Bike Settles at two speeds....

Been having issues getting the biked tuned and thought I was confident with my carb cleaning until I started reading The Church of Clean!

Having read from top to bottom and have to confess it redefined what I thought of as clean so I have just spent three days executing the steps meticulously and now I can report with confidence, those carbs are holy!

I discovered the enrichment circuit holes in the bowls were not completely clear (I hadn't realized they existed previously!) I also purchased a rebuild kit and changed all the seals, gaskets, float valves etc even though I thought the other ones seemed fine, now I can be sure.

Have to confess, wet balancing the carbs again felt like punishment for not doing this right previously and it took 11 iterations and 4 hours.

OK so now I am confident about the carbs and the valves were re shimed a few months ago too so I have now started testing and have the morgan carb tun on to start tuning.

Bike fired straight up - Smile!

However.... I have two speeds at which the bike settles at, a lower speed and if I blip the throttle it then jumps up several thousand revs and stays up high. If I adjust the tick over main screw to bring the revs back down from the higher plateau it will then drop below the revs needed to stop the engine dying.

I should mention that the bike has been rejetted to try to compensate for the pods and short exhaust cans. I have broadly followed jetting advise found here (+1 pilot, plus 4 main) actual advise I found would have lead to +3 main but I have +4 and thought I would start my test with that and see what happenned.

I intend to go get the bike dyno tested and work towards a correct jetting but don't want to start this (expensive) process if I have other issues.

Does this sound like a jetting issue or something else at play here, I am thinking the higher plateau is when the main jet kicks in.

Thanks guys.

 

A couple of other points. Pulling out the choke kills the engine (suggesting it is too rich?).

And dont take offense but please don't advise me to put the air box back on and the stock exhaust, however well meaning it just isn't a possibility!!!!

I know that this is better for the running of the bike and that it is unlikely to ever run as well again without them.

The bike has been chopped and pods are the only air filters that will fit the frame.

 

check the throttle linkages, free and clear
check for vacuum leaks
go back to that running sync and check it again, when you do that, see that the idle knob is truly setting the idle speed
are you confident in the condition of the throttle shaft seals

 

I know you don't want to hear it, ... but you're between a rock and two hard places.

Pods elicit a Lean Condition.
Exhaust Mods exacerbate the problem.

There's no definitive solution or standardized recommendations for re-jetting.
What recommendations exist for re-jetting are the results of guess-work.
There does not presently exist, any prescription that will definitely solve your performance issues.

*** (It is MY personal opinion that Dyno Testing trying to resolve performance issues on quarter-century old, normally aspirated engine, having absolutely nothing at all to reprogram related to improving power ... or even the ability to make alterations to the timing curve or fuel delivery ratios ... is a complete waste of time and money.) ***

 

Thanks for your input guys.

I need to press forward Rick as I am where I am. I have a modified bike and having seen other similar mods running I know it is possible, just a nightmare to get it right, no point looking back now.

I certainly dont want to start the dyno route if I have other issues to resolve so trying to establish whether the symptoms are jet related.

Polock, I think you may have hit on something in it makes me feel like a fool. I saw reference to the throttle shaft seals and I couldn't see them in my carb diagram. I wondered what where they were. When I stripped my carbs I split the rack and clean them with the butterflys held open but didnt remove them..... that's why I never got to find those bloody seals!

Also when I got the rebuild kits, I used the seals that I had and they were not part of the kit so thought my job was complete.

In other words, I have no idea of the condition of these seals!

Back to the drawing board..... Also have to find a supplyer this side of the pond.

Thanks for the help.

BTW just watched a video on removing the srews on the butterflys for Mikuni's showing that you have to file them down. Is that true of the XJ550 too?

 

Ome other area just thought might indicate my own stupidity.... I dont have a centre stand and have been tuning the bike on the side stand. Having spend hours trying to get the wet balance right on the carbs, putting the bike on an angle to tune could be a bit idiotic?