Noobie with noise problem. HELP!

GREENPANE · New Member Joined: May 13, 2009 Posts: 4

Hi all, great site! OK, so I'm helping a friend out with a 72 XS650. We had it bored to 81mm (it was already at 80mm) and slapped some Wiseco pistons in it.

First problem- I put the camshaft in the way the illustration showed in the 72 service manual. I installed it with the cut mark at 12 o'clock and the dimple at 3 o'clock. after killing my leg for 2 hours I studied the pictures a little harder and found out the points were on the WRONG SIDE! I thought I had maybe been too drunk when I put it in and was just a dummy. When I checked what I did wrong I found the the illustrations was WRONG and so was I a little. The dimple is supposed to be at 9 o'clock not 3 o'clock like I had it. But if I put the dimple at 9 o'clock the cut mark is at 6 o'clock. Well anyways I put the cam in with the points on the correct side and with the cut mark at the 6 o'clock position (opposite of everything that I could find about how to install the cam) and turned it over and watched the 4 strokes as they should be to the best of my knowledge. It started on the third kick and sounds great. Cam made wrong? Aftermarket cam? If I have it in 180 would it still run and sound normal?

Second problem- I had found out the throttle shafts seals were leaking air so I replaced them. The new ones made no difference. I get no idle rise when I spray my chemical of choice on the manifolds but as soon as I spray the shafts the idle rockets up. If trying to swell the seals by spraying all different kinds of oil on the seals. This is not a major concern cause better carbs could be had.

Third problem and my main question- I adjusted the valves at (.012'') exhaust and (.006'') with the engine cold just like the service manual says and yes in thousandths. Now when warming up she's nice and quiet but once warm the right side makes all kinds of noise up top. I took the cover off and checked the lash and it grew to .013''. I did nothing but let it cool all the way down and it shrunk back to .006''. I didn't check any of the others, only the right side intake cause that seemed to be where the noise was coming from. I did do some searching and found that that this noise seems to be common but didn't find anything about the lash growing. So the question is why is it growing? Rockers made of bimetal? lol! And also if it's growing an extra 7 thousandths what should I set the lash to????

Whew that was a lot of gabbing. Smile

PS. I ride a RD400 Daytona Special. No stinkin valves! Laughing

-Terry

xsjohn

Read you speal...stock cam try 6 and 4 thousands (cold).........and those wiseco's may be high compression... that wouldn't help the noise situation either when it warms up and it will.................

xsjohn

GREENPANE · New Member Joined: May 13, 2009 Posts: 4

Cool thanks! I did a lot of searching and figured you would probably be the first to answer. Wink

Weisco said the piston was 10.5:1 and that it's what they put in all the 650's. Sure takes a man to kick, even with one sparkplug out.

GREENPANE · New Member Joined: May 13, 2009 Posts: 4

UPDATE!

So I did only the intakes cold at .004''. Started it up and it was still quiet during warm up. Then it got loud again. I checked the right exhaust and it also grew from .012 cold to .018'' hot. I then adjusted it hot to .008" hot for the hell of it and started up. Now the noise was coming from the left side, imagine that Wink

. Adjusted it to .008'' and all the noise went away and it idled way better too!

xsjohn · Posted: May 15, 2009, 2:15 am Post subject: Re: Noobie with noise problem. HELP!

Stock is around 8.5 to 1......All that 10.5 to 1 compression is going to do is beat it to death......ok for racing for a short time then take it apart....has no place with a street bike with little cylinder cooling fins.....especially an air cooled XS.........others might disagree but they don't know what the hell they are talking about.....even wiesco if they think you will get any utility out of it........9-1 is heavy.....and you better retard the timing a bit ..........

ain't worth it to hop these up any if miles are what you are looking for....after 40 years of Yamaha's and some factory training this is good advice...........

xsjohn

GREENPANE · New Member Joined: May 13, 2009 Posts: 4

I was thinking of retarding the timing a little and didn't know that 10.5 to 1 was too much. These were the pistons that the owner supplied to me. No wonder it is so hard to kick. lol!

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Yamaha xs650