Re: Karizma/Karizma R

Many more happy returns of the day [MENTION=32286]psr[/MENTION] sir !!

Re: Karizma/Karizma R

Thanks for the Good wishes.

Re: Karizma/Karizma R

Wishing you many happy returns of the day. We await cake and a party .

Re: Karizma/Karizma R

Forgot to post in the morning:-Happy birthday to [MENTION=32286]psr[/MENTION] sir. Many happy returns of the day and also a joyful year ahead.

Re: Karizma/Karizma R

Thanks for remembering and the Good wishes.
@ AK3D Thanks for the Good wishes....No cake ...only concession is I didn't have to cook and do the dishes to-day.

Re: Karizma/Karizma R

Thanks for the kind thought and Good Wishes.

Update

I took time for this update as I wanted to wait and see for the results before updates. The final conclusion is that, I have unnecessarily changed the bore that is working good. This proved costly to me, both financially as well as time. Of course, I have learnt a lot practically which is invaluable.

A brief of the events before updating this: Opened the engine to replace cam chain and ended up replacing the bore with new one. After this there was too much exhaust smoke in the morning. Opened the engine again and replaced the cylinder/head gasket again. Since then, there was little smoke in the morning. Waited for a week to see if the smoke goes away.

Last Monday, opened up the engine at my mechanics place again, as the exhaust smoke in the morning was not decreasing. What we found was a shock. The new bore got scratches. Engine oil is there on the piston head. Gasket has oil on inlet side.

The piston head shows carbon formation on exhaust side only, and the inlet valve side is wet due to engine oil leak. Similar observation on the top of the head. So, oil had been leaking in to chamber from inlet side. Also, the gasket has oil stains more on inlet valve side. The intake and exhaust manifold were dry completely indicating no stem seal leak.








Now, the major shock, scratches on the bore. When we removed the bore, my mechanic found one of the two dowel pins missing. The cylinder was opened at another mechanic's place the second time, so we are not exactly sure who missed the dowel pin. This missing dowel pin is the cause of the total mess. Because the cylinder was not properly seating due to missing dowel pin, the piston skirts touched the wall of the cylinder. The scoring is more at the bottom of the cylinder indicating the culprit to be missing dowel pin.








After this, I opened up the crankshaft and checked for play in the conrod bearing. It seemed to have no play. For time being, I decided to close the engine with the same crankshaft and the old bore. Replaced the dowel pins and gaskets with new ones. Finished refitting the engine in 3 hours. Rode the bike for a week without any exhaust smoke. Touched 110 kmph a couple of times, so guessing the compression is also set well within limits, thought I found the bike to be rough a bit. The slight knocking in lower gears and lower rpms is still there when the engine is hot. But, thats not a major worry for me now.

Re: Update

Thanks for sharing, learned something new today, Ravi. Awesome to hear you have the problem finally nailed! Sad though to hear of the avoidable reason why this occurred. However, alls well that end well and in the end the satisfaction you get when riding a mechanically sound bike after all the trouble you have been through will compensate the time and money spent.

Re: Update

Very good Ravi, seems you've sorted things out apart from the knocking issue. Hopefully that'll be taken care of soon as well.

All : I found this very useful link AGCO Automotive Repair Service - Baton Rouge, LA - Read Sorted by Category . Though it is for 4 wheelers, a lot of the theory and engine related stuff applies to 2 wheelers as well, like the timing chain page.

Edit : We already know this thanks to the thread and well informed people, but interesting nonetheless.
Oil Changes http://www.agcoauto.com/content/news/p2_articleid/54

Re: Update

[MENTION=32286]psr[/MENTION] sir, [MENTION=28527]sibun[/MENTION], and other experts, please pour in your interpretations after seeing the pics above. My interpretation might be different; would like to hear from you all and learn more.

Seems I have sorted out the idling issue too with a sequence of experiments with my carburetor. Will narrate them soon.

Re: Update

Hope I was of some help to you in your trouble shooting...
Good Luck.

Re: Karizma/Karizma R

Good to hear from you Chetan. Hope your rebore doing good. Mine has been doing good, but I unnecessarily changed it, and finally came back to it. You could read what happened in the last 3-4 pages. Regarding your speedo issue, change the gear hub; its around 250 rupees. Everything will be fine then.

Thanks for the pics Arun. I have taken the pics from the top view when the bore was fitted. As you read in my other posts, the bore was fine. I am back on the rebore now. Its doing fine and I could touch 110 kmph too. And this was the pic I took when the rebore was fitted. It appears fine.



