I second the request for a video about adjusting carbs on your 400 as well. If you ever get around to cleaning them a video on removing would be a life saver, (and cleaning but there are videos on that around) Thanks for the upload
Yes - that's how you do it. Start the bike, let it warm up and get it idling at normal RPMs and then loosen the lock nut, wait a few seconds then tighten it again. If your bike is like mine, you'll hear the chain quiet down once the nut is loosened. Good Luck!
Important note- the cam chain tensioner should adust by itself by loosening the nut and have it auto adjust. These old bikes the spring gets stuck often. Mine did. Another video on suggests taking the cover off and hitting it with a screwdriver. Much easier is loosening the one nut and when it doesnt move hit it gently with a small hammer. Mine pushed in immeadiately and fixed the problem! 1 minute repair.
I always thought the old Honda twins had both pistons up, or down, at the same time, like an old Triumph or BSA or something. But apparently not, that's interesting to know. Also I didn't know those were three valves per cylinder, also interesting to know.
Sure - I suppose the chain might jump if you were to rev it up while the tensioner is loose but it is intended to be set while the bike is idling. Do a web search on setting the timing chain tensioner for a Honda twin and you'll see that the overwhelming majority of people are doing it this way. You may be right for other types of engines but on a Honda twin, this is how it's done.
I rebuild the carb and synchronize them and it runs alot better, but this high idle is bugging me. I read on line people having this problem is a leaking manifold boots or the valves are to tight. I'm going to try adjusting the valve today. Thank for the info.
I had some valve noise coming from the top-end so I decided to do the valve lash adjustment. Otherwise, the bike ran more or less perfectly. I would think a high idle problem would be caused by something wrong with your carburetors. I would check them first.
I also have a CM400 and mine has become quite noisy around the crankcase-area, I think it might be related to the cam chain. It sounds pretty much the same way that yours did. About the cam chain chain adjustment, did you loosen the tensioner when the bike was running and then it adjusted itself?
Did you have any trouble with it running before and thats why you adjust the valves? or is this just routine maintance? I have the same bike and I am having high idle problems. Sometime it idle fine and sometime it idles fast. I checked intake with starting fluid and no change in idle so manifold rubber boots are fine. I think it my valves are out of adjustment. Any ideals Thanks
Hi, I know this is an old video nut I need some help on my cb400n (same engine) was running fine but wanted to adjust the timing chain tension. Followed the manual, was running stationary and wanted to loose the nut. It was already very loose and the engine sounded different (not in a good way) I cant tighten the nut down. How can I fix this?
My 79 CM400T sound much like yours did before you adjusted the cam chain. I've adjusted the valves and cam chain but it still has excessive valve noise in the top end. Do you think maybe the cam chain tensioner is not working properly?
holy fuck man iv been working on bikes sense i was 8 years old and i know from experience that if you loosen it while its running there nothing to hold tension on the chain and it will just slap and jump timming big time and even bend your valves this is the first time iv ever herd of doing that hahahah maybe so but not likely
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I second the request for a video about adjusting carbs on your 400 as well. If you ever get around to cleaning them a video on removing would be a life saver, (and cleaning but there are videos on that around) Thanks for the upload
Yes - that's how you do it. Start the bike, let it warm up and get it idling at normal RPMs and then loosen the lock nut, wait a few seconds then tighten it again. If your bike is like mine, you'll hear the chain quiet down once the nut is loosened. Good Luck!
Important note- the cam chain tensioner should adust by itself by loosening the nut and have it auto adjust. These old bikes the spring gets stuck often. Mine did. Another video on suggests taking the cover off and hitting it with a screwdriver. Much easier is loosening the one nut and when it doesnt move hit it gently with a small hammer. Mine pushed in immeadiately and fixed the problem! 1 minute repair.
Perfect video, very educational.
I always thought the old Honda twins had both pistons up, or down, at the same time, like an old Triumph or BSA or something. But apparently not, that's interesting to know. Also I didn't know those were three valves per cylinder, also interesting to know.
Both pistons indeed do go up and down in sync.
I have an 81 CM400 and the way it works is the top end cam has two up and two down as per stroke.
Yes they both go up and down together like a Triumph ,Bsa or Norton, I have a CM450e a CM450c and a CMX 450 Rebel and theyre all like that.
Sure - I suppose the chain might jump if you were to rev it up while the tensioner is loose but it is intended to be set while the bike is idling. Do a web search on setting the timing chain tensioner for a Honda twin and you'll see that the overwhelming majority of people are doing it this way. You may be right for other types of engines but on a Honda twin, this is how it's done.
thanks for the help, got exactly what i needed to know from this.
Glad my video helped - thanks for watching!
I rebuild the carb and synchronize them and it runs alot better, but this high idle is bugging me. I read on line people having this problem is a leaking manifold boots or the valves are to tight. I'm going to try adjusting the valve today. Thank for the info.
I had some valve noise coming from the top-end so I decided to do the valve lash adjustment. Otherwise, the bike ran more or less perfectly. I would think a high idle problem would be caused by something wrong with your carburetors. I would check them first.
I also have a CM400 and mine has become quite noisy around the crankcase-area, I think it might be related to the cam chain. It sounds pretty much the same way that yours did. About the cam chain chain adjustment, did you loosen the tensioner when the bike was running and then it adjusted itself?
Thanks for posting. I'll be doing this soon.
Possibly - or your cam chain could be stretched beyond it's service limit....
The balancer chain makes a similar noise. Twenty minutes to adjust. Consult a manual because it can be deceptively complex.
cool cool i have the Manuel for mine im gonna half to check er out not saying your wrong iv just never herd of it cool man take care
So you're saying the factory service manual is wrong? Maybe you should go work for Honda and straighten them out!
hey would you happen to have a sitter coil I'm in desperate need of one
Good video but wow your bike sounds sick
How so?
Did you have any trouble with it running before and thats why you adjust the valves? or is this just routine maintance? I have the same bike and I am having high idle problems. Sometime it idle fine and sometime it idles fast. I checked intake with starting fluid and no change in idle so manifold rubber boots are fine. I think it my valves are out of adjustment. Any ideals Thanks
Do you have any videos on adjusting the carbs your 81 cm400 c
+Micheal Hill I don't....yet. If I ever need to adjust them I'll make a video about it.
Hi, I know this is an old video nut I need some help on my cb400n (same engine) was running fine but wanted to adjust the timing chain tension. Followed the manual, was running stationary and wanted to loose the nut. It was already very loose and the engine sounded different (not in a good way) I cant tighten the nut down. How can I fix this?
You may need to replace the tensioner ... Sounds like it make have broke on you
@@SevenFortyOne thanx for the reply. th-cam.com/video/KekP2gNNbyo/w-d-xo.html
this is the tension now. thoughts maybe?
hey two turns for valve adjustment on the same point if is a cm400
My 79 CM400T sound much like yours did before you adjusted the cam chain. I've adjusted the valves and cam chain but it still has excessive valve noise in the top end. Do you think maybe the cam chain tensioner is not working properly?
holy fuck man iv been working on bikes sense i was 8 years old and i know from experience that if you loosen it while its running there nothing to hold tension on the chain and it will just slap and jump timming big time and even bend your valves this is the first time iv ever herd of doing that hahahah maybe so but not likely
hahah you dont do that bud while its running it will jump timming right off the bat lol wise idea i tell ya hahaha
Alot of chatter