Big problem this time - bike sounds like a sewing machine and no power

[xwhatsit]

Ah here we go. Now, not being able to kickstart my bike due to rooting plugs every 2 days I can handle. Replacing a rear tyre I can handle. Borrowing wing mirrors I can handle. Aralditing the dash unit 3 times I can handle. I can even handle crashing with no gloves.

But I've never been more sad and upset today on my way to my exam. Coming along the top of Symonds St, just where you leave Khyber Pass, I was tootling along then suddenly... what's that very loud clacking noise? Why does the bike have no power? Why has the engine stopped? I pull to the side of the road onto the footpath, try to turn it over... no cigar (expected due to problems starting it hot anyway) so I bump start it. Get a good head of steam up and jump side saddle like normal, drop the clutch in 1st gear (2nd gear runs engine too slow). Wtf?! It just keeps rolling, but it's making that horrible clicking noise again. Is it in gear? Yep. I roll it back like I normally do, until it hits compression... what compression? It just keeps turning over. Shit.

So I turn off the ignition, put it in neutral, and roll down the hill side saddle scooting along with my foot along the footpath. Get to exam, which I think I failed (can you get an aegrotat for bike-related stress? lol). Was thinking about calling AA but thought I'll try and start it one more time. Pull plug out - thread looks fine, plug looks ok (not smashed in -- I had images of a piston hitting the sparkplug or something lol). There's good spark when I kick it over. Put it in, get the bike started off the kick! But it still clacks away like a mofo. I thought... fuck it... I'll ride it home... I was so angry I didnt' care if I did any more damage. Well, it got me home, even on the motorway, but making an awful noise (it sounds louder in my helmet than the engine many times), and it might be my imagination due to preoccupation with engine but it felt like it had shit-all power.

Now, when I got home, it occured to me the decompression lever might be doing funny thigns. But it appears to be working like normal -- when I pull down the kickstart, the decompression lever rolls back about 10 degrees then forward about 45 degrees+ as you move the kickstart through. So, I don't know about the insides of this thing, but could the decompression mechanism be broken inside? Have I done something worse, like fucked the exhaust valve?

Now, here's a disclaimer. My father (who was a marine engineer and used to do offroad racing) happened to be in the country this morning, and helped me clean the carburettor. [It was pretty clean, actually]. Now, put back together, mixture adjusted, the engine felt really nice. Felt way more powerful than before. Revved easier, didn't die when you pull the throttle quickly from idle (the automatic fuel pump thing connected to the throttle was sticky before). Everything was all packaged up nicely -- but after he caught plane home and I went to uni, it died about 45 minutes after being put back together. Could fooling around with the carburettor cause (what seems like) compression issues?

Man I'm stressed. It's funny how quick I've become attached to this bike and it's kind of breaking my heart when I listen to it and rode it home like that. I hope it's nothing major -- she's done 50,000km+.

Does anybody have any advice?

[JMemonic]

I suspect unless you dropped chunk of something that does not belong in a motor then your maintance work is unlikely to be the cause of the problem, so dont go kicking youself over that one.

Sounds like either a trip to the mechanics or time to learn how to rebuild an engine, if you have any internal damage its pretty hard to tell how much and how bad it is from the outside with out getting the motor apart.

Best of luck with it.

[TonyB]

Its not something simple like the chain slipping is it?

If it turns out that the engine needs a rebuild, send me a PM. I can do piston kits, conrods, big and small end bearings and crank pins. All seriously cheap.

[bungbung]

Honda ohv + clack clack clack = broken valve stem (in my case) but as yours still ran, how about super wide valve clearance?

[MSTRS]

Is it possible that the camchain has jumped one tooth?

[TLDV8]

I think you need to remove the valve cover and check the various components.
If you need a hand,send me a PM.I am local.

Having access to a workshop manual would be a bonus so cam timing,decompressor action,ignition/coils etc etc could be checked.

[cowpoos]

buy a new bike......

[xwhatsit]

OK here's the story.

Thinking it sounded and felt like it would be if the decompression lever was stuck open, I checked that out and it looked fine. The spark plug was taken out and I put my finger over the spark plug socket and turned the engine over and there seemed to be piss-all compression. The tappet covers were pulled off, inlet and exhaust, and I had a look around. Couldn't see much, so I turned the engine over until it hid TDC and had a look again. Hang on a minute -- there's 4 valves, 2 for intake, 2 for exhaust -- and each of those pairs should line up, right? Well at TDC the exhaust valves don't line up. One valve is closed, the other is still open. WTF?

So off comes the top of the engine. Can't see too much, camchain/cam seems fine. It was decided that the head would have to come off. Hehehe. So, the cam/camchain assembly has to come out -- and the chain tensioner, right? Holy mofo, that chain tensioner I have no idea how that a) works and b) comes out. Pulled out a bolt and it seemed to be free but still seemed to be attached. So that has to stay put lol. Had a hell of a time taking the cam sprocket and chain and camshaft out -- does anybody know how to do this properly? It was bloody impossible and to get it out was a fluke. Anyhow it came off eventually, and so did the cylinder head. Man there was a lot of black shit on the cylinder and head -- should it be like that? Maybe that relates to the spark-plug-rooting-problem? At any rate, look at the cylinder head (it's very pretty haha with the four valves all lined up) and work out why the left exhaust valve is stuck open. The valve seat/ring/thing has popped out and is preventing the exhaust valve from returning. Ok. So I just have to replace it, right?

After a moment's reflection, the question pops up: why did it come out? Shouldn't these things stay put? I put it back in, and use a ball hammer to gently pin-tap the aluminium around it over it so it can't come out again (it's there for good now lol). In the sunlight doing this, something makes my heart drop all of a sudden. There is a crack running through between the spark plug socket and the exhaust valves. It's long too, you can see it from the top of the cylinder head and out the bottom too.

Shit.

Cracked cylinder head. :shit:

:bye:

So that's it, I think. New cylinder head. How much are they? I'm thinking at least a couple of notes, maybe five. I don't have $500. But then, after thinking for a while, I wonder. That crack didn't just appear yesterday. It must have been there for a while, right? And it was only yesterday when it finally caused the valve seat to come loose. That's nice and stuck in tight now. So, I think, well, lets put it back together... and sell it! Muhahahaah!. But then that's too evil, so I think OK I'll just ride the fscking thing until it breaks again. Cylinder head cracking won't be too fatal. There's nothing to come loose and root the piston or anything. So the whole engine goes back together again, tank back on, seat back on, wires all plugged back. It's waaaay harder putting an engine back together than taking one apart hahah! And that camshaft/gear... WTF?! How the hell do you do that? Can't wait til I have a Haynes manual and they tell me the proper way. Make sure all the camgear is in phase with the piston and all of that. Everything goes back together, noticing on the way that quite a few of the cylinder head bolts have odd threads and don't look standard. One or two of the threads on the head are threaded too, so a new cylinder head is useful for that too.

Kick it over. Nothing. Kick it over again, keep kicking, wtf?! Why won't this start. I can smell fuel. This sucks. I've fscked the engine for good. Oh wait... spark plug lead :innocent: . I laughed for a while about that ^_^. Now it starts, really easily! Yay! Sounds right too. Leave it to idle for a while to make sure nothing will come loose and blow up the garage in a Hollywood-style explosion. No it's all cool.

I take it for a ride. Everything works OK. The only issue with it that worries me is that it feels slightly less power and a bit stiff, not as free as it was before. I wonder if this is psychological or not? There's plenty of oil in it.

I rode it to work, a ~30km round trip, with motorway bits, and it didn't fly to pieces. It stalled quite a few times, while idling at the lights and when I went to pull away. I think it's being starved of fuel. I wonder if after putting it back together I need to adjust the mixture again? I also noticed that the automatic fuel pump thing on the carb which connects to the throttle is sticky once again. This is probably why it dies when I turn the throttle after idling for a while. Will have to look into that later, I can live with it for now.

So yeah. My first engine. Interesting, I can't believe how much stuff is inside it lol! It's beautiful though, in a strange way. I'm a musician, and I can't help but use the tired old orchestra analogy. Everything is in harmony. At least until some buffoon drops their cello and tries to play it out of tune. Then it all comes to pieces.

Of course I'm now looking for a cylinder head for it. Any idea where/if I can get one? How much will it cost me? The bike runs... but for how long. So I'l need a new head eventually. I feel sad in a way that I'm running her knowingly broken, but in another way there was a huge sense of joy when it fired up after being in a million bits in my garage. I took some photos... might include them in a later post when I can arsed to get them off the camera.

Buying this bike is the best thing I ever did. I'm sort of taking a crash course in engineering and coordination by trying to ride the thing around. I love bikes.

Cheers for all your help,

-Tom

[Ixion]

Profane oath. That is one tough little bitch of a motor to run at all in that state. Honda sure build em tough

props for getting it all back together well enough to run at any rate.

the cracked head will bite you sooner or later, prolly sooner so you need to source a second hand (uncraked) head. These models did have a head cracking problem if I recall correctly.

[xwhatsit]

Hahaha. It starts easier than it did before ^_^. I'm thinking that the reason it was impossible to start when hot was due to the crack (metal expanding and less compression than normal).

Yeah I want a cylinder head ASAP. I'm too fond of the bike to want to hurt it again. I know a wreckers online (they're in Wellington or summat) that's got a CB250RS but I don't think they'd let me buy just the head, would they? They'd want to sell the whole engine.

I haven't heard much about them cracking heads. Have heard nasty things about the balancer shafts and the like but the last thing I was expecting was a cracked head.

[Ixion]

Wreckers will, often sell a head separate.

Someone has most of an XL250 including engine on Trademe , closes tomorrow. current at $151, met reserve

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-accessories/Engine-drive-train/auction-74044587.htm

[xwhatsit]

Arse! Quick, does anybody know if it's the same engine as the XL250S? I know for sure the XL250S is the same engine as CB250RS, but is the XL250 the same? That would be wicked...

Cheers

[xwhatsit]

Oooh he has a photo... shit the engine looks close! Holding the laptop next to my bike, it looks identical... should I go for it? Can anybody confirm that's the same engine? It's old though maybe the engine's shagged on it too lol. Man I'd love to get it though, loads of spares... and then I'd be a real biker! Two bikes! One fscked one!

:cool:

[Motu]

Oh dear oh me....I thought only cast iron British singles could take that sort of ham fisted treatment.I guess you learn something every day.

[Ixion]

Well, it's back together. And running. I'm impressed.

[xwhatsit]

Yeah... engines don't scare me anymore. Arthur C Clarke once said... `Any technology sufficiently advanced is indistiguishable from magic'. Well my engine is not magical anymore. I know stuff about it (ok, maybe not much) and I like that feeling :cool: . I think I'd like to get into this mechanical game. My next bike I think I'll get something a bit older again... something that I can wrap my head around.

I'm seriously considering that XL250 though. If I can get it for under $200 I'll be pleased. Could somebody please look at these photos: http://images.trademe.co.nz/photoserver/54/28858554_full.jpg and http://images.trademe.co.nz/photoserver/11/28858711_full.jpg and tell me if you think that's a CB250RS motor? It looks damn near identical, except it's missing the rev counter gear and decompressor lever. I wonder...

[Motu]

Not knowing gets us though where others would give up....ignorance is bliss....

[xwhatsit]

Did I do something stupid? I mean... I guess it's not smart to run around on a cracked cylinder head. But would you have given up at some point when disassembling the engine?

I don't mean that to come out rude, I sound mad. But I'm interested... what did you mean by that?

[Ixion]

Well, you might be unwise to embark on a tour of the South Island on it. Cracked head and all. But the proof of the pudding etc, it's together, and running. And as you say apart from the risk of being stranded , a cracked head prolly wont break anything else.

I'm just astonished it actualy ran in that condition says a good deal for Mr Honda's engineering.

Not many bikes would take that sort of treatment.

[xwhatsit]

Ah yeah... I knew that having an oldish bike might put me in some level of risk right from the beginning so I've got an AA membership if I really get into the shit.

You guys are starting to scare me lol. I knew that fixing it up like that wouldn't be permanent but I wasn't that worried that I was doing something very naughty lol! That said... it must have been running cracked for a while. These things just don't happen overnight. I wonder if that's why the guy sold it to me... he'd only had it 4 months or summat... and the head has obviously been apart before with all the non-standard bolts in the thing.

*Sigh*.

[Ixion]

Don't fret. I've done worse. So has Mr Motu. I'm just impressed that a modern engine can handle it. Usually these days anything at all not exactly right and they won't run.(It certainly wouldn't if it were water cooled. Go the air cooled engine)

It's back together. And running. That's pretty creditable.You did well . And at worst it dies on you and you have to call the AA for a lift. Anything you get in the meantime while looking for a replacement head is abonus

In theory cracked heads can be reapired by welding or metalstitching . But its not always terribly successful and likely to cost as must as a replacement or more.

[xwhatsit]

Haha. Not really a modern engine... unless 1978 is modern.

