Topic: CB350f Copper Gaskets (formerly Spark Advancer Springs)

[camshaft1991]

I'm looking to see if anyone has any advice on obtaining the springs for the spark advancer on a cb350f. I've replaced the coils, spark plugs, spark plug wires, spark plug boots,  points, condensors, all the jets, new carb boots, new exhaust valves (which i seated and ground them in along with the previous intakes), and a new camshaft from Dynoman Performance. I also have completely rebuilt the engine with new gaskets seals, o-rings, cam chain, cam chain components, crankshaft bearings, new pistons and rings, and bored out by .5mm.

At its idle, 1200 rpm, the bike stutters and can sometimes want to stall out and drop to 500rpm or so. When revving, the engine is slow to return back to idle. I had my tires replaced and aligned by a shop and they told me it was most definitely worn spark advancer springs.

I've looked at the forums and I read how people have cut their springs or bought similar sized springs from automotive stores. I know the spark advancer is sold as one unit, but I was wondering if anyone is in the market for selling these specific springs. And if anyone knows someone who can make custom springs let me know. If anyone else has the same issue I would be interested in getting in on a bulk order of these springs.

[gtmdriver]

I'm new to the CB350F so I stand to be corrected but I've been working on bikes and cars for 50 years now and I've never come across a problem such as yours being caused by worn centrifugal advance springs.

Why would it be an intermittent problem if the springs were worn? Surely they would just allow a little more advance through the revs and hit maximum dvance a little earlier?

Is this a common problem with the Honda SOHC fours?

[Jerry Rxman Griffin aka MuthaF'er]

Check with yamiya750.com. They have 750 springs. They also do 400 stuff. Perhaps one in the same?

[camshaft1991]

Oh wow they do have them. Thanks! It's for the 400f but both spark advancers on the 350f and 400f have the same part number. Also, they do wear out. I know this because I've replaced everything related to the ignition with the exception of the advancer. After 40+ years parts under tension will wear out like my forks and shock absorbers, but that's a later project...

[754]

let us know if that fixes it..

[camshaft1991]

Just got around to replacing them and there is a difference compared to OEM. The pair from yamiya750 are smaller in gauge, are more coiled together with about 2.3mm more  coil but relatively the same overall length.

They look high quality and are but I now have an issue with starting. It seems that I have cylinders 2 and 3 not sparking with a spark gap tester. I put the old springs back on and still no difference. I get backfire from running the starter but I cleaned and checked my plugs. I've played around with the ignition plate for the 1-4 points and nothing changes. The points have some corrosion but not much. I took the ignition plate, with the points on, off as a whole. I had it propped up on a box next to it so I wouldn't have to disconnect any wires.

I ran it two weeks ago to dry the carbs but i also checked for gas in one of the carbs. There was gas but if I have backfiring while starting then I should have gas flow.


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[camshaft1991]

So both points are sparking but I can't read any spark when I connect the spark gap tool to plug boots 2 and 3. 2 and 3 plug boots are longer and deeper than 1 and 4. Maybe the tester can't fit inside? The plug boots, and coils are new. The plugs themselves are three weeks new.

Overall, it almost makes me think that I have the petcock is off, but like I said before, there is gas in carbs and I'm getting backfire from prolonged use of electric starter. I also take 15 min breaks on starter so I don't burn it up. Could there be a short?


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[gtmdriver]

Instead of using the spark gap tester why not just pull the plugs and lay them on the head with the plug leads connected? That way you'll know for sure whether the plugs are firing.

[camshaft1991]

Thanks for that gtmdriver. I don't know why I didn't think of that before but now I have all 4 plugs are sparking blue and no engine start with the exception of the starter turning over.


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[camshaft1991]

I have a suspicion or know so that my rings have been installed wrong, because that is the only part of the engine I had let someone else do. I'm burning oil but my "mechanic" told me it was the engine breaking in. The smell of the exhaust and the the oil dip stick say otherwise. I also don't notice any oil leakage anywhere on the pavement. Also from what my workshop manual says the only other reasons are piston seize, blown cylinder head gasket/warped, seized valves, faulty valve timing and EXCESSIVE WEAR OF PISTON RING OR CYLINDER.


