Possible Engine Seizure - REBUILD THREAD: *HELP!!*

Re: Possible Engine Seizure - REBUILD THREAD

mlinder said:
I don't know where "over here" is, but there were over a quarter million cb350's sold worldwide.

But, go for it.

Have fun cracking the cases and dealing with the gear shift linkages :) .
Click to expand...

Nothing beats a bit of positive encouragement! ::)

"over here" is the UK and a replacement engine is about £300 + shipping...with no guarantee that it even moves! I can get the parts I need to rebuild, repair and renew for about £200, plus I learn how to do it and how my engine works. If I can find a cylinder head and pistons from a 350 then I'll do that, but repairing what I have makes sense - to me at least!
 
Re: Possible Engine Seizure - REBUILD THREAD

Why by new Jugs, it looks to me like you could bore the 250 out to the 350 and just get pistons and rings. Then you know the bores are good versus unknown used.
 
Re: Possible Engine Seizure - REBUILD THREAD

Oh, I'm a very positive person :p

You'll need jugs and pistons, not the head.
 
Re: Possible Engine Seizure - REBUILD THREAD

mlinder said:
Oh, I'm a very positive person :p

You'll need jugs and pistons, not the head.
Click to expand...

Sorry, when I say head I meant what you call jugs.
Rebores are 35£ a cylinder plus pistons and rings it adds up a bit over just some new rings (which are still expensive! £31 a set!). Is there enough meat to the cylinder sleeves to allow a 350 rebore without compromising integrity??

To be honest, I don't really need the extra hassle or speed, the 250 is quick enough for me: I'm a pussy! Haha
 
Re: Possible Engine Seizure - REBUILD THREAD

No, when you buy the jugs, you should be getting the sleeves with them.
 
Re: Possible Engine Seizure - REBUILD THREAD

Can I ask what you mean by rolling the valves on glass... How will that make it easier to tell if they're straight? Or will it be obvious when I do it?

I've ordered some lapping paste and tool too.
 
Re: Possible Engine Seizure - REBUILD THREAD

It will be obvious when you try it. If the valve is bent (and I'd bet that at least 2 valves are bent) they will roll with a wobble. Straight valves will just roll in a large circle, bent ones are obvious.

You could try to grind the valves and that will show up any bends too. If the bend is minor, the valve will only touch in one or two spots.

FYI the 350 isn't much faster than its little brother but it accelerates a bit faster. You should be able to get a 350 barrel a.k.a. jugs, block, cylinders and bore and hone that to fit new pistons. I'm not sure about the differences between the 250 and 350 heads though.

Strip the motor completely taking lots of notes and pictures and with a manual and even better a parts list, then clean and inspect everything and if it's all OK rebuild it as a 250 or 350. There's nothing complicated in there but take your time and use the right tools. Use a rear axle to remove the alternator rotor - NOT a 3 legged puller.
 
Re: Possible Engine Seizure - REBUILD THREAD

Managed to pull the broken rotor bolt nice and cleanly, and get the rounded RH cover bolts out too so happy days 8)


teazer said:
It will be obvious when you try it. If the valve is bent (and I'd bet that at least 2 valves are bent) they will roll with a wobble. Straight valves will just roll in a large circle, bent ones are obvious.

You could try to grind the valves and that will show up any bends too. If the bend is minor, the valve will only touch in one or two spots.
Click to expand...

Makes sense, I'll definitely do this.

teazer said:
Strip the motor completely taking lots of notes and pictures and with a manual and even better a parts list, then clean and inspect everything and if it's all OK rebuild it as a 250 or 350. There's nothing complicated in there but take your time and use the right tools. Use a rear axle to remove the alternator rotor - NOT a 3 legged puller.
Click to expand...

Yeh, for once I'm being quite strict about going slow and being organised. Everything is going into little baggies and labled up and put into a dedicated box in order of removal.

Now, I was about to order a 3-legged puller... what is this axle trick????
 
Possible Engine Seizure - REBUILD THREAD

The rear axle can be screwed into the rotor in order to remove it.
 
Re: Possible Engine Seizure - REBUILD THREAD

You screw the rear axle into the rotor until it bottoms out hard. Then you lean on the spanner to get it really tight. And here's the trick. Smack the end of the axle sharply with a large hammer. The combination of end loading and sudden shock usually works. SOmetimes you have to repeat a few times. Tighten, smack, repeat until it comes loose.

Hit it dead square so you don't bend the axle or damage anything else. I keep a spare cut down shortened axle for that purpose.
 