Yeah I don't really want to try and repair the head. Especially as many of the bolt (sockets? Whatever you call where the bolts wind in) are threaded. It's obviously seen some abuse. My borrowed torque wrench and half-guessed torque settings were wasted on it haha.

This is such fun. Going to ask the bank for approval on a loan (what I really mean by that is ask mum if I can borrow $200 off her ^_^) and get that XL250. If that's not my motor in it (according to photos) I'll eat my helmet.

Thanks for all help! Maybe you'll see another thread in a week... `where did this bolt come from? I can't find where it's supposed to go...'

^_~

[Racey Rider]

Wow, Good effort!

Surprised to hear the valve seat was still usable. Go the backyard Mechanics! The best way to learn to be sure.
Well done for getting it all back together. And Running!

You say some threads are stuffed. Won't they be in the barrel not the head? (ie. the bolts go down through the head and screw into the barrel.)

[nadroj]

I spent friday night with a wrecker chasing a Kawasaki KC100 right hand switch block to no avail but he did take me to 3 sheds in the country where he had heaps of spares ( and I mean heaps). I don't have his phone number but I travel past weekly so can call in & see him if you want me to. Just send me your details and the bike model & parts required & I'll see him next week if you haven't already found what you need. He seems to have heaps of 80's parts, mainly Japa's, including some GSX1100 & Z900 parts but the majority are smaller motors. He also has several race bikes and 2 sidecars (one with a TM400 2 stroke single motor, the other with GSXR1100)

[xwhatsit]

Nadroj: Thanks! I've sent you a PM and will be in touch if the trademe XL250 doesn't pull through.

Racey Rider: Yeah valve seat was undamaged, it just became... unseated :P. The threads that are stuffed are the ones that the valve cover screws into. I think. I may have forgotten. If I pick up that XL250 then I've got a cylinder barrel too. When I swap the head out I'll take a look inside the barrel too, check out the pistons and rings etc.

It does run, but it may just be the carb needs tuning in again (due to different airleaks in the engine now or something?) because it idles even worse than before. If I get the XL250 and the carb on it is suitable (I don't think it's standard from the photos I saw) I might take a look at that, because my carb is a bit rooted (the throttle-triggered automatic fuel pump thingie). If not I think I know how to fix it.

I really should be studying for exams, but this is far more interesting lol.

[Motu]

But I'm interested... what did you mean by that?

The exhaust valve seat performs a pretty important function.It is supposed to be an interferance fit,it came out because it was loose,and had been loose for some time.So rattling around in the head it no longer makes good contact with the surounding metal....peening it in tight doesn't mean the seat is actualy contacting the head.Plus the seat face and valve seat will of been damaged,the valve possible very slightly bent.Now there is a very poor heat path from valve to seat to head - if the seat doesn't fall out again soon,it will burn before long.Even mechanics don't fit valve seats,these are done at an engine reconditioning shop....although I have replaced valve seats in Briggs and Stratton engines....

[thehollowmen]

Holy (bleep)

I'm amazed that it still ran, although not too surprised.

good luck getting her fixed up.

[JMemonic]

Its been said but good job on the effort to fault find and figgure out what is needed to repair the bike.

Personally in your situation I would look at a second hand head as opposed to welding the old on up, get it cleaned up and check it for cracks and faults before you attempt to assemble it on to the bike, lapping in the valves would be a good idea as well that way you can see if there are any defects in the seats.

[Mr. Peanut]

What's a valve? :)

[Macktheknife]

Good effort XD, well done. good luck with the XL motor too.

[Mole_C]

Nice work, maybe i shld try take mine apart sometime :yes: Na, ill probably break it all :P

With the idle thing you don't have a little knob to turn the idle level up and down do you? Mines on right hand side near where you put the oil in. It could be as simple as turning that up a click :shit:

[xwhatsit]

Yeah I've tried a variety of adjustments to the idle level since I've had it (first of all because I'd never used a manual gearbox before and kept stalling it when I went to take off ^_^). But no... I can get it to reliably idle at 2500+, or 3000+ to be safe, but anythign less than that, it will stall within 30 seconds. I'm not sure if it's missing or anything. Suspect it probably has to do with the sparkplug once again, it's not sparking well enough so it misses, and when it misses at low rpm multiple times it doesn't have enough momentum to keep going. Will worry about that later, once I fit the new head (if I can find one!), and set up the carb properly.

[Posh Tourer :P]

with a weak spark, it is quite likely it won`t idle.... I would check the coil (the HT lead comes from it) and see if it is damaged at all. Also see if you can get another one to try in its place. Check the HT lead for physical damage too. You might just take the HT lead off the coil and make sure there is plenty of copper showing on the contact area. Also try checking the battery and replacing that. If you have a multimeter, check the voltage output. That shouldnt have an effect, but it might if it is really bad. Points can also cause problems. Under the right hand side engine cover (IIRC).. These are cheap to replace and wear out commonly. Check that they are clean and making contact face to face fully and that they arent offset.

That should keep you going for a while. If it isnt one of those problems I'm a bit stumped.... Does it foul plugs more when you ride with the headlight on??

P.S. I've sent an email, I'll let you know...

[xwhatsit]

With a fresh plug I get a nice big blue spark when I kick over the bike with the plug out; with a plug I've ridden more than 100kms on there is non-existent/very weak spark.

I'm not too worried about this bit yet. The cylinder head crack is right next to the spark plug socket so maybe something is going on there.

Cheers for the email, Mr Tourer! I've just got replies from two of the wreckers I contacted earlier and they have nowt.

[lb99]

Did you buy it?
I had a CB250RS about 15 years ago, cracked head and all.
use the rev counter drive out of the Cb250 in the XL Head, Im pretty sure the valve timing is just line the crank up to TDC, put the cam in LOBES DOWN and put the chain on the sprocket so that the marks line up with the head, then slip the sprocket on to the cam, and do all the bolts up, dont use the rocer cover studs to compress the valve springs or you will strip some threads(trust me, I know:doh:)also make sure the oil feed to the head is unblocked . I cant remember if the XL had a different cam profile, but the XR did Im sure it was wilder, the XL,XR,and CB all have the same bore, but have different compression ratios, and gear ratios too.
My CB went fine with an XL250s bore, piston, head and cam, they are pretty simple and rugged motors, I used to seize mine quite regularly, always just waited until it cooled down and it always fired up easy as, as you can guess, I had a top end rebuild down to a fine art.

[xwhatsit]

@lb99:

Great story, man! From your avatar it looks like you have the same taste in bikes I do ^_^. Yeah I used the same basic technique to put the engine back together (knowingly with the cracked head; I've done about 50-60kms at least after putting it back together, it doesn't seem to be getting worse thank god). I used a spanner to hold down the valves (god that spring is stiff) and borrowed somebody to take the little collets (sp?) out.

I didn't know the XR250 had the same/similar motor as well? Hmm. Yeah I noticed the XL250S on Honda's Japanese website is rated at 20PS, while the CB250RS is rated at 26PS or thereabouts. I don't need to replace the cam yet but I'll keep that information in mind. I did hear that later CB250RS models had more power -- 33PS -- could this be due to cam profile? Might be interesting to investigate that.

Hahaha why do you think you seized it regularly? I hope I don't end up doing that :lol: . Will have to keep an eye on the oil changes.

No I didn't end up buying the XL250S (if that's what you meant). I was counting on ~$200, but it ended up selling for ~$400. I've just been quoted $175 from Econohonda (yay! Somebody has one!) but won't purchase it yet until I hear from some other people. $175 is a fair bit of money from a student hahah so I want to make sure I can't get it for cheaper first.

Motu earlier mentioned that I may have bent a valve too. It looked fine to me when I pulled it out but then again I don't know much about mechanical things yet. How is an easy way to tell? Is it something I can see with the naked eye, or will even a minute bend in it cause problems? At least valves look significantly easier to obtain than heads.

Thanks, everybody.

[gijoe1313]

Yowsa! Sounds like you are getting down and dirty with the innards of your ride! On ya! Nuffink like doing the business for yourself and kudos to those who know what they are doing and giving ya some hard won advice!

Hope you spend some time riding it! The only thing better than being a Tree-shade mechanic is getting out in the sun and riding :scooter:

Keep up the good work and Make Peaceful Running of Soundful Motor So All Your Ride Will Belong To Us!

[xwhatsit]

For Great Justice, Launch All Camshafts!

[T.W.R]

:gob: sounds as if you inherited that problem from the previous owner and it's lunched itself on you:angry: commendable effort getting it running again, wouldn't use the bike though until it's fixed.

safe enough to trackdown a replacement head from any of the XL/XR 250s (XL250S through to XR250RB)from 78-83ish most of the variations were with cam profiles in the head itself, other changes came from carb size differences, & lighter cranks in post 80 models etc.
The 84 XL/XR RFVC heads were notorious for cracking, not the earlier ones.
you don't have points either, it's all controlled by a ATU rotor & CDI

[lb99]

I seized mine coz I brought it (at 17) sight unseen, of my girlfriends brothers mate, and never even thought to check the oil, and rode it home over Kilmog Hill just out of Dunedin, I was flat out going down this long straight downhill when I noticed it was loosing power, next thing......lockup at 140+, sure enough, no oil:doh:, on that bike I learned a lot of things, the top engine mounts kept brakeing because the frame was sooo bent that if you drove though a puddle you would leve two wheeltracks behind, no problem, get engineer to make engine mounts out of 4mm plate, then go back to engineer to get him to helicoil all of the rocker cover studs that stripped when the motor kept trying to tear its self loose from the frame, tried this several times before I gave up and put up with the motor moving about a bit on its mounts.

I learnt that you cannot do without a gudgeon clip, it only takes 30 km on the highway to make a nasty score on the cylinder bore( enter another bore and piston), I learnt heaps of things on that bike, eventually the big end went and I sold it to some schoolboy who was keen as, and brought an NSR250:Punk:

[xwhatsit]

Bah well I think I've killed it this time. Well, not killed it. But injured it rather badly at least.

Recently it had been getting louder and louder, so I looked where the exhaust attaches to the head and noticed that the big plate of metal holding the exhaust to the cylinder head on the right exhaust was hanging off at the bottom. Upon closer examination I saw that the bolt had actually come right out of the head -- kind of worrying seeing as the bolt is supposed to stay in the cylinder head and you wind a nut onto it to hold the exhaust in. Pulling it out I noticed a whole lot of metal shavings inbetween the threads on the bolt, so it has been stripped, maybe a helicoil put in (I don't know what it looks like, I'm only guessing). So I wound it back in as good as I could with some pliers, bolted it all back together, started it up, and although it's still not 100% sealed (if I put my hand in front of the head I can feel air flow pulsing in time with the engine firing), it's a hell of a lot quieter.

Anyway, coming home across Mangere Bridge about 20 minutes ago, passing some cars, revving it out to 6000-6500rpm to pass some cars. Felt good, really powerful, awesome, and a lot quieter of course haha. Turning off onto my onramp, there's a long straight bit before the lights and I just let go of the throttle and let the thing engine brake in 5th gear from 6000rpm to 3000rpm before shifting down. Somewhere at about 4500-5000rpm the thing started making this godawful clatter that sounds quite familiar. However, I'm not 100% sure but it doesn't seem quite as bad as before, and power loss seems a lot less. I wondered if the exhaust had come out again but a quick visual scan seems to say nothing there, and it doesn't have the loud Harley/tractor type pot-pot-pot noise it did when the exhaust was semi-open before, just a horrible clatter like when the valve got fscked before.

So yeah... I knew it would happen eventually (you can't ride on a cracked cylinder head for ever lol), but I was hoping I would make it until after exams. Pain in the arse. I'm impressed it held up that long though lol... I think I've become a life-long Honda fan (yeah I know they're not the most manly bikes, but I think it's pretty cool that I can abuse it like that (lb99 seems to know how to do it too hahah) and it took maybe 800kms before it died).

Good thing I love riding it so much, or I might not be so forgiving of the old gal...

[lb99]

get yourself another cylinder head, an XL250 one will do, but it will probably be silver, if its chucking valve seats away then its definatly rooted, the crack in my head was between the plug and a valve and just made it a bit smoky, oh, and do the exhaust studs up before you do up the rear exhaust mount, then you dont have to use them to bend the pipe, abuse away, the top end is a piece of piss, but the bottom end is as tricky as fuck (balancers and chains and stuff:angry: )

[xwhatsit]

Yeah the crack I've got is there too, between the plug and a valve. Do they do this as a matter of course? Is it a XL/XR/CB250RS `thing'? Bloody bloody bloody...

Yeah I've been trying to find a head anyway, I can get one from Econohonda but that's $200 which isn't easy when you're a student. There's another man who may be able to help me for (hopefully) less dollars but I will have to wait a while before he will have time to have a look.

[lb99]

but its the same head, so its probably common, I know a Honda nutter down here who might have one, whats the cam like? are the bearings still ok?

