Warthog

I have maybe posted to you on the RS forum...can't remember. I have the same symptoms exactly. I did my valves and heads 3K ago and the moment I started her up from the valve job she did the same thing. DId it before and since... Always has! I thought it was one of the problems caused by the sticky valves. Yes I really had valve problems, after I went in there but putting her back together didn't solve the lope. I am convinced now I have a weak lifter. It was the only thing I didn't change out during the rebuild of the heads. I also ran yamalube (due to new rings) and really made it worse...seems the older the oil was the worse it got. Changed to synthetic 500 miles ago and almost smoothed out. Tells me the lifter likes better oil and can pump up better. Don't know if that is the real problem but that's my story and I'm sticking to it until I take the rear head back off this winter.

Ray

I had the same problem. 2004 with hardkrome 3" straights.Settings are 37.5 pilot jet,2.5 turn on pms,4th clip on needle,180 main ,kuryakyn twin velocity air filter. I've had the same problems as you.Found that the baffle fix on this site under hard krome baffles using the crumb cup in your exhaust seems to really help by giving some back pressure Look under Tech tips. http://roadstarclinic.com/content/view/51/105/.The sound does change some however.Maybe you could try the thunder monsters.

Post edited by: ROADHARD, at: 2005/06/07 22:01

Post edited by: ROADHARD, at: 2005/06/07 22:03<br><br>Post edited by: ROADHARD, at: 2005/06/07 22:03

I too have 04 R* and the problem you describe is one I am having. I did the &quot;stage III&quot; stock exhaust mod based on an article I found on this site. I added a DynoJet kit and followed the recommendation in the article. I replace the pilot jet, #170 main and put the needle clip on the forth position; PMS is at 3 1/2 turns out.

With the needle in 4 (no washer) I can smell it is running rich - exhaust stinks. The flat spot is still there only not as bad. If I move it to 3 and add a washer (1/2 step leaner) the stink goes away but the flat spot gets worse. The flat spot results in a kind of popping sound in the exhaust almost like a misfire. You can feel the engine isn't running smoothly and like you said just a little throttle movement in either direction is like flipping a switch; everything smooths right out. I can't seem to get rid of the backfire on shut down. I am wondering now if this has to do with the float level.

1) Help! This is frustrating hell.
2) Anyone know how to check the floats without the special tool?

Sorry I can't help you with the flat spot but checking the float level is no big deal and does not require special tools.

I did mine and found it a bit off right from the factory.

Do you have the manual? If so the directions are in there and quite clear.

Doc

Sandbag after reading your posts I wanted you to know that Ive read a lot of similar stories the last few years. Just about everyone on this forum knows more about mechanics then me so Im far from expert. But Im wondering if problem isnt a fuel system problem at all. Could it be an electrical misfire or stumble? Some of these things seem so elusive that after youve tried everything you can think of maybe look somewhere else for problem.

Warthog, I have been fighting a dead spot in my throttle since the day my Roadie was new. PMS adjustments until I can do them in my sleep. I changed to a DynaJet Jet Kit and find that have far more room to adjust. My bike is basically stock - I chopped out the baffles in stock exhaust, that's it.

The problem has always been much like what you are describing. If I try to maintain speed (just of idle) my carb goes flat. It makes a knocking crackle in the heads that causes the bike to sound cheap and performance suffers.

You know that all the circuits of the carb have to be in harmony to get optimal performance - exaggerate one part and you will effect the whole. Gram mentioned a simple way to test a main jet. Air box off, engine warmed up and running turn your PMS screw all the way in - your engine should die or nealy so. If it doesn't the main is too large.

I have this problem. With my main too large, I'm guessing that finding that harmony in the other circuits is impossible. I am dropping back to a Dyna #165, needle in the 4th slot, PMS out 2 turns and starting the process again. I bet that this fixes the hesitation (flat spot) because currently my PMS screw is basically ineffective and won't alow me to adjust the off idle circuit.

If you've already been down this road - sorry I couldn't help. I'd rather error on the side of too much information than not enough.

TAMaule

Blokes,

I had the same issues whilst sorting out my back firing problems on a 1999 R*

The state Yamaha dealer recommended I try dropping the size of the pilot jet. the result of this was to cause a flat spot just above idle when the throttle was just cracked open. ie. too lean in the cross over from idle irrespective of the PMS adjustment.

Loping at small throttle openings was caused when I went too high in the size of the pilot jet. Once again irrespective of the adjustment of the PMS.

Oddly enough I have ended up with the standard jetting for the needle and pilot circuits, but went up in the main jet.

I intend to try increasing the back pressure a tad in order to reduce the back firing further.

Hope this gives you a few clues.

cheers
Trev.

PS. Here in Oz our fuel is not as good as yours in the states and the octane can vary between 81 and 83<br><br>Post edited by: Bustedbiker, at: 2005/07/09 06:54

Well, I dropped back to a DynaJet 165 main, needle at 3.5 and the PMS at 1/2 turns out. The dead spot is far less pronounced than before. If I turn the PMS all the way in - what happens? Will try that on the ride home.

I know this ugly noise in the upper engine is carb related because I can get it to change throttle positions by changing carb settings. I'll be damned if I can find the right configuration.

The further out I turn the PMS the worse it seems to get. I think I'm back to stock if this ride doesn't change it for good.

I can't believe that Yamaha would even allow this to go on - other than this one problem the RS is a thing of beauty. I am very disappointed in this one area. I would think it would be to their benefit to get involved.

tamaule

dont give up hope brother...
these things are always easier to fix than it would seem...
personally i am running a maxair a/c.... a set of HK 3&quot;...and a dynojet kit...
i am running the #175 main and the factory #35 pilot...
the needle is set on 4 1/2 and she is running smoothly....
even better now that i have baffled the HKs with a quite small diameter baffle...
i have reduced the 1 5/8&quot; straight through baffles to 1 1/4&quot; with 2 pieces of copper (1 piece 1.5&quot; with another piece of 1.25&quot; drilled with various holes)...
i do understand your frustration and it is my estimation that if youve ONLY drilled your stock pipes... you need to go to stock on the pilot jet and then tweak your PMS some ...the #165 main may be a lil lean but the #35 (factory) pilot is definitly needed... i think youre running too rich in your pilot circut...just MHO...
warthog<br><br>Post edited by: warthog, at: 2005/07/12 00:09

&quot;if i had a sticking valve i would loose that cylinder completly and contrary to what i may have read on the internet the rear valves are not a problem as far as sticking is concerned on these engines...&quot;

That is incorrect on both counts. There are a lot of discussions surrounding 'sticky valves' on the R* Forum. There seems to be a problem with some of the 04's and it appears that Yamaha is fixing some/most for those owners who complain enough. From your dealer comments, you may be more succesful if you can find another dealer who is more supportive.

The dealer is correct re the pilot. I remember a discussion a while back re the newer carbs having a plug rather than the jet.

Good luck,

Doc