Good morning everybody,
As this is my first post here, something brief about me and my bike. My name is Christopher (yes, I will fill out my profile), live in Madrid/Spain. Some months ago I bought a 350 Scrambler (built in Spain) on which I am working on right now.
Since it is a spanish version, it has a Amal carburator and the valve adjustment is to be done by screws and not shims. It is said that this is an advantage, we'll see.
And here go my first questions:
1) As I need to adjust valves (I won't touch rest of motor, just some helicoils as it loses some oil, as it runs quite well), is there any manual about valve adjustment with screws where the process is well explained? Or can something explain me how it is done?
2) Which carburator (Dell'Orto) would fit exactly on this motor and where could I find one? The Amal lacks the choke-part and when it's cold it is difficult to start the motor).
Thanks a lot by now, regards ...
Valve adjustment on 350 Scrambler (no shim version)
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darren nix
- Diana
- Posts: 66
- Joined: Sat Dec 04, 2004 1:40 am
- Location: sunshine coast queensland
g day mate, if you can get your hands on a haynes workshop manual, i got mine from phil at road and race a few years back, that gives you a good base to start from , plus there are a lot of smart people on this site , when they notice your message they are quiet helpful with there answers, good luck over there
Spanish SCR valve adjustment
Hi Christopher,
I’d be glad to take a stab at explaining valve adjustment on your 350 SCR. I assume you have none of the factory tools so we’ll improvise. Remove the two valve covers and the spark plug. You need to bring the cam to the correct position in order to set the valve clearances. This position is with the piston at top center on the compression stroke. Put the bike up on the center stand and shift the transmission into gear (2nd is fine). Place an indicator of some kind (something soft that will not damage the piston such as wood dowel, a drinking straw, etc.) in the spark plug hole and, while holding the indicator in as vertical a position as possible, carefully rotate the rear wheel forward until the indicator rises up as high as it will go. As you turn the engine, note whether the exhaust rocker arm is rising (valve closing) as the indicator rises. If the exhaust rocker arm is still rising when the indicator reaches the top of its travel (the intake valve will also start to open as the indicator reaches top center), then the engine is at the top of the exhaust stroke (valve overlap). You will notice that no valve clearance is perceptible at this position since both valves are open slightly. You need to rotate the engine 360 degrees until the indicator is at the top of its travel and the rocker arms are not moving as the piston reaches top center. At this position, you should be able to move the rocker arm up and down and notice the slightest clearance between the rocker arm and valve. The piston need not be perfectly positioned at the top of the stroke. As long as it is within several degrees of top center you can adjust the valve clearance. You will see a set screw and locknut on the ends of the rocker arms bearing down on the valves. Check the clearance by inserting a feeler gauge between the valve and the ball that is held captive in the socket at the end of the set screw. This ball has a flat ground on it that should be positioned at the point of contact with the valve tip. Be careful during valve adjustment that when you insert the feeler gauge to check clearance that you do not rotate the ball such that the flat is not in contact with the tip of the valve stem. According to my Haynes manual (which addresses servicing of the Italian version), valve clearance is set at .08mm for the intake valve and .13mm for exhaust if the “white” cam is installed. The “green/white” cam is set at .13mm and .25mm respectively. You can check the specification of your cam by removing the bevel cover on the head (may have a tach drive?) and looking for the daub of paint on the end of the cam. Often, this paint has disappeared but chances are you have a white cam. If you remove a bevel cover that incorporates the tach drive, be sure to verify that the tach drive coupler is correctly in place when you replace the cover. If you neglect this, the coupler can wedge in the bevel gears and lock up the engine. Start with a feeler gauge of the correct size for the valve you’re checking and determine if the valve is tighter or looser than this clearance. Make sure the ball is not rotating and preventing you from inserting the feeler gauge. The valve clearance is set by loosening the locknut and turning the set screw in or out (as the case may be) in order to fit the feeler gauge between the valve and ball. It’s probably easiest to simply back off the set screw a turn or two, lift the rocker up and insert the feeler gauge being careful not to rotate the contact ball. Press the rocker arm down and tighten the set screw to the point where you feel some resistance when you slide the feeler gauge between the valve and ball. It should take some effort to slide the feeler gauge between the valve and adjuster. Do not remove the feeler gauge yet! At this point, tighten the lock nut while holding the set screw in position with a screwdriver so it doesn’t rotate when you tighten the lock nut. You will probably notice that the clearance loosens when you tighten the lock nut. You must compensate for this by setting the clearance slightly tighter than ideal when the lock nut is loose and anticipate how much clearance you will gain when you tighten the lock nut. When you are satisfied with the clearance, withdraw the feeler gauge and set the other valve in the same way. You can try checking for proper clearance by attempting to insert the next thicker feeler gauge but it can be difficult to check this way since the ball will tend to rotate. Reinstall the valve covers and spark plug and don’t forget to put the transmission back in neutral.
