Topic: :( oil coming from #1 4 days old. cb750k8, poor acceleration on highway.

[turin39789]

Got my new to me cb750k8 and I took it up on the highway today.  I'm missing the speedo cable(coming tomorrow), but it seemed like it has no guts when it gets going.  I feel like my 550 was faster and the 750 is having trouble keeping up.  Even around town when I try to open her up, she does ok then just seems to slow.  Seems like it didn't want to shoot up past 5k rpm on the highway, though she did so in the driveway in nuetral.

It has a non-stock exhuast, 4 into 1 with a cb1100x blackbird muffler on it.  Could this be restricting it too much?  It came with stock pipes that have some holes and rust issues, wondering what kind of shop I'd have to take these to to get cleaned up.  They also rattle when picked up, making me think there are baffles floating around inside.

It has a dyna ignition, so I'd think the timing would be on, but thats where I think I should look next.

Just wanted to get some ideas bouncing around, I'm supposed to take her on an 80 mile trip right after work to a job tonight, starting to get a bit worried.

Thanks

[TwoTired]

An 1100 cc engine breathes far more air than a 750.  So, the muffler should have much less restriction than the stock one.

Still got the stock air filter?

Were the carbs re-jetted and adjusted for the exhaust back pressure change?

Assuming yes and no to above....

You either need to put the stock pipes back on (repaired of course),  or re-jet your carbs, which have non-replaceable idle jet (unless you are quite determined) and non-adjustable slide needles (unless you get needles from a 77 carb), and will have to trial and error fit larger main jets,  do plug chops and read spark plugs to determine what to adjust in the carbs, or take it to a dyno facility and pay them to tell you what adjustment the carbs need to run with you changed exhaust.

Ain't it great when PO's don't tell you their mods aren't complete yet and you just bought a project they didn't feel like finishing?

Cheers,

[turin39789]

An 1100 cc engine breathes far more air than a 750.  So, the muffler should have much less restriction than the stock one.

Still got the stock air filter?

Were the carbs re-jetted and adjusted for the exhaust back pressure change?

Assuming yes and no to above....

You either need to put the stock pipes back on (repaired of course),  or re-jet your carbs, which have non-replaceable idle jet (unless you are quite determined) and non-adjustable slide needles (unless you get needles from a 77 carb), and will have to trial and error fit larger main jets,  do plug chops and read spark plugs to determine what to adjust in the carbs, or take it to a dyno facility and pay them to tell you what adjustment the carbs need to run with you changed exhaust.

Ain't it great when PO's don't tell you their mods aren't complete yet and you just bought a project they didn't feel like finishing?

Cheers,

Yea, I bought it off the forum though and the PO seems to be more knowledgable than I am.  I def want to get back to the stock exhaust, but I'm not sure if I need to find a vintage shop in the area or if any old muffler place with a decent rep can handle the job.

She felt a bit wobble this morning too, but I do have two stuffed sidebags on the bike.  I'm hoping I'm just getting used to it, have the long ride tonight to figure it out.

[turin39789]

motherfreakin oil pouring out of cylinder 1.


Day 4 of ownership.  Have to go work for 30 hours straight, will post more afterwards, late enough as it is

[turin39789]

Sunday I took the bike for a ride around the neighborhood before buying and it seemed ok, felt a bit of a flat spot when I briefly took it onto a 45mph road, but was excited.  Rode the bike to the bank and then home, where I had to study instead of riding. 

Wednesday rode it to work and it felt a little slow.  I went the speed of traffic on a 55 mph(call it 65) highway for about 4 miles.  When I came out of work I noticed some oil on the ground but figured it wasn't me.

Started to ride it on the trip I was looking forward to, stopped for gas near my house before taking off and noticed smoke coming from near the exhaust pipes, saw oil coming from the #1 spark plug.  Pulled the boot and there was a small puddle in the hole. 

Rode it a mile home, and drove the old Turd Ferguson Tercel instead of my neat new bike.

Shot at 2008-05-01

So, how bad is this.  What are my options?  Here are three quick pictures I snapped as I was loading the tercel up.

[Bob Wessner]

If you're saying the plug cavity is filling with oil, then overflowing and leaking to the ground, the only thing above that, would be the valve cover gasket I would think.

[rugger81]

Wouldn't that most likely mean that the little pucks underneath the camshaft holder is leaking?

[mcpuffett]

Is the spark plug tight ?  , cheers Mick.

