[Desert Rat]

I bought my 69 Bonnie T120r with right hand exhaust pipe blueing and heat discoloration near the head but didnt think much of it till now. I started it after rebuild and only after about a minute of running the right pipe was definitly hotter than the left by sight and on feeling the air coming out of each end, the right side was not only pretty warm but blowing stronger than the left. My novice mind decided that this could be caused by an exhaust valve sticking open during combustion thus blowing out hotter air at a higher power. Make sense? I had the valve guides renewed but a Harley mechanic took care of the head reluctantly and admitted he hadnt worked on a Triumph in 20 years and never willingly and aftr looking around he was the only person who would touch it. He knows HD really well but maybe not Triumph. Could he have missed something? Could it be the valve sticking open and if so should I just bite the bullet and pull it off and send it to a pro or is there a simpler fix? The timing is good and the blue pipe tells me that this was a problem before I bought it.

 

[kickstarts]

I'm no Triumph expert(there are several here though) but if a valve is sticking open, you'll definately notice it. The bike will run like shit.

If it's not popping and backfiring, I'd focus on the carbs instead

 

[Tony the torch]

so it was kinda like taking your Jaguar to the Toyota dealership for a service?

it is not going to do a lot of good to keep trying to run it, pull the head and find out what the problem is.

 

[Desert Rat]

Oh all right, was kinda trying to avoid it but knew I had to do it in the back of my head. Done it twice already so am getting pretty good. Checked out your website, Tony, really amazing work you do and thanks for the advice.

 

[ManxRacer]

Not sure why you think a valve is sticking open. More likely your right carb is running way too lean.

 

[Tony the torch]

you may be right Manx, a compression test should answer that.
30% of your fuel mixture is gone when the pilot circuit is plugged up.
If you pull the head and do a gasoline test to see what quality of valve job you had done.

 

[Desert Rat]

I guess I just figured it was more than just the carb with all the discoloration on the pipe. The pipe was blue when I got it and I bought new carbs and tuned them the same. Im pretty new at this so its just a guess at the valve. I may tear into it and if I do Ill post some pics. Worst case theres a trump guy in Albuquerque, 3 hrs north who'll line me out .

 

[Bodyworx]

At first thought, i wouldnt really think of a valve either, this is why: First, if you had an exhaust valve open during combustion, you would not have had a stronger pulse, maybe hotter but not stronger. It would indeed run like shit and perhaps hotter. First thing i would do is check the plugs. They tell the real story in most cases. Get good at reading plugs and you'll save yourself a lot of headaches in the future. In my experiences with these animals, they run pretty hot. If there is an imbalance in temp, i would also suspect fuel. What do the plugs look like? There is a lot of information via the google box about reading plugs. Just a thought. I am sure someone will correct me if i am wrong. Are your pushrods all the same length? Don't think that is a stupid question. Ask me how i know that? Any slightly bent? Start your process of elimination and go from there. you can never have enough information when tracking down a problem but you can always have too little.

 

[Desert Rat]

Hmm, good tips. Ill check the plugs and look into tuning the carbs again. You think running it is risky with it running so hot? Bodyworkz, youre in the south west, know any triumph folks in the Las Cruces area?

 

[fouraceswes]

If you have stock points, the trouble could come with timing too. Hot pipe, bad running, too advanced on one side...maybe.

 

[scottto93]

Could be anything mentioned above.....couldn't ya just pull the plugs and read their fortune?

If a valve were sticking open it would probably be promptly hit by the piston and bent (or worse) and in turn kill compression.... you could also have a dead cylinder if the plug is wet from flooding....and in turn would sound like a lawnmower...funny but that's what i think it sounds like...and it'll idle like shit..

 

[Daturat100r]

Check and reset timing statically ignoring alternator rotor markings,happened to my triumph and it was from timing with a light with a loose rotor outer causing mistiming.Initially the outer part of rotor only came loose when it got hot,new one was the cure

 

[Desert Rat]

Unfortunatly my time is at a premium and havent checked out these tips, like the general direction of leaving the head in place. This all makes sense but do you think its all coincidence that the previous owner also ran the old right side carb lean causing the pipe to discolor before I even touched this basket? Thanks for the info, Im glad this forum is a curious bunch...

 

[Bodyworx]

I've seen stranger coincidences. I don't know anybody in that area but surely you be better off figuring it out. It will well round you better and help you become one with that machine. Just my .02. Process of elimination. Get a notepad and check things one at a time and take notes of your observations to share. Hope that helps.

 

[Glider]

Not likely a sticking valve. Also, doing a valve job on a Triumph is not rocket science, any competent HD mechanic should be able to do a good job.

The solution to all problems starts with a proper tune-up. Take the carbs apart and check that all jets are as per the manual, time it like the manual says, adjust the valves like the manual says, sync the carbs like the manual says..... Get the picture? Once you know that everything is set to factory specs, and if the bike still runs poorly, only then should you start considering things like 'sticky valves.'

As far as pipe bluing goes, if the chrome is cheap they'll blue quickly, if the bike is just sitting there running with no air blowing over the pipes they can turn blue.

Modern bike makers use twin-walled header pipes to prevent their chrome pipes from bluing. And they do so only to keep the bikes looking 'pretty' and because customers always complain about the pipes turning blue.

As an old-time Triumph rider, all blue pipes mean to me is that the bike's being ridden.

 

[Desert Rat]

So I went through the timing again, then again and fired it up. Even running, even exhaust, sounded good, but still ran hot as hell but guess thats how it goes. Took it for a slow ride through the neighborhood and turned some heads, now to all the oil leaks...
Thanks for the advice and direction steering.
Chris
PS. Just on my way to pick up a '73 Triumph Tiger, super cherry, and for $3500! Gonna need to have a yard sale to make room in the garage