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-   -   My Unicorn turned OFF instantly while riding (https://www.team-bhp.com/forum/motorbikes/58471-my-unicorn-turned-off-instantly-while-riding.html)

Hi Friends,

I recently did a complete Engine work on my Unicorn and it has got almost all new parts in the engine include the Bore and Piston bought from Honda Showroom, I did almost 10000 Kms after engine work and did not exceed 60kmph for first 5K Kms and 70-80kmph for second 5k Kms. Still I was not satisfied with the performance and Bike was over revving and it was struggling to cross 80kmph, engine noise was too high. Well when I consulted the mechanic one who did the Engine work said that the new Bore-Piston bought from Honda Showroom belongs to new edition of Unicorn which may be not that powerfull as the old unicorn was (2005 model initially when Uni was launched).

Yet we again decided to do a Re-Bore using old Bore which came with along with the bike, Bore was in decent condition and this time I was thirty for POWER and we did a re-bore with 200cc piston with bigger Sleeves, no engine work involved. Bike has Stock carburator, Stock Exhaust.
I took the delivery of bike on 02-05-2009, started riding back to hosur from chennai on 03-05-2009 at 11AM, did visit MMSC there was a Apache Event. Did not spend much time as I had long way to ride. I did maintain speed of just 50-60kmph during my ride to setup the engine, stopped for 10min for every 50kms. Reached Home safe at 6PM.

The compression was tooo high and kicker was very tight, could not start the bike easily, hence I replaced with a complete custom Free Flow
exhaust. After installing free flow bike had no difference in pickup, kicker became bit smooth was able to start the bike in 1-2 kicks.
I ride to White field from hosur every day to my office which is 40Kms oneway.

On 08-05-2009 I started to my Office and after 30Kms of ride Bike suddenly turned OFF while riding, I was shocked. Spark, Bore,Bore head, Exhaust were dam very very hot, Speed was just 60kmph. It took 30 Min to start again once the engine is bit cooled (Engine Oil used - Motul 20W-30).
Bike continued to turn OFF for every 10kms of ride. Today morning I decided to put back the new Bore/Piston which was bought earlier and installed it with stock exhaust. Bike was very smooth, engine starts revving high after 80kmph, again bike turned OFF today while coming to office while riding speed was just 60kmph. When I called my mechanic in chennai he said if the bike is turning OFF even with two good Bore's then issue could be with something else so try testing the bike with known good sleeve piston, CDI unit, Magnet , Air filter Box one at a time.

Iam really in a very bad sutuation now I cannot be without my bike because thats my only means of transport to Office everyday. Now Iam
scared to drive 80km a day. Please help me I need all your valuable inputs.please:

Have you checked the carburetor for any defects? Maybe the fuel supply cuts off?

Get the electrical checked,The Starting Circuit,The CDI and also the igniton keys,they are most of the time faulty and you have been conned with the engine and power story so far with all those models there have been no change in either part number or part design of any engine components in the Unicorn.

+1 to that . Check the complete electrical system . I'm almost sure that the problem lies in it.

To me it sounds like the engine oil is the culprit, becuase if the bike is over heating, more than likely it will turn off automatically after a few kilometers.

When you changed the block to the new one recently, did you also change the engine oil? I would suggest draining the entire oil and filling it up with Castrol and see if that helps.

Regards,
Abhishekh Jain.

I did replace with Castrol Power1 Engine Oil, replaced the Bore Head Top Unit which pumps the oil, The carburator sleeve rubber had a gap and its now pasted properly.
Iam waiting for a known good CDI unit for testing purpose, proably will get it in next couple of days. Bike is kept unused now.

Looks like the engine is starving, oil is not able to lubricate the cylinder walls & rings properly. That is why the bike is overheating. Rarely I have seens Unicorn engine being repaired.
Please replace the oil & fill it with 20W40 as it has higher resistance to heat. Use Honda /Castrol branded oil & change the oil in front of you.
Hope this should work.

