Gen 1 Cam Timing

[VentureYZ]

Looking for a little help.

I am to the point where I need to check the cam timing on my 87 to make sure it is correct. Been working on this project all summer now and the bike is still running lean. I am sure there is someone out there that can guide me through this process rather than trying to figure out the complicated procedure axplained in the Yamaha Service Manual. I already have the carbs and valve covers off. A diagram would be great, even a hand sketch. Is there any way that the TCI unit could be causing a lean condition ?????

Thanks for such a great site.

 

Mike Allen

[icebrrg3rd]

I will try my best, I'm pulling this from recent memory but I could be off. I'm sure I'll be corrected if wrong.

 

First remove the covers shown from the flywheel/stator cover. The large one exposes the nut you need to rotate the engine, the small one the timing marks pass the pointer.

 

Rotate the engine COUNTER-CLOCKWISE until you get the T1 mark at the pointer. Look at the rear bank of cylinders and see if the SMALLER dots line up with the marks on the cam holder. Rotate 360° if the dots aren't lined up. Once those dots are lined up with the mark and you are at T1, those are correct. Next rotate the engine COUNTER-CLOCKWISE 360° + 70° to get to T2. The front bank of cylinders should have the LARGER dot lined up with the cam mark. If any are not lined up, then you have cam timing issues.

 

Hope this helps.

 

-Andrew

[mmaleney]

Can you tell us a bit more about what you are doing, what year what changes you made to the bike what pipes ect. I to have a project I spent all summer geting the carbs to run right so I may be able to help you

[VentureYZ]

The pics sure are a wonderful thing. After seeing them it was so much easier to understand how these cams are timed. I did check mine and they look to be in time. A little history on my project.

I bought this bike 2 years ago with 15,000 original miles on it. It has been stored in a garage till the PO purchased it and owned it for 2 years. I purchased the bike and rode it home, it ran like crap. I tore the bike down to the frame, sandblasted the frame, swingarm, valve covers, oil pan and carb caps then painted everything with PPG Concept 2000. Most every upgrade out there was performed on this bike at reassembly. The bike is completly stock engine wise. My problem is that it seems all four cylinders are running lean to the point it is starting to melt the center electrode on plugs. If I block off half of the air intake on the filter cover it runs alot better telling me that it wants more fuel. The carbs have been completly torn down and gone through twice now, spending at least 24 hrs. each time in the ultrasonic cleaner. I have been wrenching on, rebuilding and restoring just about any thing with a gas engine on it for 35 years so the mechanical, electrical stuff is what I do every day. I build machine tools every day plus I have a home machine shop. This one has me stumped. I also ride a 84 Honda V-65 Sabre a pull a trailor I designed and built complete with mechanical surge brakes. I don't post much on the site because I am so busy working but I try to log on at least once a day and read up. Again I must say that this site and the members on here are unbelievable, best $12.00 I have ever spent. Oh by the way, I have working real close with Earl (skydoc17) on this issue also. What a great guy and a definate asset to this site. Mike Allen

[frankd]

Have you checked the fuel level in the float bowls?? Maybe the floats were all adjusted too low?

 

Frank D.

[mmaleney]

Do you have stock pipes on the bike.

[mbrood]

The boost sensor controls the timing advance but I don't see how that can change the fuel/air mixture. Most of the air jets can be checked for the proper size (they are stamped on the end) here's the main area to look and then there's one in behind the diaphragm. If somebody was trying to "optimize performance..." they may have downsized the fuel jets or increased the air jets.

 

http://www.bergall.org/temp/venture/carbsup.jpg

 

Here's a link to the stock main jets number in the different bikes.

http://www.bergall.org/temp/venture/venture-carb-part-differences.html

[VentureYZ]

Everything on the bike as far as electrical and engine components are stock Yamaha stuff including the complete exhaust with the famous collector baffle mod. Bike only has !5,000 miles on it. I am really starting to think that whatever gremlin is in this bike has been there from when it was new. I have been reading on the Venturers web site where the are changing the main, pilot and the two air jets to get these bikes to run better. Maybe a little input on this matter. When I figure out how to post some pics of this project I will do that.

Still have not heard anything from Earl (skydoc17) hope everything is OK.

 

Mike Allen

[mmaleney]

Try turning the pilot out 5 turns out from full in that is where the low end on mine started to run OK, then shim the jet needle with some ss washers you can find in a hardware store, again on mine i had to add 2 to each needle to get the spark plugs to turn brown. I have a harley pipe on mine and that is the only non stock part on mine which would have any affect on the carbs running lean. Did you check the gas flow from the tank before the pump and also the output from the pump.

[VentureYZ]

I did indeed have the fuel mixture screws out 5.5 turns and no luck. I originally installed a set of Earl's needle shim kit (.060) that actually lowers the needle to lean out the low end mixture. I have removed them and installed the originals (.120). Are you saying that you actually added shims to the stock set-up. This is why I was thinking of going to 42.5 pilots instead of the stock 37.5 ones. Somehow I have to get more fuel into this motor.

Ths fuel tank and fuel pump has all been cleaned, new filter and fuel pump run with no restrictions. Are both of the air jets in the end of the carb removable, I was thinking that only the one was removable.

 

Mike Allen

[mmaleney]

I added the shims to make the mixture richer not leaner so my ss washers sit on top of the larger plastic washer on the needle and underneath the clip only then did the motor start to pull like a stock bike. Over winter I to will go to a larger pilot jet maybe one size bigger not sure what # that is but I think 42.5 is a lot bigger than 37.5. Not sure bout the air jets, just one I think. Are you useing stock spark plugs, you said they started to melt at one stage.