Topic: CB100 top end woes

[Tugboat]

Well, I'd pulled the top end off of this CB100 motor to replace the head.. turned out the head & cam were fine and it was just a stretched (possibly never-adjusted) cam chain that was the source of the aluminum in my oil.

I'd already bought a replacement head & had its valves re-cut and a new valve seal installed. Swapped that over, along with a new piston/cylinder kit that came with the motor and took it out to break it in this past weekend. I made it about 15 miles before it started losing power and finally stalled, though it wasn't locked up. Pulled it apart last night to find this:

[strynboen]

oil . or say..or missing oil..have somone used silocone gasket..and bloked the oil line hvere the pressure valve is,,just under cylender gasket in engine block..if it have same oil pressure system as cd 50

the head can be fixed....just get  the cam surface drilled aut and press a bushing inn..get a new cam amd lifters...klean oil lines and thek pump pressure..and it are running again

[grcamna2]

Hi Tug,sorry to see the damage,it's happened to me also,I had to get another head w/ cam,etc. Somewhere the oil passage to the cyl. is blocked like strynboen said.

Do you have an extra fuel cap for your 82' tank that I could get from you ?

[dhall57]

Sorry about the issue with your CB1000c Tug I know your sick, I would be. The last post I saw prior to this the bike was doing great and all was well

[grcamna2]

dhall,this is his CB100 (w/ 1 less '0') & I hope he can find why oil isn't flowing up his cylinder stud to the head;I hope the clutch sidecover oil flow passage isn't blocked;that's happened before.

[dhall57]

I guess I need to put on my glasses I was seeing another 0

[grcamna2]

I guess I need to put on my glasses I was seeing another 0

I'd like another $0. added in Dec. myself 

[strynboen]

does it have that chlutch sentifugal filter..and strange littel hole piston vith a spring vho transoport oil..from rotating krank to stasonary sidecover...it have to be korrekt mounted so oil not leak aut..the spring must be at crankshaft side..and the bearing can be thanged to a sealed type..so no oil pressure not leak througt the bearing..still i only have vorked on cd 50/65 engines..they are not 100%exact as the 100...

[grcamna2]

does it have that chlutch sentifugal filter..and strange littel hole piston vith a spring vho transoport oil..from rotating krank to stasonary sidecover...it have to be korrekt mounted so oil not leak aut..the spring must be at crankshaft side..and the bearing can be thanged to a sealed type..so no oil pressure not leak througt the bearing..still i only have vorked on cd 50/65 engines..they are not 100%exact as the 100...

Yes,the CB100 has that centrifugal filter w/ the spring loaded 'oil lock piece' type of arrangement built into the clutch sidecover that sends the oil from the filter & up through the passages in the clutch sidecover which mates to the right side engine case that sends oil flow to the top end along the cylinder stud up through to the head & camshaft area.

[strynboen]

there are a metal filter screen in the engine main block..and a other issiue are the oil pump drive..its the cam chain vho drives the pump..but the drive runs autside the chain..and can be crused so the pump not are driven ....take the ignision aut and all this stuff are free for inspeksion..and the can chain tensioner can be kontroled at same time...some have hydralik powered tension..other have adjustabel..tension

[Tugboat]

I've been doing some tinkering. I had a buddy kick it over for about 30 seconds to see if oil was squirting out of the hole at the back of the head that supplies the top end & nothing was coming out, as expected.

So I dropped the motor, pulled the head off and turned it over to see if oil would come out of the passage where one of the studs comes up... nothing. Pulled the cylinder off to see if it oil would come out of the oil jet at the base... nothing.


I drained the oil, which was super nasty - after only about 15 miles. Some metal in it, but not very much... and some of the super-fine stuff was probably residual. I studied the oil flow diagram from the manual for a while and decided to blow compressed air into the jet and see if I could blow out any obstruction. Well, this popped out of the passage just below the jet, and was the source of the obstruction.


F@^%ing fingertip of the glove I was probably wearing when I put the side cover back on. I vaguely remember it pinching but thought it just ripped. Should've checked. Boo.

