QuestionMike,
Thanks for e-mailing me back. Since I contacted you last, I have done some of the things that you suggested. I back the adjustment off on the lifters for the front cylinder and took the pushrods off and pull the tappet guides and lifters out of the crank case housing. I looked everything over very carefully. Both ends of both pushrods looked good. The matching surfaces between the pushrod and the lifters looked good. The wear on the matching surfaces between both lifters and the tappet guides they were in weren't scarred or gaulled. The roller surfaces on both lifters were smooth and the bearing seemed to be tight and run freely. I visually and used my finger to check the cam lob surface for defects. I couldn't detect any either way. Next I pulled the rocker box off the front cylinder. The surfaces on the vavle stems had been touched up when I had the vavles and seat ground. The intake stem looked like it did when I put it toghter but the exhaust vavle stem had a little bit of wear showing. I took the nuts off the ends of the rocker shafts and pulled the shafts and the rocker arms out of the rocker box. The push rod matching surfaces on both rocker arms were smooth and not gaulled and the valve stem matching surface looked the same way. There did seem to be a little more wear on the vavle end of the rocker shaft for the exhaust valve and on the matching surface of the rocker arm bushing than I remember seeing. I check by owner manual for the rocker arm shaft to bushing clearance. It calls for .0005 inch to .0035 inch. I cheched to shaft size and the bushing size the best I could with a 6 inch dial caliper. The size difference is on the high side of the tolerance. What I wonder is this; since there were some wear marks on the exhaust vavle stem that weren't there before. And the wear on the rocker arm bushing and the matching surface of the rocker arm shaft seems to on one side and on the same (exhaust vavle) end. Could that combination be enough to make the fit loose enough to make it rattle? Since I am not famillar in what might be considered good or bad in this situation, maybe you good give me some insight as to whether or not you thing this might be the source of my problem. I almost forgot to mention that the rock arms and shafts are original equipment and have never been changed or replaced.
Thank for your continuing assistance in this matter, DeWayne
Followup To
Question -
Mike,
Thanks for responding so quickly. As I mentioned, I checked the pushrod adjustment three times. Once when I put the engine together and twice since then. Both times I checked them after I got it running and drove it, the adjustment wasn't that far off. I didn't think liffter collapse could be part of the problem, since it has solid's. A person wouldn't think that piston slap would be a problem since the pistons are brand new and the cylinders were bored to fit them. So the upper valve train would seem more to me where I should look. So with that thought in mind, I have another questions. The engine still has the factory cams in it. I have heard of problems with valve spring binding from over travel? If that can and does happen, could it be caused by the valve stem heights being to short or long from the valve seats and faces being ground? If you would, e-mail me and let me know what you think.
Thanks, DeWayne
Followup To
Question -
Mike,
Greetings! I own a late '84 XLX. I bought in June 1990, it had 6,600 miles on it at that time. In the winter of 1999 (with about 18,000 miles)I did some major chroming. Rocker boxes, gear case, primary case, swing arm, triple tree, swing arm, ect. At the same time I pull the top end off and went thru it. Bought .010 over Wiseco 10 to 1 piston and rings and had the cylinders bored to fit them by very reputatle automotive/motorcyle machine shop. Also had them rebuild the heads at the same time with new Manley valves, springs, guides, spring seats, ect.. I did all the mechanic work taking it apart and putting back together again. Everything went along fine until the last year or so. I started fouling out the back spark plug all the time. I got a coulpe of comments from people riding behind me toward the end of the riding season last year that they saw a little white smoke coming out of the back pipe when I took off a stop. So after Christmas I pulled the bike into the a self service autoshop at the Army base that I work at and tore the top end off. It had 27,850 miles on it at that time. What I found was that the wrist pin retaining clip came loose and slid over and scored up the side of the rear cylinder wall. Was so deep that it couldn't be cleaned up. The machinist at the automotive/motorcycle machine shop where I had the work done at said that it was a more common problem than I thought it was. I ended up buying a new rear cylinder and a new set .040 over Wiseco forged pisons and rings. Again I had them bore both cylinders to fit the pistons. Also had them grind the vavles and seats. Again as before, I did all the mechanic work to tear the engine down and put it back togehter again. I have never had the bottom half apart, nor did I replace the wrist pin bushing because they both seemed to bo all right. I reset the lifters before I started it for the first time and checked and reset them twice since then. I hadn't driven more that 50 miles since I got it back togehter and what I started to hear was a mechanical "tapping" noise that seems to be come from the top end of the engine somewhere. I took a engine stethscope and listened all aroud the engine with it. I can't seem to detect anything out of ordinary with it. The "tapping" noise is real bad or loud but you cah hear it over the noise of the straight pipes on the bike when it its running. I did replace the shaft seals on the rocker boxes but I didn't take them completely apart when I did that. I run sraight 50 weight oil and changed it and the filter after I got the engine put back together. The motor seems to have sufficient oil pressure. Could the noise be something in the vavle train? A wrist pin going bad? A cracked piston? A broken ring? Blade/fork connecting rod bearing? Any insight, speculation or ideas you might have would be "very" helpful.
Thanks, DeWayne
Answer -
Sounds like you are having valve train noise or piston slap.
I would check to see if you are having a lifter collaps. To check it, check the pushrods at the bottom of there stroke and see if one is lose. Other than that, if that in not the problem, I would take the heads off and check the rockers arms for damage. The next step would be to pull the cylinders and recheck the bore.
Good luck and happy riding
Mike
Answer -
I didnt know you had solid lifters in the bike, so they cant be the problem. I stated piston slap, just incase the shop that did the boring, did them right using pressure plates. I have seen this happen.
Another thing you can check is the roller bearings that the lifters ride on. You could have a bearing going out.
You can check the rocker boxes for a cracked rocker arm.
You could be having a cam bearing going out also.
Your valve cant bind, since they are set up for the stock cams. You only have that problem with high lift cams.
Other than the above, You will have to start tearing the motor down and inspect each part as you go.
To bad I cant hear the sound on here, I could better diagnose the problem
Mike
AnswerYour valves will show wear marks due to the fact that they dont ride on roller bearings. Check the top of the pistons for a mark to see if the valves are hitting the pistons.
You said that you rechecked the pushrods after riding. Did you cneck them when the motor was cold? Pull one of the cylinders off while you have it this far and check the up and down play in the rods. There should be none.
Mike
