Topic: Was going ok with a rebuild... (update) 03/03/10

[Thunder]

Hi guys, well instead of putting up a lot of different posts , I'll put this up as/when i come across problems.

I hope you will bear with me as it's quite a long post.

I bought this bike,


By thunderdome at 2009-05-07

BIKE 1 however the engine did not match the frame number.(we need both when registering vehicles).
The guy i bought it from, did however manage to get it through roadworthy and thus into my name. so, she is licensed.
The guy who sold it two me rode it daily  for around six years.
In South Africa the engine is known as the Bushman, because it can run forever
It doesn't smoke and goes cleanly although she feels very "loose" is probably the best word.(worn)

I met the mechanic who put her together(engine)out of spares he had.
 He then said he still has the original engine for it, which he replaced with the current one because it (original)was smoking.

I expressed interest and he offered to sell me these two.
BIKE 2 (the original engine for BIKE 1)
BIKE 3 (a model who's license back payment makes getting her on the road complicated affair.)


By thunderdome, shot with E71 at 2010-02-24


Since i am having alot of fun on BIKE 1(which i am hoping to get original) i thought i would take the engine from BIKE 2
(the engine on my papers/and the one that smokes)
 and redo her top end with new cam-chain /gaskets/poss rings/cam guides. (thanks to the forum  , i kinda knew where and what needed to be done.)
I thought i would take the unbroken cylinders, pistons and head  (BIKE 2 has broken fins)from BIKE 3 and stick em on BIKE 2.

Before removing the engine from BIKE 2 i got her started and she sounded very nice(except for the cam-chain),and she smoked.

In my shed i took the head off BIKE 2. The Head was barely torqued down, just short of finger tight???
The Cam chain was tight on the cam sprocket(did a lift test) but the cam guides were totally shot(worn into the bulk of the guide roller).
The cam looked good (no burrs or running grooves, just one or two tiny pits, although not on the running surface.) and the cylinders were smooth with no ridges.
The Pistons had quite a bit of Carbon on them.

I measured the pistons and the first letdown.
They seemed oval. I took measurements with a digital vernier and the wear seemed pretty constant across all pistons.

By thunderdome, shot with FinePix Z100fd at 2010-02-24

By thunderdome, shot with FinePix Z100fd at 2010-02-24


I don't have a bore gauge, so i measured the cylinders with the vernier as best i could.They were also slightly outta spec and oval.
(unfortunately i hadn't taken a lot of pics up to this point,cellphone only, but after thing went pear shaped i got a digital camera for posting.)

Cool,i thought, lets look at BIKE 3's engine,which from outside appearances looks much better, and i suspect had engine work done on it quite recently.
I took the cam cover off (The cam chain BTW could be pulled slightly off the sprocket) and the cam restraining bolts and i found this.



By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24



They appear not to have any wear on them, they are not smooth like BIKE 2's, rather they have a slightly Matt appearance.(new?)
The cam seems in fantastic condition.

By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24

There was this however

By thunderdome, shot with FinePix Z100fd at 2010-02-24

A sludge in all the nooks and cranny's, almost like grease.Old Oil?

The i took the head off, and my evening went to hell.



By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24


By thunderdome, shot with FinePix Z100fd at 2010-02-24

By thunderdome, shot with FinePix Z100fd at 2010-02-24


Rust everywhere especially around cylinder 4?

When i aligned the cam for removal(it says so in the manual) i detected a slight resistance which i took to be compression. ,probably breaking the rust seize.
The head also seemed not torqued down particularly hard.
As you can see it appears the rings at some point rusted to the cylinder and although i can feel the rust, i could scrape it off with my fingernail.
Underneath felt smooth.

The base does not want to come off , so I've sprayed everything with penetrating oil in the hopes it will come right tomorrow.
If the pistons and bores are within spec do you think i can get away with a hone and rings?

I really cannot face a re-bore and new pistons, AAAAAAAAAAAAAAAAAAAAAAA, that's why i walked away (before i broke something) and posted this.
Anybody got hopeful news?
Once again any and all advice is welcome, basically i wanna know how you guys would proceed.

