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Almost forgot to the first time, LOL. Now I always check myself.

Unrelated weirdo problem, while we're chatting. The throttle grip has a lot of free play in it that I don't remember. The carbs will open fully when it's twisted but there's probably an inch or more of free play in the thing before it takes up tension. I didn't disconnect anything other than unbolting the carbs from the heads and putting them back on.


1964 RE Interceptor 750, 2007 RE Bullet 500
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So now you have a lot of free play in your throttle grip that wasn't there before ...but your carbs open fully when it's twisted ??

Perhaps this will come across as a stupid question, but since you didn't elaborate further...did you check to make sure your throttle slides are fully closing when they should ? Based on your description, it sounds like your slides may be sticking OR your cables are binding somewhere they weren't before.

When you reattached your carbs, you may have inadvertently over tightened and warped the bodies enough that the slides are binding. It can happen.

Last edited by oilyamerican; 05/18/21 8:41 pm.

They say every dog has his day..
Trouble is, nobody tells the dog which day it is !

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I'm not an over-tighten guy, but the not fully closing gave me pause. I looked at them and they seem to 'bottom', plus they are both the same. There is some gap; I mean, they don't block off the opening fully (and shouldn't, right?). Here's a link to a photo of a random one but mine rest closed about the same: https://www.classicbikepartscheshir...02-fully-refurbished-p2970-3316_zoom.jpg


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Its the slide at the FRONT (ie nearest the engine) that bottoms down.
The cut-away at the back like we see there can never bottom out.
You might be able to see it with a torch, but I'd say its looking good anyway.

If you poke a fairly thin rod in there, you can feel if the front of the slide drops down on it.
Don't let go of your rod and lose it, that would not be good !

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Please define "some gap" . It should be almost nothing at an idle. And as Rohan said, it's the front of the slides that bottom.
You can try a thin welding rod, say a 1/16th of inch as a feeler gauge to determine if there's any appreciable clearance.
If the slides are rising and falling in unison and appear to be seating , then your cable/s must have jumped the track somewhere.


They say every dog has his day..
Trouble is, nobody tells the dog which day it is !

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I typed out the full story which follows. It's a long read; sorry! But I need some new ideas.

This is the video where it quit. Proof that it actually did run!

I got on it with a decent handful of throttle but not wide open. And it just shut off. Note: it was firing on both cylinders, though I suspect the left bank was weak.
Back home I cannot get it to start. I do a compression test and find the left bank is zero. Pulled the head and found a burnt exhaust valve. This was pre-existing, I'm certain, because the left exhaust never sounded quite right. I suspect the valve burned and the exhaust pipe was discolored from the timing chain tensioner coming loose, which is how the bike came to me. I only found that by accident because I took the mag off to have it rebuilt (preventative measure). After installing the mag, timing it properly and fixing the tensioner it started and ran as shown in the video.

Okay, so it died and had no compression on one side. I replaced the valve, compression rings and pushrod seals and put it all back together.
The rockers/valves all move.
The tensioner has not moved.
The marks on the cam gears are where they should be and line up to each other.
I have compression (tested multiple times).
It pulls vacuum through the intake (tested with the carbs off).
I have spark to both plugs. I've checked multiple times that it is timed correctly, retimed it multiple times, and tried switching the plug wires around even though I knew I had it right. No progress.
I've changed the plugs with another pair of the correct Champions.
I've checked and re-checked the valve clearances.
It seems to be getting fuel. Thinking there may be an issue with the carbs (doubtful, but hey, I'll try anything at this juncture) I've sprayed starting fluid through the carbs with the throttle open as well as removing the carbs and spraying directly into the intake ports. No pop of any kind. This is the thing that troubles me the most.

Previously, I would suffer a loud backfire and a violent kickback on occasion. I believe this only occurred when I had a lot of fuel in the cylinders. This has not repeated in the most recent rounds of testing.

I know...the above sounds like a timing issue. But I have literally checked/reset the already correct timing probably a dozen times by now.

How I set the timing:
Lock the auto advance with a zip tie fully advanced
Find TDC for the cylinder the mag is ready to fire on
With the bike in gear, bump the rear wheel backwards to 3/8" before TDC
Set mag points to just ready to open and lock on the auto advance unit
Remove zip tie

There is no key. This bike only has a kill switch. Which since I have spark can't be the problem as it interrupts the magneto.

Despite the dead cylinder, I believe the reason the bike suddenly quit was the securing bolt on the advance unit (on the magneto) came loose. If the cylinder had crapped out on it's own I still should have fired on the other one. The sudden death seemed electrical-like, which you can hear in the video. I believe whatever that was may still be the reason it is not starting today. Finding the bad valve was just a bonus.

I have literally spent the last 3 weekends screwing around with this thing and have made zero progress. I'm completely baffled. I don't pretend to be a genius mechanic but if I have spark, compression and gas/ether it should try to start. I'm hoping someone will have a fresh idea.


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Hello Dwight,
How has this project turned out for you?
I have a "64 also.
Jon Lange

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