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exhaust seems to get too hot just after a few secs?
i have a 94 suzuki dr125.ive jus found out the manual isnt right as it states the valve clearance needs to be the same for intake & exhaust.but when both are set the same the exhausts valve clearance closes up.which isnt supposed to happen. so today instead of setting both clearances to .08, i set the intake to .08 and the exhaust to .13. now heres where it gets important. i started the bike up and it started very quickly(as ive been waitin 2 wks on an offset wrench to set the valves) but as i was slappin the left side fender on(it jus pops on into lil rubber boots) and i got on the bike the exhaust was very hot to my leg( it hadn been started up even 15 secs yet) i tapped the exhaust header w/ my finger and it was very hot....any suggestions on what might be going on?? do you think i set the exhaust valve incorrectly?? the fuel mixture is fine,lean wud cause the engine to run hot and my bike doesnt run lean as i am an excellent carb plumber and the spark plug says so. so any help as to what may be going on wud be appreciated,also the rocker arms hittin the valves seemed a bit louder than it normally is but i figure the valve springs are gettin weak.
yes it says to set them cold. u break stuff wen u do it hot. and i figured weak springs wud cause more chattering of the valves as would a worn down rocker arm or shaft
i figured sumbody wud tell me im settin the exhaust too wide,if the exhaust jus get hot that fast ill start to worry more bout the noisy chattering coming from the top end
andy if u didn read the 1st time i set em 2 specs i came back an the exhaust was closed up.so i was looking for abetter clearance for the exhaust or wondering if the way i had it set was 2 wide causing the quick gain in heat
timing is great, engine's at TDC and the cam is facin down // \\
and wrong again andy, wen the engine is warm i can stick the feeler gauge an the exhaust remains where .08 fits but the exhaust swells up closed,which is why i set the exhaust clearance wider
an in know the exhaust gets hot i jus didn kno it happened so fast...if the clearance is closed shut its gonna keep that valve open and not seat properly correct? which is y this engine needs a wider exhaust clearance. i wud think they'd both swell a lil my self but the intake stays where i last left it even when i check it warm,the exhaust valve was my prob i wasnt sure about. i guess it was jus alil 2 wide instead of .13 i brought it down a size feeler on the exhaust and its quieter now.im happy now i jus needed to experiment w/ the exhaust clearance myself.its good now tho
and yes my bike will tell me exactly how the air/fuel mixture is by the plug, it'll be coated w/ white residue(lean) or a black soot(rich) on the thread of the plug. my spark plug will give me an exact reading of how the air/fuel mixture is.
6 Answers
- Anonymous9 years agoFavorite Answer
Sounds to me like you have set the clearances correctly. You mention the exhaust header which will get hot enough to burn within seconds. 15 seconds running at the header will be hot enough to burn your skin.
- AndyLv 79 years ago
Things expand when they got hot.That's why the clearance decreases.That's the purpose of having the clearance in the first place.Too much clearance can make the valve train noisy.I would reset it to the specs.The exhaust valve clearance reduces faster because that valve gets hot faster than the intake valve.My guess is if you let it warm up fully you'd find the reduced clearance would be the same on both valves.The header pipe is going to turn hot within seconds(especially right near the head).If you really think it's abnormal and your sure the carb is adjusted right then like the other poster said..i would suspect the timing is wrong.
Edit When you say the engine is at TDC and the cam is down your talking about static timing.We are talking about ignition timing,a completely different thing.
- The DevilLv 79 years ago
Read your manual again carefully. Does it say set the valves cold or set them hot? Call the Suzuki shop and talk to a mechanic about the valve setting and check that against the book. Write in the correction. If the rockers are noisy, the valves are set too loose. That would make the exhaust valve open a tiny bit late. Exhaust pipes can get hot enough to light a cigarette. The valve springs are not making the noise. Excess valve lash is the reason.
- ?Lv 79 years ago
Opening up the lash on the exhaust is not going to cause the issue you speak of. I would bring your cold lash on the exhaust in to about .010-.011. If you have weak valve springs, the extra lash will put alot of opening and seating intensity into the valve which will induce vale bounce.
Looking at the color of the porcelain on the spark plug is NOT where you read fuel enrichment. If the heat range of the plug is right for the application, you can have a slobbering rich mixture and STILL have a bone white porcelain. Also, you can't get good plug readings without putting the engine under a load. Unleaded gas is also VERY difficult to read on a plug.
Over octane an engine will make hot/late burn in the exhaust, retarded ignition timing will, too high of a distillation curve(boiling point) with the gasoline can cause it.
BIG air bleeds in the carb with small jets will make lean transitions in the fuel curve.
Lean burns slow and late.
Email: camshaftshaun@gmail.com
Source(s): Camshaft design/manufacturer, full competition race engine building/development, failure analysis of internal engine components, carburetor blueprinting, drive-ability/mpg/durability expert, super-tuner. - How do you think about the answers? You can sign in to vote the answer.
- Anonymous9 years ago
I would check your ignition timing.
Also, recheck the valves.
listen to it. If the valves are louder, you might be right. Triple check it all.
Just don't drive it until you figure it out. Better to take your time than ruin your engine.
Good Luck!
Source(s): Mechanic ./ owner Sakowski Motors and Ride Free Motorcycle Tours www.ridefree.com
