Is this the way the head should look?

[razorboy]

Hi Guys,
My CR250R is starting to get really frustrating. Sunk a lot of dough and effort so far but this really pisses me off!
I determined that there was some slight warping on my head so I took the head into a automotive machine shop for resurfacing. I got the head back today and it looks like its been run through a beltsander? I mean it has a grain going in one direction with some pretty decent scoring.
Since I had never done this work before, I decided to go ahead and put it on the bike. It would not start and when I checked, there was coolant coming out all the way around the head. I actually could have guessed this was going to happen from what I saw on the head. This can't be correct right? What should I do cause they may have ruined this head. I am also curious about the head gaskets ability to seal everything up.
I have thrown some pics in for you all to see.

One more question.
After resurfacing a head, is it necessary to install a thicker head gasket to make up for the amount of material that has been removed?

TIA

 

[viking20]

It does look like its too coarse.....Use some fine sand paper , 600/800 and 1000 on a flat piece of glass or similar.
Do it in a cross motion , or circle it around if the paper is big enough.
You can use a thicker base gasket , and the head gasket can also be doubled on the Hondas , if you should think this is nessecary.
I have experienced that the dowels between head and cylinder was to long after levelling the head on a Honda.
When everything is ready , make sure that the head mount to frame still fits , you might have to file the holes. If the bolts are forced through , the stress can lead to the gasket leaking , or the head may warp.
I have seen lots of motorcycle parts more or less ruined by car engine repair shops :ohmy:

 

[Peer Lovell]

You can re-use the head gasket, but coat it with some spray copper gasket coating first.
That should help the seal.

 

[razorboy]

OK<
So I did what you suggested and used 500 and 1200 grit to clean up the surface. It went really well and the surface is almost "glass" like ---- very smooth.
Put it all back together again and the bike fired up after a couple of kicks......yippeeee!
Nope, still leaking coolant at two locations on the head.
:bang:
I took it apart again and now I can clearly see that the top of the cylinder has got an uneven surface. The problem is that because of the studs, I can't run it over sandpaper like I did with the head. Well not until someone informs me how to get the studs out of the cylinder-----if possible?
Now it is ALL torn down again (4 or 5th time) and the jug sits on the bench. Hopefully, this is the last time so I can move on to get her dialed in. Once it was running, I went for a hop and the performance is really crappy, Bike has no power 1 and 2 and only starts to pull a little going into 3rd and beyond. No problem, I'll save that for later.

Need help with that cylinder though...

Cheers
Bernie

 

[YZ165]

Man, sorry to hear about the bad experience at the auto shop. I own one and hate it when bone-headed car guys jack up perfectly good motorcycle stuff. You can usualy get the studs out by putting two nuts on each stud and tightening them against eachother. Then use the bottom one to back out the stud. If that doesn't work, you'll have to get a stud remover and use that. Sears has 'em. Good luck, and stay away from that car shop with your MC stuff! LOL, YZ165

 

[razorboy]

Thanx for the support and the information.
Sears has the stud remover for 24.00 which might as well be a million bucks to me now.... it so erks me to spend more money on this project. Man, it better be worth it ...lol
I'll try stacking the nuts first though..

Cheers
Bernie

 

[razorboy]

Studs are VERY tight.
I snapped off two 13mm open end wrenches attempting the dual nut strategy. Any other words of wisdom because now I am fearing that a stud is going to snap off in the cylinder.
I may just clean it up and opt for some of that copper seal helper that was mentioned earlier? However, I hate like hell to put something back together that I am not 100% happy with

Cheers
Bernie

 

[Rcannon]

sometimes you can heat the cylinder up with a propane torch. This helps the studs to break free.

 

[bikepilot]

That spray copper gasket sealer works great. I raced a KX250 for a year with a badly scored cylinder and probably warped head. I had sent my usual cylinder and head out for replating/porting etc, but the plating place was taking forever, so I resorted to mounting my junk spare parts. Surprisingly it worked well, never let me down. I even got several holeshots and a race win out of the deal:)

I say, clean it, spray both sides of the gasket and bolt it together:)

 

[razorboy]

Yes, I think its the quick fix for now. I want this thing done for next weekend. Cripes, I bought it last year and have only ridden the damn thing 10 times! Once I get all the other bugs worked out of it, I'll go back to the cylinder and do it right. I hate not finishing the job but I am fearful of snapping off a stud.

Cheers
Bernie

 

[viking20]

I doubt you will get it leakfree , with just some spray.....Try heating around the base of the stud. The Honda gaskets is not exactly the best design , at least not on the similar 125´s..You could clamp the stud in a vice and try turning the cylinder , while you carefully apply some heat...Its frustrating when you keep having trouble with a bike and you just want to ride , but we have all been there , and you WILL get through it !
Good luck !