[grcamna2]

Tug,
When you removed the clutch side cover and viewed the case passage where it mates up to the clutch side cover,is that where that piece/fingertip of glove came out? you mean it squeezed it's way into the small oil passge  ?

[Tugboat]

Yeah, it was jammed up into the oil jet via pressure. For reference, oil comes out of the pump and goes into this passage between the side cover & the block (red) and comes out the oil jet (yellow) up to the head. This (red) is where it must have pinched, because the holes at either end are too small for that piece of rubber to fit (twss).

[grcamna2]

Got it,a blocked oil galley 
I hope you're able to find your parts locally.How's that place right there in town 'Nashville motorcycle repair'..,do I have the name right? Do they have used parts there ? I'm kind of looking for some used stuff too

[strynboen]

i  alvays..loosen the pinbolt head at the top,( on head),hvere the oil pressure goes up..to thek the oil komes aut.

.it does not destroid the topgasket to run some sekunds..vith a loose bolthead..and vhen the oil sqveese aut i are shure the pressure are at the top end...

[Tugboat]

Good call @strynboen. That, and before I put the cam in I'll check to make sure that oil comes out of the little hole in the back of the head that feeds oil to the cam.

Nashville Motorcycle Repair is run by my good bud Andrew. It's THE place to take your old moto to here in town. I can't recommend them enough. They do have some stuff in stock that the dealerships don't - gaskets, floats, points sets... that kind of thing. But no used inventory to speak of.

It so happens that my original head was in good shape.. its cam too. So I'll be using those on the re-rebuild. In fact, I just got a call from NMR that they've finished lapping in my valves so all I have to do now is wait for my new gasket set to arrive. I'll flush out the bottom with kerosene again in case there are any chunks of the burnt-up cam in there, then put it all back together.

[WhyNot2]

Where are you ordering the gasket set from, I'm almost ready to put mine back together?

Thanks man...............good luck with yours going back together.

[grcamna2]

Good call @strynboen. That, and before I put the cam in I'll check to make sure that oil comes out of the little hole in the back of the head that feeds oil to the cam.

Nashville Motorcycle Repair is run by my good bud Andrew. It's THE place to take your old moto to here in town. I can't recommend them enough. They do have some stuff in stock that the dealerships don't - gaskets, floats, points sets... that kind of thing. But no used inventory to speak of.

It so happens that my original head was in good shape.. its cam too. So I'll be using those on the re-rebuild. In fact, I just got a call from NMR that they've finished lapping in my valves so all I have to do now is wait for my new gasket set to arrive. I'll flush out the bottom with kerosene again in case there are any chunks of the burnt-up cam in there, then put it all back together.

tug,it's good to know that you can use those orig. pieces,it's not easy to find one of those that is still in good shape.

[calj737]

I guess I need to put on my glasses I was seeing another 0

I'd like another $0. added in Dec. myself 

My gift to you, Bill

$0.000
Next time, ask for another comma $1,000.00 becomes $1,000,00.00 

[grcamna2]

I guess I need to put on my glasses I was seeing another 0

I'd like another $0. added in Dec. myself 

My gift to you, Bill

$0.000
Next time, ask for another comma $1,000.00 becomes $1,000,00.00 

Cal,are you offering me another comma? lol,    I'll receive  that for Christmas !

[Tugboat]

I just got a gasket set off ebay. This one:
http://www.ebay.com/itm/Honda-CB100-SL100-CL100-XL100-Gasket-set-complete-New-/320369123130?pt=Motorcycles_Parts_Accessories&hash=item4a977cdf3a&vxp=mtr

Should be here this weekend.

[grcamna2]

That seems cheap for an entire gasket set;did you pull off the cover for the oil filter/slinger? and clean it out

[Tugboat]

"Made in Japan" -hopefully it's ok. Yeah, I've got the whole oil pump assembly & the centrifugal "filter" off currently. There is WAY less metal flake in my oil than when the cam chain was rubbing against the case & cylinder. I think it'll be okay.