After Tune... Problems (Heat, Idle, and vibrations)

[Blazing Hornet]

So let me give you the backround.
The bike was running ok a few days ago, had some bad vibration around the 4-5K mark where you could here the whole bike buzz and the idle liked to dance once and a while. So I took it upon myself as the bike is due for its service at 30K km. I began with the valve adjustments, most of the valves were tight so they had to be adjusted but there were some which were ok. After this I went on to doing a carb sync. The carbs were off especially the difference between pairs (1&2) to (3&4). As I did the adjustment the closer and better tuned I got the more I had to decrease the idle as it was idling up. After all this was said and done I put the bike back together.

Here is where I went wrong, I flipped the vacuum and breather hoses where they connected to the tank which I found out after taking the bike for a spin. It would die the moment you gave it a quick blip and the engine was noisy as hell.

So I fixed that put all the lines so that they were connected in the right spots and took it out for another spin. The gears change ever so smoothly from how they used to and the power curve seems to be much more smoother overall. HOWEVER, after riding the idle will not come back down to 1200, it just sits up at 2500-3000. I can force it down by leaving the bike in gear until the revs are down to 1500 and the bike will idle down to 1200. But next stop it idle back at 2500. The bike does appear hotter but this could just be me looking for something wrong. The other noticeable think is that the buzz from 4-5K is now gone, but vibrations are strengthened it seems from 7-9K. Any ideas on what is going wrong? I did not touch anything else other than the valves clearances and the carb sync.

[Kreylyn]

So let me give you the backround.
The bike was running ok a few days ago, had some bad vibration around the 4-5K mark where you could here the whole bike buzz and the idle liked to dance once and a while. So I took it upon myself as the bike is due for its service at 30K km. I began with the valve adjustments, most of the valves were tight so they had to be adjusted but there were some which were ok. After this I went on to doing a carb sync. The carbs were off especially the difference between pairs (1&2) to (3&4). As I did the adjustment the closer and better tuned I got the more I had to decrease the idle as it was idling up. After all this was said and done I put the bike back together.

Here is where I went wrong, I flipped the vacuum and breather hoses where they connected to the tank which I found out after taking the bike for a spin. It would die the moment you gave it a quick blip and the engine was noisy as hell.

So I fixed that put all the lines so that they were connected in the right spots and took it out for another spin. The gears change ever so smoothly from how they used to and the power curve seems to be much more smoother overall. HOWEVER, after riding the idle will not come back down to 1200, it just sits up at 2500-3000. I can force it down by leaving the bike in gear until the revs are down to 1500 and the bike will idle down to 1200. But next stop it idle back at 2500. The bike does appear hotter but this could just be me looking for something wrong. The other noticeable think is that the buzz from 4-5K is now gone, but vibrations are strengthened it seems from 7-9K. Any ideas on what is going wrong? I did not touch anything else other than the valves clearances and the carb sync.

You have a vacuum/air leak. This is allowing more air vs fuel than needed, and leaning out the ride. (hanging idle = lean. Excessive vibrations = lean. Extra heat = lean).

Start with some starter fluid or the like and spot spray around all the rubber parts and boots. Double check your sync (and the vacuum port for the petcock is blocked off when you do).

If nothing, then let the engine cool off to room temp. Pull the airbox, carbs, and carb/engine boots. If the orings on the engine boots are flat, replace them. Inspect boots for any cracks. replace if they are.

Use gasket sealer on the airbox boots to seal them to the airbox.

Make sure the airbox boots are in good shape and seal them onto the carbs off the bike by taking the air filter out, reach into the airbox and push each boot on properly. Make sure it's correctly tightened and properly seated for each boot on the carb body.

Check the carbs and make sure all the rubber seals and caps are in good shape, with no holes. Also double check the vacuum line for the petcock is properly sealing, has no holes in it, and is being blocked off or plugged onto the petcock at all times your checking things.

Krey

[Blazing Hornet]

Seems it is all good now.

I pulled the tank ran it and sprayed some engine starter around and it did not rev up. Shaking my head I reconsidered how I carb sync'd it. I went back looked at the vacuum gauges I used and realized that of the 4 which are various brands, I had read off the wrong units on one.

So back to the carb sync I went, Carbs 3 & 4 were the ones not tuned together well. I also made the lines seal better to the connectors which resulted in the carbs all being slightly off eachother.

When all was said and done I readjusted the idle rpm and drove it and boy what a difference. Power through the whole band was improved. Smoothness through the gears and no vibration at any rpm range anymore!

Thanks Kreylyn for the help

Now for some suggetions to future carb sync'ers.
When removing the caps on the carb vacuum ports i found a samll awl worked great for removing the clamps. Just stuck it right through the two eyelets and pulled off. When removing the rubber a pair of angled needle nose pliers worked great. When reinstalling some silicon spray on the inside of the caps worked great for sliding them back on. Best of all...

The tool that worked the best for getting those darn caps back on without removing your fairings or carbs was a PLASTIC STRAW. That's right. put the cap in the straw so the straw bites it enough slide that cap on and use a flat screwdriver to hold the cap where it sits while you remove the straw. For putting back on the clamp I sprayed the outside of the cap I just installed with the silicon spray put the awl through the eyelets of the clamp and slid it back on SLOWLY. (I say slowly because this worked so well that the clamp quickly slid to eh base of the cap which made me have to start over again removing the cap and all). At this point with the awl still in the clamp I used the flat head screwdriver to hold it while I pulled the awl out.

Just some suggetions may save you from ripping the bike apart after dropping these things in it like I did the first time. Now the carbs can stay attached and the fairings all on

[TRPUT]

... or ... add 6" of capped vacuum hose to carbs 1 - 3 and never have to dig in there again.

[Blazing Hornet]

I am resurrecting this thread as the problem seems to have returned (kind of). Colder weather is approaching and my idle needs to be adjusted. Instead of the recommended 1200 rpm, it is just below 1000. I thought it would be a simple fix by adjusting the idle screw but it made it run horribly. Turn it one way the idle drops (not what I want). Turn it the other way the idle begins to climb and I stop it at 1200. Now I blip the throttle and it hesitates and almost wants to stall ??? I took it out for a ride like this and brought the rpms up at crusing speed and when slowing down to a stop the rpms won't frop below 3000 unless I force them down with the clutch. If I do this I can bring them back down to the 1200 but the moment they go back up when riding I have to force them down the same way ??? Any ideas what is going on?

[DaBears]

Sounds like the same prob

[tone]

Re sync carbs at the lowest tickover you can get the ajust tickover & test ride the bike then post the result, i would also suggest using good quality gauges such as morgan carbtune, sync done with anything else always seems off when checked on these but not the other way round

[Blazing Hornet]

Re sync carbs at the lowest tickover you can get the ajust tickover & test ride the bike then post the result, i would also suggest using good quality gauges such as morgan carbtune, sync done with anything else always seems off when checked on these but not the other way round

Do you mean resync them at a low idle? Are you not supposed to sync them off idle? I previously adjusted to the idle ajust screw so it was running at about 2000 rpm and synced them there.