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[camshaft1991]

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[camshaft1991]

If my rings are in fact upside down and my cylinders are possibly scorn... Would my engine not fully turn over and start because of that? I know I need to get inside my cylinders but I want confirmation if that is what it boils down to


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[gtmdriver]

Shouldn't stop it starting up unless it's allowing so much oil through that it's fouling the plugs, but you would have noticed that when you took them out.

If the plugs are sparking as they should then either they're not firing at the right time (ignition timing) or there's something wrong with the fuelling. Since you've just had the advance unit out of the bike I would start by checking the ignition timing.

[camshaft1991]

Well I went ahead with my thorough inspection. I dropped oil pan and it smelled worse than the first time I drained the oil. Did not smell like normal used oil. So I took the engine out, attempted to dismantle the top end and when I removed the cylinder head the cylinder jugs came out too... Now I have to figure out how to separate the two. Hopefully liquid gasket was not used.

The Pistons look great, but I can't seem to get a good look at the indicator marks on the rings, but I think there might be scoring/black streaks on the cylinders. The streaks don't come off with a wipe of a finger. Is that normal wear? Here are some pics.  This is around 300~miles

Also my plugs were fouled after adding more oil. There wasn't enough oil to even foul the plugs But seriously




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[camshaft1991]

Can't believe I've made this thread into a top end rebuild thread. Anyways I dropped my engine pieces at a machine shop to have everything checked out with my cylinders.

The cylinders are scorned but I do not know what was the cause. Whether it was poorly seated rings or running to rich to the point where the gas washes off the oil lubricating the cylinder. A notable bike shop in New Orleans told me my engine could be breaking in or I could of had rings seated wrong. So I checked the rings when I pulled my cylinders off and the small lettering was up and all 3 rings on each were separated making a triangle (120 degrees from each other).
My oil pump had one stripped thread on the case.. but if it was a problem it will be fixed. I haven't been able to check for leakage because I could not even get the engine running. it is slightly dirty around the oil pump but I could not notice anything severe nor any puddles.

Also my pistons were not fine. Even in the Iphone pictures you can see some wear. And just to reiterate this 300 miles. The motorcycle shop in New Orleans tells me it is possibly burning oil or the engine breaking in. The machine shop I went to in my hometown, Baton Rouge, saw my engine dismantled and told me it was too rich and would wash the oil away. Has anyone heard of stuff like this before? Let me know. To clarify, I live in New Orleans but I have my dad's shop/garage in Baton Rouge so I can work on my bike.

Also does anyone know anything about the thickness of the cylinder and cylinder head gaskets for the CB350F? I'm thinking about using brass for gasket material so I won't have to deal with the peeling and stuck gaskets. I'm also probably going to have another rebuild in the future. Dunno what it would be for but call it intuition.

[754]

 Your non running problems to me sound like your coil wires got switched..

[flybox1]

Long shot here, but something relative as i had similar issues....what brand carb kits did you use, and did you replace the metal tipped float valves with the ones in the kit?

[camshaft1991]

To 754: I didn't switch the coils to see if it would work but then again they were in the same position when the bike ran. I'll try it when I can get everything back together.

Flybox1: I sadly do not. My "mechanic" got them from a store. He insisted that the bike should run rich for the weather we have in the south, but what brand are you thinking of? I'll  try to look for a brand emblem. The kit was originally from 4into1 but he used different main and pilot jets from a local store.


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[camshaft1991]

Alright
So when I took the engine apart, I found scoring on the cylinders and pistons. The rings were installed properly but the tops of the pistons were yellow and was an indication of running too rich. A machine shop pointed that out to me when I had my engine worked on. They also mentioned that it was "washing out the oil in the cylinders". I also had another problem with a stripped thread for the oil pump. The thread previously would not allow the oil pump to tighten all the way on and possibly could of been where oil was leaking out of. I have never seen an oil puddle develop before with my bike, but I think the bike previously has been leaking oil when it runs and has been dripping on the final drive chain. The bottom of the oil pump exterior was dirty and oily. Even if I'm overthinking this, I can at least rule out the leaky pump.

