Author Topic: 1KT Engine Trouble. Help!  (Read 495 times)

IOMTZ

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1KT Engine Trouble. Help!
« on: January 23, 2018, 10:21:34 PM »
Hello I'm after some advice, i purchased a 1kt this time last year as a project but it has a issue where between 8500 9500 rpm 1 cylinder will cut out / start running rough, this didn't both me at first because i knew i was going to rebuild it.

So i did rebuild it full engine strip, new pistons, con rods, main bearings, gaskets oil seals etc, carbs cleaned and new jets etc fitted. new reeds. complete new ignition system (bar CDI) but still i have the same issue where one cylinder will stop firing however if i cover / block the exhaust of the running cylinder well holding the revs at 9000 and up the bad cylinder will chime into life uncover the exhaust and rev perfect through to redline ?:-| until i shut the throttle off and try to rev her up again back to square one. 

now the only thing i didn't change was the crank lab seal because i ordered one gave it to my crank builder and it turned out to be oversized & he said the old one was abetter fit & seamed fine.

I have also ruled out the power valves being the issue as I have run the bike with the servo disconnected with the valves in the fully open and closed position with the exact same results.

any advice would be greatly appreciated. Cheers             
« Last Edit: January 24, 2018, 11:05:55 AM by IOMTZ »

Bob the B

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Re: 1KT Engine Trouble. Help!
« Reply #1 on: January 29, 2018, 12:54:59 PM »
Is it always the same cylinder cutting out? If so which one?

IOMTZ

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Re: 1KT Engine Trouble. Help!
« Reply #2 on: January 29, 2018, 11:35:23 PM »
Nope it swaps between cylinders, I知 thinking possibly the cdi is at fault!  :(

tzr-v4

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Re: 1KT Engine Trouble. Help!
« Reply #3 on: January 30, 2018, 12:19:23 AM »
On 1KT like on other Yamaha the ignition is a waisted spark one so both cylinder get a spark every half turn.

Before changing the CDI, I'll check :
 - spark plugs,
 - HT wires,
 - HT coil,
 - wiring loom
      - orange wire from CDI connector to coil.
      - grounding to negative
      - pickup wire from stator

These are less expensive so have to be checked first in my opinion.

Olivier.
Olivier.
TZR250 2MA & 2XT, RD500s et TZR-V4 building...

IOMTZ

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Re: 1KT Engine Trouble. Help!
« Reply #4 on: January 30, 2018, 01:33:18 AM »
Thanks for that, I知 on the second set of new plugs (was paranoid I had duff ones) & it痴 had a new ht coil, pick up coil and stator with exactly the same results as when the originals were fitted, so I知 scratching my head a little. ?:-|

teezer250

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Re: 1KT Engine Trouble. Help!
« Reply #5 on: January 30, 2018, 12:52:19 PM »
Thanks for that, I知 on the second set of new plugs (was paranoid I had duff ones) & it痴 had a new ht coil, pick up coil and stator with exactly the same results as when the originals were fitted, so I知 scratching my head a little. ?:-|

Did you buy a genuine yamaha coil as the cheap pattern ones have been known to fail under high revs and not up to the job?
If you bought spark plugs off ebay, they could be fake.Buy from bike shop or Halfords etc. NGK BR9ES.
Have you put new plug caps on and trimmed the ht leads back a few millimetres to expose the wires?
2 examples below, I have the second type on both my 1KT's:

https://www.ebay.co.uk/itm/NGK-LB05E-R-Spark-Plug-Cap-Resistor-Cover-Red-90-8898/272137063618?epid=1416224513&hash=item3f5ca20cc2:g:lk0AAOSwezVWxIx6

https://www.ebay.co.uk/itm/NGK-LB05EMH-R-Spark-Plug-Cap-Resistor-Cover-Red-90-8160/271684961959?epid=27012075227&hash=item3f41af86a7:g:APIAAOSwhDdXELIw

New pick-up coil and stator,are these from electrex world? I have them on one of my 1KT's,no real problems at all.

Make sure all the connectors are solid and not suffering from corrosion,I had the negative battery lead hanging on by a couple of strands of wire where it bolts to the battery terminal.
Coil spade connectors may be corroded where the wire crimps on.
Check fuses are clean and sound and correct sizes(amps) and fuse box terminals and wires for corrosion.

Another thing is the fuel flow might not be sufficient at high revs.
Problems could be,blocked fuel cap breather,clogged fuel filters(tank and carbs),incorrect float heights,main jet nozzles tiny atomizer holes clogged.

Are the powervalves in sync when turned as the joining piece between the barrels may be worn or the powervalves where the joint goes may be worn leading to left valve opening fully and the right one trailing a bit behind not fully opening.

At some point in owning both my 1KT's, (14 years and 3 years) I have had to do the above to sort out running problems.

After doing all of the above advice,the only thing left may be to change the cdi.
« Last Edit: January 30, 2018, 12:54:59 PM by teezer250 »

IOMTZ

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Re: 1KT Engine Trouble. Help!
« Reply #6 on: February 20, 2018, 10:13:04 AM »
Hi thanks for all that information however I知 still no further along with my issue. Is there anyone in the uk that would let me send you my ecu and plug it in too your bike too see if it is at fault. Cheers

mellorp

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Re: 1KT Engine Trouble. Help!
« Reply #7 on: February 20, 2018, 07:19:11 PM »
Or you could just go with a zeeltronic http://www.zeeltronic.com/page/yamaha.php
Mellion say If it ain't broke thrash it until it breaks

IOMTZ

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Re: 1KT Engine Trouble. Help!
« Reply #8 on: February 22, 2018, 09:37:59 PM »
Cheers for that the zeeltronic sounds good, however I知 still trying to diagnose the cdi as being the fault hence why I could do with plugging it in to another bike  (-P)

teezer250

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Re: 1KT Engine Trouble. Help!
« Reply #9 on: February 23, 2018, 03:07:36 PM »
Hi thanks for all that information however I知 still no further along with my issue. Is there anyone in the uk that would let me send you my ecu and plug it in too your bike too see if it is at fault. Cheers

I could help by testing it on my bikes,but not for a few weeks until the weather warms up..

Both sets of carbs need taking apart and ultrasonic cleaning due to using castrol r40 gumming them up.
Also both bikes are awaiting new fuse boxes fitting to improve electrical power due to originals fuse terminals and wires corroding causing weak spark and hard starting.One bike is also awaiting a replacement wiring harness to be fitted.

Too cold to work outside stripping and replacing parts at the moment,only have a 8' x 6' shed with both bikes in and little room to work in there.