Sid, thanks for the input. We found that there was no problem with warpage. As you read in my posts above, the cause for the leak is the missing dowel pin. Replaced the gasket again and so far there seems to be no leakage. Lets see how it goes.


Sir, my interpretations were almost yours. Even with the carb experiment too. I couldn't have come to proper conclusion without your help. I just want to know anything more that you can add after seeing the pics.

Re: Karizma/Karizma R



It seems to be alright there's some timing issue.

Re: Update

Will reply tommorow .

Re: Update

Seems I have solved the carburetor issue as of now. The issue used to be the hovering idling when the engine is warm, and difficult to start when the bike is cold. Sometimes idle would be low and sometimes high when the engine is warm. Also, the carburetor is thought to have played a part in the lower-gear-rpm knocking that my bike has. Most of the inputs I got were from [MENTION=32286]psr[/MENTION] sir.

As I do not know about the carburetors, I had to first study a lot to understand the carburetor, its mechanics, and the function. Watched some videos as to how to open the carb.

• Finally, as a first step, opened the carb myself, cleaned the jets thoroughly with metal cleaner.
• Cleaned the pilot system passages thoroughly.
• Replaced the carb insulator and the air injection tubes with new ones to arrest any vacuum leak.
• The AFR screw was relatively new as I have replaced it one year back. Removed it, cleaned and put it back.
• Opened the TPS unit, cleaned it thoroughly with anti-rust spray and checked and corrected the erratic resistance values. The output voltage signal also checked and found it to be in limits.

Even after this, idling seems to the same more or less. After this, opened the carb slide, checked the diaphragm against strong light for any holes and found it to be fine. The slide piston was falling freely and the clunk test was passed. As per psr sir's advice, cut three turns of the diaphragm spring to allow free lifting of slide without any sticky nature.

Even after this, nothing has changed. At this point in time, thought there could be some issues with carburetor at micro level that we were not able to identify, and a carburetor change was suggested. I was in no mood to replace it as the new carb is whopping 6k.

One day, I found the old AFR screw in my spare parts bin and thought of comparing it with new one. Opened the carb again to clean the air cut-off valve. Took out the AFR screw from the carb and compared it with new one and found to be same in dimensions. When I was putting the AFR back, I found the O ring in the current screw to be hard as plastic and the O ring in old screw to be rubbery. :O Immediately, I exchanged the O rings. After that, the idle seemed to have been working better. But the next day, it was more or less like before, but there was definitely an improvement. Bought a new AFR screw and tried that too, but in vain.

After this, I met this nice enthusiastic xBhpian [MENTION=57196]nithin2767[/MENTION] and he readily agreed to my proposal of exchanging the carb (he owns a black 2007 ZMA R). We both swapped the carbs for a day. This way I got a day to thoroughly observe the bike with a different carb. My knocking problem has not gone indicating there is no problem with my carb. Also, the idle seemed to be quite stable with Nitin's carb in my bike. On Nithin's ZMA-R, Nithin didn't find any difference apart from the hovering idle when the engine was hot. So, its finally concluded that there is no issue with my carb apart from the idling issue. Nithin didn't find any knocking with my carb in his bike.

So, carburetor contributing to knocking was ruled out. Found there is nothing wrong in my carburetor except for the idling.

Determined to find out the problem with carb, with the help of psr sir, I did a thorough check of the carb, focusing on the places where air leak could take place. First thing is carburetor insulator. Ruled out possible air leak in insulator because when I used Nithin's carb in my bike, the idle was stable, indicating the insulator on my bike to be fine. Second thing, cleaned up all the idle circuit passages with chain cleaner thoroughly, including air cut-off valve chambers. Third, opened the choke cable from the carb and refitted it very tight ruling out any possible air leak.

Now, as a last measure, we have used the O ring from old AFR screw, so now we have two O-rings in AFR screw. After all this, the idle seemed to be a bit stable when the engine is warm. Here is a video of the idle when the engine is warm. There is a slight hovering of the needle, but I guess thats normal. Just let me know if thats not normal.



The other issue with the carb right now is, the rpm needle comes to idle slowly after the throttle is closed. This has started after I cut three turns from the carb slide spring. Thought it could be issue with air cut-off valve, and cleaned it thoroughly and the problem still remains. So, I guess I should get a new spring and check.