Skip to main content

Honda CB750

So, while I get the Z750 back on the road I'm using my backup bike. its a 1982 Honda CB750 imported from Japan in 1999. I've had it since 2010 and it's been off the road more than on since then. it needed a new exhaust, and I just didn't make the time to get it fixed, so that kept it garaged for a few years.

but it's all up and running now (well, sort of). I was riding it to work a few weeks ago, and all was fine, but on the way home, it started to play up. I'm not sure how to describe it really. I was using a steady throttle doing about 65 (it is an old bike) when all of a sudden it started to feel like the breaks were being pumped on and off fairly quickly. I pulled in the clutch and let it coast and it was fine. that ruled out the breaks to me.

this went on for a couple of miles, and then it cleared up and was fine again.

when I got home, i did what you always do when you have problems - I Googled it. Some of the results pointed to HT leads, and as it had been raining and then dried up during the ride home, I felt that this was the probable cause. off to david silver where I ordered new HT leads, new spark plugs and new spark plug caps.

it took a couple of weeks for the HT leads to be in stock, but they eventually arrived. It's still amazing to me that we are all getting so impatient. it's not that long ago that any mail order would have been 4 weeks for delivery, but these days next day delivery is considered slow !!

anyway, the leads arrived, and one by one I put the new leads and plugs onto the CB750. I did this one at a time so that I didn't get the plugs connected to the wrong connector on the coils. so it was take off cylinder 1 spark plug and HT lead, fit the new plug cap onto the lead and fit to the bike. new plug in and connect it up

onto cylinder number 2. and yes you guessed it. stuck fast. Oh F***. what to do now? 

well after the panic subsided, I made sure that I had a really good fitting spark plug socket on it and tried again with a bit more force, and what do you know. it turned. but boy was it corroded in there, I needed to use the socket until it was all the way out. the threads were covered in rust. I tried to get the crap out of the way of the plug hole, but didn't want to do too much as getting crap into the engine s very easy when there is a great big hole directly into the cylinder.

well, at least it was out. new HT lead, plug cap and plug back onto the bike.
I got lucky with the last two cylinders as they were fine, but I'm really going to need to keep an eye on cylinder 2.

so, it's back on the road and now it runs...... just as badly as before.

after about 10 minutes of riding, it starts playing up and then after about a minute, it cleared up again. sod it!

so now, I'm guessing it's a fuel delivery issue. I don't think it's the carbs as I would guess that it would always play up, so I'll put an inline fuel filter on it and see if that helps.
and until I get that filter, its fingers crossed whilst riding it.
Labels:

Comments

Post a Comment

Popular posts from this blog

Project Z750 part 16

The piston puller has arrived. it looks like a pair of pliers, but works opposite so that when you press the handles the "nose" of the pliers expands. the idea is that you put the nose into the piston, grip very hard and turn and pull the piston so that it comes out. the theory is great, but actually using one isn't. in use you are trying to grip as hard as you can, and at the same time trying to pull the piston out of the caliper (as well as maybe turning it if it's stuck like mine). it took a herculean effort to get one of the pistons out, I was gripping as if my life depended on it, trying to twist the piston and pull it out of the caliper. when it turned (a little) it gave me renewed hope of getting both pistons out, and eventually the piston was out, so just one more left. so now on to the fifth and final brake caliper piston. I put the piston puller tool into the caliper, gripped with all my might (no laughing please) and twisted. Well something mo...
Post a Comment
Read more

Project Z750 part 18

I have done a bit of reading on how to clean brake caliper pistons, and found an article that said you could use fine wet and dry to clean corrosion off them [ http://www.motorcyclenews.com/new-rider/choosing-kit/2006/november/jan26-05-how-to-service-brake-calipers/ ]. as it suggested using 1500 grit wet and dry, I decided to be cautious and start with 3000 grit. I cut the wet and dry into strips about an inch in width. I put some wd40 onto a strip and started polishing the rear piston. After quite a while I started to notice the difference. it was getting cleaner. well, it was working, but it was going to take a long time. well, I was patient and I really didn't want to rush it and ruin the pistons. Over the next couple of weeks, I polished all of the pistons using the 3000 grit wet and dry. As it seemed it was going to take the rest of my life using 3000 grit wet and dry, I decided to take a risk and bought some 2000 grit. yep I was really pushing my luck here. I cut the 20...
Post a Comment
Read more

Project Z750 part 14

I thought that some photos would be in order rather just all that plain old boring text, so here is a front caliper and it's pistons:  This is the caliper before I managed to get the slide off. the pistons show a before polishing started and part way through. Here are the pins that hold the pads into the calipers. again you can see the before and part polished (I hope you can tell which is which) I thought I would show a picture of the rear caliper in pieces: there are more bits for a single caliper than I realised. The rear is a single piston caliper. and one of the front calipers. the front calipers are twin pistons (as I hope you noticed) I dont think that I will be able to remove all of the corrosion from the caliper pistons, so it looks like I will be getting all new caliper pistons. I'll order them once everything has been cleaned thoroughly.
Post a Comment
Read more