[xwhatsit]

No cam bearings :lol:... the thing just runs directly on the head. Even somebody like me who doesn't know much about engines was surprised to see that... the Haynes manual says some people do/did conversions to roller bearings. But no, there are no bearings for the camshaft, if that's what you mean. The top end looks in pretty good shape... possibly there's a bent valve (or two now, if it's the other exhaust valve this time), but I certainly couldn't notice it when I pulled to pieces.

[moko]

No cam bearings :lol:... the thing just runs directly on the head. Even somebody like me who doesn't know much about engines was surprised to see that.

Something Honda were notorious for.250RS was a best-selling bike in Britain and far too many got taken out when they trashed the heads because of the lack of bearings,hardly any left in fact.Lots of Chinese trail-bikes sold over here now,they`re mainly XL125 and 200 copies BUT the Chinese have modded them with camshaft bearings.SO,not only are they copying Honda but also improving them,think that says it all for the future.

[lb99]

3 of them I think, thats the bit the cam spins on in the head, but the are made out of the same stuff the head is (chocolate!), they dont have replaceable shells like they should. so when you run a bit short of oil, the first thing to go are the crappy bearings in the head, Have a look at those bits on the head and the inside of the rocker cover, as well as at the corresponding bits on the cam, do they look hammered? like excessive scoring?. I talked to the guy I know, and he will have a look, it would probably take a few days, though, but it will most likely be cheaper too, this guy has these motors coming out of his ears, its just a matter of finding a good head (maybe even a black one), when you do put it back togeater, make sure the oilways are clear, it think it might get pumped up beside one of the head studs, anyway its easily blocked, so be careful.

[xwhatsit]

Oh I think I know what you mean now, just the surfaces that the camshaft sits on? Like, not actual moving bearings like ball bearings or taper bearings, but just the surfaces the shaft touches? I will have a look when I take it apart (hopefully tomorrow after my last exam). I'm pretty sure last time when I took it to bits it was in good shape, the camshaft looked fine... but I wasn't paying too much attention it must be said. Before putting it back together I just put a wee bit of oil on the bearing surfaces before replacing the camshaft, I thought it was probably prudent as when I started it up the first time oil was probably not everywhere it should be. Anyway I'm off to work... thanks for your help lb99! You're a champ ^_^.

[gijoe1313]

Sorry to hear about all the wonderful ways of learning your way around a bike Xerxes! Seems you are having a ton of fun getting oil under your nails and playing with the tools - hope you get your bike back into running order soon so we can go out for a nice little tootle after your exams!

If you need a hand or anything, just sing out! :rockon:

[xwhatsit]

Cheers gijoe, yeah I am enjoying myself despite the huge inconvenience of having to catch the bus. Gah I hate it. And it costs me $10 a pop too.

But no I pulled it down after my last exam this morning, it's the same problem... at TDC the exhaust valves don't line up. Interestingly it's the same valve again, so it seems that peening the head around it wasn't quite as effective as thought. I've half a mind to put it together back again, do the same thing again (but somewhat more securely) and keep riding until I can procure a head from god knows where.

This time around I made a more careful note of what I pulled off, and was able to do it with far less disturbance to the rest of the bike (i.e. didn't pull out half the electrics), and also kept a careful note of the general condition of things. As I mentioned earlier, half the bolts are non-standard - but what was really bizarre was a couple of the bolts going through the head cover into the head were not metric, but only fit my imperial sockets! Wtf! They were 7/16ths or whatever the imperial one is starting with 7. I think at some point in it's life somebody has abused the bejesus out of the bike, especially the head. The piston/bore etc looks pretty good, it's just the head... I wonder if the head is not original either?

lb99 I checked out those bearings, and camshaft -- it looks pretty good. There are a couple of scratches on the head cover bearings, but they don't seem too bad, are small and there's maybe only 3 or 4 small scratches. Camshaft looks sweet, although I half wish it were broken so I could upgrade it to the CB250RS-D model 33HP camshaft and accompanying head ^_^. Of course then the head wouldn't be black and might look a little strange on an otherwise black engine, but I can live with that for an extra 7HP lol.

I've also decided that I want to get hold of some new exhaust collets, as the left hand side pair are pretty much more rust than metal; the right one is OK but could probably stand a replacement.

Hanging out to get this engine fixed up... I can't wait to get back on the bloody thing, and catching the bus is a bit of a nightmare, both financially and time-wise -- last night I left for work at about 4.30, started work at 6.15 (I only got there at 6.00), finished work at 8.30 (no customers, Guy Fawkes), got home at 10.40. So I spent $10 on a bus for earning perhaps $20 after tax, so I made perhaps a little more than $10 for being out from 4.30 to 10.40 - 6 hours. Please come back to life, Miss Honda! :cry:.

[xwhatsit]

Woooo so I bought the Econohonda head, spending $10 a day in bus fares suddenly made the $200 price for a new head look less silly. Anyway, I don't know how long it will take to get here, the guy does overnight shipping but the money might take up to two days to clear according to my bank, and of course he's actually got to get the head from whatever it's attached to as well. I should think it would be hear by Friday though.

Anyway, feeling in a motorcycling mood, I decided that despite having a new head very shortly I wanted to ride the bloody bike so I put it back together after re-seating the valve ring and munging some aluminium over it again. Looks horrible, but the engine started perfectly and seemed to run OK. Went for a quick circuit around the block and came back and called it a night. Man you get a sore arse riding without a seat :lol:! Not recommended.

So that's two top-end rebuilds, and soon to be a third... with fingernails like mine I think I should give up this maitre d' lark and become a miner ^_^.

[xwhatsit]

OK, yet another post in this epic tale of a less-than-mechanically apt beginner biker.

Bike, unsurprisingly, threw a valve seat again on the way home from work haha. Ah well I'm learning. Got an email from Mr Econohonda (Malcolm?) who told me... `the head I was thinking of is suspect, will get you another one instead, sorry will be an extra day'. I'm happy with that. Some bastards would just throw the munged head at me. I got another email today saying `couldn't find another bare head, so I'm sending you a good-condition head with valves in it, for the same price'. Woot! Save me from busting my arms pulling valves out and back in four times! Supposed to reach here tomorrow sometime.

Here's where I need advice, though. The existing head is pretty shagged, with threaded bolts everywhere. The valve cover, however, is in reasonable condition; or at least it was until yesterday I managed to completely root the thread which holds the rev counter drive into the head. This thread is not in the head, it's on the valve cover. Arse. This is, of course, not a critical thread; not holding anything important together. However, it does cause a pretty bad oil leak as the thread is so stuffed it doesn't hold the tachometer drive to the engine tight enough to prevent oil leakage. I epoxied the gap up, after reading a couple of posts which vaguely suggested something like that, but I would like to do a proper job.

My question is: helicoil? Is this something I can do myself? How much are they? The valve cover is made of (as lb99 put it) chocolate, (or aluminium), will the helicoil stay in there properly?

Any other solutions? Thanks guys.

[lb99]

OK, yet another post in this epic tale of a less-than-mechanically apt beginner biker.

........
My question is: helicoil? Is this something I can do myself? How much are they? The valve cover is made of (as lb99 put it) chocolate, (or aluminium), will the helicoil stay in there properly?

Any other solutions? Thanks guys.


just take the cover to a reputable shop to get a helicoil fitted, it shouldn't be too dear, you can buy a kit, but its not worth it just for one coil, I remember getting a whole lot done in one head for about 6 bucks each a while ago in dunedin.
a good epoxy will probably do it, as the drive is kind of clamped in place between the rocker cover and the head, I'd give it a go because that shows how tight I am:innocent:

good score on the head, Malcolm is a top bloke, its good to see new bikers getting looked after.

Good luck

lb99

[MSTRS]

Can you plug it with KneadIt, then drill and tap a new thread in????

[xwhatsit]

Oh, I thought just one coil came in a helicoil type thing? So it's not, say, a sub-$20 thing I can buy from Repco and do with an electric drill? Ah well I'll give an engineering shop a go; any recommendations from anybody? Bear in mind that I'm pretty broke hahaha. This bike better give me some love after throwing 75% of my income at it! Lol.

Yeah, epoxy might be a temporary solution... as you say, it's pretty solidly held in place between the head and cover anyway, so I'm not worried about it coming loose. It's just the oil leak.

Yes, this Malcolm guy does seem to be a pretty good guy. I've mostly talked to him on email but I called him up when I actually purchased the head; he obviously knew I am not the most clued-up biker in the world and asked me a whole lot of questions to ascertain I was after a CB250RS head and not a CBX250 head. Much better than the people I've encountered in certain (unnamed) shops who have been too lazy or patronising to help a newbie biker find a spark plug for his bike.

[gijoe1313]

Crikey - your missus might throw a wobbly if you've thrown 75% of your non-disposable income at another girl! (even if it's a pyscho hose beast!) Sounds like you're getting valuable biker experience in fixing your ride up. Anything else after what you've gone through will be a doddle! :niceone:

[xwhatsit]

Psycho hose beast? Is that a `lifestyle assisting product'? :lol: Maybe Dover's missus would be pleased if he spent lots of money on one of those?

Well 75% of income is piss-all when you're a low-paid maitre d' and studying. For the record though, girlfriend is not well-pleased by the bike, after binning, and especially after my hands smelling like oil and looking dirty even after scrubbing them for half an hour haha.

Oh well, I now have valuable relationship experience, in keeping happy a) one cute but full of worry HK girl, and b) one cute but full of expense Japanese girl ^_^. I'm glad neither read this forum.

[MSTRS]

.... my hands smelling like oil and looking dirty even after scrubbing them for half an hour haha.


Use a dollop of dishwashing liquid and a teaspoon of sugar, wet and rub into a paste all over your greasy hands. Rinse off. Barring under your nails, your hands will be clean & smell nice.

[xwhatsit]

Sugar, eh... tried dishwashing liquid, left hands smelling Lemony Fresh(tm), but still had oily-bits on the palms of my hands. Will try! Thanks for tip!

[gijoe1313]

Oh well, I now have valuable relationship experience, in keeping happy a) one cute but full of worry HK girl, and b) one cute but full of expense Japanese girl ^_^. I'm glad neither read this forum.

OMFG :shit: :gob: You are cruising for a bruising! Ah well hold onto the ride and enjoy the endorphins, when it all goes pear shaped on you, you can ride your bike like a bat outta hell (once you got the valves, connections, head, gaskets, rings etc. al back together!)

:doh: The pleasure and pain that only asian gurlies can bring ... you are a brave lad!

Basic formula : Asian Female = Psycho hose beast squared by the lack of common sense that has left the building multiplied by lack of adequate funding, style, food places taken to, presents, pious observations of obscure asian holy days and then rounded off to the nearest horrible dog box they can send you to!

[imdying]

Somewhere in the depths of my memory I seem to remember someone saying CB250s did this if you put the oil filter in backwards at some stage. No idea if that's possible of not, someone here may be able to confirm or refute it. Not saying yours is, just that it may have been in the past.

[xwhatsit]

Hmm well the CB250RS doesn't have an oil filter as such; maybe you are thinking of the CB250, rather than CB250RS?

[Posh Tourer :P]

Ahhh.... errr.... yes it does....

[lb99]

it has at least one strainer, I think you take off the clutch cover to get at it from memory, I think the CBX250rs has a strainer and a filter though

[xwhatsit]

Yes lol I know it's got an oil strainer, but I think it would really only filter out pebbles or small rodents. Sorry, mixing up semantics.

[Posh Tourer :P]

Probably true enough....

[Pixie]

Your starting and idling problems are most likely related to the cracked head.The motor will have lost compression and that will affect both.No point in trying to diagnose these faults until the head is sorted.
If you are using the old valves,it would be wise to check they aren't bent.
They should be lapped in when they are fitted to a diferent head.
If you choose to use epoxy to try and repair any threads etc.Use a hi tech product filled with metal or ceramic.Araldite is a waste of time.
A & E Bearings stock a range. ph 09 838 8268

ps most bikes these day run their camshafts in plain integral bearings.eg in the head material

[xwhatsit]

Well, I've installed the new head. With all the stripped threads before, I can see now that they weren't actually stripped threads; they were helicoild that had come out! The new head too is full of them. Do aluminium threads just not have enough strength to retain helicoils? They seem weaker than the original threads. The thread in question that I stripped with the tachometer drive, was too a helicoil, so is it possible to put another helicoil in there now or is it stuffed for good?

Anyway the new head works a treat. The valves all seem in much better nick than the old ones. After putting it together, however, and putting in the sparkplug and going to kick it over, I just about crapped myself I was so scared! As I kicked down, the kickstart lever just stopped dead! It felt like the piston had gone up the cylinder and hit something solid, like the spark plug, so I quickly whipped out the plug with shaking hands and checked to see the end of the sparkplug was not squashed in, but it was fine. I then thought about it and only half screwed in the plug (with lead off of course) and gently kicked it over, and I could hear gases hissing by the plug. So it was just compression! I checked the decompressor cable and made some adjustments, which made it slightly easier to kick over but it's not anywhere near as easy as before. I now really have to stamp on the kickstarter hard if I'm to get the engine to turn over. I'm slightly worried about the bastard kicking back hahaha. At any rate, mostly the engine starts second kick now, although after riding to the house of family to pick up some mail I left the bike outside and it started raining, it was super super hard to start then.

