Author Topic: Right Side Running Hotter Than Left-UPDATE  (Read 1360 times)

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Offline Stoneman

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Right Side Running Hotter Than Left-UPDATE
« on: April 13, 2022, 08:26:33 PM »
Bringing this bike back to life. Running, but not perfect. New to 2 strokes, but have been reading a lot about them.

This 1967 GTO model is running now after 15 years sitting, and was likely sitting for a long time before that. Given that, it’s been under roof all that time and is in remarkably good shape considering age. Less than 5,000 miles on the clock.

I’ve thoroughly cleaned carbs, synced them, checked timing, points gap, condensers. New, appropriate plugs. Since both tires are flat can’t ride yet but have started it several times and run for a few minutes so it’s thoroughly warmed up.

Today I noticed the right side pipe is notably warmer/hotter than the left. Both headers are hot, and I’m pretty sure both cylinders are firing. Plugs would suggest this is so. Roughly, I’d say right is twice as hot as left feeling along the length of the mufflers. The air exiting the right pipe is warm, air on the left seems a bit cool, call it room temp.

I’d say there is more smoke coming out the right pipe compared to left. This bike is equipped with an early model that introduced oil injection rather than mixing oil and gas. I’ve checked the oil pump and made slight adjustment and it seems to be working.

So, sorry for the long background, but wondering if anyone has thoughts about why one side is running hotter than the other. Appreciate any feedback.

Thanks.
« Last Edit: April 18, 2022, 02:04:37 PM by Stoneman »

Offline old smokey

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Re: Right Side Running Hotter Than Left
« Reply #1 on: April 15, 2022, 12:04:28 AM »
There could be more than one cause, but on my GTR about 13 years ago I noticed one side hotter than the other. If I remember right it turned out that one side had a brass carb float that was leaking and that side was running richer (and colder). Good luck in your searching.
'67 350 GTR undergoing repairs with a '75 Yamaha TX500 front end

Offline BRT-GTR

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Re: Right Side Running Hotter Than Left
« Reply #2 on: April 15, 2022, 08:51:13 AM »
        I've had this problem, obviously the left cylinder, although firing, is not pulling it's weight. A couple of suggestions :-
 Check the carb slides are synced using circular mark on the slides so they open together.
 Also sync the idle speed on each cylinder. After warming the engine, Pull the plug cap on the left side and earth it to the cylinder using an spare spark plug. Restart the engine and note the the idle speed on the (good)right cylinder. Then reverse the procedure for the left cylinder and set the same idle speed using brass adjuster on the carb top.
      Reconnect the plugs, if it then idles too fast, lower each slide by the same amount on the brass adjusters. After doing the above recheck the slides are still synced and you have some slack on the throttle cables when the carbs are closed.
    That may cure the issue but as stated above there could be a number of other reasons why the left cylinder is running cooler.   Aren't two stroke twins good fun?  :-) .
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I'm so glad I grew up in the 60s & 70s. I did so much stupid stuff and there's no record of it.............Anywhere !!

Offline Stoneman

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Re: Right Side Running Hotter Than Left
« Reply #3 on: April 15, 2022, 11:44:26 AM »
Thanks for the suggestions, guys. I’ll try them.

BRT-GRT; 2 stroke twins fun? I have Two Hondas, both 1975 four cylinders, a 550 and 750. Four stroke four cylinders are twice the fun!

Offline Stoneman

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Re: Right Side Running Hotter Than Left-UPDATE
« Reply #4 on: April 18, 2022, 02:14:28 PM »
Think I got it sorted out. The problem was the left (cold running) side would run briefly or until it ran on idle for a minute or so. At that point, the carb slide was set to low and the cylinder would flood and shut down, leaving the right side running. The solution, thanks to BRT-GTR, was getting the hot side idle adjusted properly with cold side plug wire disconnected. Then disconnect the hot side and get the cold side running/firing and adjusting the idle using idle adjuster screw on top of carb. Just a note: if you do this, be sure your flooded plug is dry before trying to start engine again. Each time I pulled the plug and hit the spark end with a lit blow torch for a minute or then reinstalled the plug.


Offline BRT-GTR

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Re: Right Side Running Hotter Than Left-UPDATE
« Reply #5 on: April 20, 2022, 09:47:39 AM »
   Stoneman,  very pleased you were able to get your engine running better and thanks for the feedback, it helps others with the same problem.
        I spent weeks playing with a GTO engine, could get either cylinder running nicely but not both at the same time, aaaaaargh ! Then came up with the above procedure which sorted it.

   Glad I could help, Brian.
« Last Edit: April 21, 2022, 03:13:10 PM by BRT-GTR »
Unspoiled by progress.
I'm so glad I grew up in the 60s & 70s. I did so much stupid stuff and there's no record of it.............Anywhere !!

 


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