Hi everyone,

I have renovated my old TR1(5A8) engine and i am having troubles getting the mixture in idle dialed in.
I hope that some really clever people can help me out inhere

My problem is the front cylinder that is running really rich.
No matter how far I screw ind the mixture screw i get a really rich mixture. 13/14% on the gas tester, and a really yellow/orange color on the color tune.
My exhaust from the front cylinder also looks like an old British chimney.

I have checked the carburators multiple times, all the jets, needles, float height(many times), diaphrams and so on.

- The entire ignition system has been checked
- filters and air passages.
- carburetor mounts for leakage
- gasoline
- carbs has been synchronized several times.

When i drive it, it runs decent, but i am always worries it will turn of the engine.
The engines start really well and idles decent aswell, but in time the spark plug gets so black that it starts misfiring.

I am thinking now:
- could it be valve stem seals (but do they influence the co tester?)
- could it be worn piston rings? (The smoke is not white or grey but black)
- could it be a bad valve? (Would that influence the mixture? I guess that would be poor engine performance and behaviour)

I am really lost here and need some advice

Good morning Greg,

if you are inspecting your carburettors:
1) as nanno said before, check for proper installation of all jets to the corresponding carburettor.
2) check diaphramas for cracks or puntures in the rupper surface
3) check the stater plunger inserts for correct sitting in place, sometimes the rubberseals are old and not more so flexible. if you pull the Choke cable, watch for the moving of the stater plungers. After releasing the Cable, does the Starter plungers are going back to fully back (closed) positions? Check it by pushing the little piston on top of it. If they are able to push a little bit more in , they are open a little bit, that on the other side enriches your mixture.
4) Pilot Srew: basic setting is 2 evolutions out ( from the complete closed position. if you have turned out the Pilot screw, renew the little O-Ring, to prevent later problems. I mean, the older the Rubber material the more it goes harder. And hard Rubber is not usefull to seal sensitive adjustments.
5) after the Engine starts and warmed up perfectly let it run for a while with some raised rpm from time to time. After shot down check the colors of the ign-plugs to inspect how the adjusted mixture works. Color shout be between white-light grey and middle grey-brown. If your bike is in condition to take a ride on it, drive it for some miles and check the colors of the Ign-Plugs ceramic insulator, then.

Hope it helps you
Regards Anja

Is your engine ventilation connected to the front or rear cylinder? Normally it is connected to the rear, but i believe i have seen bikes where it was connected to the front. Mine had also high CO2 values on the rear cylinder, i removed the engine ventilation and then i could adjust the CO2 normally.

Hi Greg,

I have double checked the jets and diaphragms several times and I am sure they work and is in their correct position. Thank you.

Hi Anja,
I have also checked the starter plungers, actually disconnected the mechanism that opens them to be sure. The bike start really easy without this.
I have installed new renovation kit for the carburetors from keyster, and have also been aware on the different parts in each set for front and rear cylinder.
thank you for the input.

Hi Hornschorsch,
Mine is connected to the rear cylinder carburetor but the hose from front cylinder. will this impact the mixture you think?

Hi Ali,
I have not checked this, but i will definitely try it. I know my petcocks are rather old. I will keep you guys updated on this, during the week. thanks!


Thanks all for the help, really appreciate it  

Hi all, it's been awhile but that life when you have small children

I read another thread where someone had troubles with bad wires, so I checked my entire wire harness, I should not have done that... I now have a complete new installed  

I tried to bypass the vacumm pipe from the intake-manifold, and sadly without any luck.
Also did a compression test on a cold motor. The test showed approx. 12 Bar on each cylinder, so I assume the piston rings are fine.

My front spark plug is very black and rear very white(with black edge), any sparkplug expert that can say anything on behalf of this?

I have discovered a ticking noise from the front cylinder head, and also found that the front cylinder backfires/misfires at times, almost looks like it want to eject the front carburetor out of its manifold. When the engine is cold and I hold my hand to the exhaust pipe from the front cylinder, my hand catches some black matter.
could this be:

- Valve stem seals?
- Worn valve springs?
- Worn valve seat?  

I measured 4% roughly on the rear cylinder and 13-14 on the front cylinder.
I have synched the cards however maybe I should try it again.

It must have been condensation in the cylinder, I tried again to hold my hand in front of the front cylinder exhaust and the result was somehow different. I don't know if it is the smell of burned oil or just result of running rich.

I have recorded two short film clips yesterday of the bike.

One where i start it up cold in the morning: (The sound on the video is very 'mechanic/metallic' that is where is back fires.)
https://youtube.com/shorts/vzHNE871RM4

and one where it has been running for 20 km:
https://youtube.com/shorts/TG7u3A7eCRU

I am considering that it is a broken valve stem seal or something wrong with the valves on the front cylinder.

