Author Topic: Frame-up cb350f restoration, hunk o' junk transformation (Read 55005 times)

markreimer · « **Reply #250 on:** September 18, 2016, 07:13:13 PM »

Cool, thanks!

Took the 350 on a 500km "spirited" club ride with some guys over the weekend. We hit one of the few twisty roads we've got around here and I opened the bike up to try and keep up with the 1200cc modern bikes. What a wild ride! This bike just sings in 5th at 9K haha

The guy behind me said his speedo recorded me at 150km/h, not bad for this old bike. It's really too bad it's burning oil, because it's running so nicely otherwise.

Anyway, while I wait on the parts for the engine rebuild, may as well ride it as much as possible as snow is only 4-6 weeks away...

Oh...and here's a photo of my wife and the 350, and me on my new toy

Coldsmoke · « **Reply #251 on:** September 25, 2016, 04:36:03 PM »

Permatex #2 is what you need to put on bith sides of the head gasket if you want it to seal. Anything else will leak sooner than later.

markreimer · « **Reply #252 on:** September 27, 2016, 12:36:14 PM »

Gasket kit arrived today. Anyone able to tell from the photo if this head gasket is like the original one, with the heat activated adhesive layer, or if it's a later replacement that will need some sealant?

Also what the heck are those two thick and tall rubber pieces for??

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grcamna2 · « **Reply #253 on:** September 27, 2016, 01:40:45 PM »

You won't need any sealant applied to your oem Honda head gasket.

markreimer · « **Reply #254 on:** September 27, 2016, 01:45:05 PM »

I don't think that's 100% the case. After looking through at least a dozen 350 and 400 rebuild threads that ended up leaking, there were a number of dry-installed OEM head gaskets that leaked. HondaMan explained in one that the original head gaskets had a tacky heat-activated sealant incorporated into their design which prevented leaks from happening. Later Honda-branded gaskets did not, and would often leak as many of us have experienced. So I'm just wondering how to tell the difference. This gasket feels pretty smooth and dry, not tacky or anything like that. There are lots of people here saying their rebuilds are bone dry with copper coat. Others saying Permatex (like above), and lots saying they have leaks after installing dry or with sealant.

I find it all rather overwhelming. I'd prefer to stick with a early honda gasket and no sealant. but if someone can tell me how to identify if it isn't one, I'll be using a sealant regardless of the fact it came in a Honda package.

markreimer · « **Reply #255 on:** September 27, 2016, 02:35:14 PM »

These are the two threads I referenced:

http://forums.sohc4.net/index.php?topic=131858.0

http://forums.sohc4.net/index.php?topic=111517.0

grcamna2 · « **Reply #256 on:** September 27, 2016, 04:52:56 PM »

The only way to know for sure if it's the 'Early gasket' is to open up the package,you'll be able to tell.
The best way to keep it from leaking w/o sealant is to have the head surface lightly(.004) 'skimmed' and also keep re-torqueing the head in a cross pattern at regular intervals.

Coldsmoke · « **Reply #257 on:** September 30, 2016, 10:10:01 PM »

The ancient gaskets with rhe sealer on them are quite unmistakable as they appear to have a layer of rubber cement on the entire gasket. Regardless, either way, Permayex #2 should be applied to both sides to avoid certain rework due to leaks.

grcamna2 · « **Reply #258 on:** October 01, 2016, 05:57:34 AM »

Quote from: Coldsmoke on September 30, 2016, 10:10:01 PM

The ancient gaskets with rhe sealer on them are quite unmistakable as they appear to have a layer of rubber cement on the entire gasket. Regardless, either way, Permayex #2 should be applied to both sides to avoid certain rework due to leaks.

The orig. oem gasket w/ the thin adhesive bonded to it is real thin,if you use any gasket spray,etc. make sure it's applied very lightly.

markreimer · « **Reply #259 on:** October 01, 2016, 11:07:05 AM »

Well this gasket feels pretty smooth and hard, not tacky or rubbery or sticky. I'd say it's quite likely this is NOT one of the original adhesive gaskets then. Guess I'll use some sealant then.

All ready for the rebuild now. Just have to wait for access to the shop, should be happening soon.

Coldsmoke · « **Reply #260 on:** October 01, 2016, 05:00:57 PM »

Nice...just use common sense when applying the sealer by being mindful that it wont squish into the oil feeds or the bores. Also, have everything 100% ready because the product that I recommended tends to start curing quickly. Good luck!

grcamna2 · « **Reply #261 on:** October 01, 2016, 05:40:53 PM »

I think the Permatex "Copper Spray-a-Gasket" is very good also,but let it fully dry before installing the head gasket.

Johnny5 · « **Reply #262 on:** October 28, 2016, 04:22:01 PM »

Hey Mark,

Spent some time here and there reading through your thread. Awesome stuff! My wife is from Thunder Bay originally, so we were having a good time watching you ride the bike through snow! ....Not that I won't have snow here in Michigan soon....