At any rate having full compression is a whole new experience. Man can this thing haul arse now! Now when I'm in fifth gear and doing 60kph and snap open the throttle the bike actually does something! I'd heard Brits on the net say the bike is capable of 90mph (~150kph), and didn't believe them in the slightest, but now I can believe it. The exhaust note is still not what it should be due to a very corroded set of split collets on one exhaust (but not the other... from being on the side stand? It's the lower side), so I'll have to pick some of those up sooner or later. However the engine note is quite different, has quite a different timbre; I can defnitely hear more induction noise when I fiddle with the throttle. I wonder if that's because it's not sucking air through the cracked head now.

Contrary to Pixie's advice (I didn't see it yesterday lol) I used araldite to seal the gap for the tachometer drive. It seems relatively effective but it's only a short-term fix. I can imagine with sustained high temperature it'll probably not last too well. The bit where the head and the valve cover mate leaks a small amount of oil. I can see on the new head when it arrived, there was a small amount of orange sticky stuff left on the top surface. Is this some kind of sealant? Should I look at getting some?

Cheers everybody for all your help. I'm touching wood as I type this that I won't need much more!

[xwhatsit]

Ahem. So, after that rather enthusiastic previous post, I'm feeling rather shit now. If I had beer I would cry in it.

Was over North Shore to surprise girlfriend at work, bike hauled arse over Harbour Bridge (my first time over). After that I headed down Lake Rd in the wrong direction, worked out what I was doing and turned around. Went 200 metres down the road and the engine made a godawful grinding sound, rear wheel braked heavily (may have locked, I'm not sure), so I grabbed the clutch. Engine seems pretty seized. After waiting 2hrs for tow truck, finally got home (missed work, boss will be pissed).

Had plenty of oil. Maybe a blocked oil route? Could I have done this? Cam chain come loose and piston met valves?

This was 30km after changing the head. I would love to -- get this -- ride a bike.

Argh.

[xwhatsit]

OK, about 20 seconds after I made that post I've gone and fiddled around with the engine at around half past 10 at night. Took spark plug off, engine remained impossible to turn over even with it out. Took off the inspection plug on the (clutch? alternator?) so I could turn it over with a socket wrench. Would not budge; but turning it backwards it went around very easily (very very easily!) until it stopped hard again. Poked a screwdriver in through the spark plug hole and the piston is definitely free and going up and down. Seems to be rather `rattly' but could just be the gearbox in neutral (it seems to make a little ratchety noise when I'm coasting in neutral normally). I've decided on the camchain-is-screwed-piston-meets-valve theory. Which is... not too horrific, as I have four more valves from the old head, and I'll need a new camchain (how much for one, do you think?). Maybe a new camchain tensioner? Well those are my theories for now.

Almost a shame the piston wasn't stuck in the bore, then I could bore it out and have a CB275RS :lol: (and I've seen a guy selling a wide range of oversized CB250RS/XL250S pistons on ebay). Offtopic, but how much does a bore-out increase capacity? Enough to make my bike illegal for a Learner to ride? Not making plans, just curious.

Well I'm certainly learning quickly. Despite the rapidly alternating periods of happiness and depression, I like to fool around with this engine. It's in my blood, Dad was a rather good mechanic. If I can't finish my uni degree in compsci, I'd love to learn to be a mechanic. Don't know how good I would be at it though, my first attempts have been pretty hopeless hahah.

Oh I'd love a couple of shots of vodka right now...

[AllanB]

Crack up thread!

Good luck with that engine - sounds like it has seized now. Did you set the valves after putting the new head on?

If you ever need work head to India - you'll be a master mechanic there! :yes:

Keep us posted.

[xwhatsit]

Hahaha cheers AllanB, that made me laugh... some Indian guys at work, when I first pulled up on the bike, leaking oil and making oil smoke come off it when it idled, they thought it was the best bike ever! Looked at it, marvelled at its technological advances; didn't have the heart to tell them it's from 1980 or so haha.

No I didn't set the valves. Do you mean the valve clearances? Can they really get that far out of whack, to cause a seizure? I don't have a feeler gauge set. I checked the cam sprocket and chain timing very very carefully. I was worried the first time I went to kick it over and it had massive compression, I thought maybe I had the cam in such a way it was on the wrong stroke (the timing marks on the alternator would still show TDC whether on compression stroke or not, right?). But it ran fine until it blew up, so I must've got that right.

It's all coming apart tomorrow. I'm kind of afraid of the carnage that awaits me haha.

[lb99]

This sounds exactly like my CB250RS, head off, head on,head off, head on head off....you get the picture, your cam chain might have slipped, were you hammering it at the time? was it properly adjusted? , it sounds like the problem is definatley to do with the top end, hopefully your new head is ok, as well as your piston. dont worry about the capacity on a rebore, I've never seen a cop strip a motor to measure the capacity, in fact that frame would be a good candidate for an XR500 motor, the bottom end is the same but the barrel and head are bigger I think:scooter:

just strip it slow and careful like, look at each component for signs of torture, esp. the cam bearings ( to see if it siezed the cam), I don't know how you'd go with a guarantee on the head if it dropped a valve, but as you say you have some spares, fingers crossed.

[xwhatsit]

Hahaha yeah I remembered you saying about your bike when I was waiting for the tow truck. I haven't got a top end rebuild `down to a fine art' yet, but I'm getting faster lol.

No I wasn't worried about cops hitting me up for a bored out motor (that would suck!), I was just wondering how much a bore out increases capacity. Are we talking 275cc here? Not actually wanting to do it, just curious. Yeah heheh heared about the XR500 swap, but that would change the engine number and make my life difficult with WOF, wouldn't it?

I wasn't exactly hammering it at the time, but I was accelerating away from 20kph, so the engine was loaded. If we're talking of the cam chain slipping and valves hitting the piston, is the piston, piston rings, bottom end likely to be OK? The one thing I wondered about was the piston rings, I've heard they're quite brittle and I envisioned the piston smacking into the side of the barrel when it hit the valves and breaking the rings.

Cam bearings, can this seize a camshaft outright? Or are you talking about now it's damaged, to check if the bearings are stuffed as well?

Indeed, fingers crossed.

[lb99]

well, if the cam chain slipped then the piston would smack into whatever valve was open at the time, bending the valve, sometimes ramming it (bent) back into the head, and/or smashing the piston, and continuing the shock of a sudden stop down though the piston and (maybe) bending the conrod too, this is a worst case senario though, the cam chain on my Z440 snapped while I was puttering along, and it just stopped dead, so I pulled the clutch in and coasted to a stop.
after taking the head off all it had done was to bend a valve and mark the top of the piston, so I replaced the valve and I was away again. If the piston is ok, then the rings probably will be too
So its not all doom and gloom, its called exprience, and it happens to most of us, just crack her open and have a look, it probably is able to be fixed.:rockon:

[lb99]

pics of dropped valve carnage:yes:

these were ones that actually came adrift during opreation, so the valve head was bouncing around on top of the piston (not much space)

[xwhatsit]

Hahahahahah. OMG I hope it doesn't look like that ^_^.

No, you're right, it is experience. If money was out of the question, and the inconvenience of being stranded on the North Shore when I live in South Auckland discounted, I would actually prefer it this way, having an old broken bike. If I had some CBR250RR I probably not only would've hurt myself on it pretty badly by now, but I wouldn't've had the chance to learn all this stuff about what really makes an engine work.

The only problem of course is tow trucks, buses, and the cost of parts for a 1980s bike on a student's income.

[xwhatsit]

:gob:

OK found out the problem. Didn't take long. Check out the pics.

Some theories on why this has happened:

Didn't tighten cam sprocket bolts tight enough
Camchain was so loose it came off to the left of the cam sprocket, pushing the sprocket out until the bolts hit the head and got pulled out
I don't know how likely this one is, but the camshaft got stuck somehow, but the sprocket kept wanting to go around and pulled out the bolts

[gijoe1313]

Dizzam! That looks seriously wicked cool and sick at the same time! You'll end up being a master bike mechanic in no time at the rate you are going! Glad to hear that you managed to get your bike back and yourself safely home - jinkies, this is like the odyssey of Ulysses, new twists and challenges around the corner!

Big ups to having the bloody minded perserverance to mastering your ride!

[xwhatsit]

Hmm. After thinking about it, I'm wondering whether I should just get an entire new engine. If the motor had seized because valves had hit the cylinder, they just would've gone straight through the piston, right? And looking at the position of the lobes on the camshaft, I don't think that's happened.

What I think really has happened is that the camchain has become jammed, and the crankshaft hasn't been able to turn because of that. So, I've probably stripped the crankshaft timing sprocket as well. Also, there'll be metal shavings and all kinds of shit in the bottom of the sump. So that will have to come apart too; when that happens, I'm definitely expecting to find all sorts of other problems as well. All the evidence points to this being a stuffed engine before I even bought it.

Maybe I should just get a new engine?

[Ixion]

Mechanical jam, I suspect cos you didn't torque the camshaft sprocket retaining bolts correctly. Too loose, or too tight and the threads stripped. On some bikes these are a replace each time deal.

Unlikely to have damaged the engine sprocket, probably just came off, takes a lot to damage those morse sprockets.

Can't see if the camshaft or sprocket is actually significantly damaged, or whether it's just a reassemble properly, with Loctite (always Loctite those bolts, though some disagree)

Shouldn't be much metal in the lower half, probably just drain oil, refill (one of the few times flushing oil is a good idea), discard and refill.

Of course the cam shaft will have stopped when the chain jumped (how worn is the cam chain, anyway?), so it is possible that a valve and piston made intimate connection (ie fucked each other) , but sounds like you might have been lucky.

'Course, if you can source a GOOD repalcement engine, go for it.

EDIT Hm, looks in one picture as if the camshaft sprocket mounting lug is actually smashed. Which emans a repalcement camshaft.
Anyway, loosen up the jam and see if the bottom half turns OK.

Sorry, I suspect this one is down to mechanic error (ie you f'd up.)

[xwhatsit]

Yeah... I think maybe I might see if I can get a hand putting it back together next time lol. Any intelligent KB mechanics willing to work for beer? I'm sorry I can't really pay for your time.

Well I managed to blunder through this far just by ignorant stubborness, but I think (like when I crashed the first time) I've worked out exactly what I'm capable of. Learning, though, yes. Would like to learn more about mechanical stuff.

Yep the camshaft is pretty owned. I don't know if you can tell in the picture, but it looks like one of the camshaft bolts has actually pulled the entire thread out of the camshaft, so it would be toast anyway. I think I would like to replace the camchain anyway, according to Mr Haynes it was getting slightly long in the tooth anyway, and it's probably been a bit hammered by all this.

I'm just a bit worried that if I pull the bottom end apart (to check lower camchain sprocket, if deemed necessary) I will find piston rings, bearings, clutch etc etc need doing as well. I would imagine I could spend close to the price of a new engine in replacement parts anyway, the way some of these parts seem to be priced.

Thanks for your input, Ixion, always appreciated.

[Ixion]

Pull the top end, figure out what's salvagable , what needs replacing and post the list. See if anyone here can help, must be quite a few bits for those bikes around.

You don't need to pull the barrel or crankcases to check the lower sprocket just pull the outer cover off. But with the head off you may be able to shine a very bright light down the cam tunnel and check the lower sprocket with a little mirror on a stick.


Experience is a stern teacher sometimes, but you'll remember the lessons.

Anyone got a box of CB250rs bits in the shed?

[scumdog]

I would REALLY check that none of the shafts involved are bent or out of round, there's been a shitload (technical jargon) of force put through them during this mayhem.:yes:

[xwhatsit]

What shafts do you mean? Crankshaft et al? I'm replacing the camshaft anyway so I don't have to worry about that one.

Hmm might have to take off the crankcases anyway.

[Ixion]

You'll know if the crankshaft is bent or out of true, because the primary gear pinion runs off the end of it. Any misalignment will be pretty obvious with binding of the drive as you turn the engine gently over.

[El Dopa]

Yeah... I think maybe I might see if I can get a hand putting it back together next time lol. Any intelligent KB mechanics willing to work for beer? I'm sorry I can't really pay for your time.

Well I managed to blunder through this far just by ignorant stubborness, but I think (like when I crashed the first time) I've worked out exactly what I'm capable of. Learning, though, yes. Would like to learn more about mechanical stuff.


Mate, you're doing fucking great. I've been in a similar position to you, and it sucks, but you do learn a shitload.

I semi gave up long before I was into the sort of stuff you're getting into (I bought a new bike, so I didn't have the motivation to work on the old one any more, especially after the ballache it had caused me).

Keep smiling, even if it is through gritted teeth.