[Gordon]

Wouldn't that most likely mean that the little pucks underneath the camshaft holder is leaking?

+1

If the oil was coming out of the spark plug hole you'd be blowing huge smoke clouds out of that exhaust pipe from all the oil burning in the cylinder. 

[mystic_1]

Wouldn't that most likely mean that the little pucks underneath the camshaft holder is leaking?

+1

If the oil was coming out of the spark plug hole you'd be blowing huge smoke clouds out of that exhaust pipe from all the oil burning in the cylinder. 

+2

If it was the valve cover gasket you'd see evidence of the leak at the seam.  Can't quite tell from the pic but I'd think that with that much oil it would be evident if this were the case.



mystic_1

[turin39789]

Is the spark plug tight ?  , cheers Mick.

My thought too, but I'm not sure that oil should be in the cylinder.  Anyway it was too hot to check when I first noticed and then I had to run before I could look at it all.  I should have about an hour of free time at the house on sunday at which point  I can check whatver anyone suggests.

[turin39789]

Wouldn't that most likely mean that the little pucks underneath the camshaft holder is leaking?

+1

If the oil was coming out of the spark plug hole you'd be blowing huge smoke clouds out of that exhaust pipe from all the oil burning in the cylinder. 

+2

If it was the valve cover gasket you'd see evidence of the leak at the seam.  Can't quite tell from the pic but I'd think that with that much oil it would be evident if this were the case.



mystic_1

little pucks under camshaft..... doesn't sound cheap/easy.  I get to teach myself everything I know about motors as I need to, and I've never had to actually contemplate any actual inside the engine work before.


I'm tempted to go back to the seller, as I have less than 20 miles of seat time on the bike, but I don't know how far I'll get that way, or how understanding I would be in his place.

[Gordon]

I should have about an hour of free time at the house on sunday at which point  I can check whatver anyone suggests.

Unfortunately it will take a lot longer than an hour to pull the engine to replace the cam tower pucks.

[Gordon]

I'm tempted to go back to the seller, as I have less than 20 miles of seat time on the bike, but I don't know how far I'll get that way, or how understanding I would be in his place.

Maybe others will disagree, but please don't go back to the seller.  You buy a used, 30+ year old bike, you take it with all its problems.  Just use this as an opportunity to do a full top end check/rebuild.  It's well within your grasp, and probably needed by this time, and you'll have yourself an engine in good tune and that you know how to fix when it has problems. 

[mattcoff1]

Hey guy before you start taking the engine apart... clean the oil off and put some baby powder or similar across the ft of the engine and then run it and isolate the leak.may just be a tach cable seal or just a loose tappet adjustment cover... 
 Good luck

 Matt

[xlemming]

+1 to the tach cable leak.  Mine has a little oil that drips down by the first cylinder when its sitting on the kickstand, but it comes from the place where the tach cable goes in.  (the owner before last decided it would be better to try and caulk the tach cable in place instead of just buying a new seal)

-1 to complaining to the seller.  Unless the seller made some sort of guarantee that they were selling you a bike in perfect condition (doubtful, but possible) going back to them won't really help.  When you buy or sell a bike that old you understand that you're buying a 30 year old motorcycle, and all the oddities and worn out parts that come with it.  Typically used vehicle sales are caveat emptor.  I'd be ticked if I sold a car or motorcycle to someone and they came back a few weeks later complaining about it, especially if it was a 30 year old vehicle.

Have fun wrenching on your bike.  Like I told my roommate the other day when I told him I was going to need a few minutes to let my bike warm up before we left (he has a new water cooled Honda Shadow), I bought a vintage bike and all the fun associated with working on it.  I'm just glad I've gotten things to the point where its running fairly smoothly and I can get all the way from one place to another with out having to stop and fiddle with something on the side of the road to get the rest of the way home.  It never fun when things don't work right though.

<edited for grammar and this>
PS  I'm now just waiting for karma to come and bust my cam chain or something in that vein.

[turin39789]

Finally got my new tach cable seal.

Any advice on getting it out?  I see people say use a wood screw without touching the shaft or the walls, other saying it's a bad idea.

Also, people say to use hondabond, and I forgot to ask for some at the dealership, any similar product available at a FLAPS?

[mystic_1]

I see people say use a wood screw without touching the shaft or the walls,

That is how I do it.  Screw into the flat portion of hte seal itself, just far enough to anchor the screw, then pull.

