[ALIKA T3]

The cam sprocket you need is a two-hole 28T. It is a CRF50/70 style. You will also want to get the CRF50 style cam sprocket bolts (the ones with 8mm hex heads) and the matching cam cover with the little stopper arm on it. If you use the original screws with the 9mm hex heads, they will contact the center of the cam cover and may break loose, causing the cam sprocket to fall off (ask me how I know.) If you use the original cam cover without the stopper arm, the cover can spin and fall off.

Hello!

Thanks for the good advices!

I have a round cover that I believe is not original, it does have a thick tang inside, now I know why!
I bought two M5x12 and two M5x16 class 12.9 allen bolts this morning from the local hardware store, I didn`t measure the OD of the head but I will surely look into this, thank you!

I found a 21T kick starter spindle assembly on ebay, with a 37.72 mm OD gear, so I bought it, the guy measured for me, it looks like a match. Mine is currently 22T about 45mm OD, I haven`t used a caliper on it. so that`s 4mm less on the radius, that looks good to me on paper.

 

[ALIKA T3]

Awriiite, today is the real big day!
Everything showed up on time 👍

This is the old 22T 45mm kick starter spindle gear

This is the new 21T 38mm kick starter spindle gear I got on ebay, Fast Guy Parts, from a 1997 Z50.
Part is in great shape, clean, fast hipping, awesome communication. I wish everything was as smooth as this!

It fits! Comme Papa dans Maman 🤓

Kick starter return spring installation:

The easiest way I found is to connect the spring onto the cam halfway engaged, not fighting the spring, then spin the assembly and push the cam down into the engine case recess.

At home!

I coated the case halves with Permatex/Loctite anaerobic sealant. The excess is oil soluble, but apply parsimoniously. I hate leaky engines, and these cases are anything but new...

OMG the gasket is blocking the rod, what am I gonna do?? HELP!! 🤪🤪🧠🧠

 

[66Cooper]

A lot of gaskets come that what, maybe all. Maybe it’s to keep them in shape. You are meant to trim it to fit. Simple as that.


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[ALIKA T3]

The easiest part is done, now I installed the shifter fork and arm. I had already installed the lip seal on the opposite side.

I bought a new Honda shifter roller arm to match my new shift drum, a new bolt and a new spring.

The old parts are on the left, the spring is a little tired compared to the new one....

Checking its action range. All good and smooth.

Each wave is a gear, I noted them and double checked everything was working correctly and gear pattern correct. I wanted 1 down, 3 up pattern, I couldn`t deal with the rotary shifter pattern.

This is the oil pump and sprocket driven off the timing chain. It has a thicker side which goes towards the oil pump.
It is a NOS Honda one, but I noticed some of them have a side with a groove across the center. I always wondered why.... til today!

I was hoping to screw the sprocket on the oil pump shaft and slide the whole thing in. Hin-hun!

 

[ALIKA T3]

A lot of gaskets come that what, maybe all. Maybe it’s to keep them in shape. You are meant to trim it to fit. Simple as that.


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I was hoping someone wouldn`t get the joke even with the brain smileys 😆😆

Thanks for your help though, I do have some genuine questions coming soon, posting RN 🤙🤙🤙

 

[66Cooper]

Viewing on mobile, late at night, around a fire pit, after a few well earned...I missed the sarcasm. Haha!!


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[ALIKA T3]

Well, it looks like these evil Vietnamese rebuilders screwed this bike in every way possible down to the last detail...
I could not press the mangled oil pump shaft bushing out bc the bore got massacred with pliers trying to hold the flat part of the shaft for screwing in the sprocket, so I decided to leave it in.
Left is the old chinese oil pump, right is the high flow oil pump from TB Parts.
They are exactly the same gears, the difference is in the housing that got machined for better flow on the TB part.

So it turns out you have to slide the sprocket from the top cylinder side of the engine, but the oil pump shaft it not going deep enough ( hitting the crankshaft) to allow the sprocket to slide in. It is missing a hair, which a groove on the sprocket would allow to clear the threaded part...so I used the bench grinder and grooved that sucka in a minute.

I used the old oil pump as a shaft lock to screw the sprocket onto the shaft on the opposite end. I jammed a Torx bit in the gears. Perfect!

The TB pump came with a thin holed paper gasket but I had a thicker gasket on hand with better windows, I just trimmed one tiny part to have a better clearance in the oil holes to the block.

Oil pump housing and no gasket, one could port the block and have an even better oil flow if the pump allows it. I didn`t feel like experimenting with this but I`m sure track racers can do, or are already doing it, I dunno, just an observation for other profanes like me.