Re: Possible Engine Seizure - REBUILD THREAD

Okay, after a few hours shift at work this morning, when I get home my next step is I'm gonna split the lower cases open and I have a quick question:

Should I, after removing the pistons, put the top end roughly back together before I turn it over to split the crankcase? The guide rods for all the cylinder tubes, head, valve head etc look easily bent so would you put it back together first or is there a technique to getting it over that is easier? Or am I missing some easy way to get the guides out?
Also, any little things I should watch out for whilst splitting them? Things that might spring out, or are easily damaged as I seperate the cases???

Thanks in advance
 
Re: Possible Engine Seizure - REBUILD THREAD

Disassemble the bits for gear shifting as much as you can first.
Use a rubber mallet and a thin paint scraper to break the seal on the cases.
Are you talking about the engine bolts? Anyway, no, the engine should be as disassembled as you can get it when cracking the cases. At least, that's how I do it. The engine bolts stay attached.
Yes, some things are likely (though not guaranteed) to fall out when it finally splits open :)
I wish you were doing this 2 years ago, I would have straight traded you across your 250 jugs for some 350 jugs and pistons, and paid shipping for both. Looked for a long time for someone to sell 250 jugs.
 
Re: Possible Engine Seizure - REBUILD THREAD

Right, so after a bit of a struggle, I got the case open:

IMAG1084.jpg


Actually not as complicated as I thought, and all makes sense to me.


SO the outcome is that, fortunately, there appears to be no damage to the bottom end at all despite the chain getting wedged down there. I checked all the bearings and they are fine and quiet, the gear cogs are all intact and now DONT have little bits of metal in them hahaha. The only bitch is that one of the cylinder circlips 'pinged' into the abyss on removal so I'm gonna have to find one of those.

A couple of things, if you could help:

1) What tool do I need to remove the oil filter? Looks like maybe a peg wrench, but I dunno what size
2) Whats the best way to flush the insides all clean? Can I simply hose it out?
3) Which seals should I look to change on reassembly?
4) Do I need to use a different kind of liquid gasket on the case? or will standard blue be fine?


Thanks
 
Re: Possible Engine Seizure - REBUILD THREAD

There is a special tool to remove the oil filter, but most people make their own using an old socket, just grind it out to fit. If it was me, I'd replace all of the seals that you could. They usually come in a complete set when you buy them, so now would be a perfect time to do it and not have to worry about it again. They are not expensive either.

Here is an excellent thread on an SL350 engine rebuild that has really good pictures of the breakdown and rebuild. Its an excellent resource to compare your work. On the first page it shows the tool for removing the oil filter. http://hondatwins.net/forum/viewtopic.php?f=44&t=18706
 
Re: Possible Engine Seizure - REBUILD THREAD

Hint: Never ever re-use piston circlips. They are cheap and easily ordered from your local dealer.
 
Re: Possible Engine Seizure - REBUILD THREAD

Here's the tool you need for the oil filter:

http://www.motionpro.com/motorcycle/partno/08-0015/

08-0015.jpg


$8.99. Shipping will kill you....check the site out, there are other tools and parts that are good...combine to lower the cost of shipping.

The ID is 24mm if you are going to make one.
 
Re: Possible Engine Seizure - REBUILD THREAD

So, I made a socket but I'll be damned if I can get the sucker to move! The dam crankshaft just won't stop spinning and I tried wedging it but... No joy. I might have to wait until I put it back together to pull and clean it with some resistance in the engine. Also, I forgot how much I hate scraping old gasket off - what a soul destroying job.

so, tomorrow I'm gonna order all the stuff, piston circlips included ;) and get the cases cleaned up and prepped. I have ordered a valve spring compressor and when that comes I'll check those. Which leaves the to do list as this:

Pull valves, check straight, de-coke and lapp into head.
Clean out crankcase of old oil and metal shavings
Get cases, head and side covers cleaned up - possibly blasted
Change all oil seals
Fit new cam chain and tensioner
De-coke pistons and fit new rings
Need someone to helicoil one bolt in the RH cover (oil filter hatch) as one removal went a bit wrong :eek:
Get down to the local fixings shop and get a load of replacement case bolts & screws...the old ones are a bit rusty and I'd rather have proper hex ones than stupid cross-heads! Do stainless ones cause issues with the Aluminium casings?

Then it's reassembly time, hoping it all goes in the right way!

Still need to know what type of liquid gasket to seal the crankcases with, and the best way to clean out all the oil channels.
I know I'm going to have a load of questions when I comes to getting the top half together in the right way so that the cam is in sequence with the pistons so look out for that slice of fun!
 
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