Correct timing chain marks. is a diagram available?
I have a 1991 tt250 .i have replaced piston and rings and new gasket kit, after finding the bike had a seized piston. i got the bike free!.i have the bike running but seems to lack torque at the bottom end. i am unable to find a workshop manual anywhere. looking to see if anyone has better idea for timing marks on the cam shafts. im quite certain i havnt got the timing spot on, can anyone advise me?
Re: correct timing chain marks. is a diagram available?
If the timing chain is off i dont think it would run, id suggest getting you're cams checked and reseat your valves, i have the same bike and an electronic copy of a repair manual, not for the exact same bike however. i have not been able to find the correct copy.
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The valve train, head and cylinder must be removed from the transmission, possibly even the fuel system. You should replace the base gasket as well as the head gasket while reassembling. Be careful to not let the timing chain drop into the transmission and make note of the timing marks as well prior to disassembly. Tie the chain with a string while you slip the cylinder off the piston.
The diagram below should work for you. Put the piston on TDC. the OHC cam gear will have a single mark or may have two marks, see below. Be certain the front side of the chain is taut when mounting the gear. The cam chain tensioner keeps the back side taut.
you probably have time 180 degrees out....4 steps....(1)piston top dead center...(2) camshaft aligned with marks...(3) dist set for #1 cyl to fire ...and (4) timing marks on damper pulley aligned with marker on the cover or eng block...good luck
By "all timing marks seem to be right", are you talking about the timing marks on the alternator rotor or the camshaft timing marks? A 1985 model is a pretty old bike. If it has never had a timing chain or the adjuster guides replaced, you may need to address this issue. Not only do you need for the ignition timing to be correct, you need the camshaft timing to be correct as well.
In your problem line, you stated that you had fuel, and spark. You need three things to get any engine to run, fuel, spark, and compression. Do a compression check on the engine. If the compression is low, it won't start either. Three things can cause low compression. Bad rings, improper camshaft timing, and valves not seating properly.
If you want to get the bike running again, I would suggest you do a "top end job" on the engine. Pull the head and cylinder. Measure the cylinder for wear and bore for a new piston if necessary. Replace the rings. Have a valve job done on the head at a local machine shop. When you put it back together, do so using a new timing chain and adjuster slides. You'll be surprised at what a "New" engine feels like. Good Luck!
Did you just have the motor rebuilt by a reputable shop? If so take it back and explain the problem and they should take care of it.
If not you are kinda on your own. What kinda tick? Could be leaking head gasket, base gasket, bad valve guides, incorrect bore, piston, rings. Incorrect ring gap, leaking exhaust gasket, out of time, etc, etc, etc, etc.
Below is a generic diagram. If only one mark is present it points upward and in line with the crankshaft center line. If two marks are present they line up with the gasket surface of the cylinder head. The piston should be on TDC and the cam lobes should be pointing downward. Be sure the chain is on the crank sprocket, not wedged between the sprocket and the balance weights. Also be sure that the chain is taught on the front side of the engine. Any slack should be at the back side of the cylinder so the chain tensioner can work properly. Can I get a “very helpful” rating on this answer?
Put the piston at TDC (Top Dead Center) by lining up the timing marks on the flywheel and stator. Put the cylinder head back together with the cam installed so the high points of the cam lobes are pointing kind of downward. Pull the cam chain taught on the front side of the engine. Put the chain on the cam gear such that, when bolted to the cam, the index mark or marks are in the proper position.
The proper position depends on what markings are on the cam. Some bikes have a single mark; an arrow, a straight line or an "O". The mark should line up with the center-line of the crankshaft. If the cam has two marks opposite each other, the lines should be parallel with the gasket surface. You will need to rotate the unbolted cam left or right just a bit in order to match up the bolt holes to the gear holes.
Put the piston in with the mark on the top of the piston facing the exhaust port of the cylinder. put one circlip in the piston in the bore seated correctly in the groove. place piston over rod facing correct direction and insert wristpin into piston and through the rod needle bearing in the top of the rod. insert other circlip and seat correctly in groove. install compression rings with letter or any markings facing up. markings usually located at end gap on either side. install oil ring with straight ring on top squiggly ring in center and straight ring on bottom all in the same groove which will be the lowest groove on the piston.stagger all the ring end gaps. do not let all the gaps line up. install base gasket on engine case. clean everything and make sure everything stays clean. slide cylinder over piston and compress rings with fingers and finesse cylinder over piston. do not force. put nuts on studs and tighten to spec in service manual. install head gasket correctly and put head on and put nuts on studs. tighten to spec. reassemble rest of motorcycle and get hurt! have fun
Here's the deal > the chain position on the crankshaft cog makes no difference. No timing is done on that end. The timing is done when mounting the chain on the OHC. Run the piston up to TDC. Put the cam in a position where the cam lobes are pointing downward. Look at the cam gear. There should be two marks on one side of the gear. You should be able to see the marks from the left side of the engine. The cam is in time when the marks are parallel with the top gasket surface of the head and the gear is bolted to the cam. Now you have TDC compression stroke (good). If the cam lobes were pointing upward you would have TDC exhaust stroke (bad). Just to help you a bit in the future, I have a web site below where you can see a parts fitch for your specific bike.
re-strip top-end and remove scuffing marks from piston using 400# and then 600# wet n dry paper. recheck piston to cylinder clearance is correct, re-assemble checking ignition timing, fuel bowl level and inlet manifold "O" ring.