You shouldn't use any sealant on the new seal.  Just clean everything up nicely and push it in straight.

mystic_1

[turin39789]

got it out, got the new one in, rode down the street and back and still smoke from oil hitting the pipes.

I'm going to let it cool off then take a hose and some towels to the engine to make sure it's clean and then I'll take it out for another spin to see if I have another issue still

[OldSchool_IsCool]

If you have some spray foot powder, spray that on your clean, dry fins.  Any oil leak will turn the white powder to black sludge showing you exactly where the leak is.

If it is head gasket (the split between the head and the cylinder block) then all I can say is welcome to the club!  A lot of bikes on the forum here leak at the head/block joint.  It is repairable, but not quickly.  It will take a full set of top-end gaskets and several hours of dedicated work.  Search the forum here for "top end rebuild" for lots of details on what needs to be done.

If it is a head gasket leak, fear not, your summer of riding is not over.  By letting it leak, you aren't damaging anything anymore then it already is.  Short of it peeing on the ground, you aren't causing a tire slip situation either, just oily pant legs and shoes.  Keep a close eye on your oil level and use a rolled up paper towel crammed between the fins over the leak site to keep it under control.  Rebuild the top end when you have time.

[turin39789]

If you have some spray foot powder, spray that on your clean, dry fins.  Any oil leak will turn the white powder to black sludge showing you exactly where the leak is.

If it is head gasket (the split between the head and the cylinder block) then all I can say is welcome to the club!  A lot of bikes on the forum here leak at the head/block joint.  It is repairable, but not quickly.  It will take a full set of top-end gaskets and several hours of dedicated work.  Search the forum here for "top end rebuild" for lots of details on what needs to be done.

If it is a head gasket leak, fear not, your summer of riding is not over.  By letting it leak, you aren't damaging anything anymore then it already is.  Short of it peeing on the ground, you aren't causing a tire slip situation either, just oily pant legs and shoes.  Keep a close eye on your oil level and use a rolled up paper towel crammed between the fins over the leak site to keep it under control.  Rebuild the top end when you have time.

I was hoping this would be it.  I changed the tach cable seal, seemed like it might have dripped once or twice, but figured it might be something I could live with for a little while.

Planned to go 2up riding this afternoon.  Was doing ok, but I was seeing some smoke when I stopped at lights from oil hitting the pipes.  Got on the highway, max speed was 65 mph, pulled off on the next exit and my left leg is soaked in oil.  Will get pics up soon.

Rode it on home, had oil through my jeans and on my leg.  I think my fiancee is going to kill me for finally putting down real money on an already worked on, taken care of and ready to go bike.

[MRieck]

I'm tempted to go back to the seller, as I have less than 20 miles of seat time on the bike, but I don't know how far I'll get that way, or how understanding I would be in his place.

Maybe others will disagree, but please don't go back to the seller.  You buy a used, 30+ year old bike, you take it with all its problems.  Just use this as an opportunity to do a full top end check/rebuild.  It's well within your grasp, and probably needed by this time, and you'll have yourself an engine in good tune and that you know how to fix when it has problems. 

I agree.

[turin39789]

still havent gotten to the pics, but they are on the camera. might have time on monday to get them up.

The seller has put the idea into my head that the leak may be coming from where the exhaust mates to the engine, and now when I look at the bike it appears that the oil might be coming from the #1 exhaust.  Could be as simple as a bad crush gasket there?  Or would that point to a valve leak?  I have a compression tester that I picked up at a yard sale a while back, never used it but it might be time to try it.  The timing light that I got with it worked fine on my 4 cylinder car but I couldn't get it to work on my old 550, then again it was my second time trying to use one.

[mystic_1]

There's no oil behind the exhaust gaskets, in fact there's little oil anywhere near the exhaust ports at all.  The leak is probably coming from either the head gasket or the valve cover gasket.  If it's coming from the head gasket, suspect the sealing pucks mentioned above.

Wash and degrease the area thoroughly, then dust it it with talc or something similar, then run the bike.  The source of the leak should become apparent.

mystic_1

[turin39789]

There's no oil behind the exhaust gaskets, in fact there's little oil anywhere near the exhaust ports at all.  The leak is probably coming from either the head gasket or the valve cover gasket.  If it's coming from the head gasket, suspect the sealing pucks mentioned above.

Wash and degrease the area thoroughly, then dust it it with talc or something similar, then run the bike.  The source of the leak should become apparent.

mystic_1

will do.