Now I see why you asked me about the compression test. I hope all is well with your bike.

Thanks for taking the time to document your journey.

markreimer · « **Reply #263 on:** December 27, 2016, 10:36:07 AM »

Wel it's finally time for the top end rebuild. I was expecting to pull the cylinder and find stuck rings. However all the rings are floating freely. But pistons 1 and 2 look knackered.

Here's pistons 3/4

Cylinders look in ok condition (I think??) and in need of a hone. You can see the vertical lines in the cylinder but I can't really feel them. I think a home would probably take care of it.

So are those Pistons garbage then? I have a donor motor that might have better pistons. If the cylinders can be honed and used without an overbore then I shouldn't be in good shape without needing to order more stuff

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calj737 · « **Reply #264 on:** December 27, 2016, 10:48:22 AM »

I would not reuse those pistons. Either the pins are worn, or remote possibility is a rod bearing. The way they've worn suggests too loose a tolerance and they're rattling around. It would also be prudent to measure the bores to insure they're not tapered or out of round before proceeding.

At a minimum I'd rigid hone and new rings...

markreimer · « **Reply #265 on:** December 27, 2016, 11:14:11 AM »

I'll pull them off and check the pins. Given there is less than 6000km on the engine, what would you suspect could cause such wear so fast? Oil starvation? The top end looks pristine. Cam and lifter faces are excellent.

Now to find that spare set of pistons... where did I put then

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markreimer · « **Reply #266 on:** December 27, 2016, 12:29:36 PM »

Ok I just measured my cylinders. I measured at the top, middle and bottom, left to right as well as front to back so I could see how round they are. Good news is that every measurement is well within spec. I zero'd my tools each time and double checked, so this should be accurate.

Manuals says 47.00-47.01 is good. 47.10 is overbore time. So I should have lots of room to hone here I believe.

My extra pistons are MIA but I have a complete spare motor at my friends shop. I'll get it tomorrow and open it up. Fingers crossed there are two good pistons in there.

In the mean time I checked the valves for leaking. I have mineral spirits in here and nothing has leaked in 30 minutes. (Springs still on for this test, right?)

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RAFster122s · « **Reply #267 on:** December 27, 2016, 12:48:32 PM »

Yes, springs on...
Numbers look good, should be enough measurements. Some take readings 120 degrees apart to check cylinders for any egging.

David

markreimer · « **Reply #268 on:** December 27, 2016, 01:37:37 PM »

Ok I pulled the two bad pistons off. The pins look just fine, and the inside of the rod does too. Nice and smooth, tight fit, no scarring. Hmmm what HAPPENED in these two cylinders!?

I cleaned up the tops with a wire wheel and polished the skirt with scotchbrite. Definitely can't re use these two, there are some big scrapes running down the side.

I also found that my #2 valves have leaked fluid since my last post, which was the cylinder with lower compression. I'm going to take them out and lap em back in tonight

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markreimer · « **Reply #269 on:** December 27, 2016, 02:02:04 PM »

Next up, valves. Man it helps having a real compression tool!

I discovered my head has no valve guide seals on the exhaust side. Any opinion on adding them?

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markreimer · « **Reply #270 on:** December 27, 2016, 02:04:12 PM »

Actually I just realized I can't add them. The guide shape is different. The seal wouldn't stay on the exhaust guide profile

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grcamna2 · « **Reply #271 on:** December 27, 2016, 03:26:17 PM »

What condition are the guides in Mark ?

markreimer · « **Reply #272 on:** December 27, 2016, 03:51:22 PM »

Very good. I can't feel or see any play at all, even with the valves pulled out most of the way. Smooth and toght

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markreimer · « **Reply #273 on:** December 27, 2016, 06:24:46 PM »

Well called it a night. I lapped the valves in and replaced the exhaust valve seals. After I was done I did another leak test. My #2 is isn't leaking anymore but now 1/4 exhaust is hah!!

So tomorrow morning I'll take those valves out and lap em some more. Also open up the donor engine. Fingers crossed the pistons are stock and in good shape...

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markreimer · « **Reply #274 on:** December 28, 2016, 02:11:55 PM »

Need some valve tips.

Last night I did the valve leak rat and had one cylinder leaking fluid. I removed and lapped all the valves. Now all 8 are leaking!!!

I'm using permatex lapping compound and a suction cup stick. I lap till it sounds smooth, lift the valve up and do it again. Maybe three times, then add a bit more compound and do it again. After I wash it all off with mineral spirits.

Am I doing something wrong? The valves and seats look really clean but obviously it's not working.

On the plus side my donor motor came apart today and I scored two new pistons

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Author Topic: Frame-up cb350f restoration, hunk o' junk transformation (Read 55005 times)