Finally got a test ride in

Hello again everyone,

I just got back from my most recent test ride and I have some comments and a couple major concerns. Sorry for the Freshman essay format. I have a lot of details I wanted to include and I'm too tired from work to format things better. I also have video I can upload segments from if anyone wants to hear anything from the ride.

First, the new rear suspension (Progressive, standard duty this time) is great. Even the worst bumps feel noticeably softer. I still feel the rear bucking a bit, but it doesn't hurt like it used to. Now it just feels like the bike is being pushed up by a bump in the road. My kidneys will appreciate that.

Second, the new steering stem bearings are great and scary at the same time. Turning the bike at low speed is much easier as is making small turns at high speed. My concern here is that with a quick nudge on the handlebars at highway speeds the bike now wobbles as it stabilizes. Before it just straightened right back out. It's important to note that this doesn't apply to coming out of a regular turn. Only a swift nudge will make it wobble. Also, when entering a moderately sharp turn at speed the handlebars wobble a tiny bit for a moment before turning. I thought I had the bearings tightened correctly; just about as tight as they'll go while still falling freely when the handlebars are turned with the front end off the ground.

Lastly and most disconcertingly, the bike is making a new noise.

The idle rose to 1300 RPM after a long ride. This may be because I set the idle only after it had been running for about 20 minutes and the engine wasn't really up to temp. What bothers me is that when I went to lower the idle after my ride I noticed the engine making several very strange sounds.

The least worrisome is that the RPM's started bobbing slightly when I turned the idle down. I know the carbs are in sync and there are no vacuum leaks (at least when I checked after running it for ~20 minutes while tuning), but something I tried recently was turning the pilot mixture down a bit. In another post of mine it was suggested that I was running rich so I used my colortune and set each carb leaner.

The next two sounds really really bother me. The first is a clattering / diesel engine noise which I haven't heard since my cam chain was loose some time ago, and the second sound is sort of like a buzzing bee sound. I'm wondering if my cam chain has suddenly loosened.

After lowering the idle back to 1100 RPM I blipped the throttle and it hesitated for an instant before revving a bit and falling down well below idle. It ran rough for a second and then climbed back up to ~950 RPM.

When I first started off I also noticed that the engine was hesitating a bit until the RPM's got above ~2000 RPM. Also, when I started the engine it idled for a couple seconds, slowly climbed to ~1900 RPM (this is with half choke) and then slowly fell to ~1400 RPM. It used to rev steadily higher until the choke was lowered, but now it rises a bit (or not at all) and then falls and starts running rough.

I have already covered some of these things in other posts I've made, but these problems either haven't been solved or are new. I would appreciate any input.

Thank you.
Mark

 

Mark,
Have your carbs been to Church?.
Valve clearances are in spec?

You should do another running synch if you adjusted the air/ fuel mixture.

The buzzing can be an vacuum/ exhaust leak or just a loose component.

Idle RPM is 1050 'in the book' because (as you noted) it likes to climb when warmer a slight deviation from 1050 does not hurt anything.... plus the parallax issue when adjusting idle knob and looking at tach - What really is 1050 or 1100? