Author Topic: help, nasty noises from my engine. (Read 3727 times)

sportsvan · « **on:** October 24, 2010, 12:25:11 PM »

today i finally got my 78 f1 running after buying & rebuilding a set of carbs which took ages to clean & sort out. cleaned out the fuel tank, replaced the engine oil & connected a battery (balanced on a bucket as it is a car battery !) she eventually fired up & the noise is bad. all 4 cylinders are firing but there is a nasty clattering sound coming from the engine, i ran the bike for 5 minutes but not above 2.500. at one stage (for about 2 seconds) the clattering noise stopped & the engine was quiet as a mouse.
i have not rebuilt the engine & it has done 24,000 miles here in the uk. i dont know when it was last used but probably 3 years approx. the oil pressure light goes out after 1 second, no smoke from exhaust, all cylinders firing (all downpipes getting very hot)
any advice please?

ps. the previous owner said the bike went like a train but when i bought it the carbs had been taken off for overhauling & then,,,,,,LOST !

WHATEVER HAPPENS, I AM HAPPY TODAY !

nancy · « **Reply #1 on:** October 24, 2010, 12:41:29 PM »

I hope u replaced the oil? For the sake of the motor and clutch. Clutch will be buggered in old oil and may be making a racket. Can be relivened with fresh oil..maybe.
Regards
Mark

lrutt · « **Reply #2 on:** October 24, 2010, 01:10:13 PM »

I'd say it's likely the clutch and primary chain slapping around due to unsynched carbies. They can sound like holy hell if things are out of wack. That's just my guess as I'm not sure exactly why kind of noise you have.

If you have that good of oil pressure on fresh oil then work on getting the carbs synched up. I'd also recommend cleaning the sump screen on a bike that has sat around for a while. $10 gasket from Honda and clean out the bowels of the old gal. Try again.

sportsvan · « **Reply #3 on:** October 24, 2010, 02:29:59 PM »

i have synchronised the carbs,(they have been totally cleaned & i even bought an ultrasonic cleaning machine !) the oil is fresh, the noise seems to be coming from the top end of the engine. i have listened using a screwdriver to my ear but can't pinpoint the noise. (will clean the strainer gauze soon) is it easy to do?

thing bugging me is when i had that 2 seconds of lovely quiet in between the clattering.

scunny · « **Reply #4 on:** October 24, 2010, 02:33:55 PM »

could be a loose tappet adjuster.

sportsvan · « **Reply #5 on:** October 24, 2010, 02:37:09 PM »

will check the tappets tomorrow. still cant see why it ran quiet for those 2 seconds though !

jessezm · « **Reply #6 on:** October 24, 2010, 02:59:09 PM »

Have you adjusted the tension in your camchain?

wrenchmuch · « **Reply #7 on:** October 24, 2010, 03:17:08 PM »

When you next run it make sure you have oil in the head by checking the 2 outside exhaust valve adjustment caps while its running . If things are good a lot of oil might come out so be ready to put the caps back or shut it down quickly.

sportsvan · « **Reply #8 on:** October 24, 2010, 03:31:13 PM »

i dont know how to adjust the camchain as i cant find it in my haynes manual. i did pour about 1/2 a pint of oil into one of the tappet inspection cap holes before i tried starting the engine. how do i adjust/ check my camchain ?

Scott S · « **Reply #9 on:** October 24, 2010, 03:47:22 PM »

Did you adjust the valves? I'd do a valve and cam chain adjustment, then try synching the carbs.
Did you bench synch the carbs?

Spanner 1 · « **Reply #10 on:** October 24, 2010, 06:08:04 PM »

Folks who are not familiar ( not saying your not ! ) with the SOHC4 motors often freak-out when they start the motor after a 'slumber' and hear the normal clutch rattle in the motor which is freakin' loud and can only be quieted by a very accurate carb sync....... or pulling the clutch lever and waiting a few seconds. Does your bike have a clutch cable on it yet ?

wrenchmuch · « **Reply #11 on:** October 25, 2010, 05:00:01 AM »

Pouring oil into the top end before starting is a great idea . You also need to make sure the top end is getting oil while it is running by removing the caps while it is running . Little pieces of junk can block the oil jets in the head . This will wreck the cam , rockers , and bearings in the head .
http://forums.sohc4.net/index.php?topic=369.0
Check the third posting above for info on cam chain adjustment . Before you release loosen the tensioner's bolt to release the plunger , put something in the rear of the tensioner and push on it lightly . When you release the bolt you might feel the plunger move in . With the bolt loose push firmly on the plunger . Does it bounce back when you release pressure ? If so ,the plunger moves freely , remove the something you put in the rear of the tensioner and finish the adjusting procedure . If it doesn't move freely remove the tensioner , disassemble , clean and grease the plunger shaft , and re install . Don't turn the engine with the tensioner removed .
Good luck
Mike

sportsvan · « **Reply #12 on:** October 25, 2010, 06:50:30 AM »

I WILL ADJUST THE CAMCHAIN WHEN I GET HOME FROM WORK THIS EVENING , i did bench sync the bank of carbs & they all start to open together.
when i first bought the bike i removed the camchain tensioner (i was having problems with the kickstarter locking & electric start not operating) this turned out to be a sticky starter clutch. i did turn the motor over without the tensioner fitted by mistake. could this be a problem. (i'm sure the cam timing is ok as the engine runs fine, but noisy.
thanks for all your advice so far.