Please replace the oil & fill it with 20W40 as it has higher resistance to heat. Use Honda /Castrol branded oil & change the oil in front of you.
Hope this should work.

1) The engine is unchanged in case of Unicorn.
2) Revert back to originals for block, piston and head.
3) Check all electricals including coil.
4) You have modified the engine a bit, but did you check if lubrication was adequate ? The oil is not reaching all the parts, or it not possible for oil to reach all the locations.

I think what you need is a reliable work horse that is quick, not a bike with lot of power but is not reliable.

Unicorn is not known to give engine problems and I wonder why you needed the engine work to be done in the first place.

Take the bike back to an authorized service center and ask them to repair it. I think they will be able to solve all your issues.

Initially I thought issue could because of the low battery charge
Got the battery fully charged in Exide battery House yesterday. Exide stated that battery is fine and no need to change after testing. Its giving proper reading when tested in Multimeter.
There was no current passed from the battery when connected, Horn/Indicatora/Neutral LED does not work. Fuse in a small Box next to the battery is fine
Tested the Bike with a known good CDI unit and issue is still there, Bike turns OFF after riding 10Kms.
Iam again confused, What in wiring or the electric part could be causing the prob
Will be spending time on the bike this weekend to find the root cause

my brother rides a Honda Shine and faces similar issues - the mechanics at the dealer's service station claim there is no problem at all.

since your engine is getting overheated there seems something to do with lubrication. The engine is overheating a lot which is causing it to stall.

Hi Friends,

I faced similar issue this week with my Unicorn. I am using this bike for last 2.5 years and it’s been regularly serviced at Authorized Service Centre (Completed all free services and even had one paid service done).
This week while riding back home from my office, bike suddenly turned OFF. (Actually there was a false neutral and when I shifted back into gear, the engine stopped running.) Checked the engine, and that did not looked like over heated. Battery was also fine as indicators, horn was working normally (in fact a month back I have replaced the battery with new Excide one). Thus made one / two attempts starting the bike with auto start and bike kept cranking without actually starting engine. Then tried using Kick start. But felt the kicker to be very loose.
Had no option but to push the bike to nearest mechanic (which in fact hard to find in that particular area.) So pushed the bike for couple of KMs and when the road had slope, continued the journey with riding on the bike. To my surprise, engine started up there after. For last two days, bike is working fine as if nothing has happened.
Bike was scheduled to be serviced in October but now I am thinking to get that done ASAP. Would like to know the things to be checked so that this incident is not repeated. Please help me I need all your valuable inputs.

I can think of only one reason ! the carburetor has emptied itself for what so ever reason. (of course I believe it needs to be cleaned) The float chamber has replenished itself when you have been riding it down hill. Now that its working fine I would definitely say that your float chamber needs to be cleaned as there maybe something stopping the float to work I suppose. Since its working fine now just chill. Usually during scheduled maintenance they clean all this routinely. You have nothing to worry about.

i too own a unicorn for more than 4+ years. I had a similar issue, the culprit was the ignition key. Here what you can do.. whenever this happens switch off the ignition and switch on then start the engine it works for me...

Not completely off topic but I had a rebore job for my Kine (2 Stroke) way back in 1999 and though I had maintained 40kmph or less she stopped abruptly on more than 2-3 occasions with a sceaching noise and after a while, when started, I could smell the burning oil.

I assumed it to be the side-effects of the rebore and carried on for a good 300-400 kms after which I could feel the loss of power and It wont move beyond 50kmph (though It could easily max 80kmph).

After several trial and errors with Spark Plugs, CDI unit, Multilink, and even silencer from known good Kine, We finally found the fault with the bore which had developed linear lines concluding that it was a very bad rebore job.

The piston also had lines of the same sort and I finally decided to settle for a new Bore kit which resolved my problem.

A rebore job has to be done very accurately and carefully.

I would suggest you try and open the bore-piston assembly and check it out.