Getting there...

I re-used the old pump cover screws that had a beefier head.

Honda oil filter screen. I had posted older pics comparing with a cheaper screen with a less fine mesh. I only noticed now the screen is tapered and so is the case.🙈

Oh, and here is where the rebuilders got me again, they had cut the snout of the oil pump to make it fit, bc the oil pump shaft bushing is too tall or couldn`t go deeper. I had to do the same...

 

[ALIKA T3]

Hello old friend, long time no see!!

Ok, now here`s the heavy sh!t I don`t understand.
These are the parts I had on this engine, minus the spring and the push rod thingy I got new last year for the timing chain.
I thought these were hydraulic actuated, hence the little ball check valve at the top of the rod.( I think it is)
The side adjuster screw is to short to do anything, so it`s basically a plug.

I got a new rubber plug too, but on which end does it go? On the check valve side, it`s a bit loose.
On the opposite side, it`s blocking the perpendicular holes a bit...

I don`t understand the purpose of any of these holes, the bore the rod slides in has NO oil galleys whatsoever, it`s bascially a dead end with a threaded plug from the outside.

So the side adjuster screw wouldn`t match any of these holes,I checked. Also I can tell the adjuster screw got cut, so now it`s just a fancy plug.

I read there are 2 types , maybe more, of these chain tensioner mechanisms...
Mine cannot be related to oil pressure, or there`s something major I`m missing since I don`t see any oil galley holes. The double adjuster types are for newer bikes, so what are these engine cases? It doesn`t make sense! Will the spring be enough for chain tensioning? I mean, it`s pushing strong on the tensioner arm with the plug screwed in ....

 

[ALIKA T3]

Got these studs a while back from DrATV. He kindly supplies 2 nuts to install them. Well, he put 2 M6 nuts, so that was useless , the case threads are M6, thhe top threads are M7...
I also got the dowel sleeves. They are so hard to slide down past the M7 top threads!

One stud is going West...I didn`t do this !!

Piston installation.
The marking ( R here) on the 2 top rings faces up. The shiny outer edge ring goes on the top, the black ring in the 2nd groove and the bottom groove gets the 3 piece ring.

Ok, so the 2 small black square section rings are for the cylinder head and cylinder, but they are way too thick!! Seems sketchy to force them to squeeze down upon torquing the head, no? Their OD is small too, I don`t like this...
What is the big green ring for? The small green ring looks like a valve stem seal, should I install it on the intake or is this a generic seal kit TB Parts supplies?

Fnck me, the studs are too long, the disc grinder is at the shop... needs 6mm off.

Looks like I have the correct camshaft end cover according to Davmo. One piece is broken off but that shouldn`t matter much.

Ok, now another super legit question, how do you prevent the dowel sleeve to walk out from the center of thecamshaft? A washer under each bolt could do it... What is its purpose anyway?

I wish the cam gear holes were not symmetrical too, now I have to find out which way the cam goes... and I dunno what thes 3 extra holes are for, it bothers me, especially the off centered one!

 

[ALIKA T3]

Viewing on mobile, late at night, around a fire pit, after a few well earned...I missed the sarcasm. Haha!!


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Haha! Good week end times it sounds like! I cracked one too posting these updates and questions 🍻

 

[ALIKA T3]

Ok, as far as the timing chain tensioner goes, I think I got the guts of a hydraulic system into a manual adjusting system.
Awesome, more stuff needed....

 

[davmo]

Ok, so the 2 small black square section rings are for the cylinder head and cylinder, but they are way too thick!! Seems sketchy to force them to squeeze down upon torquing the head, no? Their OD is small too, I don`t like this...
What is the big green ring for? The small green ring looks like a valve stem seal, should I install it on the intake or is this a generic seal kit TB Parts supplies?
View attachment 273378


Looks like I have the correct camshaft end cover according to Davmo. One piece is broken off but that shouldn`t matter much.
View attachment 273380

Ok, now another super legit question, how do you prevent the dowel sleeve to walk out from the center of thecamshaft? A washer under each bolt could do it... What is its purpose anyway?