Good Morning Kennihs,
to your starting Audio: It sounds that your ignition is not working correclly. First impession was "only one Cylinder" is working.
That is corresponding with the black face of spark plug Cyl2
Q1: Do you have a Flash-Light for checking the Ingnition Point? If yes, check both Cyl 1 and 2 for proper timeing.
Q1.1: Does the Spark Plug Cap(s) is/are in good condition?
Q1.2: Does the Ignition wire Cyl2 is good at the end which is drilled in the Spark Plug Cap. If not, cut a little piece off to get a good end before
        connect it to the spark plug
Q1.3: Ignition Coils: Cyl2, is the left one (seen in drive direction) Check electric wires for good conditions. Are all wires without any cracks,
        are the connection plugs without corrosion on the contact surface?
Q1.4: Check wires from the pick-up coils. (left side of the engine, right abow the clutch-link-cover, in front of the air-filter-housing. See Pic.
        Check for thermal deformation because of the head in the nabourhood of the Cyl1 exhaust.
Q2: Double Check the Starter Plunger, they are Rearly fully closed. Check it by push them down by using your finger.
Q3: All O-Rings new? You can check it, while the engine is running, spay it with brake cleaner a little bit.
     If rpm rises with the influence of alcohol the O-Rings are not good.
Q4: Pilot Screw (s): 2 evolutions out from full closed position?
Q5: JET-NEEDLE: Cyl 1: Y-21  and Cyl 2: Y-20 , The Cyl1 (rear) is tendencly more rich then the Cyl2 (front) for inner cooling.

If you are not sure, whether the spark plugs are ok, if they are new or not, innerchange them form cylinder to cylinder. If spark plug from Cyl2 is working correctlly in Cyl 1 it is ok     a.s.o.

Syncronizing the Carbs:
1) Be sure both Throttle Flaps ar not closed. So you can use the Throttle cable at your handlebar. Therefore use the Cable Aduster.
1) You are able to sync the carbs properly or must you turn in the adjustment screw fully to there end in?
    If it is so, try to shorten the spring behind the adjustment screw a little bit to get the screw more in.
2) Do you have in place the screws for the Throttle Flap adjustment? See pic. Sometimes it is neccessary to use both of them.
   The right hand one is to understand as master to adjust Idle rpm during normal operation.
   During adjustment of the carbs is could be possilbe to adjust the left hand one, also. However, the left hand screw is to handle with care !
   Use it for fine adjustment after the main work of syncronisaton of the carbs is done. Only for adjusting Idle running.

With kind regards
Anja

Good Morning Kennihs,
that is a good idea, remove for testing, the foreign revolution indicator.
Connect all wire in the OEM-Way and test it again.

On your videos, the front (Cyl No2) spark plug is truely dead, at all.

In the original layout, the orange wire, which comes from the TCI-Unit for the L/H Ignition coil, will used for the Rev-Ind, as signal source, also.
---
The Plug-Connector of the OEM Revolution Indicator shows 4 Wires:
Blue = comes from Light-Switch for Illumination the Scale
Black = Frame Ground
Brown = Wireharness ground ( inside the Wire Harness some "Ground" Needs are feed together inside the Wirediagram )
orange = impulse source ( from TCI-Unit towards left Ignition Coil )
---

So, if you need a signal source for your foreign Equipment, use the orange wire.

AND if your engine fires up in a correct way, let it run for a wile  to remove all oil charcoal deposits inside the cylinder.
When the ignition problem is solved, sync the carburettors. I do not think, that it will be neccessary to insert other Needles for "fine" tuning the carbs.

If all original Needles and jets are located correctely inside the Carbs, and these are synchrinised properly and the CO-Screws (Pos 28 **) are from fully closed two revs-out adjusted, the engine shut run very well.

** see my images about the carburettor parts, I had placed abow.

Kind regards
Anja

You can use a small 2mm drill to try to get the blocking stuff out. Just per hand and soft turning it. When blowing it out does not work.

Hi Kennihs,
any progress?

happy Eastern
kind regards Anja

I drilled out all the small brass bushings, and tried to dig out som foregin matter I observed.
The reason for taking them out, was when i compared the flow through the pilot passages(I blew by mouth xD) i found great resistance in the carburetor.

I found some plastic/fibers in the passage, and they were quite difficult to dig out. Maybe som eearly tinkere tried to clean the carburator beforer me

I did a VERY ruff adjustment of the carburetor, and assembled everything again, this time with no smoke from the exhaust and two sparkplugs that did not build up crazy carbon deposits within a few minutes.

For now I believe the bike kan be tuned correctly, but i will let you know and post a video when that time comes

Thank you so much for all your inputs so far