BTW ,the engine in BIKE 1 is running , but it is made up of second hand parts/fins are broken , and it feels worn,So if i could avoid opening it i would like to.
(and i still get to ride )

I really wanted to do this engine up nicely(got a guy waiting to respray etc), then put it on the bike with her new cloths(resprayed tank, side-covers etc)

Thanks for listening
Thor

[camelman]

Once you have it apart, you can check your cylinders for wear.  If the wear/rust/badness can be removed by honing, then you are in good shape.  Just hone the cylinders, put in new STD rings, clean up the pistons (they are aluminum right?), and clean up the head.  The valves don't look great, but that surface rust should clean off easily enough.  Make sure your valve seats are in good shape, and that the seal.  If there are any issues with them, then you might be able to lap them smooth.

Don't get too frightened about rust.  It can be removed without issue as long as it has not penetrated too deeply into the metal.

Camelman

[Thunder]

 ,Tx mate, tis what i was hoping to hear... (but i won't get my hopes up too much).
Hopefully i can pull the cylinder on the weekend.
 Any body got a workaround for measuring bores with verniers?

[markb]

I agree, it may not be as bad as it looks once you start cleaning it up. Where are you measuring the pistons, near the top or near the skirts? They will be oval. You should measure the piston at the skirt, 90 degrees to the pin holes and should be 60.85mm minimum.  I would recommend using a micrometer for the pistons and a bore gauge for the cylinders.  Oh, and if you don't have a manual you need to get one.

[campbmic]

For measuring the bore you can use telescopic gauges which are little sticks you put inside the bore that have a spring that spring open. Then you measure how far it sprung open. I honestly measured each cylinder in 30 different positions.

If your pistons are oval then your bore is most likely oval. The first thing I did in my engine rebuild was to measure the cylinder bore.

If its out of spec you know you will need to get it bored out, new pistons, and piston rings.

If its within spec then measure your pistons to see if they are up to par.

[Cormac]

+1 on telescoping gauges. Just a little clarification, they are shaped like "T"'s with the cross piece being spring loaded, and a tightening device on the standing leg. You insert the cross piece into the hole, release the tension and pivot the whole thing front to back, about 10* from perpendicular, and tighten the lock when it is at it's most compressed. Remove and measure with your calipers (micrometer is better). There is a fair amount of "feel" involved, so you might want to practice for a while. Cheaper (and less accurate) way is to use internal calipers. Looks like a divider that flares out at the bottom. Spread, lock, and measure. Finally, and probably best, get a machinist to measure them for you. If you are afraid of getting cheated, go to an industrial machine shop instead of an engine shop. They won't lie, cause they aren't going to do the bore job.

[Thunder]

Cheers for the help. I know a guy who races classic bikes, and he's got a bore gauge.
So with a bit of luck I'll be able to measure them on the weekend.

[Jerry Rxman Griffin aka MuthaF'er]

Get a set of heavy duty cylinder studs. The stock studs will stretch more over time as noticed by the "loose" nuts. Unless you put a kit in the upper frame members you can not retorque the head without removing the engine. The frame kits are available too. 

[Thunder]

Hoo kay... been looking at HD studs, ow but probably no ways around it.
Getting em made up is a no go right?

Went and bought a set of telescoping Gauges and a 50mm-75mm micrometer,
so will measure all when i get the cylinders off.

How would one tell if one had HD studs installed? (hoping , but doubtful)
I have been reading here and i could tell if the threads were larger than the main stud body?

Cheers
Thor

[wrenchmuch]

Stock studs have reduced diameter as compared to the threaded portion of the stud .
http://forums.sohc4.net/index.php?topic=65735.0
In the first pic in the link above you can see HD studs on the left in a group and standard studs on the right with tags . There are 2 studs in the HD group that are reduced shank diameter . These would be used in the center rear locations where oil is sent to the head . I know of no HD stud kits available now like this . HD kit in the pic is from RC engineering . Dynoman , APE , both sell HD sets . All studs in these sets are the same diameter .
Good luck with your build and keep posting pics.
Mike

[Magpie]

If the studs are "stretched" so that the nuts actually reach the non-threaded portion you will not be able to torque the head of course. I had a Honda mechanic come by the house to do a leak down test on my 750 and asked about the nuts not seeming to feel right tightening up. He suggested putting a second washer under each one. I know, it sounds crazy. However, I did that with the exception of the front corners because it appeared the nut didn't go down far enough to have the whole nut on the stud. I then went to torque the head nuts and it was much better. He suggested to got to 18 foot pounds as well which is over the workshop manual's settings.
Just a thought.
Cliff.

