CB750 Compression Test & Motorcycle Clutch Adjustment | Honda Cafe Racer Project Bike | 03
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- เผยแพร่เมื่อ 15 พ.ค. 2022
- Honda CB750 Compression Test & Motorcycle Clutch Adjustment | Honda Cafe Racer Project Bike | 03
In this Honda CB750 Cafe Racer project episode, I am checking some of the issues I found during the first start of my new Honda Cafe Racer build.
Decent budget compression tester: ebay.us/VHtsJz
When I first started this bike, it seemed to have an oil leak from the head gasket, it also seemed to have quite an exhaust leak. I also noticed that the gear change didn’t seem to be engaging the gears correctly.
I decided to compression test the engine using my compression tester. It is quite easy to use and gives a good indication of how healthy each cylinder is. I found that the pressures seemed quite low. If I hadn’t noticed the oil leak I may have thought about giving the engine a few heat cycles to see if they improved. Sometimes when an engine hasn’t been run for a long time the rings and valves need to settle in a bit. But I am intending to have the head off the bike anyway so this isn’t the way I will try to address it.
I also took a look at the gear change. It has a set of rear-set pegs, so I wondered if the linkage was causing the problem. They seemed to be OK, so I turned my attention to the clutch. I could see that the clutch push rod adjuster was quite far in, so I reset it. This did the trick and the gears seem to select fine now. That should save me a gearbox, clutch strip-down :)
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Looking forward to seeing this old cb750 on the road again. Makes relaxing viewing.
Me too! But, it's going to take a bit of work, it will happen! Keep having to learn new skills, I am playing at being an upholsterer at the moment.
Compression test with the carbs off or with full throttle will give better results, but looks like mismatched reading so top end off to investigate anyway.. Good call on the clutch. Look forward to next instalment.
Forgot to mention the throttle was wedged fully open. I was surprised that it went up with a bit of oil. Be interesting to see what I find.
@@SPANNERRASH Indeed, the motor looks like it has been cleaned. always good to strip it and not have to take the motor out of a newly coated frame later.
Good call. Should check valve clearance too.
Nice watching your progress!!
Thanks, Hope I can keep the progress up.
Good shout regarding the clutch adjustment. Looking forward to seeing how you get the engine out (will you lay the bike on its side and drop it out or lift it out?). Maybe a good investment would be an after market wiring loom from DSS. Would save a lot of messing around with all those loose wires! Good luck with the project and I'm looking forward to the next installment.
Just seen there are other comments on how to get the engine out. I used a piece of 2" X 4" strapped to the back of the engine with one end long enough to feed through the engine space as the engine was lifted out of the right hand side. My daughter and I lifted it quite easily (and she's skinny!). Looking forward to see which way you go.
I've got some ideas for the wiring, hope they work out. I am really impressed with eh M-unit. You will have to watch the video where I wash my old loom in the sink to see how much I enjoy messing around with wires :)
Another great vidio Les. Love watching what you're doing with the bikes. Looks like we're going get quite a few videos with this bike. Great price. I'm not jealous 🤣 .Good luck with it. Cheers Alan
I think I am going to really enjoy doing this one. We're still discussing the colour. I am from the "Shell Suit" generation, doesn't go down well with the millennial though!
I had a 76F they had a clutch that slipped from factory I put a Barnett clutch in did the trickI also put a heavier chain on and sprockets
I'll have to see how the clutch works out, not sure if I am going to open that part up yet. Also this has a heavier chain, that doesn't look like it has been used at all. Not happy with the way the front sprocket was attached, you'll see it in a later video. I'll need to look at that when I come to put everything back.
Hi Les, another great video, yes you are correct, a bit of lateral thinking and a bit of research but then thats what we do when we have these old bikes 😀
Really enjoying the videos as always and look forward to the journey ahead, inspirational and educational as always mate 👍
Just need to sort workshop out before i start on k3 project and some dohc ones too ! Thanks again for taking the trouble and time to post !
Thanks Tom. Working on an old bike is being creative with a wonderful 3 dimensional puzzle. No wonder we enyoy it. Spend more time on research an pondering than any spannering I get to.
Great video as ever and I got a mention!, does life get any better?.
I’m sure you already know that the way to take the engine out is lie the bike on its side and lift the frame off the engine, I didn’t know that when I did mine and Christ they are heavy to manoeuvre out! 😄
Hi Mark, I do know the lie it on the side method. You'll have to wait for the next video to see if that's how we do it! :)
what year is the CB 750 ?
The frame is a 1975 F series. The engine is also an F series with GE in the number, but the actual digits, 100nnnnnnn with the last 4 being less than 7414, would make it a Sandcast, which it isn't, I can't see any listing of these engine numbers so I don't really know the year. It isn't the number on my V5 (title) document which has a 1979 engine number. Hope this helps. Maybe somebody will comment about the F series frame and engine numbers to clear it up.
One year I think was a fast cb 750 was in 72 but that's a guess they used to use those motors for choppers back in the day