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1978 TR7RV running poorly

2K views 17 replies 4 participants last post by  EagleLakeWood 
#1 ·
I'm trying to get my newly acquired TR7R running after what I believe to be a 10 year rest. I changed all the fluids and was thrilled that I actually got it started. It certainly doesn't run smoothly. I'll list out some of the factors and maybe you can offer some advice.

Coils
The previous owner put new ignition coils in. The resistance reading on the coils is (the number in parenthesis is the setting for the ohm meter):
Right side:
Primary 3.8 (200)
Secondary 5.8 (200k)

Left side:
Primary 3.9 (200)
Secondary 6.1 (200k)

Plugs
The left side plug looks pretty normal. The right side plug is quite a bit more sooty (see attached). I suppose this would indicate a rich mixture, but why only one side (single carb)? I put in new plugs and they did the same thing.

Carb
I don't have a lot of experience adjusting carbs, but I did notice something. The air pilot screw is loose and I think it's working it's way out when the bike is running. The throttle screw seems similar. Am I missing a spring inside both of those, or an o-ring. I'll consult the diagram for my carb. When I had it running, I did adjust both of these to various settings and there wasn't anything that made a profound difference.

How it runs
It won't stay running unless I have some throttle on, despite changing the idle setting.
There's a lot of popping.
It bogs down when I try to rev it up.
It backfires sometimes when I'm trying to start it
I sometimes experience blow back (an air pop) from the carb/air box
It doesn't exactly start easy. My foot hurts from kicking it 50 times.
The choke doesn't stay on. Is this normal? I push it down and it creeps back up.

I don't believe there's been any major work done to this engine. I could be wrong. The bike has around 6000 miles on it.

Any guidance is appreciated.
 

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#2 ·
Hi,

The air pilot screw is loose and I think it's working it's way out when the bike is running. The throttle screw seems similar. Am I missing
an o-ring.
You are. 'O'-rings provide both a seal and additional friction to maintain the screw setting despite vibration. Fit the 'O'-rings, set the pilot air screw 1-1/2 turns out from fully-seated and see what still remains from your list of 'problems'. :)

Hth.

Regards,
 
#3 · (Edited)
............The air pilot screw is loose and I think it's working it's way out when the bike is running. The throttle screw seems similar. Am I missing a spring inside both of those, or an o-ring...........
for just a few bucks you can get both a throttle and air-pilot screw with "new/unworn" tapers and brand new o-rings/rubber collars.
 
#6 ·
Hi,

for just a few bucks you can get both a throttle and air-pilot screw with "new/unworn" tapers
The throttle adjusting screw can only "wear" when the slide is in contact with the end. Given most of this contact is when the bike isn't in use, how does it "wear"? Moreover, the throttle adjustment is a function of the distance between the adjusting screw thread and the slide, what difference does wear on the end make?

The pilot screw doesn't "wear" because it isn't in contact with the "seat" (if it was, there wouldn't be any air in the pilot air/fuel mixture).

Hth.

Regards,
 
#5 ·
UPDATE:
I tested for spark and the right side (the side with the tainted plug) has no spark. That explains a lot. I did check the spark a while ago and both were firing, but that was before my wiring meltdown here. Is it possible that I damaged a coil during that?

It may be one of the spark plug wires. So tonight I'll test the wires and try one of the original coils that I have if it's not the wire.

I'll update again when I have something intelligent to say (it might be a while :grin2:)
 
#7 ·
Hi,

Is it possible
It may
try one of the original coils
The bike already has two sets of HT components (coils, leads, (screw-on caps?), plugs), one set of which works. So why not just swap each pair of components between the working and non-working sides? When "working" and "non-working" swap, you've likely found your faulty component?

:badum

Hth.

Regards,
 
#11 ·
High temp silicone will seal up that exhaust balance pipe.I use it on all exhaust joints and there is a type used for sealing heating boilers in black colour.Go for the highest heat rating available and smear all over the pipe before sliding it together.Not just a little bead.Smooth it on at least an inch of the pipe.Even low temp will work and burns a little but stays put.
 
#12 ·
I bought some copper colored sealant good up to 750 degrees Fahrenheit. It said it was for sealing exhausts so I figured it was a good choice. I sealed up the balance pipe, the joints at the motor and the silencer connections.

The first time I started it, I had some smoke and that great smell of chemicals burning, but after that, it was good and held nicely. Except for the unsightly color, it's doing the job nicely.

Thanks!
 
#16 ·
The Premier carbs will certainly last longer.i found i could wear out the body on a standard carb in 10,000 miles without an air filter.The premiers are still fairly new on my bike now so wear will not be known yet.
If you have a choice of plugs,fit some Champion N3C.I have never had one foul yet.Of course,you do have other problems that are causing fouling.
I use a Gunson compression tester which gives a fair indication that,at least,the two cylinders have near enough equal pressures.
 
#18 ·
At the rate I get to ride, the standard carb will last me a lifetime.

I've been running the N3Cs, but like you said, I've got other issues beyond the plugs. The new carb arrived today, so I'll put that on this weekend along with the new silencers. That sounds a little too ambitious, but we'll see.
 
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