Babelfish

My VTR are running a bit rough, there seems to be much more vibrations than it used to be. I can't be exact but it seemed to start after a CCT valve crash. Only one exhaust valve replaced, and everything seemed to be in order. It has about 10 000km since that, and I have no reason to think that it is down on power or misfire. In that respect it's perfectly normal with the occational backfire, but every now and then I feel the vibrations are a bit too hard. It occour at any rev and when hard(ish) on power and it feels like I suddenly have a single and not a twin. At low revs there I feel this hard "thumps" as if it is a single. Still no power loss, just the vibration.

Earlier I suspected the valve crash, but now I've rechecked and alltough the front sylinder are not spot on the marks (1-2 deg off) I start to doubt that theory.

I've seen some of the carb-problems here on the forum, specifically the slides and vacume problems and started to wonder if my problems migh be the carbs. The've never been synced but that should not ususllay influence vibrations on power, will it? But could there be other issues. Clogged jets, slide hanging, or any other things that might cause the two sylinders to be out of sync on power? What do you guys think? Anny suggestions apprechiated.

Thumper

So you disassembled the head to fix the earlier valve failure, which would require removing the carbs, but you never sync'ed the carbs after reassembly.

I would for sure look at doing this and making sure yo do not have a Sparlk Plug or Spark plug wire problem first.

The carb sync is much more critical on a v-twin than an in-line four. Also make sure the carbs were seated back into the intake boots all the way. Air leaks can cause strange running problems.

If you were to post your location you might find out that a fellow forum buddy may live close and have the carb sync stuff available to assist you, you never know.

Babelfish

Yeah, I did the job myself, except for the actual swaping of the valve. Had a shop doing that as well as a quick lapping of the seat.
New spark plugs are on the list. Syncing of the carbs will be done later this summer as soon as I get the tools available. The carbs have been removed a couple of times but I'm pretty confident they are well seated. Have done this a fewtimes on my RS250 as well.

So you think syncing can solve this?

Thumper

Don't know, might and it might not, thing is anytime you pull the carbs or make a valve adjust ment you can affect the air flow thru the carbs, thus you need to sync.

Hard to tell, just one of the things you should consider doing.

Are you sure the valve you replace didn't tighten up and may not be closing all of the way.

Babelfish

What do you mean tighten up?
I did a compression test afterwards where the values where within spec.

Thumper

Valves can seat further into the head when new or newly installed. Slim chance that yours did this and now has zero vavle clerance, but hey anything is possible. YOu could verify easily by doing another compression check and or vavle clearance check.

Just ideas, could be the carbs and slides you mentioned, but unless you pulled them apart or they were not working correct before the engine work i would doubt they are the problem other than carb sync.


Do the simple stuff first, Plugs, compression check, make sure the plug wires are on good, carb sync.

Babelfish

No, thats not it. Checked all clearances two weeks ago, allthough two where a tiny bit tight they may well be within spec.
Thank you for the ideas. I'll definatly do the carb sync ASAP.