MisterButtercup
Member
Hello! Starting a rebuild thread for my 1980 CB400T with 37,400 miles. Going to use this as a way to keep my notes together and in the same place, as well as ask questions of the knowledgeable folks here. The previous owner told me that it needed a new fuel filter and spark plugs, but it had a newer chain and tires that he put on before it was parked, and would probably start with a new battery and plugs.
Pick it up, and find out that the front brake lever is both a bit stiff and doesn't do anything to stop the bike. Went to unload it from the uhaul trailer and the bike started leaning, I try the brake but nothing happens and the bike tips over, denting the fuel tank on the side rail, enough that some paint flaked off, but not enough that I'm worried about any holes or anything (it only dropped about 1-1/2 ft onto it's side, thankfully). Was able to laugh and say "Well, it's mine now!" and stopped worrying about any other cosmetic issues. There was also some white crusty residue around the bottom of the brake reservoir, so I'm thinking that one of the seals broke due to age, so a master cylinder rebuild kit will be purchased for a rainy day rebuild, both for lever as well as the caliper.
My neighbor(who has a '93 goldwing) asked me about the tires, and we checked the date codes, tires were new in late 2005. So I'll use those for now so it has something rubber, but will change those out before I hit any decent speeds or any roads with anything resembling a curve.
In late May/early June I changed the oil - complete with new filter washer - changed out the spark plugs, put some new fuel in it - drained/flushed the carbs with the new fuel, and was able to get it running! I rode it for 1.2 miles up and down a side street, and pushed it for another .2 miles when it died to try and help it get back home. It would run ok, making a lot of noise, but then it seemed like it would heat up and I would lose throttle response. no matter what it would just bog down, and then I'd have to open the choke to try to start it, and even if it did start while warm, with the choke open, it still wouldn't rev and would soon die regardless.
Also noticed a tiny bit of fresh oil had leaked out onto the front of the engine, by the head gasket area on the right cylinder.
Borrowed a compression tester, and was getting around 160/170 on both cylinders. Also noticed when giving the compression test that ever now and then a spurt of air would blow out from the valve cover gasket on the back left side. Not every time, but enough to notice and think to myself "hey this shouldn't be a thing..."
Also, when doing the compression test I saw that the left side spark plug was already oily, The right side was not.
The chain is rusty in the middle, but doesn't have kinks. The sprockets are definitely somewhat worn, but the previous owner had already purchased new sprockets, but never put them on! Be jealous of my completely brand new and shiny sprockets. I'll keep an eye on this chain, and when it starts showing wear I'll go ahead and replace everything, but for now it should be fine.
That's how it sat for the rest of June and July, and then a week ago I realized that it's not getting any more fixed, and I just need to start doing something! Had paralyzed myself into worrying about what to do with the new gas I sloshed through the tank, but it turned out that it wasn't too bad, and the few rusty particles were easily filtered by a coffee filter, I can use that in other things, and the best part, the new gas in the tank isn't actually rusty! so I guess it was just a few spots, but no new rust, and the gas is mostly clear, but not any bits were rust tinged, so really really happy about that. Keeping the gas in there for now.
I pulled the carbs off, labeled the throttle(both) and choke cables. The carb intake boot on the engine was already cracking when I started, and were already shot. I wiped out the cylinder intakes and stuffed some paper towels in the holes so critters don't get any ideas.
Next up(tomorrow, Saturday the 16th if I can swing it) will be re-installing my new battery and testing the LongDistanceRider recommended voltage points to rule out any potential electrical issues, I want to be sure those gremlins are fed before midnight.
The last thing I can think of is I need a new gasket for the rear brake light, and also to fabricate mounts for the new bolts, as two of the three mounting threads broke off, and I want more than just one small (8-32nd diameter) bolt to keep it on.
Questions - Answers appreciated but never expected, I know there are a lot! Again, this is my journal/build record for the motorcycle, and these are also questions that I need to ferret out and get answers to on the restoration journey to make sure that I'm keeping track of everything. Let me know if there are more that I need to ask! So please, if you don't feel like answering some or all of these, don't! I'll be back with notes and more updates as I go along.
Overall/Random:
Carbs
If you read this far, then I thank you, I apologies for the lack of pictures, will re-read how to get those set up on the site and try to get some posted soon, and also I hope you have a great Weekend!
Pick it up, and find out that the front brake lever is both a bit stiff and doesn't do anything to stop the bike. Went to unload it from the uhaul trailer and the bike started leaning, I try the brake but nothing happens and the bike tips over, denting the fuel tank on the side rail, enough that some paint flaked off, but not enough that I'm worried about any holes or anything (it only dropped about 1-1/2 ft onto it's side, thankfully). Was able to laugh and say "Well, it's mine now!" and stopped worrying about any other cosmetic issues. There was also some white crusty residue around the bottom of the brake reservoir, so I'm thinking that one of the seals broke due to age, so a master cylinder rebuild kit will be purchased for a rainy day rebuild, both for lever as well as the caliper.
My neighbor(who has a '93 goldwing) asked me about the tires, and we checked the date codes, tires were new in late 2005. So I'll use those for now so it has something rubber, but will change those out before I hit any decent speeds or any roads with anything resembling a curve.