[Thunder]

Hi

Well thanks for all the help and advice.
It's been real hot here (34), but i sweated my way through a weekend of cleaning and measuring
 35 year old crud just doesn't wanna move....(not talking about me )

So i got the muck off


By thunderdome, shot with FinePix Z100fd at 2010-03-03

(power paraffin/cleen green)
Then following the advice from the forum i bought these on the friday

By thunderdome, shot with FinePix Z100fd at 2010-03-03

By thunderdome, shot with FinePix Z100fd at 2010-03-03

So i took some measurements both with the digital vernier as well as the micrometer measuring from the centre-to lower of the piston,using the centre hole (of the three at the piston top, and got the following figures.

By thunderdome, shot with FinePix Z100fd at 2010-03-03

By thunderdome, shot with FinePix Z100fd at 2010-03-03

By thunderdome, shot with FinePix Z100fd at 2010-03-03

By thunderdome, shot with FinePix Z100fd at 2010-03-03

By thunderdome, shot with FinePix Z100fd at 2010-03-03

Then i measured the cylinders, and i made sure it was in the middle-lower part of the cylinder @90 deg.

By thunderdome, shot with FinePix Z100fd at 2010-03-03

By thunderdome, shot with FinePix Z100fd at 2010-03-03
(this varied between 61.01- 61.03).

Now i double and triple checked the Micrometer with the measure given, but it seems to measure the pistons as quite close to what the bore is, even bigger? i know this cannot be, as they are all standard(300)?Bad measuring?

I have eight pistons as i took apart 2 engines, but this ones cylinder fins are in good shape.

So what do you guys think?

I bought this as well


By thunderdome, shot with FinePix Z100fd at 2010-03-03

So am i good to go? The engine is getting sprayed, so i will be blocking all the holes and ports and making some cardboard "gaskets" to protect the mating surfaces.
I will be ordering rings from David Silver(Std size) and should get em in about two weeks.(no reflection on DS, got a mate who will bring them back for me)

I got a photo of one if the valves stems which i hope to be cleaning when i do the valve stem seals? Opinions?



By thunderdome, shot with FinePix Z100fd at 2010-03-03


By thunderdome, shot with FinePix Z100fd at 2010-03-03


By thunderdome, shot with FinePix Z100fd at 2010-03-03



And finally the current state of the pistons



By thunderdome, shot with FinePix Z100fd at 2010-02-24

By thunderdome, shot with FinePix Z100fd at 2010-03-03

The Hd cylinder bolts are a bit out of range at the moment, and i don't mind the work , can i torque the engine down, run it, then remove engine and retorque?
(see i have been reading the threads )

So this is where i am at the moment, awaiting your reply's  

Thank you so much
Thor

[wrenchmuch]

I have the same telescoping gages you have I think (Made in China) . I had a hard time getting it to lock properly and not move it at the same time . Tightening the gage seemed to move the setting while in the bore .I finally gave up and bought some Starrett gages (Made in USA ) . The difference in how well they work is HUGE ! The gage has to be square in the bore to read properly . Putting a piston in the bore might help give you something to square the gage to . You might also try using the Micrometer to measure the gage instead of the caliper so that the same tool is measuring both the piston and the bore eliminating any difference between the tools . The micrometer is a much better tool for this kind of measuring . If the tools you have are still giving you results you don't trust you might try putting the piston in the bore and using a feeler gage to check clearance at the skirt of the piston half way down the bore (read this somewhere around here but have no direct experience with procedure ). I dipped the top of my pistons in a Combustion chamber cleaner sold by a place called Canadian tire here in Canada (non aerosol ) . The carbon dissolved completely . Quick wash in soapy water and they were almost as good as new . Worked on the valves and brass carb bits too . The stuff was mostly petroleum distalates .
Hope this helps
Mike

[bucky katt]

engine and frame numbers arent supposed to match. if they do on these bikes THEN you get concerned

[Cormac]

As noted earlier, using these telescoping gages requires quite a bit of "feel". Doesn't help that the cheapie Chinese jobs kinda suck anyway. You can't just put them in the hole square and expect a good reading, you absolutely have to rock them a touch. With a fair bit of practice you will get good at this. Took me a good hour or so back in college to get consistent results. To this day I still take a few "practice" measurements every time I have to check a bore. +1 on starrett if you can afford them, Mitutoyo is serviceable and costs a lot less.

[VTCBike750]

AND.....What happened next?

[wrenchmuch]

A Resurrection and its not even Easter yet .