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Old 08-01-2008, 10:11 AM   #1
jayflap OP
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Location: Wauwatosa, WI
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Question '71 CB350 - Valve adjustment

Hey everyone,
I am new here (sent here by a couple of members) and need some help adjusting my valves on a 1971 Honda CB350. First things first, the bike was my uncles originally. He barely rode it and sold it many years ago to a friend of mine for $1. Well two years ago my buddy says he doesn't want it and asks if I want it back. I said I would take it and it has sat here for about 2 years now. The bike has only 4500 miles on it, but needs some love to get it going again. The carbs are apart (they were HORRIBLE) and I am still awaiting the arrival of the rebuild kit. In the mean time I decided to do some other things to pass the time, and things that obviously will need to be done.

I decided to adjust the valves and am having a hell of a time. I have a shop manual (thanks SOS) and have been reading that. It says you are to aling the LT mark with the timing mark and check the rockers to make sure they are loose, and if not rotate 360 and align the LT mark. Well I can get it to stay at the LT mark when the valves are closed but not when they are open. The engine just shoots right past the mark. I can hold the wrench there, but then I couldn't measure and adjust since two hands is all I have with me. I have tried with the plugs in and out figuring that the plugs would keep it under compression so if I took them out it should not have any compression to keep turning the generator.

Any ideas? Thanks in advance.

Jason
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Old 08-01-2008, 10:46 AM   #2
Mista Vern
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Been a looong time since I worked on one of those, but IIRC you can wedge the wrech against something to hold it in place or put it in gear and trun the back wheel, which then turns the engine. Generally the wieght of the wheel/friction of parts keeps the engine from zooming past the mark.

Good on you for bringing her back to life!
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Old 08-01-2008, 10:58 AM   #3
jayflap OP
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Thanks for idea. I tried the wedging concept and that is just not working well for me, but the idea to put it in gear, pure genius!!! Thanks again.

Here are some photos of the carbs just to give you an idea of what the heck I got from my buddy. SOS has already helped me out on the carbs, so a HUGE Thank you to him.





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Old 08-01-2008, 11:10 AM   #4
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Yuk! Good luck with the carbs! If they don't turn out I am sure some replacements will be easy to find on e-Bay or bike salvage yards.
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Old 08-01-2008, 11:13 AM   #5
jayflap OP
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So far the one I cleaned up (kept the other one together for reference since this is my first bike that I have had to revive from the dead) looks great. The power of chemicals helped that one along. I dipped it in gunk carb cleaner for an hour and she looks good. Now if those darn rebuild kits show up I could put that one back together and work on the other one.

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Old 08-01-2008, 11:25 AM   #6
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pulling the spark plugs makes it easier
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Old 08-01-2008, 11:31 AM   #7
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Thanks Grinder. Like I mentioned, I did have them out before and it still shot past, but now using Mista Vern's advice, I will try it with plugs out and in gear.

Thanks again guys.

J
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Old 08-01-2008, 12:31 PM   #8
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In addition to putting it in gear, you can tighten up the rear brake adjuster so the brake drags just enough so you can still turn the engine but it won't roll over.
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Old 08-01-2008, 02:23 PM   #9
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Talking

You're never going to get it! I'll bail you out, for $1.50 I'll take the problem off your hands.
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Old 08-01-2008, 03:00 PM   #10
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If I recall, the LT mark only works for one side. If you roll it past the LT mark 90 degrees, there is a spot where all four valves are closed - the valves are what rolls the engine at the LT mark, so you'll be able to feel the lack of tension, and wiggle the rockers. If not, crank it around 360 degrees. This is the same spot you use to tension the cam chain - don't forget or the chain stretches and makes bad things happen...

Also make sure that the T shaped stamp in the end of the valve adjuster points up and out (towards the respective tappet cover), or your valve timing and rocker geometry will be off. Have fun!
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Old 08-01-2008, 04:28 PM   #11
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Nice Pics.

Jayflap,

I know the spin past the "T" that you are talking about. Don't get too concerned with the position of the LT (for the left cylinder). What is important is that you are on the compression stroke and that the cam lobes for that cylinder have not engaged to open the exhaust valve yet. So if it rolls past the "T" by a small amount it is still alright to adjust the valves as long as there is still play (i.e. the cam lobes have not engaged). The piston needs to get quite aways past "T" of the compression stroke before the exhaust cam lobe starts to approach the rocker face (that is your valve clearance). If there is any doubt, be sure that you have some clearance by checking that the rocker is free when you roll the engine to the "T" mark. You can burn a valve if there is not enough clearance, but you would really need to have way too much clearance to cause any damage.

Take Care.
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Old 08-01-2008, 04:56 PM   #12
jayflap OP
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Quote:
Originally Posted by JeffPM
You're never going to get it! I'll bail you out, for $1.50 I'll take the problem off your hands.
Weren't you just saying that you are enjoying watching ME doing this one??

SOS, thanks again for all the help. I am going to give it a shot when I get home tonight. I get out of work at 10pm, so I will be in the garage doing just a few things. BTW, glad you like the pics. I told you the carbs were rough!!! The one looks good now, I cannot wait to get it running.
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