Scott S · « **Reply #13 on:** October 25, 2010, 12:22:23 PM »

What about the valves? Have you adjusted the valves?

sportsvan · « **Reply #14 on:** October 27, 2010, 02:20:56 PM »

ok then. i checked the valve clearances, ok, did canchain tensioner adjustment (spring & plunger are both free) .after 2 days of rain & work i went outside (this is england in the autumn (fall to you Americans) connected my car battery up & she fired up, STILL NOISY) PULLED THE CLUTCH IN FOR 20 SECS, STILL NOISY . TURNED ENGINE OFF AS NOISES STARTED TO GET WORSE, found canchain tensioner plunger end level with rear of body

basically i have this situation now: when i rotated the engine backwards (in gear using the rear wheel to turn it) cam chain tensioner plunger would move in & out (looking into the hole on the adjuster) now, the engine will not turn over (it did not seize up) i removed the starter motor & the 2 left hand engine covers, all looks ok.
i removed the camchain tensioner adjuster on rear of cylinder (chain has some play but will not move)
looks like the problem has to be with camchain tensioner / components. has anyone got any ideas.

if these hondas were as simple as my XT 500 life might be a bit less stressful.
thanks.

scunny · « **Reply #15 on:** October 27, 2010, 03:02:24 PM »

your cam sprocket retaining bolts might have backed out. just throwing that one out for a looksee.

aasp87 · « **Reply #16 on:** October 27, 2010, 06:49:14 PM »

Quote from: wrenchmuch on October 24, 2010, 03:17:08 PM

When you next run it make sure you have oil in the head by checking the 2 outside exhaust valve adjustment caps while its running . If things are good a lot of oil might come out so be ready to put the caps back or shut it down quickly.

Hi, I have the same nasty noises on my CB550's head... I suspect that there's not enough oil coming up to the camshaft, when I remove the valve caps there was only a poor oil splash, how much it's the normal amount of oil there?
Thanks

sportsvan · « **Reply #17 on:** October 28, 2010, 03:00:02 AM »

well it looks as though i'm gonna have to do a top end rebuild with new camchain & tensioner & any other scary things i find inside.
how much of a pain is it to remove the engine, & can i lift it out myself (i am not a wimp or a body-builder !)

is this a big job & should i look for any specific known faults with these engines at the same time ?

HedNut · « **Reply #18 on:** October 28, 2010, 03:26:52 AM »

Cheap stab...
http://forums.sohc4.net/index.php?topic=64333.0

You can do the work without pulling the engine....otherwise...I had to lay my bike on its side and squirrel the engine out by lifting the frame off of it. (that involves removing pretty much everything) But I'm sure there's a better way!

Good Luck!

scottly · « **Reply #19 on:** October 28, 2010, 10:01:20 PM »

Quote from: sportsvan on October 27, 2010, 02:20:56 PM

basically i have this situation now: when i rotated the engine backwards (in gear using the rear wheel to turn it) cam chain tensioner plunger would move in & out (looking into the hole on the adjuster) now, the engine will not turn over (it did not seize up)

I suspect you messed up when you turned the motor backwards with the adjuster loose; the chain may have drooped down where it wraps around the crank, locking the motor.
PS It makes problem-solving more difficult when you start a new thread, leaving out the prior details...

Legin · « **Reply #20 on:** October 28, 2010, 11:09:33 PM »

Stating the obvious but you did tighten the pinch bolt on the adjuster ?

bryanj · « **Reply #21 on:** October 29, 2010, 05:19:40 AM »

If its 78 it aint an F1,

Turning the motor with the adjuster mech removed can allow the camchain to jump the sprocket and posibly bend valves

sportsvan · « **Reply #22 on:** October 29, 2010, 11:22:27 AM »

1, NO i didn't do up the pinch bolt. think this my stupid fault

2; yes it is a 1978 F registered april 1978 engine number cb750f .....
it is an f1 supersport.

bryanj · « **Reply #23 on:** November 17, 2010, 10:06:08 PM »

Might be registered 78 but what is the build date on the vin plate?

BeSeeingYou · « **Reply #24 on:** November 17, 2010, 11:05:05 PM »

Isn't there a difference in the model identification between the U.S. and Europe/UK? An F1 in the U.S. is not the same year as an F1 in Europe/UK.

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Author Topic: help, nasty noises from my engine. (Read 3727 times)

aasp87