element51 Posted April 25, 2009 Posted April 25, 2009 hey guys my 1980 xs400 is making a high-pitched chattering noise around 3k rpm. It's very loud when riding, and happens throughout the whole rpm range. It's been doing this since i first got the bike. Since the clutch was on its way out, I changed the clutch, and also synched and cleaned out the carbs. In a possibly related issue, the engine doesn't pull past 6k rpms at WOT. However, it goes all the way to 9k if i leave it at 3/4 throttle. I uploaded a youtube video so you could hear the sound. Any ideas? http://www.youtube.com/watch?v=ZtvLYmsoPH0
Madison Motorsport Posted April 25, 2009 Posted April 25, 2009 OUCH! That sounds pretty awful. It does sound to me as though it is running dry. Are you certain of good oil circulation?
Moderator drewpy Posted April 25, 2009 Moderator Posted April 25, 2009 not running clean, maybe you have an air leak in the manifold. have you tried spraying wd40 over the inlet sto check for airleaks? checked your valve gaps? could also be tensioner blades for the cam chain
element51 Posted April 26, 2009 Author Posted April 26, 2009 not running clean, maybe you have an air leak in the manifold. have you tried spraying wd40 over the inlet sto check for airleaks? checked your valve gaps? could also be tensioner blades for the cam chain I sprayed starting fluid on the butterfly seals and the carb holders, but there was no change in rpms. is the procedure to check valve gaps in the service manual, or is there a write-up? Can I check the cam tensioner/chain at the same time?\ As far as oil, i changed it recently and its between the marks when the put the bike is on the center stand.
Moderator drewpy Posted April 26, 2009 Moderator Posted April 26, 2009 I sprayed starting fluid on the butterfly seals and the carb holders, but there was no change in rpms. is the procedure to check valve gaps in the service manual, or is there a write-up? Can I check the cam tensioner/chain at the same time?\ As far as oil, i changed it recently and its between the marks when the put the bike is on the center stand. the procedure is in the manual which you can get in the sticky that yamagod has posted. for the cam tensioner, you will need to lift the head off and it might be a good idea anyway, so you can check valves, rockers for wear etc oil should be ideally on the top line, but between is ok, are you using the correct grade (20w 40 in usa, 20w/50 in uk) and are you checking AFTER just resting the dip sick ontop of the casing (ie not screwed in!) drewps
element51 Posted April 26, 2009 Author Posted April 26, 2009 the procedure is in the manual which you can get in the sticky that yamagod has posted. for the cam tensioner, you will need to lift the head off and it might be a good idea anyway, so you can check valves, rockers for wear etc oil should be ideally on the top line, but between is ok, are you using the correct grade (20w 40 in usa, 20w/50 in uk) and are you checking AFTER just resting the dip sick ontop of the casing (ie not screwed in!) drewps I am checking by looking into the sight glass on the side of the crankcase, it's between the lines, using 20w40. I will check valve clearances in the coming weeks, what gaskets do I need to order?
Moderator drewpy Posted April 27, 2009 Moderator Posted April 27, 2009 I am checking by looking into the sight glass on the side of the crankcase, it's between the lines, using 20w40. I will check valve clearances in the coming weeks, what gaskets do I need to order? its cheaper to get a "top end" gasket kit rather than separate items. then you get everything you need ( or thought you didn't need) don't forget you also need a torque wrench for the head. drewps
lhurt Posted April 27, 2009 Posted April 27, 2009 Just to check the valve clearances, you don't need any gaskets as far as I know. I used a bent feeler gauge. There are four gold colors caps on the heads that take a fair amount of torque to remove. When open there is enough room to get a feeler gauge down in there between the rocker arm and the valve. http://www.motorcycleforum.com/showthread....1312&page=2 Also check and make sure it not something else on the bike vibrating at that rpm. My center stand used a make a racket because the rubber stopper had disintegrated. I used a section of bicycle inner tube and some zip ties to fix that. Use a piece of garden hose to help clarify where the noise is coming from. I have an excerpt from the service manual for valve adjustment in word. Is there a way to included it as an attachment? Also I have a couple videos with sound of my engine for comparison if you're interested here: http://lucashurt.blogspot.com/ Luke
Moderator drewpy Posted April 27, 2009 Moderator Posted April 27, 2009 Sorry I thought the reference was for head removal to check the valves and rockers etc. checking valve clearances dont need new gaskets drewps
element51 Posted April 28, 2009 Author Posted April 28, 2009 thanks guys. I havent thought about checking for loose nuts+bolts, but will do so. Adding oil to the top of the line(even a little above it) didnt help. I also noticed that the noise happens most between 3-4k. I'll check the valves this week or the next
element51 Posted May 2, 2009 Author Posted May 2, 2009 the valves were on the loose side, so i tightened them up, and the noise seems to be gone while the bike is stationary. It's been raining here so i didn't ride yet but the valve adjustment seemed to do the trick.
GaSo Posted May 4, 2009 Posted May 4, 2009 Interesting. My bike makes a little noise around 3 to 4k as well, a light clanky noise seemingly irrespective of engine load. I'll have to check my valve clearances as well, thanks for the post and the followup information!
element51 Posted May 5, 2009 Author Posted May 5, 2009 Interesting. My bike makes a little noise around 3 to 4k as well, a light clanky noise seemingly irrespective of engine load. I'll have to check my valve clearances as well, thanks for the post and the followup information! just took it out for a spin today and the engine is much quieter overall, but the noise was still there. turned out that the center stand was hitting the crossover pipe on the exhaust.
GaSo Posted May 5, 2009 Posted May 5, 2009 lol! nice well, you have a happier engine AND now that you've found the source a quieter bike Looking at my center stand I see there isn't any rubber to prevent it from banging around, will have to do something about that myself as well.
lhurt Posted May 5, 2009 Posted May 5, 2009 Centerstand! Wahoo! Do I get a gold start for a helpful recommendation? Glad you got it sorted Element.
Moderator drewpy Posted May 5, 2009 Moderator Posted May 5, 2009 Centerstand! Wahoo! Do I get a gold start for a helpful recommendation? Glad you got it sorted Element.
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