 

[crazy4nitro]

That spray copper gasket sealer works great. I raced a KX250 for a year with a badly scored cylinder and probably warped head.

How bad was your cyl. scored? do you have pics?

Crazy4nitro

 

[handywork]

Sorry to ask the obvious,the surface of the head needed cleanning up and that`s natural as they do many of these a day and fine grit paper on a glass surface is the best way.But as I have machined heads,brakes etc. myself,qualified boilermaker,and have done a bit of machining and fab work.Now for the machinist to get low spots,it would have to be low on one entire side,the feed slides or travel slides are faulty on milling machine or shaper,the vice wasn`t secured(then it would spit out and really damage it),or it moved in vice(see previous).The head would be checked on 3 parameters on set up,feed and travell calibrated on minimum 4 equally opposing points(also double checks level).Well what I`m trying to say is a few simple things,first did you remove head studs properly and in sequence,did you torque up head studs with equal pressure and in sequence rememberring to do it in stages.Not saying you didn`t just asking before I make the next observation as if you take it back to be rectified that`s what he will blame it on.Second do you know how much the cut was eg:0.025mm,0.050mm,0.075mm etc. Judging by the meat on the bowl lip of the head it looks rounded and it probably needs to go a bit deeper but I don`t know if he can and still leave a decent lip to aid gasket seal.The lip looks from the photo to have a somewhat rounded lip edge.Now the lengths of the studs might be a prob if they bottom after head work,check this by putting a small ball af alfoil around bottom of one stud,assemble and tighten stud down finger tight or just nipped.Take apart and see if foil was squashed by stud and how far.Your might need small equal shims under stud head.But what really caught my eye was,did you decarbonise the head,it looks like it`s been cleaned by an acid bath as no visible scuffs from buff.Are you sure he did actually machine it and not just wash it,the marks will still appear on surface when the gaskets completely removed,looks like he took your dough and just soaked it.Is the alloy any duller in sheen?and looking towards the rear bowl lip edge it looks a bit rounded,they need a good lip edge to seal and if he machined it,it would be a sharper edge from being taken down.Tell you what,print this out,take the head and this thread back to the shop,and ask to be refunded or problem rectified and if he wants my proffesionnal opinion he can contact me on [email protected] ,I really wasn`t having a go at you just explainning the process and what I perseive to be the problem and I hope it works out.

 

[handywork]

To add smear a little grease,not oil on head studs before assembly,avoids snapping studs,and get a better torque reading and a bit more equal force distribution on head.Be carefull to not heat the crankcase or surface too hot too (not red hot) concentrate heat mostly on stub and try to move while heating as was said with 2 nuts,or a good quality set of vice grips locked down,probably needs loctite to break away and it will with a bit of heat.Now the stud to shear it was either fatigued and that would explain head warp,or as I said before it`s bottoming out or catching.Check this,and remember the grease OK.Are you sure your using a torque wrench,and correctly?snapping a high tensile 7 or 8mm stud takes a bit of effort,far more than the head ever needs.

 

[razorboy]

Thanx for the input.
The head was definately worked on. It appears that it was put through a beltsander or something because the finish on it was very coarse and grained in one direction. Anyway, its too late for that because I already sanded it down. Its mirror smooth now.

I tried for the last time last night to get the studs out of the cylinder. They are way too tight to get out. I used a propane torch to heat up the surrounding area to no avail. I have snapped studs and bolts off before so I am confident when I say that this is taking too much effort. I have no idea why they are so tight but I am not risking snapping one off.
I decided to go at the top of the cylinder with my 800 to 1200 grit paper to smooth it as best as I could. I am going to go this spray route to see if it seals it enough for the time being. The cylinder face actually looks pretty darn good.

Yes, I have followed all manual procedures for installing the head including proper torque and criss-cross tighening of the head nuts. I'll check back with you guys after this next attempt and let you know if it worked or not...

BTW
Does anyone have a brand name for this spray copper gasket stuff. Where do you find it?

Thanx
Bernie

 

[viking20]

Brand names over here doesnt mean much to you anyway , so I´ll leave that out , LOL...
The leaking of coolant to the outside , though annoying , is not THAT critical. Just be carefull that you dont have even a small amount of coolant in to the combustion chamber , it will ruin you piston crown very quick.......As in :" I didnt even notice any smoke from the exhaust , or drop in coolant level " Been there a few times myself , and it can ruin both piston and cylinder.

 

[razorboy]

OK,
I picked up the stuff at Kragan Autoparts.
In the US, it's call "Ultra Copper" and it is made by Permatex.
You can get it in a tube or a spray. I opted for the tube.
I guess I will give it a try tonight to see if it works.

Wish me luck!