I wish the cam gear holes were not symmetrical too, now I have to find out which way the cam goes... and I dunno what thes 3 extra holes are for, it bothers me, especially the off centered one!
View attachment 273381

The larger green ring goes in the head gasket around the lower right engine stud. It should fit flush with the head gasket. The smaller green ring is an exhaust valve seal for the early stock Honda heads, and is not needed for the race head. The big flat black seals are for the oil return from the head, and its low pressure at that point so they are fine. That is not the correct round cam cover. The one you are looking for has an external arm on the outside edge that engages the small boss on the outside edge of the mating surface (in your last picture, it is the little bump on the bottom right.) I believe the 1992 and newer Z50's and the CRF50/70's use the cover. There is a finned version for the Z50J that I have used that is kind of cool. You will also want to get the rectangular cover for the other side of the head for the same models (1992 and up) if you don't already have one. The Honda 8mm screws for the cam sprocket actually have a flange that overlaps the center dowel. Its purpose is to keep the sprocket perfectly centered. Not sure if this model timing chain tensioner is the same as the others like this one on Z50's, but the type with the external screw like you have uses a solid steel lifter with a rubber cap, that is flattened on one side (this is where the locking screw hits it.) There is a small spring at the bottom that fits partially inside the lifter, that is held in place on the other end of the spring by a screw-in insert (it screws in where the bottom plug goes.)

 

[ALIKA T3]

Thank you David!
Very helpful intervention

I spent some time last night on the computer and apparently the 1973 K3 Z50 has the mechanical timing adjuster. I was fooled ordering the hydraulic plunger last year bc the one that was in there was indeed hydraulic too but all grinded out to make it look straight.... Was prolly bent for some reason, but it wasn't the correct one to begin with. I ordered the new hydraulic one with the part number listed in the diagrams for my bike. One more mystery, these cases are prolly not original and got very well re-stamped, or they had different versions in Vietnam.
I found a very nice used kit with everything I need on ebay from a 1980 ATC 110 to go back to mechanical adjuster. Indeed the plunger is tapered, makes sense, as to not slide down past the side ( perpendicular) locking screw.

It's easy now that I know what's up. Live and learn...
As for the right side cover, mine seems to be similar in function.

As for the round cam cover, I'm confused.
Mine is self centering, it has 3 prongs for this purpose. One is broken do it doesn't line up well without some help.
What's the difference with the TB cover if they both center?
I'm not a fan of the fins look bc I wanted this engine to look more vintage, if I could avoid using the finned cover, that'd be great. I do like the increased cooling feature though, I'm torn...

If there's a more correct new plain round cover out there, I'm game!

 

[davmo]

This is the style of cover you need:

THIS COVER FITS ALL XR50'S AND XR70'S AND ANY OTHER 50 70 OR TRX90 HEAD'S THAT HAVE THE LITTLE ARM TO KEEP THEM FROM SPINNING.

ALSO WORKS ON THE MONSTER HEADS

82D

$16.49

The little arm is to keep it from spinning. On your original cover, the missing internal arm was to fit in the notch on the head. This is so the semi-circular arm on the inside of the cover is aligned where it fits toward the front of the sprocket (it is to counter the torque of the chain and keep the cam from floating.) If the arm is not there, the cover will contact the sprocket and spin off. I learned this lesson the hard way. Looks like the correct rectangular cover.

 

[ALIKA T3]

Hello!
Ok, got it, thank you!
I found the correct round cover, on newer CT70, CRF and XR 50 & 70.
Part number 12341GB6910. I like searching by part number, I found new listings cheaper than used junk 😆😆

The one I have seems like it's for older bikes, CT70 and Z50.

Part ordered

I'm going to have this older style cam washer modified, I couldn't drill it, it's some super tempered steel!
2 new holes will be done. It will secure the centering hollow dowel thingy.
It will fit the cam under the allen M5 bolts I have, I can't find shouldered ones class 12.9 that may or may not fit. This way, no interference possible with the long bolt.

On this pic, I used a shouldered 1/4-20 bolt, it fits snug into the sleeve and the washer to center both perfectly, in order to see where to drill the 2 new holes, you can see none of the existing ones line up.
The machine shop will do it for me.

 

[dirtbkr188]

Personally, I don't think you even need to use that cam washer at all, that was meant to be used with the old journal bearing cams, not the newer ball bearing cams. If someone feels otherwise, they'll speak up.

 

[davmo]

Personally, I don't think you even need to use that cam washer at all, that was meant to be used with the old journal bearing cams, not the newer ball bearing cams. If someone feels otherwise, they'll speak up.

Dirtbkr188 is correct, not needed.

 

[ALIKA T3]

Dirtbkr188 is correct, not needed.

Yes, it's for older models, but I am repurposing it as a cam sprocket sleeve retainer since its bore is perfect for that
I don't have the shouldered bolts in class 12.9, can't find them here, it's faster for me to do this than waiting for a week to get and find the proper bolts. This way I can finish the timing and install the motor til I get the round cam cover in the mail. Living in Hi delays everything :/