[lb99]

:gob:

OK found out the problem. Didn't take long. Check out the pics.

Some theories on why this has happened:

Didn't tighten cam sprocket bolts tight enough
Camchain was so loose it came off to the left of the cam sprocket, pushing the sprocket out until the bolts hit the head and got pulled out
I don't know how likely this one is, but the camshaft got stuck somehow, but the sprocket kept wanting to go around and pulled out the bolts



:gob:

:niceone:

ahh, well you live and learn, we all have to do it. I do know a dude who has a heap of bits, its just pinning him down thats the problem, I can probably get an XR cam which I think has more lift and duration than the CB, I'll track him down on the weekend.
hopefully you can get away with just the cam and some valves, would you put an XR motor in if I could put you in touch with one?, its the same just silver with higher compression, possibly a different cam, and different gear ratios

[xwhatsit]

Thank-you lb99! I would put in an XR motor, the problem being is I'm not exactly the richest guy in the world right now; spent a good chunk of my money on that head, and now it looks like it may be trashed (will post up photos soon, the bearing surfaces are really badly scored, and the old camshaft was jammed in, I had to hammer it out, so I think it's stuffed). So... I would, definitely, I would love to start afresh without all the problems of the old motor, but there's a couple of things: a) how much would the motor cost, and b) it would have a new engine number; does this mean the $400 COF routine?

I don't need valves, hopefully, I haven't actually taken the head off yet as I didn't have time today, but I have four valves from the old head which are OK I think. Camshaft, definitely, and the cam sprocket looks stuffed to me (again, I'll post photos, but one of the bolt holes in it is actually stretched, it's not round any more). Cam chain would be prudent, as I think it was approaching the service limits anyway, and will definitely be stretched now after the carnage I put it through.

One particular question is that when I pulled out the camshaft, I heard a `tick, tock', and no, it wasn't a clock, but I believe it was one of the cam sprocket bolts falling down into the sump. Arse. Will this require me doing some major disassembly, to get it out? If I'm changing the cam chain I will probably need to pull a lot of stuff off anyway, so I suppose it's not the end of the world.

Thanks for everybody's help once again. If I was on my own I'd be stuffed! I suppose this can be one of my `motorcycle stories' I can tell the young bikers when I'm old and grizzled...

[Ixion]

Well, some slight positives (or at least amelioration of the negatives). Different engine doesn't need any paperwork - since it's more or less the same engine model. If the tick tock was a bolt you'll prolly need to pull off the drive side cover - it will have fallen down through the cam chain tunnel and now is somewhere down by the lower cam chain sprocket. Unless you're rather unlucky (and it dives down a passageway into the crankcase itself) you should be able to retrieve it . Try not to rock the motor or turn it on its side. And you'd need to pull the cover to change the cam chain. It's not a big job , usually just remove kick start, few bits and pieces and take out the screws. Try to get the gasket off intact so you can reuse it.

Pity about the bearing surfaces. But sometimes they can be cleaned up, especially if the damage is a short duration event like this rather than prolonged grinding wear.

Post some piccies of the head once you have it off.

[xwhatsit]

OK, cheers Ixion. The bike is on the centre stand, and isn't going anywhere, so hopefully it'll be easy enough to retrieve.

I thought they checked the engine number at WOF? I know when I did a VIN check on the internet before I bought the bike the engine number was listed there, so it seems to be officially recorded; will it not be a problem the two numbers don't match?

[Ixion]

No, they record the engine number, but people often swap engines. It's the frame number that "identifies" the bike. Never had anyone check engine number at a WoF.

[xwhatsit]

Oh brilliant. Perhaps if lb99 has an engine for me, for a price that won't have me dropping out of uni, that could be an option :D

[FROSTY]

ya silly bugger---why in gods name diddnt ya wheel the bike over the road to the caryard like i told ya to?--
i had my toolbox out back

yea that was me in the green shirt-came over to help ya out in belmont

[xwhatsit]

Hahahah! You know I had a sneaking suspicion you were a KBer, normal people usually aren't so friendly, and I saw you had a bike...

No well after I rang the AA I thought they'd be about 10-20 minutes or something, and I told them I'd meet them down on the corner. Didn't know I'd be waiting near 2 hours...

[lb99]

I'll do my best for ya, usually a good motor for anything will fetch a premium, your bottom end is most likely still ok ( fingers crossed) and maybe the head is too, its a pity I'm not in scabby old Auckland or we'd have the bike in my garage by now.; post a list and pics an we'll go from there

chin up dude.

[xwhatsit]

I'll do my best for ya, usually a good motor for anything will fetch a premium, your bottom end is most likely still ok ( fingers crossed) and maybe the head is too, its a pity I'm not in scabby old Auckland or we'd have the bike in my garage by now.; post a list and pics an we'll go from there

chin up dude.

Cheers mate! I think in fact you're rather glad you're not in `scabby old Auckland' if you ask me ;).

Good news first. Bottom end seems fine, rotates nice and smoothly, the only damage I can see is a couple of marks on the piston where the intake valves hit, but I think that all it did was cut through the thick carbon layer on it ^_^.

Alright, here's the photos. I've omitted a couple, notably of the valve cover, as although there is a gouge or two on it, it's not on the bearings and looks to be quite minor (it's in the cam chain tunnel, well if you can call it that in the valve cover).

The pictures:

Piston, with two little marks from intake valves. Is it OK? I think so, but what do the clueful people think?
Cam sprocket, camshaft. Camshaft is definitely toast lol. Bit of it still attached to cam sprocket
Sprocket seems OK, apart from the now elliptical bolt hole. Correct me if I'm wrong, but it's not seaworthy, is it
My $200, 35km-old cylinder head. Bearing surfaces look bad, but my biggest worry is the bearing where the tacho drive fits; see how one edge is bent? The camshaft doesn't want to fit in there anymore. Can this be repaired, or is it toast?
The head from the top. Is it going in the bin?
Heheh now those are bent :D. I'm glad it was the intake valves; I have a pair from the old head that haven't been subject to any abuse, at least while I've had them. Should be easy enough to change; will the oil seals need to be changed too? (BTW, please ignore the large single cat hair on the valves in this shot...)


Alright, there we are. So, all in all, it could be worse. I'll need a new camshaft, cam chain, sprocket (unless that elliptical hole is somehow deemed acceptable) at least. I'm very much hoping the head won't need replacement, but it's looking a bit the worse for wear. I noticed you said, Ixion, that you can sometimes remachine the bearing surfaces, but is mine too far gone? (Point of interest, in the Haynes manual it says that many owners would take their heads to have needle roller bearings installed in them). But the bottom end looks sweet, thank god for that!

[FROSTY]

Dude --The way it was locked up solid I'd like to see what the cam chain tensioners look like -I have a sneaking suspicion one has broken,not been fitted propperly--or backed off

[xwhatsit]

Dude --The way it was locked up solid I'd like to see what the cam chain tensioners look like -I have a sneaking suspicion one has broken,not been fitted propperly--or backed off

Here they are... they look fine to me, but then again I'm not the brightest tool in the shed. The spring-loaded tensioner has wear on it, but then again it's supposed to; Mr Haynes says nothing else on the matter but `using a cam chain tensioner until the metal shows through is bad practice'. Lol. The cam chain guide looks pretty mint too.

BTW: that's the best shot I can get of the chain tensioner, as I can't get the bastard out. I took the upper and lower tensioner bolts out, and it's free to move forward and back in the chain tunnel, but there seems to be some sort of pin or something holding it in at the bottom, and it just swivels on that but won't come out.

[lb99]

:shit: you are a machine dude.

but seriously, that bearing looks rooted, but I have seen them worse, if you clean up that outer bearing edge carefully with a file, you might be able to save a few bucks in the short term, its hard to tell from the photo, but if it was me (bush mechanics) I'd give it a go, shit like this never stopped Bert Munro, that cam is fucked, I'd say that one of your sprocket bolts came out and jammed on the inside of the head(big curved scar), but if the sprocket is still flat then I'd give that a go too, the bolts only stop the sprocket from falling off, its also held on by the shoulder that it sits on on the cam, but saying that a replacement cam would probably come with one anyway, valve stem seals are easy to replace, but you fuck em when you remove them, but if you can't get them cheaply from honda, take it to an engine reconditioner, because sometimes car ones can be the same.
is your head warped? sit it on a flat surface and see if it rocks, that may be why the cam won't fit, mind you it wouldnt surprise me if that cam is bent, cause it took a hell of a knock
Your best bet is for a new head, cam, chain and a gasket set, but that means dollars$$$$$

cheers

[xwhatsit]

OK, thanks. Would you say that the valve seals will need to be replaced? Do they bend?

Alright, I'll check out if the head will sit flat; will have to get those studs out somehow first. Hahah I might give it a go too, to clean up the head, pending disapproval from other KBers? Lol.

Yep the sprocket is still flat, so I can keep it? Woot.

Gasket set, that's a new one. My head gasket, I think it's metal, if I cleaned all the grime off it. It seems very solid, but is it still recommended to replace? The other question re: gaskets is that I just saw a new thread come up last night about a guy asking how easy it was to replace his rocker cover gasket; I posted a useless reply in the order of `Bikes have rocker cover gaskets? :gob:'. So am I supposed to have a gasket inbetween the head and the valve cover? The first time I opened it up, I noticed there was some of that crispy black stuff that you smear on and it hardens up. Missing a gasket if I'm supposed to have one would explain oil leaks...

[Ixion]

Valve seals don't bend but they do wear. Most bikes have a rocker cover gasket, but not all. And use of one of the "plastic gasket" products is common. And usually works OK

I *think* the head could be cleaned up. But you'd need to do it yourself, no professional mechanic would touch it. A job for that well known engineering firm Bodger & Bashit.

I'd be a little hesitant about that cam sprocket. The danger is that the bolt hole is ovalled. That could allow the sproket to rack about on the other bolt if there is any slack between the sprocket inner face and the camshaft boss, which could cause the bolt(s) to lossen off, and here we go again.

But, if you can't get another one cheap, it's not way out of line (they are still available new! About $US35 . I'm impressed).

I agree with Mr lb99's assessment of cause. The "missing" camshaft sprocket bolt came out. That then allowed the came sprocket to twist and flex, snapping the remaining lug and flicking the chain off. Why the bolt came out ? Dunno. No Loctite. Not torqued, too loose. or too tight and stripped.

It's hard to tell without actually seeing it, how bad that scoring on the centre bearing is. The damage on the outer bearing surface is not such a biggie, it can be cleaned up, thats a ball race sits there , you just have to keep it in place.

Toolmakers file, scraper, small punch , little light hammer and LOTS of patience.

[xwhatsit]

Schweet :D. OK I'll look for a new cam sprocket as well, if it might cause something similar to happen again haha.

The missing camshaft bolt, before it fell into the sump when I was pulling it out (it was rather finely balanced in a spot I couldn't get it out), looked like it was covered in metal. I.e. it was smooth, instead of threaded, and wider than usual. So I wonder if it pulled out the camshaft thread? So hmm at any rate, I'm definitely going to borrow a torque wrench and get some loctite when I put it all back together. Heheh won't forget to do that in the future, now, will I!

Query regarding the outer beraing, you said a ball race sits in the groove, my camshaft doesn't have any ball bearings, is it supposed to? I think the very outer groove has something to do with the tacho drive, I don't think it locks into it, but maybe it's like a gap for oil or something. Don't quite remember how it all goes together, will have to have a closer look.

Heheh, I can put up with `lots of patience' bit.

Thanks guys.

P.S. If nothing else, I've managed to boost my post count rather nicely :lol:

[scumdog]

I like your attitude dude, you'll go a long way in this world!:rockon:

None of this namby-pamby wringing of hands and snivelling about how hard life has been on you.

[xwhatsit]

Hahah, thanks, I think, unless you were being sarcastic!

I can do the whinging if you like, `no money, no bike, not getting any from the girlfriend now I'm poor and not a bad biker dude :'('

Nah well I fucked up, I've got to fix it now, and it's a lot easier to do when you've got the collective brains and generous spirits of KB behind you!

[lb99]

head gaskets are usually a one use item , but sometimes you can repeatedly use them, but they crush the first time you torque the head down and dont spring back, your bike doesnt have a rocker cover gasket, although some bikes do.
just make sure the rocker cover and head are clean and smooth on the mating surfaces and maybe use a small amount of some sort of sealant (you dont need to glue it togeather) and you should be sweet

I am trying to get hold of the XR dude, his phone is engaged so at least someones home.:yes:

[xwhatsit]

OK, so I'll want a new head gasket then? Unless... I keep the crushed one I already have, because it'll be thinner and increase compression ratio! Muhahaha! No, anything more than about 8hp is too much for me, so I think I'll just get a new head gasket *sigh*.

Thanks for your time lb99! You know my first primary school teacher was from Blenheim, and she was a real cutie (my dad wanted to go to all the parent-teacher interviews haha), so you lot must be All Right lol.