In late May/early June I changed the oil - complete with new filter washer - changed out the spark plugs, put some new fuel in it - drained/flushed the carbs with the new fuel, and was able to get it running! I rode it for 1.2 miles up and down a side street, and pushed it for another .2 miles when it died to try and help it get back home. It would run ok, making a lot of noise, but then it seemed like it would heat up and I would lose throttle response. no matter what it would just bog down, and then I'd have to open the choke to try to start it, and even if it did start while warm, with the choke open, it still wouldn't rev and would soon die regardless.
Also noticed a tiny bit of fresh oil had leaked out onto the front of the engine, by the head gasket area on the right cylinder.
Borrowed a compression tester, and was getting around 160/170 on both cylinders. Also noticed when giving the compression test that ever now and then a spurt of air would blow out from the valve cover gasket on the back left side. Not every time, but enough to notice and think to myself "hey this shouldn't be a thing..."
Also, when doing the compression test I saw that the left side spark plug was already oily, The right side was not.
The chain is rusty in the middle, but doesn't have kinks. The sprockets are definitely somewhat worn, but the previous owner had already purchased new sprockets, but never put them on! Be jealous of my completely brand new and shiny sprockets. I'll keep an eye on this chain, and when it starts showing wear I'll go ahead and replace everything, but for now it should be fine.
That's how it sat for the rest of June and July, and then a week ago I realized that it's not getting any more fixed, and I just need to start doing something! Had paralyzed myself into worrying about what to do with the new gas I sloshed through the tank, but it turned out that it wasn't too bad, and the few rusty particles were easily filtered by a coffee filter, I can use that in other things, and the best part, the new gas in the tank isn't actually rusty! so I guess it was just a few spots, but no new rust, and the gas is mostly clear, but not any bits were rust tinged, so really really happy about that. Keeping the gas in there for now.
I pulled the carbs off, labeled the throttle(both) and choke cables. The carb intake boot on the engine was already cracking when I started, and were already shot. I wiped out the cylinder intakes and stuffed some paper towels in the holes so critters don't get any ideas.
Next up(tomorrow, Saturday the 16th if I can swing it) will be re-installing my new battery and testing the LongDistanceRider recommended voltage points to rule out any potential electrical issues, I want to be sure those gremlins are fed before midnight.
The last thing I can think of is I need a new gasket for the rear brake light, and also to fabricate mounts for the new bolts, as two of the three mounting threads broke off, and I want more than just one small (8-32nd diameter) bolt to keep it on.
Questions - Answers appreciated but never expected, I know there are a lot! Again, this is my journal/build record for the motorcycle, and these are also questions that I need to ferret out and get answers to on the restoration journey to make sure that I'm keeping track of everything. Let me know if there are more that I need to ask! So please, if you don't feel like answering some or all of these, don't! I'll be back with notes and more updates as I go along.
Overall/Random:
- One of the sponsors of this website is scrambler cycle. How well is their parts fitment? I'm leery of parts copies but thinking of using them for some gaskets and carb boots(mine were cracked when I looked at them the wrong way they cracked some more) but would be nice to know before purchasing that there won't be issues.
- It seems like the mesh screen for the petcock on this exact motorcycle is unobtainium, Can one be used from an earlier/later model CB? Does it matter?
- The previous owner told me that his mechanic recommended a fuel filter change as he had the same bogging issue, but these bikes only have the mesh screen, no other inline filter.
- Does this bike have a cush drive?
- This is a reminder for me, will dig into that when I get closer to getting a new back tire/rear brake shoes.
- Keep a half gallonish of fuel in the tank, fill it, or empty it and let it dry out?
- For the Front brake reservoir, the white plastic has spiderweb cracks all around it. Send it, replace it, or doesn't really matter? I'm leaning toward replacing it if I can find a reasonable replacement.
- Also not sure how to remove just the reservoir, so might try to source a front brake lever/reservoir/master cylinder and replace the entire thing.
- I adjusted the rear brakes a little bit, but will need to adjust them a lot more before I can get them within spec/would like them to engage sooner than 2-1/2 inches down ballet toes. Would it be recommended to just get new brake shoes and replace those when I get a new rear tire? Haven't taken the back tire off yet to look at the brakes, but thinking that might just be something to do, as I like brakes and stopping whenever I want to.
Carbs
- Question for Long Distance Rider regarding the carb rebuild and recommending replacing the screws with the allen bolts, is there a recommended resource for those bolts?
- The left side carb had a lot of what looks like carbon buildup on the intake as well as the butterfly valve on the carb. This was also the side where there was oil on the plug. Would changing out the valve cover gasket solve this? or is this a sign that the timing is a bit off?
- As noted above for the carbs, I plan on taking off the valve cover and at least replaceing the gasket. Will probably also check clearances while I'm there.
- Is this also a good time to check timing?
- Thinking hard about pulling the head and changing that gasket as well. I will read more about it in the shop manual, but is that a job that should just wait, or something that "while I'm down there" it's worth doing? The small oil leak has me concerned, as that's also something the previous owner had mentioned, and I could see where it had been leaking.
If you read this far, then I thank you, I apologies for the lack of pictures, will re-read how to get those set up on the site and try to get some posted soon, and also I hope you have a great Weekend!
