The oil pump control plate has the marking L3B and a scribe mark at about 2:O'clock. The only marking I can find on the pump body is the word MIKUNI but no corresponding cast line. Approximately where in relation to the word MIKUNI should the scribe mark on the control plate be set for the closed oil pump position?

 

Some wheel were a little different on the 350 versus the 400,but the manual calls for marks on both the 350 and 400 to adjust the same way. Kinda vague on where the manual shows alignment,but it's the small square block to the left side on the oil pump.This mark on the wheel aligns with the body mark when the throttle slide just begins to open. Here's one members pics of his 400 oil pump. You can faintly see the other mark on the square part of the pump body to the left. Plus the instructions from the manual are vague to say the least.

 

Thanks for the response. The plate is like the one shown in the Clymer manual. It is quite different from the one you reference. The mark on the plate in the manual is marked width the letter B and is around the 2 o'clock position, about lined up with the letter N in the word MIKUNI on the right side of the pump. Have you any idea about where this MARK should line up with the word MIKUNI?

 

Best I can remember on the 350,when you tightened the adjuster you had around 1/2 inch of threads showing at the top of the oil pump adjuster when the marks aligned.Same as the 400. Around here the mark you have on the wheel should be close to the small casting mark on the pump body.If you can't see the mark,set the pump wheel mark center of this small casting. Basically the main difference on the two pumps was the oil inlet from the tank on the pump is down low on the 350,the 400 oil inlet is up at the top of the pump.Other than that,that's all I can remember off the top of my head and also looking back at the manual.

 

Thanks again for your insight. The L3B plate on this pump definitely has its only scribe mark on the right side of the plate, standing in front looking rearward. For the most part, the plate completely covers the left post.It is visible though at wide open throttle and definitely has an easily visible cast timing mark. There is a small opening in the plate about where the end of the adjuster cable is attached and through this opening at closed throttle the very innermost end of the cast mark is visible. This is almost directly opposite the scribe mark on the plate. Any idea how this was originally adjusted????

 

If you can't align the mark like on the 400,then I'd adjust the pump to where when full throttle is applied the oil pump wheel is set to maximum travel.Just turn the adjuster cable screw at the top out. When you release the throttle back to an idle see if the notch or the mark on the wheel lines up with the mark on the casting body.

 

Thanks again. I set the pump so the bottom of the adjuster tube is flush with the inside of the pump housing. This gave me about a half inch of thread above the lock nut. I then did a ten mile test drive at just off idle in low speed at 3 to 5 mph. It used 3.5 oz. oil and i.2 gal gas for a ratio around 43.5/1. Is this a bit rich? The machine was not under any significant load.

 

Pretty close as the factory sets them at approximately 50/1 ratio.You can leave at this setting if you want to or drop the adjuster a tad.About 1/2" of adjuster threads showing is what I usually ended up with on the 400s when the two pump marks lined up.Figured the 350 was about the same.

 

Thanks so much for your help. The machine was willed to me a few years ago and I am just now getting around to getting it into running order. The piston had a crack in the skirt but the cylinder checked out at the upper limit for bore clearance. I scarified the cylinder and replaced the piston with a standard Wiseco. I'll try this for awhile and see how I make out with the plugs..

 

Further to my last post, I received a picture of the oil pump from a '93 owner/maintenance manual. It shows an oil pump timing mark at about 8 o'clock. If the throttle is held wide open the timing mark is clearly visible to give a person an idea where the mark is when looking through a small hole in the moveable plate. I have the picture in the computer but cannot figure out how to include it with this post.