[lb99]

anything more than about 8hp is too much for me, so I think I'll just get a new head gasket *sigh*.



DUDE, you can never have too much horsepower!


You know my first primary school teacher was from Blenheim, .......so you lot must be All Right lol.

uh, yeah except I grew up in Dunedin

[xwhatsit]

DUDE, you can never have too much horsepower!



uh, yeah except I grew up in Dunedin
Neeeehhh... I ride like a super-nana. I ride like a great-great-nana :D. I should've got a Velocette, like my grandpa had :scooter:. I bet that would be more reliable than a Honda! :shutup:

[lb99]

I bet that would be more reliable than a Honda! :shutup:

Heap
Of
Nasty
Decaying
Alloy

dont worry Hondas outnumber everything else in my garage by 3 to 1

[Ixion]

Air cooled engine, you can usually reuse the head gasket unless it is visbibly damaged. Water or oil cooled is another matter. Check the price, they can be painful.

Sprocket, you should be able to get it with the camshaft , prolly not cost any extra.

The bearings, I'm not familiar with the single cylinder hondas. Only fiche I can find on line appears to be a slightly different engine (how many ruddy 250cc singles DID Honda make anyway!).

It may be a plain bearing with some other fitment, it's hard to tell from a picture. main thing is any plain metal bearing surfaces need to be reasonably free of damage and scoring.

Source a camshaft then sing out , some of us will come round and hold an ernest panchayet over the remains and see what can be done.

EDIT: Yep Velos were pretty reliable. Just bits fell off.

[lb99]

I talked to the guy I know, he says he can do a cam for $30 incl sprocket if he has a good one, so let me know if you want me to get him to look one out.

he reckons that the centre bearing in those heads is not too important, its only there to stop the cam from whipping about, so as long as the two outer ones are ok-ish then you should be ok, but it might be a bit noisy.

I thought I might have had you a whole bike for $75, but it turns out to be a cb125t (twin) so if anyone wants one then pm me for the number

[FROSTY]

dude if it was me--i'd haul the barrel off and have a lil hunt in the bottom end for that bolt --actually even if ya hafta turn it upside down and give it a shake--that there bolt aint gonna be good for ya--ya dont want lockup number 2

[Ixion]

If the bolt went down the cam tunnel odds are its happily sitting at the bottom, in the primary drive case. Just have to take the cover off, need to do that anyway to change the camchain. Unlikely to have migrated into the chaincase itself, with any luck

Definately needs to be recovered, of course.

[xwhatsit]

Thanks all! Yeah, Ixion, I've been looking for a parts fiche for it for ages, but I've got nowt.

Sweet, so I can keep that gasket? It looks pretty good.

Hmm well all three of the bearing surfaces are pretty scored up, not just the centre one. As far as I can tell it's not warped, so that's good. With a new cam shaft I might check how it fits into the head, and if the stiffness in the old cam shaft is not just due to the shaft being bent.

lb99, that's great! Thanks so much for that! $30? That is so much cheaper than I thought. Obviously that comes with those wee little evil bolts too? I don't suppose he has a camchain too, or seeing as they're a wearable part I'd be better off asking Econohonda? Is that a XR250 cam, btw? *Manic grin from more horsepower*

$75 for a CB125T! :D:D:D! Haha hell yeah I want it! But I can't have it :(. Stay away from bucket racing until I have my primary means of transport sorted and I can stop catching the bus :sob:.

No, I do plan to hoik that bolt out, I don't imagine I'd be doing the engine any favours by leaving it there. Hopefully I won't have to resort to shaking anything upside down, I doubt my puny forearms would be up to shaking any largish chunk of aluminium with any security :lol:.

[xwhatsit]

Wah! Check this out!:

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-accessories/Engine-drive-train/auction-78736168.htm

Reckon it's OK? Buy now for $80, who knows, could get it for less! Looks a bit corroded... and the end bearing looks quite different from my CB250RS head, where the tacho drive attaches, but could work? Don't care it's a different colour to the rest of the engine.

What does everybody think?

[xwhatsit]

Ooo yes! And this:
http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-accessories/Engine-drive-train/auction-78258522.htm
Amazing the stuff you find when you look for mispellings...

See that's a whole bike. Oddly enough it has a knobbly rear tyre. Guy says it turns over but does not fire... does it look in too shit condition to scavenge parts off? Then again it's in Wanganui, wtf.

[lb99]

although that seller is a bit of an old pirate (Hi Terry), I think XRs had no rev counter drive, and just had a bung instead, I'd be a bit suss about that bike for $200 though, although that knobbly looks pretty good, its really rusty, check out the chain and sprockets, unless you need other parts, you could probably fix yours for cheaper.

[xwhatsit]

It won't just plug into the cam? The locking bolt for it is on the valve cover. Will it leak oil?

[lb99]

the rev counter drive should fit ok, is your head really fucked?, you should see if mister Ixion can check it out for you, he seems to be in the same city

[xwhatsit]

Well the head is not too happy, as Ixion said earlier it may be able to be cleaned up, but is it possible using a head with nasty bearings could end up with another seized engine before Christmas? Maybe a new head is best? Although I'd way rather do it on the cheap, unless it causes more expense later.

I'll definitely buy that cam+sprocket off you, now all I need is to source a camchain, and sort this head out. Yay! Loud noises!

[lb99]

I would pay to do it properly, but if your poor then you gotta do what you gotta do.
source a cam chain from econohonda, I think it should be about $80

[xwhatsit]

OK hmm I'll give it a shot. Cheers for the advice, hope the crazy policemen in the parking lot didn't give you a ticket!

Thanks.

[xwhatsit]

Well, the trademe head is gone, so if I do need another one I'll be back to the old waiting game for a while.

In better news, Sir lb99 has turned up a camshaft and sprocket for me! For thirty miserable dollars! Unbelieveable. However, one bolt on the sprocket is missing, which brings me to another question.

Bolts, bolts, bolts. Well, of course there's the cam sprocket bolt, but there's something else too... while in the garage yesterday, I had a look at the head and all of this stuff (grieving over my bike's body?). Anyway... I think I'm missing a head bolt :ohshit:. It's quite a long bolt that I think is lying in the bottom of a container of old sump oil which is now long gone. Faarrrrrrk! So I need a replacement. I saw a thread up a while ago (thread, lol) about how it's hard to find Japanese bolts because they use a different standard to what is commonly stocked in NZ. Now... OK... `original' bolts are obviously best option. But can you go into a hypothetical `bolt store' (do such things exist?) and say, `OK it's this long and has this thread, I'll have just the one for $3 thank-you'? I think I can do this as the bolt is the same as another one on the head.

One more question before I go (yeah, I never stop asking them, do I? Have to learn some answers of my own one day). A couple of the helicoils in the head are looking a bit less than 100%. It may be due to my ham-fisted carrying ons, but I don't know as I was hardly pulling very hard on the lever (torque wrench for Christmas). At any rate, along with the farked helicoil in the valve cover, if a helicoil is already been put in, can it then be replaced again? Or am I stuffed? If they can be replaced, what is a nice place in Auckland that will do them for a figure along the lines of what somebody (forgot) mentioned earlier in the thread, $6 per thread?

Thanks guys. I'm slowly being educated.

[Posh Tourer :P]

I'll be home in two weeks, so maybe I can get in touch with my friend a bit mroe easily and you can come and scavenge a bit??? He has a kinda complete second bike (obviously missing a head for now...)

[Kickaha]

. But can you go into a hypothetical `bolt store' (do such things exist?) and say, `OK it's this long and has this thread, I'll have just the one for $3 thank-you'? +

Yes you can, just look up fasteners in the yellow pages

[Ixion]

As noted, bolts are redily available. There are bolt specialists, but for the common or garden variety, I find Messrs Bunnings stock a good variety at reasonable prices.

However, use of a generic bolt would be unwise in either of the two cases. They will probably be high tensile bolts at least. I think they are still available , try Econohonda, about $US5 and $US10. I imagine Mr lb99's friend might be able to find a head bolt?.

Helicoils can be replaced, dunno who does them but most engine reconditioners would I imagine.

[riffer]

Just caught up with this thread. What an entertaining read. Well done for your persistence. Bling awarded. :yes:

[Pixie]

The Bolt Shop on the north shore
MSL in rosebank rd
SteelMasters in penrose
You'll need to be specific about the tensile strength ,remember

[lb99]

who's your daddy?

Its even got two bolts, don't lose them 'cause they're special

I'll have a look for a rocker cover bolt shortly, you should be all set by wednesday

[toymachine]

Waitemata Hydraulics could be a place to go for bolts etc too

I'm going to be trying there when I get a chance for a load of new bolts etc

[Pixie]

Waitemata Hydraulics could be a place to go for bolts etc too

I'm going to be trying there when I get a chance for a load of new bolts etc

Only if you really want to pay the highest prices in town

[xwhatsit]

Wo0o0o0o0! I have a camshaft, sprocket, bolts, and also four assorted bolts which may or may not match up to my head cover! Thank-you lb99! Green rep is needed for this man!

It was especially exciting receiving this package as the parts inside the cardboard box were wrapped up in Christmas paper! Hahaha. Early present :D.

On a less happy note, the camshaft doesn't want to go into my head. It goes into the old cracked head nicely, and rotates beautifully, but in the new head, no cigar. The reason for this is visible in the photos I posted earlier, the edges of the outside bearing are bent and sticking out. I used a small hammer and a square screwdriver (it was in my Mitre 10 screwdriver set... WTF is it for?) to tap one of the sides into place, but being aluminium it broke off. Is this really bad? It's a tiny 2mm piece of aluminium... does there need to be a perfect seal between camshaft and bearing, or is a tiny missing bit going to matter? On the other side I managed to get into a fairly decent shape, so that the camshaft will sit in and turn, but not smoothly yet as I need to spend some more time flattening the metal down. Is this like a piston bore; very exacting level of finish and improbably precise tolerances, or is it more like the top of a piston; being a little scratched and beaten up is not ideal and will reduce efficiency, but isn't terminal?

In other words, lb99 mentioned earlier on having an ugly looking bearing surface will cause more wear, but won't cause another top-end seizure; to what extent is this true? Pics will follow presently so you can see what I'm talking about.

Thanks all for helping a smacktard, especially lb99 (I don't mean thanks for helping lb99 the smacktard, I mean special thanks to lb99 for helping a smacktard :D).

[Ixion]

More like a bore than a piston crown, but not quite so demanding. However, knocking bits off is to be avoided. Dont use a scredriver it's too concentrated a point, use a small rod , about maybe 6mm diameter, side on. Try to tap and roll not hammer. And patience LOTS of patience. Allow a few days, not hours, Just gentle tappity tap tappity tap.Until it is reasonably close . Then you can use the old camshaft as a former to clean the journals up.

[xwhatsit]

Cheers for that. So I haven't stuffed the head by knocking off a 2mm piece? Will take pics. The hammer I'm using is slightly too heavy I think, so I will borrow an ultra lightweight one from my Uncle and use that, and find something a bit more suitable to use for hitting stuff.

As a side note, what is a journal? Wikipedia tells me `In mechanics, a journal is the section of a rotating shaft (such as an axle, driveshaft, or spindle) that contacts and turns in a bearing.' My English isn't so good, so it seems to me that according to Wikipedia the journal is on the camshaft, but that can't be right. Can you please explain to the n00b ^_^.

The cam is visually quite different from the old one, on the lobes. I wasn't prepared for how different the CB and XR camshaft would be; I thought that the quoted `greater lift and duration' would be something I couldn't pick with my eyes, but you can see they are different things. I wonder how the engine will react instead... One thing that came to mind was, unless my understanding of the Otto cycle is quite wrong, having these changes in the cams would cause more mixture to be sucked into the engine. Does this therefore necessitate carb modifications? Like, for instance, rejetting? As I suspect the engine was running lean before (although that may have been due to cracked head), I don't really want to lean it out anymore as I can't afford to replace melted bits lol.

Thanks for taking the time to read all the stuff I write. My virtual voice is sore from constantly going up at the end of sentences because I ask so many questions haha...

[Ixion]

Well, I'm sure Mr Honda would be horrified at a 2 mm piece being missing from his bearing surface. But in practice, it's unlikely to be disastrous. If the bearing surfaces aren't good you will lose some oil pressure, but those engines are (I think) roller bearing bottom end, it's not like a white metal crankshaft.

A lighter hammer is good tapping not bashing is what is needed here. And use something that spreads the impact insofar as is possible on a curved surface.

Technically I think wiki is right the journal is the rotating bearing surface. But it's a convenient misuse of the term to describe the fixed bearing surface (I don't really think there is a term for that?), the context makes it plain

And a hotter camshaft will probably need rejetting , but you can sort that out with some plug readings once its running. The lean running on the old head was probably because it was drawing a bit of air through the crack on each stroke.

[xwhatsit]

Ta muchly, the missing bit of metal is right next to the chain tunnel, so unless my 3D representation of the engine when assembled is far off, I can't see how it will lead to drop in oil pressure, and the head cover does not have a matching bearing up top.

