, this Covid-19 thing is slowing everything and killing off small businesses everywhere.
......
.... even my local "Fish and Chip" shop has closed down, which sucks. It'll be interesting to see what businesses come back/start up again after the virus has been wiped off the face of the earth.

Chinese restaurants?

[Terry in Australia]

What a shame, this Covid-19 thing is slowing everything and killing off small businesses everywhere.
......
.... even my local "Fish and Chip" shop has closed down, which sucks. It'll be interesting to see what businesses come back/start up again after the virus has been wiped off the face of the earth.

Chinese restaurants?

I've got no problem with Chinese people Per, just their POS Commie arsehole government who knew this fcuking virus was gonna cripple the world's economy and kill millions, and did nothing to stop it getting out, in fact, encouraged Chinese citizens to travel outside China so that the rest of the world could be infected.

Their turd of a premier got the sh1ts with Oz's Prime Minister for stopping Chinese visitors coming to Australia very early, which is why we've had less than 1000 dead compared to all of the hundreds of thousands of innocent people dead across the rest of the world, who's leaders were a tad slow to do anything that might have slowed down the spread of the virus.

When all this sh1t is over I'm looking forward to eating at my favourite Chinese dumpling restaurant, I used to walk there from the barracks every lunchtime, so often that they knew me so well they didn't bring me a menu, just my plate of Satay beef with rice and vegetables, and my can of no sugar coke. I just hope they're still operating, we've pretty much been in lockdown for the last 6 months, and those small businesses are closing their doors permanently, which is a tragedy.

Apologies for the political commentary, I just wanted to point out that the Chinese people are just as badly off as we are, in fact a hell of a lot worse living in a country where there's someone constantly looking over their shoulders, waving a big stick. What a nightmare. 

[PeWe]

I like the Chinese restaurants in Europe that pop up as mushrooms everywhere!

I have visited really fine restaurants in China, mostly Shanghai and Nanjing area, totally different food. Work related, I did not pay.

The western versions taste really fine if not better.

I missed that a lot in China when eating in an own room served by 3 persons, menus are thick books. Round rotating glass table for ordered dishes.

The Chinese-Thai cuisines in Thailand taste also really nice.

[algophobe]

Don’t know if you saw the news but Cycle World will be leaving print, too, next month!

https://www.asphaltandrubber.com/news/octane-acquires-bonnier-motorcycle-group/

speaking of which.. you may know Don.. what happened to the Garage Company? last i thought they were unloading alot of stuff to move to new location.

[SOHC4 Cafe Racer Fan]

Don’t know if you saw the news but Cycle World will be leaving print, too, next month!

https://www.asphaltandrubber.com/news/octane-acquires-bonnier-motorcycle-group/

speaking of which.. you may know Don.. what happened to the Garage Company? last i thought they were unloading alot of stuff to move to new location.

Last I heard, Yoshi closed up Garage Company as a business. I think he still has a massive collection but no plans to open a new location.

[algophobe]

So I finally got a chance to start taking the engine apart.

Decided to go with the no weld frame kit. However in my excitement I did not take into account the ignition key switch mounting point to the left and front of the frame and started cutting. Guess I'll have to figure something out down the line.

The motor removed from frame and got to working on the engine.

Got all the fasteners off the head, and can't seem to get the head off. I double check for any remaining bolts that I may have forgotten. I used Permatex gasket sealant in mimicking the Hackaweek videos... did I screw my self up in using this?

Any advice on getting the damn thing off? I also tried lightly heating the gasket with a torch.

[algophobe]

so i realized i had a major brain fart and found 4 bolting points i missed next to the position of the spark plug and the 4 underneath the rubber disks (apparently a common mistake based on my search on the forum). off comes the head easy as pie and realized i didn't use gasket sealants and thought. the valves look dirty but ok. the piston and cylinders look ok... no gash on the wall of the #4 cylinder. however after cleaning the face of the pistons, a small chip on #4 and #1 piston face... not sure how this happened.

to recap, the #4 cylinder had compression issue that resolved with a squirt of oil into the chamber, making me think that there is a problem with the piston ring.

on to removing the cylinders, which will be a challenge since I DID place permatex gaskets sealants. I guess some people recommend using a sharp knife and split the gasket.

[algophobe]

So I managed to pry off the cylinders. I was expecting to see something significant that could cause loss of compression on #4 cylinder but came up empty handed. no hole in piston and it looks great except for the small scratch, the rings weren't cracked and sprung readily open. cylinder were fine. i'm really confused now.

not sure what to do next except just replace the piston rings along with the cam chain and cam chain roller while i'm at it.

by the way i was looking on the parts list. K2's have 8 additional dowel pins and cushion inbetweent he header and cylinder but this engine didn't have them. no groves to even put them in. maybe its not a K2???

[algophobe]

i'm racking by brain.. what could cause a loss in compression on a new build after riding it for 200 miles ?!?!? did i compression test it wrong or maybe i didn't torque down the head enough or it loosened? any experienced builder's advice would be appreciated.

btw i ended up buying an used copy of Hondaman's book on Amazon.

[calj737]

I haven't read your thread lately, but did you confirm the valve clearances before disassembly? Is it possible that one of the offending cylinder valves was not seating? Is it possibly bent?

I am huge fan of a leak down test prior to disassembly (for future reference).