I'm still in process of preparing for the rebuild but I am moving forward with converting my cylinder head gasket and my lower cylinder gasket to copper. I've given them both to a CNC shop and have ordered the sheets of copper. I ordered .024" (lower) and .042" (head) copper sheets. I think I ordered copper 190 which is 99.90% pure. It is rated soft and is annealed, which I do believe is required for automotive use. If this all goes well, I will post the autocad files to SOH4. I know there are copper cylinder head gaskets for the 350F but they are all for the big bore kit which is a 52mm bore. The OEM head gasket can fit up to 1.0 OS.

I have no clue what brand of jets I have in my carbs but they are matched in size and numbers to my left over Keihin jets. Why the Keihin jets were not used in the first place, I have no idea.

[flybox1]

Keihin jets ARE OEM....anything NOT marked with the Keihin 'K'  is aftermarket and is suspect.  Put back in your stock jets after you clean them up.
Carbs should be jetted for the bike (intake/exhaust), and in some cases elevation..... but for the weather?  C'mon....we'd have to re-jet 4 times a year 
Methinks its time for a new 'Mechanic' 

[chewbacca5000]

These are super sensitive to the fuel level in the bowls too much and it will blubber and studder.

[camshaft1991]

Well the mechanic is out of the picture and I do have another set of untunable carbs with keihin jets. I think I know which carb makes them untunable but I'm not going to worry about that when I have another functioning rack of carbs.

Anyways 1 out of the two gaskets I have had made fit where it is supposed to go. It was not the CNC shop's fault, but mine. I should have never used a gasket as a template. They are not made to be exact, but are made to fit. They only fit in because they are made of flexible materials that can give way when fitted in. Copper does no give so easily. I tried drilling out the holes to make a better fit but one of the shavings of copper fused to the surface. I don't have a deburring tool but I should have gone out and bought one. I at least have a copper cylinder head gasket to work with, but I am worried about how much it will compress under torque specs.

On top of this all my rings scratched my cylinders when I fitted my cylinders. I don't have a piston ring compressor but I used the round curve end of an o-ring pick to pop in each ring. A slow process but I didn't use the pointed end. The pistons were reluctant to move and I noticed a scratch on one of the cylinders. After taking the cylinders off I noticed one of my pistons had the scraper on top. In the end they all were scratched and cylinder #4 had the worst obviously. I'm going to see if a motorcycle shop can hone and install my pistons. The rings should be still good. I just hope I can get by with a second hone.. The shop I know of is reliable but like any other shop they are backed up with months of other projects. They did a good job mating my crankcase halves.
pictures
1 gaskets when I first got them
2-3 lower cylinder gasket after my botched drilling
4-7 scratched cylinders in order from 1-4 (lower end)
8 o-ring pick (jury ring compressor)
9-13 scratched cylinders in order from 1-4 (top end)
14 correct piston with black scraper in the middle #3
15 incorrect piston with black scraper on top #4

[camshaft1991]

And now I gouged an intake valve or maybe it was already before I took it out. The valve guide seems fine when I put another valve through. Going to get a heavy drink now.. [IMG]http://uploads.tapatalk-cdn.com/20160619/0925f6d593701ee6553023a30bd60497.jpg[/IMG


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[754]

You should move this to the main forum, not getting seen here much.
 Your metal gasket will not crush much if at all, it's solid metal.

[camshaft1991]

I know it is solid made of a metal, but do copper gaskets work if they do not compress? I was contacted by guy named Lani who sells them but I had my gaskets made by a local CNC shop. Just realized my topic was brass.. I met copper.

Also I need help from admin to clear up the Tech forum under SOHC/4. I was confused on moving the post and I accidently posted two duplicates. I need to delete the topics that say: MOVED and MOVED MOVED