Rejetting... that bridge will be crossed when I come to it :). Coming soon: a thread where Tom asks every question known to man about jets, sizes, how the screw in, what tools to use, why can't I find any in the bloody Southern Hemisphere, oops I broke it, I need to find another one...

[lb99]

Thanks all for helping a smacktard, especially lb99 .....

must....resist....red....rep......


Cheers for that. So I haven't stuffed the head by knocking off a 2mm piece? Will take pics. The hammer I'm using is slightly too heavy I think, so I will borrow an ultra lightweight one from my Uncle and use that, and find something a bit more suitable to use for hitting stuff.



have fun with the metal forming, the shaft end of a large drill bit is good for a dolly, tink, tink, tink, tink, tink, tink, tink, tink, tink, tink, tink, tink,...
do it under the neighbours window late at night


Ta muchly, the missing bit of metal is right next to the chain tunnel, so unless my 3D representation of the engine when assembled is far off, I can't see how it will lead to drop in oil pressure, and the head cover does not have a matching bearing up top.


I think that bit is to wipe the oil from the cam and help it drip down the middle of the cam chain tunnel on the return journey, rather than being pumped out the rev counter drive, and down your new jeans.


Rejetting... that bridge will be crossed when I come to it :). Coming soon: a thread where Tom asks every question known to man about jets, sizes, how the screw in, what tools to use, why can't I find any in the bloody Southern Hemisphere, oops I broke it, I need to find another one...

try and get your mitts on an XR carb, even if its just to try it out.
Its worth a crack

Dont forget to lap in the valves you swapped

[xwhatsit]

These bearings scare me. I'd really like this to be the last time I have to take the engine apart... I'm hoping to organise some extra cash so I can get hold of a new head, if one should pop up. In the mean time I'll continue with the head I have, it's in better shape now but it still worries me.

Here's one on eBay: http://cgi.ebay.com/ebaymotors/HONDA-XL250-CYLINDER-HEAD-1978-4-VALVE-XL-250-1977-1979_W0QQcmdZViewItemQQcategoryZ35595QQihZ010QQite mZ200059032232QQrdZ1QQsspagenameZWD1V

$US19.99 < $NZ30. Shipping would be horrendous I imagine, and it may take some time to get here... but probably not before I have a cam chain sorted :D. I've got all the valves I need. I should've pounced on that one on trademe I posted about earlier. What does everybody think?

Cheers.

Edit: $US50.85 shipping for it to be here within 10 days, more at peak periods (it is Christmas!) :shit:... for a total of about $NZ100. Not too shocking I suppose, half the price of Mr Econohonda.

[xwhatsit]

Random thought: valve lapping grinding paste on the head bearings and old camshaft to `lap' it with?

[xwhatsit]

Heh. Figured out the problem with the head. The bearings are now pretty good, but the camshaft still had a bit more friction that I would like. What was discovered was that the camchain tunnel has `closed up' slightly, probably from getting hit on top by one of those bolts, and is now pinching on the cam sprocket mounting lobes. So I'll file it back slightly, I think. There's only like half a mm in it.

As an aside, I bought an entire CB250RS off Mr Posh_Tourer's friend (thanks guys!). Of course, though, when I looked at the cylinder head... it had a crack in it :D. So I'm going to steal the bits I want, then part it out on Trademe. So if anybody wants CB250RS bits then I'm your man, lol (bucket racers want the frame and front end?).

When I have the money I'm going to buy a camchain and some gaskets and put the engine back together. Just another question, though (of course) -- what do you fine gentlemen recommend for ridding your bike of metal shavings? There's a fair bit in there. Somebody said a while ago to flush the engine with oil. How do I do that (I'm assuming you mean before I put it all back together and run it)? I'm terrified that there's some metal bits stuck in a tiny oil hole and I'll get 20kms down the road and my crankshaft will melt.

Cheers, guys.

[scumdog]

I've flushed out engines using diesel and also kero - kero would be my pick.

Leave the sump-plug out and pour shitloads through the motor as fast as you can get it in.

Helps if you haven't turned the motor over as all the filings will be where they fell and will wash off easily.

If you can reash through the sump-plug hole you may be able to do a 'sweep' with you finger and remove any filings that never got completely washed out.

Then put in the sump-plug, a new filter on, new oil in and give it a go.

Good luck

[Ixion]

I'd go with kero. If you can try to turn the engine upside down (even if it means turning the whole bike upside down), and pour some through "backwards" - in through the drain plug out through the barrel hole (I assuming the barrel is off).

Most of the trash will have gone down the cam chain tunnel, would be worth thinking about pulling that cover off if it isnt already.

I've known a lot of engines that had this sort of thing happen, they seem to survive better than you'd think. The main thing is, when you get it going, just fill it with some very cheap oil. And after about 15 minutes running, drain the oil, refill with more cheap oil, drain that after about 500km and replace with decent oil, replace that after a couple of thousand k.

[xwhatsit]

Ah, thank-you. I've turned the motor over once or twice, but not at any rate of knots, just to make sure it was free. I have pulled off the right-hand sidecover, in order to get at the camchain, and also the oil strainer (now that was a mess!).

The barrel isn't off, but if I turn the bike upside down the oil will still find it's way out a passage in the barrel I think. Would it be worth taking off the barrel? I suppose checking the rings wouldn't be stupid, either.

That 15-minutes-of-oil trick sounds like a good idea.

Thank-you to my forefathers who have gone and mashed engines before me, then worked out how to make them go again :D

[xwhatsit]

I've just got paid a sizeable amount (yay for holiday pay!) so have gone ahead and ordered the following bits:

Camchain $67
Head gasket $62
Right side-cover gasket $25
Base gasket $??
Exhaust collars $9.50 each (mine are rusted to hell)


Thank-you to Neil from Econohonda who was very helpful -- as was Malcolm who helped me out last time with the cylinder head.

I pulled off the bore, as well -- that's why I need the base gasket, the one on there looks like a cheap pattern part, and broke in half. I've attached some pics of the piston, and also my garage in general -- two bikes! Not much room for laundry, lol.

The bore looks perfect, not a mark on it. Shiny as a mirror. The piston and piston rings look great too, apart from the valve dents in the top I already knew about. The piston is a beautiful thing... as is the bottom end. I spent ages just staring at the conrod and crankshaft, and the bearings -- it's just so perfect how it works, how the bearings go around at half the speed of the crankshaft because they're working like planetary gears. Beautiful. Humans can't have designed something so amazing. The piston rings, too... I did some reading on how they work, and the oil scraper ring, and how they rotate slightly to scoop the oil down inside the piston. My bike isn't exactly a Sport 1000 in terms of looks on the outside, but inside it's stunning.

Anyway I'll stop boring you with useless crap. Bring on the parts shipment!

[imdying]

Still having fun then :D :D

[xwhatsit]

Still having fun then :D :D

Yeah, 'course! I'm no quitter :D

[gijoe1313]

Yeah, 'course! I'm no quitter :D

Righto, might as well use my 1000th post in this here thread (seeing as you're channelling the spirit of the pioneering biker and all! :yes:) Glad to hear that you got some dosh to fix up more of your ride!

That's sweet ... looking forward to seeing you back on the road and riding those lanes on two wheels of freedom yeehaa! :woohoo:

And btw, I bet you say that to all the girls! :o :msn-wink: :devil2:

So... when is all this going to come together then huh? Huh? HUH? :shutup: And all that moola spent on your japanese girlfriend...I don't think your chinese girlfriend gonna like that one bit! Would love to be a fly on the wall when she finds out about this! :lol:

[xwhatsit]

Righto, might as well use my 1000th post in this here thread (seeing as you're channelling the spirit of the pioneering biker and all! :yes:) Glad to hear that you got some dosh to fix up more of your ride!

That's sweet ... looking forward to seeing you back on the road and riding those lanes on two wheels of freedom yeehaa! :woohoo:

And btw, I bet you say that to all the girls! :o :msn-wink: :devil2:

So... when is all this going to come together then huh? Huh? HUH? :shutup: And all that moola spent on your japanese girlfriend...I don't think your chinese girlfriend gonna like that one bit! Would love to be a fly on the wall when she finds out about this! :lol:

Lol! I'm honoured you chose to spent post #1K in my thread -- congrats, not surprised it didn't take you very long, lol.

Nah... girlfriend #1 (or is it #2 :D) is quite pleased I'm on my way to have the bike fixed -- when it's running, I earn a lot more money as catching the bus is a lot more than riding my bike. Not sure she's keen on the idea of me actually riding it though, there will be guilt trips about my wee crash and associated minor injuries, I'm sure.

God I make her sound horrible. She's a lovely sweet girl, almost as lovely and sweet as my Japanese gf :msn-wink:.

[xwhatsit]

Well tonight (well, last night actually seeing as midnight just ticked around) I spent putting back my motor together with the invaluable help of my Uncle. With him there we put the whole engine back together, and valve clearances as well (I haven't got around to buying feeler gauges yet). After he'd gone, I finished the job off, putting on the tank, cables, exhausts (what a bastard! Stripped a nut, lucky I had a spare on the parts bike), and brake. Filled up oil too, made a hell of a mess...

Well I go to kick it over... nothing! Of course. So I keep kicking it and kicking it, until it finally catches for a second. I gave it another kick and it roared to life! -- very quietly =^_^= (new copper exhaust gaskets and new collars make for a silent machine!) -- until I let go of the kickstarter and the decompression lever is allow to return and the engine can't cope. I keep trying, but it keeps doing the same thing. I go to bump start it, and it runs for a bit more, until it looks like the battery runs out, and because of the low revs and cold engine it can't keep up the momentum.

No matter! I'm too tired now to keep trying -- time to have a beer, have a shower, and go to sleep. I'll keep booting the thing in the morning.

The plan is to go how it was suggested to me earlier in this thread -- run the thing (continuously! :D) for 15 minutes, then drain the oil and put some more in for a further 500kms. Pretty confident I got 95% of the shit out of the sump, but it's cheap insurance ($15 for 4 litres of crappy Caltex car oil from Warehouse, lol).

So relieved, and tired.

Wish me luck, and thank-you for the help that got me here.

[lb99]

weird shit, are you sure you have got the valve timing correct?, check the basics first, spark, compression, fuel, timing.
Well done for the re assembly though, good luck with the fault finding.

lb

[xwhatsit]

No, I'm not worried about the stalling -- valve timing is spark is great, compression is f**king awesome (yay for head gaskets and no cracks in heads!). The thing has always been a bastard to start, and I was only half hoping a rebuild would cure that. The batter is dead flat, so that will cause some strange things. Now that the engine is sealed up properly, and has got your slightly more aggressive XR cam in it, I might have to play with things like pilot mixture and even idle speed.

Last night I was absolutely stuffed, I could barely muster enough strength to kick the thing over. Today I'll get it going -- then ride it to work, with a bit of luck :D

It's pretty desparate, innit, having no bike?

[gijoe1313]

Crikey! What a mission! :yes: On ya - want me to pootle Daisy over and let it give your baby some moral support? :innocent:

[lb99]

No, I'm not worried about the stalling -- valve timing is spark is great, compression is f**king awesome (yay for head gaskets and no cracks in heads!). The thing has always been a bastard to start, and I was only half hoping a rebuild would cure that. The batter is dead flat, so that will cause some strange things. Now that the engine is sealed up properly, and has got your slightly more aggressive XR cam in it, I might have to play with things like pilot mixture and even idle speed.

Last night I was absolutely stuffed, I could barely muster enough strength to kick the thing over. Today I'll get it going -- then ride it to work, with a bit of luck :D

It's pretty desparate, innit, having no bike?

oh, ok it probably is just a flat battery, mine wnt like a pile of poos with a flat battery from memory it wouldn't rev out and stuff. kinda answers your question about removing the battery huh.

IMO I wouldn't bother rejetting to suit the XR cam, its not that much different to the cb one. I don't think it would make much difference to your overall performance, you should figure out how to make it easier to start, they should start first kick. ya dont wanna break that kickstarter (as someone else here has found out)

[xwhatsit]

Oh aye, the flat battery thing is giving me pause for thought about removing the thing.

That said, she started this morning 3rd kick, still with a dead flat battery. However, coming home tonight after work, I had to bump start her again. Odd. My thoughts are tending toward coils and other electrical things, to be honest. It's not the end of the world, I can live with that.

Yeah, got some verniers and checked the difference in the CB and the XR camshaft. Interestingly, the CB camshaft has a bit more lift, but the XR is much more aggressive in profile. My kneejerk reaction to that is, a dirtbike needs more lower-down power but not necessarily so much top-end max power. Looks like the exhaust valve opens slightly later, too. It's all moot, though, the fact I have full compression now far over-rides stuff like camshafts :D

Drained the `15-minute' oil this morning, glistening with aluminium. I think I've slightly over-filled the replacement oil, which I know isn't ideal. Is it worth draining some out? At the moment I'm leaking enough oil out of my tappet covers (shot O-rings -- will order some new ones on Monday) that it'll probably be right in a few hours :D.

