CB350 rebuild at home

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yasirsa (yasirsa) 2013-11-08 04:22:50 +0500 #201

abbasi sabb this is bottom area cylander and head is not been fiited yet when the crank was not assembeld i was doubtfull on center left bearing it was hard i thought it will be loosen but its not good anyways am taking it to machinist he has to fix this

yasirsa (yasirsa) 2013-11-08 04:27:00 +0500 #202

this one bearing get harder and softer in 1 round

msabbasi (msabbasi) 2013-11-08 05:13:16 +0500 #203

Ok sorry.... I saw the chain since there was no picture of the top of the engine so I thought maybe cam was connected. OK as you said you need to go back to the machinist. But I still say that measurements have to be made to see what is wrong. Please see post #200 on page 10 to see the arrangement of a dial gauge on the crank. In your case the dial gauge needs to me fixed like this:

You will need to know why is crank hard in only one place as it is turned? Is the crank bent or is there problem in the main bearing journal dia. BTW are the main bearings new or old? Did you have the crank polished or ground? I just thought of an idea, you could put a little amount of blue oil paint on the crank main and then turn it and look at the bearing to see where it is touching.

yasirsa (yasirsa) 2013-11-08 06:28:44 +0500 #204

they are old bearing janab but they were in excelent shap externall 2 bearings installed new . mid ones bearing can be open and can be replace with new balls bearings. i think some of them or maybe 1 of them ball is bit larger size thats why its harder when the load comes on it

yasirsa (yasirsa) 2013-11-08 06:34:19 +0500 #205

this crank has 4 bearing on it. without feeler gauge i can feel up and downward issues

msabbasi (msabbasi) 2013-11-08 10:37:15 +0500 #206

I think there is something seriously wrong. Your machinist will have to be consulted.

yasirsa (yasirsa) 2013-11-09 13:57:36 +0500 #207

Sent from my LT26i using PW Forums mobile app

yasirsa (yasirsa) 2013-11-09 14:06:19 +0500 #208

OK crank is reopened pull out with puller tool bearing is reopened because the roller are replaced with over size rollers due to pale. in pic number 2 the surface polished for smooth rolling operation and its done but problem is still there i think external bearing seem not ok or maybe incorrectly installed will check it tomorrow

msabbasi (msabbasi) 2013-11-09 20:21:55 +0500 #209

While trying to understand the design of the crank of your bike I came across this website. You may find it interesting:

Honda Cb350b4 (general Export Type Km/mile) parts list partsmanual partsfiche

When you are analysing the problem of your crank, pay attention to the line of the crank as shown on the picture below:

I might be wrong but from the drawing below I understand that when pressing the crank at locations circled in red if it is not done properly, the centre line of the crank will be wrong and will lead to the problem you are facing. I can't see any dowels to ensure that the crank line is correct when assembling. As mentioned earlier, put a dial gauge to the crank to find out where the problem is happening.

If all else fails come down to Pindi for a day on any Sunday and I'll introduce you to my Lathe guy and help you get it sorted out. My guy is very experienced and has all the measuring tools.

Regards

yasirsa (yasirsa) 2013-11-11 02:58:23 +0500 #210

i cant see photos you have uploaded for me . i think this is due to over size rollers am removing new bearing which they are installed on outside if am faild i will surly contect you instAllah

msabbasi (msabbasi) 2013-11-11 04:36:53 +0500 #211

Are you using a computer? If you are using a computer, please refresh the page, you will see them. It is important you see them. Also visit the website for which I have sent you the link. It gives all the drawings for your bike.

yasirsa (yasirsa) 2013-11-11 06:23:27 +0500 #212

i checked it 3 computer and my android phone no display any of them

msabbasi (msabbasi) 2013-11-11 06:40:50 +0500 #213

Sorry, found the problem. The links were disturbed. Have a look now. Should be OK.

yasirsa (yasirsa) 2013-11-12 03:21:17 +0500 #214

thank you abbasi sab these pics are saved in my cell i will share with my machinist

yasirsa (yasirsa) 2013-11-12 16:39:31 +0500 #215

OK fault has been traced out your given diagram has help me take a look in diagram part number 13 this bearing is special type it can be movable right to left or left to right the previous bearing was totally fixed it was modified now am looking for this bearing you see kam k andar kam khair Allah khair karray agay thanks anyway i will update more after muharram inshallah. i dont know orignal bearing part number so i may go for modifying it

msabbasi (msabbasi) 2013-11-12 23:22:14 +0500 #216

Yaser Sb.,

I am glad the drawing was of help. The Original Honda part number for this ball bearing is 91002-874-003. It not a normal bearing and so the price is high, about Euro 60.50. I don't think you will be able to find it. However it can be ordered from the web site I sent you.

Xulfiqar (Xulfiqar) 2013-11-13 00:52:28 +0500 #217

that bearing is a pain - this cause of binding is also caused by a warped crankcase - It is absolutely necessary to measure the true of the crankcase bearing housings on a special jig, The crank itself should be checked with a dial gauge for run out. Even a slight run out will set a disastrous vibration that destroys the bearings.

msabbasi (msabbasi) 2013-11-14 00:49:08 +0500 #218

Yaser Sb.,

I was reading your post again this morning and noticed that you are talking about a bearing that can move left and right. I think you are talking about a cylindrical roller bearing. Just as a matter of my understanding see the picture below. I am comparing the most widly used types of bearings. One on the left is a cylindrical roller bearing while the one on the right is a plain ball bearing. Roller bearings do not take axial thrust, i. e. they allow left and right movement.

Is the one on the left what you are talking about?

Modification of this very crucial part may lead to disaster. I would recommend discussing your modification plan here on Pakwheels. Zulfiqar has much experience in this area.

Xulfiqar (Xulfiqar) 2013-11-14 01:23:17 +0500 #219

This bearing has a light press fit only on the crank and is very uniquely sized - thats why its a special Honda part no. This was also the major PITA for the Honda CD175 engines.

The issue that causes the failure is out of true crank (setup without dial guage) and warped crankcase. Furthermore the locating pin is what causes the bearing to stay put. A different bearing can cause binding in this case or even clearance.

The remedy is to buy a genuine Honda part no - and make sure to load it up with assembly lube on installation.

msabbasi (msabbasi) 2013-11-14 04:15:59 +0500 #220

Nicely said!! In addition to the main bearing issue, I suspect that in the past the crank may have been disassembled to get to the big end bearings and reassembled carelessly causing the crank line to be no longer true.

Using the dial gauge seems to be an issue. Sometimes when the customer insists on a certain (proper) way to get the job done, the shop owner tells the customer to take his business elsewhere. Having said that, not taking proper measurements at multiple locations is like shooting in the dark :o. Tolerances are so tight that just a couple of thou out of true and we are looking at spun bearings and what not.