Sputtering When given any gas

NerdyNerd

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Hey all... I'm back.
So I have the engine in and set up.
It starts and idles fine.
Can't find any vacuum leaks with starter fluid.
Jets are stock and the mixture screw is at 2.5 turns out.
I have tried upping jet sizes and dropping with no change but the bike will not go past 2000RPM without just sputtering. When cold it just dies when I give it any gas, when warmed up it will sputter unendingly with any fuel.
I did a teardown and installed new gaskets everywhere.
Any ideas? I have a feeling its timing related at this point and I'll need to tear it apart again.
 
I have a feeling its timing related at this point
The symptoms could indicate a timing issue. Easy enough to check: remove right cam cover and left rotor cover, put rotor at TDC and the dowel pin on the R cam end should be @ 12 or 6 O'clock.

Check ignition with a strobe light: 'F' mark @ idle and advancing clockwise with rpm's
 
The symptoms could indicate a timing issue. Easy enough to check: remove right cam cover and left rotor cover, put rotor at TDC and the dowel pin on the R cam end should be @ 12 or 6 O'clock.

Check ignition with a strobe light: 'F' mark @ idle and advancing clockwise with rpm's
I have so much to learn. I wasn't aware that I needed the strobe light on the TCI models
 
Yeah, the strobe is the only way to check ignition timing. With OEM ignition, it's rarely off.

I've seen too advanced cam timing cause the symptoms you're having though. Only need allen wrench or screwdriver there (as the case may be)
 
I had an issue that behaved like yours when my bike was fully warmed up and running 50-60 mph. It died on me. It would start and idle perfectly. As soon as I tried to get on and go, no doing. One of these fine folks sent me a TCI to try. That was it. I sent my TCI to @rickthefix. I believe he reflowed the solder joints and it once again runs like a new XS650.
 
I had an issue that behaved like yours when my bike was fully warmed up and running 50-60 mph. It died on me. It would start and idle perfectly. As soon as I tried to get on and go, no doing. One of these fine folks sent me a TCI to try. That was it. I sent my TCI to @rickthefix. I believe he reflowed the solder joints and it once again runs like a new XS650.

I've also had a TCI box do what yours is doing. Replaced the box about 4yrs ago. Good ever since.
 
Ahem.........there's a few things that can be checked before jumping to a faulty TCI unit (although that is a possibility). Besides the TCI unit is ~$900 new (CMSNL.com) and $400 used.....
 
Ahem.........there's a few things that can be checked before jumping to a faulty TCI unit (although that is a possibility). Besides the TCI unit is ~$900 new (CMSNL.com) and $400 used.....
Absolutely. For starters, look at the rotor and see if it's a Chinese knockoff. I know of 2 or 3 times when that caused stuttering off idle. An easy way to check that is to disconnect the Reg/Rec and see if it runs normally.
Have a read here.
 
Hmm.....so all we know, so far, is that it's a newly installed motor after a top-end (?). In troubleshooting, I like to start with checking last work first: hence cam timing, compression, then electrical/ignition and finally back to carbs. Could be lots of things, but that's just the way I'd go about it
 
Hmm.....so all we know, so far, is that it's a newly installed motor after a top-end (?). In troubleshooting, I like to start with checking last work first: hence cam timing, compression, then electrical/ignition and finally back to carbs. Could be lots of things, but that's just the way I'd go about it
Yes, you're right. Always start with what got f**ked with.
 
Yes, you're right. Always start with what got f**ked with.
Yep. I think I'm going to tear it out again and make sure cam timing isn't bad. Does anyone have a walkthrough or an explanation of where the cam is supposed to sit in relation to the TDC? I had a hell of a time finding that prior and not 100% sure it's where is should be.
 
1680294903251.png


Do you see that notch on the cam pointing straight up? That's with crank at TDC.
 
Yep. I think I'm going to tear it out again and make sure cam timing isn't bad. Does anyone have a walkthrough or an explanation of where the cam is supposed to sit in relation to the TDC? I had a hell of a time finding that prior and not 100% sure it's where is should be.
You don't have to "tear it out" to check the timing. Just put it at TDC and check R end of cam for dowel position: on yellow line...
cam dowel TDC.png
 
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