Somebody must've told everybody that I'd rebuilt my engine, because everybody keeps trying to kill me today. Going through that arsehole of a Royal Oak roundabout, some young blonde bird did the usual; looked straight at me, then went anyway. Was about 2metres off the arse of my bike (would've been sweet anyway) when I saw her face turn to an `OH SHIT' and she slammed on brakes. Car behind her just about hit her. How exciting.

Thanks to the Kawasaki Adventure bike rider who gave me a lesson in lane-splitting in rush hour traffic on Manukau Rd. Very impressive. I've learned how to do a `wing-mirror shuffle' now, lol.

Cheers all.

[Ixion]

Flat battery will give very erratic results. Depends too on if its a short type flat or a high resistance type flat. Charge it up or replace it.

[xwhatsit]

Aye, well, just came home from a quick pootle to Mission Bay with young GiJoe and his mistress Daisy (cheers man!) -- battery's well and proper charged now, lol. Still had to bump start it. Thinking coils, or CDI or something. I really am not worried -- first thing is to replace the valve cover O-rings so people don't keep yelling out my bike is on fire with all the smoke (hell, my bike was smoking more than that dirty two-smokin Daisy whore!). I thought real men bump started their singles anyway :D

Unbelieveably good feeling to get back on two wheels again. Just about on par with when I rode for the first time, except with niggling feeling in the back of my head about every little noise in the engine. Nothing like the cool night breeze in your face, two-pot stroker scream mingling with my mellow thumping in a peculiarly melodic way.

Hope I've bolted her up for the last time. I'd bawl if she blew up again.

Thanks for the company, GiJoe -- and thanks to everybody else in this thread who've tirelessly given advice and answered my often trivial questions. Don't know what I'd do without you lot.

[gijoe1313]

Cor blimey - he's proper 'umble like this young'un he is! Ee by gum, I think he's a keeper! :yes:

Cheers for the spirit of the impromptu pootle! Always nice to have a fellow biker to chew the fat with! Funny thing on the way back home ... some boy racers were doing the "doof doof brrmm brrmm" thang (and no, Xerxesdaphat, it wasn't that other boi racer in Ellerslie :msn-wink: ) ... they saw me and decided to "give that stoopid bikerboi the learn" , well wouldya know it ... I just happened to be riding little Miss Daisy rather then my more sedate little ol'Hornet! :woohoo:

Ringa-dinga-dinga-ding-ding later ... some haze of two-stroker smoker goodness, and they realised that the little yellow bike was faster then they thought! My goodness ... Miss Daisy is bringing out that hoon factor in me :innocent: She's a little pocket rocket, and thank gosh Natalie was there to keep her in line! (Natalie is the CB250RS natch! :msn-wink:) Mad props and big ups to the boi racers though, when I slowed down - they pootled up quick smart and did the "chur chur" bro ta me - all good clean fun! :chase:

Lovely night for a pootle ... 500kms on Miss Daisy ... another 500km more to do before the end of this week! :sunny:

[Deviant Esq]

Mate - where to start? xerxesdaphat - you're a legend buddy. Love the attitude and not losing hope - this saga's been going for 4 months and still you kept at it even without mechanical knowledge to begin with, dipping your mitts into your motor happily time and again, and getting it back together and running - you're a braver chap than I am for cracking it open! And much more patient sticking at it this long. I'd have probably panicked and pouted and sent it into a bike shop, where, hundreds of dollars later it would've emerged worse! :dodge:

This thread was a bloody good read. Top marks to you for taking the time to post up your progress including photos etc, and honourable mentions must go to lb99 and Ixion for their useful advice as well. Had a good laugh at lb99's advice...
tink, tink, tink, tink, tink... do it under the neighbour's window late at night That cracked me up, that man deserves more bling than the pitiful amount I dish out :(
As does xerxesdaphat. Can't say it enough - top effort, good guy. Hope your exams went well mate. I'd happily join you on Wendy (my NZ250 :o ) - go the singles - for a pootle if you lived a bit closer to Christchurch!
:2thumbsup

[xwhatsit]

Hey, cheers man, very kind words there! Oh yeah, I would've loved to have sent it into a bike shop, but I couldn't afford that so I didn't really have a choice. It's like being a crack addict -- getting a taste of it so you're hooked, then you'll do anything to get that taste of biking again.

Aye, Ixion and Lb99 in particular have been a huge help, would've been much slower progress without them. They do indeed deserve bling :D

Haha! Yeah I'd love to go for a crack around Christchurch someday -- at some point during my student days I want to take a month off work or so and head down to the South Island. Beautiful part of the world, you lot are lucky sods. Yep, I think I'm a confirmed single nut too ^_^ -- I like the simplicity and bare-bones nature of knowing each of those thumps is coming from the same place. Hard to explain.

Respect for wading through such a long thread, haha :D

[gijoe1313]

Oh poops, I don't have a single cylinder in my stable yet! Hmmm ... must start looking around for my next ride! :innocent: :sweatdrop

[Ixion]

There's something about a tuned single cylinder 250. Different sort of buzz to a two smoker (or a big single) but they can be pretty cool.

I like small bikes in many ways they're more fun than big ones, because you can ride them to their limits. Its really a buzz to push a bike so hard that you are right on the edge of the machine and your own capability for miles on end. Which you just cant do on a big bike on the public road. And the small bike shows you up immdediately if you don't get things EXACTLY right. With horsepower to spare, you can cover up mistakes just by giving it a bit more throttle, the brute power cover up. Can't do that on a small bike, so the buzz when you DO get it exacty right , swooping through a series of curves, holding the engine just *SO* on the cam, holding *ALL* your speed through the curve, is really nice.

'Tis the difference between Mozart and Metallica.

[avgas]

I second that Ixion. Its just pure fun.
While the big bikes are fantastic, these is nothing quite like a little single hitting an apex of revs, and apex of brakes then it hits the apex of the corner.
Pure art

[xwhatsit]

Well it hasn't packed up yet, so that's good. Starting hasn't improved; will fit the coil and HT lead from the parts bike when I have some spare time and see how that goes. Although the spark is blue when I check the plug with the thread against the head (this is correct method, no?), could it be that it's not producing such a nice spark inside the engine? I've heard this is the case. Also, to check the HT lead to see if it will jump spark across to ground (the head again?), do I pull off the plug cap? Or leave it on.

My valve inspection cover o-rings arrived this morning, so I fit them and head off to uni. It's cut down on oil leakage significantly, but it appears that there's still some leaking out between the head and the valve cover itself. Now, there's no gasket for here (well I bloody well hope not -- or it's been without one for some time), so my Uncle applied this black shit in a tin with a brush that dries and goes crusty (I think it's British). Obviously it's not doing the trick. Now, this is a valve cover off the parts bike, so could it be warped? Or perhaps my head has become warped when the camchain seized. There must be some misalignment for it to leak oil even with this black sealant. How can I stop it leaking? Silicone?

Thanks for your answers.

[Ixion]

What state is the battery in?

Have you tried a new plug? Is it possible that with all the drama with the cracked head that the carb settings have been maladjusted . Specifically, the cracked head would have tended to make the machine run lean - so someone may have wound the pilot jet adjustment in (or out, whichever way your one goes ) to richen the mixture. Now without the leak it's too rich

If you are getting a good spark and a new plug I doubt it is spark (your method of testing is fine).

Once running does it idle reliably and well, about 1000-1200 rpm? Respond cleanly to the throttle?

If the valve cover is just a cover, you can fit a gasket - I suspect there would have been one originally . Or is there a groove in the cover and/or head - in which case it was designed to have a plastic seal.

Sounds like your uncle used shellac (smelly stuff?) , which will seal almost any joint if it is not warped. So you may be correct about warping. The silicones will seal a SMALL gap . Alternatively (once again, assuming it is JUST a cover ) you could get a bit of sheet cork and cut a gasket.

[xwhatsit]

What state is the battery in?

Have you tried a new plug? Is it possible that with all the drama with the cracked head that the carb settings have been maladjusted . Specifically, the cracked head would have tended to make the machine run lean - so someone may have wound the pilot jet adjustment in (or out, whichever way your one goes ) to richen the mixture. Now without the leak it's too rich

If you are getting a good spark and a new plug I doubt it is spark (your method of testing is fine).

Once running does it idle reliably and well, about 1000-1200 rpm? Respond cleanly to the throttle?

Nooo... well... I've been treating the starting symptoms before and after rebuild as a group. As far as I can detect, there's no difference between how it was before and how it is now. The carb may well be up the tree. In the past I have tried new plugs, with good success -- typically, putting a new plug in would make it start on the first or second kick (once, rode to Repco, bought a plug, tried to start with the old start but not even bump starting would do it -- put in new plug and it started straight away). EDIT: and as far as I can recall, it idled much better with the new plug, and started well for maybe two or three days before it would turn to shit again.

It won't idle to save it's life. I've noticed after the rebuild (good compression, maybe?) it is happier at low revs, but eventually it'll just conk out without warning, and I don't want that to happen with the starting issues the way they are so I keep blipping the throttle so it revs around 2Krpm. It sort of responds well to throttle around 1000-1200, but sometimes it'll stall when I twist it.

Battery is fully charged, appears to be holding up well. Got a bit more than 12V in it, maybe 12.5 or something. It's probably not in best condition, after being discharged a couple of times, but would it still cause issues?

[Ixion]

If the battery is reasonable it is probably sufficient for a kickstart bike - no voltage drop from the electric starter to worry about.

Definately sounds ike the carb needs tuning.

I'd suggets another new plug (you imply I think that you haven't replaced it since the "old' motor) - the cracked head may have been stuffing them up so a new one may last well now.

And see if you cna get it to idle, if it will idle OK it will probably start OK

[xwhatsit]

Nup, haven't replaced plug since did motor. Have a brand-new looking slightly different model plug (but still in the same series) that came in the box of bits with the parts bike. Will give that a whirl.

I'll have a play with the carb. I know it's pretty clean inside, hopefully the idle circuit isn't blocked as that looks a bastard to clean out. With a bit of luck the pilot mixture may be the only thing I need to do.

The plugs always look the same after they've run for a bit -- white/light grey electrode, but dead clean, no deposits or any shit. I just pulled the plug out now, the insulator is white with maybe a slight orange/brown spot or two.

Will follow the procedure in Haynes of how to set pilot mixture tomorrow. I have a spare carb too... it's probably pretty stuffed though.

The oil leak is worrying me though. Would that goopy orange silicone crap be a good idea?

[Ixion]

Hm. Mr Motu will have something to say about the goopy orange crap. Try to get a better one, Loctite do a good range. Check the cover for warping if you can .

The plug should NOT look white (like a new one looks) It should be a choclate brown , about the colour of fruit and nut chocolate. A whiteish grey plug definately indicates a lean mixture. But I assume that your comment about colour is based on plugs running with the old cracked head - as I said that will certainly have made for a lean mixture. The orange brown spots may indicate that the mixture is more correct now (it takes a few hundred kilometres for the full clolour to show). Deposits are not really what we are worried about here.

Definately has been running lean in the past. And a greyish plug usually indicates that its been overheated (the effect of lean mixture) and ruined. Definately replace it.

Replace plug, see how it gos , if it still won't idle or start, look at the carb. More likely to be fiddled settings (in a vain attempt to compensate for the elanenss), rather than anything blocked.

[xwhatsit]

Hahaha yeah I know the goopy orange crap's reputation, but that'd be better than my engine giving off smoke at the traffic lights. It's not a two-stroke, you know ;). I'll check out Loctite, then.

Ooooh ok, chocolate brown, then? Well I'll give the new plug a shout tomorrow then, and try and get the pilot mixture right. Hopefully it will stay good for a while.

Thanks for the help.

[xwhatsit]

Well I've had a bloody frustrating morning. Put the shiny plug in, started third kick or so despite the shitty weather. Idled quite well, even without choke, and right down to the recommended 1200rpm +/-100. Went for a short ride to get her up to temperature, came home and followed the method outlined in the manual on how to set pilot mixture. Thought I got it right, so went for a short ride again. Bike stalled while idling at an intersection, could not for the life of me get her started again, even though I could start her just before when hot. Flooded engine trying to start, finally managed to bump start her but wouldn't idle at all any more. Came home, sweat pouring off me from the effort to start her, pulled out the plug and it was all grey like the other one.

Now, the manual doesn't say, but if I'm screwing it in, does that make it leaner or richer? I've made up my mind that carbs are a bitch. Horrible fiddly pieces of shit and now I'm feeling pissy. How much are those exhaust analyser thingies I've heard references about? Would make things a hell of a lot easier.

</whinge>

Oh and a while back I talked to my Dad, he mentioned he'd put straight pipes on his cruiser and then took it to the shop to have it put on the dyno and the carb tuned. It cost him $100 in Australia. Is it comparable here? Almost wouldn't mind just dumping a weeks wages on getting this frigging thing right.