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

[PeWe]

It's so nice with refurbished clean parts that ensure functionality.
Fresh guides with valves cost some, but is the base for a well working engine.

Inlet ports work better with a harsher surface than a polished.
Something about how fuel and air mixes.
My last head, recently refurbished.

[algophobe]

Yes. I cut back the intake ports to make the transition wider but left all the castings and roughness alone. I see you had your's knife edged

[PeWe]

Yes, support the guides and maybe better for air flow compared to a naked round guide.

[algophobe]

So before putting her back together.. i want to replace the cam chain (part of the while you're in there to do's). I bought the endless EK chain and a few extra links to do this without having to spit the case. Anyone have any advice? Is it an easy thing to do? Would you trust it?

[PeWe]

I should open the cases and replace all chains.  The stronger cam chain with rectangular side plates.
Primary chains, BMW Diesel engine late 1990's timing chain with 68 links. 2 of them.

Why rivet chain when you have engine out without cylinder?
 When at it, new cush rubbers in the primary chain drive hub too.

[algophobe]

I should open the cases and replace all chains.  The stronger cam chain with rectangular side plates.
Primary chains, BMW Diesel engine late 1990's timing chain with 68 links. 2 of them.

Why rivet chain when you have engine out without cylinder?
 When at it, new cush rubbers in the primary chain drive hub too.

it's a bit of me being lazy i guess, I've had the case split apart at the beginning of this build about 5-6 years back. only put 600 miles until i had issues with compression, therefore went thru the trouble of taking the top end apart again. it was an oversight on my part in not changing all the chains at that time. but now, i'm in a situation where i have the bottom cases still intact with the cylinders off and only hoping to replace the cam chain by breaking it and slipping it through then reassembling the top end again. i've never broken apart these cam chains before and have the Motion Pro chain tool. but not sure how to best flare out the solid pins.

[scunny]

You may have the taper type joining link. you just press on the side plate with vice grips or similar.
That is what is in my 650 for the last 10 years. I was worried about the clip, so took it to the local morse chain experts, and they assured me that is the way to fit it, no peening over.

[algophobe]

Well that's good to know... I measured the thickness of the pin mid body and at the end and there appears to be no difference. I ended up using the chain riveter to flare it out a little bit even though it didn't have the hollow tip. not major peening over but it makes me feels a little more secure. The chains is still nice and laxed. It took me three tried without binding up the link.. thankfully I bought three extra Master links. Phew!

[algophobe]

Made some progress. With my limited experience, so far I've realized that my least favorit part of a build is putting the cylinders back on over the pistons. Especially those outside pistons and rings.. no great way to keep them stable after the center two are on.  Got the head on as well and torqued down. have to order up some new dowel pins to place back on the cam towers. but I had a chance to modify the cam towers and added extra oil holes and widened the rocker arm oil holes as well according the Hondaman book.

[algophobe]

Managed to get a little time to finish putting in the cam and rockers. My little man visited me in the workshop and thought it was time to introduce him to the build.. you know "start em young"? He has pretty good motor skills for a 2 1/2 year old. But I turned by head for a second and he's already drop two ratty dowel pins that i've replace into the opening access to the spark plugs. fortunately he didn't put them into the channel for the cam chain... PHEW! lesson learned!

i decided to leave out the 8 small bolts that holds the rods for the rockers as suggested by Mark Paris's book, along with the additional holes for oil on the cam towers.

[algophobe]

With the engine nearly back together, I worked on the frame. Ended switching from the weldless frame kit to the Gordon frame kit as I noticed that the shop started making them again and had some available. it would solve my issues with remounting the key switch since I cut it too far forward. Mocked it up and started TIG welding it into place after tacking them together. I’ve just started TIG welding this year so its been a rough start. Kinda tricky with the solid inserts welding to the roughly 1.6 mm thickness stock tubings. I bought a basic Lincoln setup and welded using 95 amps with 0.3 pulse on 220 volts using 3/32 created tungsten and 3/32 rods.... a work in progress learning this stuff.

[algophobe]

So this happened... I was testing fitting the center piece after welding the inserts in and before final welding of the inserts to the main frame portion. bolt it down and hit resistance and now can't be backed out. not even with a little impact hammer. the heat may have shrunken the center piece a little bit also distorting the threads. the top half of the insert is straight (threadless holes) and the bottom half is threaded (which was welded circumferentially yesterday). if that wasn't bad enough a second bolt that was put in smoothly now won't back out either. i should have lubed it or re-tapped it before screwing it down or something. trying to figure ways to salvage this. at little heat torch? lube? just cut it off and drill it out?

[algophobe]

I managed to get the bolts off by cutting the head which allowed me to remove the center piece of frame insert off the frame.. then welded the nub of screw to a long 1 inch square bar and twist it off.. the welding heated the threads enough to make it easier to come off. With the other stuck screw which was flat to the surface, I drilled the center out of it and tapped it to recreate the threads. Then grinded down the welds and then painted. Alot more work than I had bargained for but I'm happy with the result.

[Terry in Australia]

Looks good mate, interesting re: the welded frame kit, I installed one years ago using a MIG and had no issues at all threading the bolts in or out? But there you go, you learn something new every day.

[BenelliSEI]

Lot of effort, but I agree; nicest installation. Very clean look..... Never used one, but that would be my first choice.

[algophobe]

Thank you. The problem with the threads may have been my welding technique.. as I am learning how to TIG, I may be applying too much heat distorting the threads. I lingered in one spot too long trying to fix my beads. The larger slug at the head of the frame didn't have same problem, I'm only guessing because it has more mass to distribute heat. 