Regarding carbs: The Italian versions came with a Del’lorto VHB 29 and you can use a stock Italian version intake manifold. Some early models used a SS129D although these are very expensive. The Del’lorto PHF in 30mm, 32mm or 34mm is also a popular conversion. I’ve even seen Mikunis installed on these bikes. Looks like Metrakit is the Del'lorto source in Spain or Eurocarb in the UK. These carbs turn up on ebay from time to time as well.
Ciao!
I’d be glad to take a stab at explaining valve adjustment on your 350 SCR. I assume you have none of the factory tools so we’ll improvise. Remove the two valve covers and the spark plug. You need to bring the cam to the correct position in order to set the valve clearances. This position is with the piston at top center on the compression stroke. Put the bike up on the center stand and shift the transmission into gear (2nd is fine). Place an indicator of some kind (something soft that will not damage the piston such as wood dowel, a drinking straw, etc.) in the spark plug hole and, while holding the indicator in as vertical a position as possible, carefully rotate the rear wheel forward until the indicator rises up as high as it will go. As you turn the engine, note whether the exhaust rocker arm is rising (valve closing) as the indicator rises. If the exhaust rocker arm is still rising when the indicator reaches the top of its travel (the intake valve will also start to open as the indicator reaches top center), then the engine is at the top of the exhaust stroke (valve overlap). You will notice that no valve clearance is perceptible at this position since both valves are open slightly. You need to rotate the engine 360 degrees until the indicator is at the top of its travel and the rocker arms are not moving as the piston reaches top center. At this position, you should be able to move the rocker arm up and down and notice the slightest clearance between the rocker arm and valve. The piston need not be perfectly positioned at the top of the stroke. As long as it is within several degrees of top center you can adjust the valve clearance. You will see a set screw and locknut on the ends of the rocker arms bearing down on the valves. Check the clearance by inserting a feeler gauge between the valve and the ball that is held captive in the socket at the end of the set screw. This ball has a flat ground on it that should be positioned at the point of contact with the valve tip. Be careful during valve adjustment that when you insert the feeler gauge to check clearance that you do not rotate the ball such that the flat is not in contact with the tip of the valve stem. According to my Haynes manual (which addresses servicing of the Italian version), valve clearance is set at .08mm for the intake valve and .13mm for exhaust if the “white” cam is installed. The “green/white” cam is set at .13mm and .25mm respectively. You can check the specification of your cam by removing the bevel cover on the head (may have a tach drive?) and looking for the daub of paint on the end of the cam. Often, this paint has disappeared but chances are you have a white cam. If you remove a bevel cover that incorporates the tach drive, be sure to verify that the tach drive coupler is correctly in place when you replace the cover. If you neglect this, the coupler can wedge in the bevel gears and lock up the engine. Start with a feeler gauge of the correct size for the valve you’re checking and determine if the valve is tighter or looser than this clearance. Make sure the ball is not rotating and preventing you from inserting the feeler gauge. The valve clearance is set by loosening the locknut and turning the set screw in or out (as the case may be) in order to fit the feeler gauge between the valve and ball. It’s probably easiest to simply back off the set screw a turn or two, lift the rocker up and insert the feeler gauge being careful not to rotate the contact ball. Press the rocker arm down and tighten the set screw to the point where you feel some resistance when you slide the feeler gauge between the valve and ball. It should take some effort to slide the feeler gauge between the valve and adjuster. Do not remove the feeler gauge yet! At this point, tighten the lock nut while holding the set screw in position with a screwdriver so it doesn’t rotate when you tighten the lock nut. You will probably notice that the clearance loosens when you tighten the lock nut. You must compensate for this by setting the clearance slightly tighter than ideal when the lock nut is loose and anticipate how much clearance you will gain when you tighten the lock nut. When you are satisfied with the clearance, withdraw the feeler gauge and set the other valve in the same way. You can try checking for proper clearance by attempting to insert the next thicker feeler gauge but it can be difficult to check this way since the ball will tend to rotate. Reinstall the valve covers and spark plug and don’t forget to put the transmission back in neutral.
Regarding carbs: The Italian versions came with a Del’lorto VHB 29 and you can use a stock Italian version intake manifold. Some early models used a SS129D although these are very expensive. The Del’lorto PHF in 30mm, 32mm or 34mm is also a popular conversion. I’ve even seen Mikunis installed on these bikes. Looks like Metrakit is the Del'lorto source in Spain or Eurocarb in the UK. These carbs turn up on ebay from time to time as well.
Ciao!