[algophobe]

So this happened... I was testing fitting the center piece after welding the inserts in and before final welding of the inserts to the main frame portion. bolt it down and hit resistance and now can't be backed out. not even with a little impact hammer. the heat may have shrunken the center piece a little bit also distorting the threads. the top half of the insert is straight (threadless holes) and the bottom half is threaded (which was welded circumferentially yesterday). if that wasn't bad enough a second bolt that was put in smoothly now won't back out either. i should have lubed it or re-tapped it before screwing it down or something. trying to figure ways to salvage this. at little heat torch? lube? just cut it off and drill it out?

Next time, place a piece of shim stock between the frame and welding lugs before welding. The heat of TIG welding will definitely pull the removable section. And if you do thread bolts in, coat them in anti-seize before welding. This will help prevent them from galling and allow them to screw out once everything cools off.

And next time, drop down to 1/16” or smaller filler. You’ll need less heat, leave less work afterwards, and have ample strength anyway.

when you refer to a shim, are you talking about placing a thin ring to fill the gap like this? pardon the bad disproportionate drawing.

[algophobe]

Dropping the engine back in was a sinch with the frame kit installed. I decided to relocate the rectifier/regulator to another location with better air flow for cooling and simplifying the wiring coming from the stator. Decided to upgrade from the cheap white connectors to Apex versions bought from Revival.

[algophobe]

So this bike is gonna fight me every step of the way it seems. I’ve finished putting back the wiring. The oil system installed and I’ve kept the valve cover off to allow me to inspect the oil flow to the valve train. I fill the oil reservoir with 3 quarts and connect the starter directly to a 12V AGM extra battery and turn over the batter for 30 second bursts or so. No oil noted the the top. I disconnected the oil filter since it would be directly down stream from the oil pump and nothing comes out.

I’m curious if turning it over with a motorcycle battery alone would produce enough oil pressure to open the OIL LEAK STOPPER VALVE on the OIL PUMP. As long as the engine turns then there should be enough pressure right? When I first put the engine back together in the first round, I use a truck battery and it worked... not sure if that would make a whole world of difference.

I guess at this point I’ll have to empty the oil tank again and check the hoses and oil galleys. If that doesn’t work then I’ll have to check the oil pump.

Hopefully no critter has crawled in during the year that the engine was sitting still with the two oil hoses off and oil filter off.

[Gamma]

Following your post now, as I’m getting close to doing the same and turning her over on a spare battery

[algophobe]

Following your post now, as I’m getting close to doing the same and turning her over on a spare battery

I was reading your post, nifty build, following as well. you sure make it look easy.

apparently a truck battery didn't give me better results any. since i used an aftermarket oil reserve tank i had to double check again to make sure I didn't cross up the inflow and return hoses. looks like I isolated the oil pump as being the issue, so it'll have to come out. I wish I had know prior to putting the engine back together and now wondering whether the oil pump may have been the issue all along that made me have to take the engine apart, don't recall the oil light coming on either. will see what awaits me from the bottom of the crank case.

[algophobe]

So before I go and remove the oil pan and pump, and I did some reading thru various repair manual and they all mention the need to prime the pump before installing it.  I dont’ remember doing this for the first part of the build and yet the oil still primed itself, during the first iteration of this build.  At the time I was using a much thinner oil so by miracle or dumb beginner’s luck, I was able to get it to prime by just turning running the engine with the battery/starter. So the pump may have introduced air bubble when I kept it dry for the last year and having turned it over many times by hand, dry of oil. So I’m curious if anyone would know the answer to this? Is priming the oil pump completely necessary? Would using thinner oil prime easier without submerging the pump in oil prior to installation? For this go round I started right off with 20w50 without priming, which may have made it difficult to rid of air from the system.

[Gamma]

I finally got around to reading your full build. Lots of interesting things to think about. I did prime my oil pump when I installed it several years ago, I have hand turned the engine several times since then, with some oil in the engine.  I am now getting nearer to getting the electrics sorted (I made my own loom like you)  I expect to turn the motor on a car battery with the spark plugs out and wait for the oil light to go out😁 Also my plugs are Iridium ones😃

[algophobe]

I finally got around to reading your full build. Lots of interesting things to think about. I did prime my oil pump when I installed it several years ago, I have hand turned the engine several times since then, with some oil in the engine.  I am now getting nearer to getting the electrics sorted (I made my own loom like you)  I expect to turn the motor on a car battery with the spark plugs out and wait for the oil light to go out😁 Also my plugs are Iridium ones😃

There was a post on here about using a shop vac to pressurize the oil tank to force oil to displace the air. I may try that first prior to dismantling the oil pump and submerge it to prime.

My luck with iridium ones was bad, the D7EAs seem to get better burn.

[algophobe]

Good progress today, the problem did turn out to be air lock in the oil pump. I modified a technique a member on the forum wrote on how to push out air from the oil pump. Instead of a shop vac and rag. I ended using my air compressor with trigger nozzle, and bought a rubber cork at ACE Hardware for $1.99 and fitted the nozzle as such. I clamped the vent hose to the lower case on the aftermarket Cognito Moto oil tank (see green clamp) and 20w 50 oil that I have in the engine already (with tank filled with 2 quarts of oil). Didn’t use thinner oil as I initially intended to. Then lightly pressurized the tank while kicking the engine over about 10 times. Air did hiss out of the top end via return hose but pressure built just enough. Then as if the Motorcycle God finally had pity on me and allowed oil to spill from the inlet at the oil filter.

I replaced the oil filter and cranked the engine over with the car battery and lo and behold the pressure on gauge shot up to 65 psi with oil pouring out of all holes on the top end.

Imagine my relief of not having to order another oil pan gasket and dismantling the pump just to prime and scraping the gasket off while laying on the ground.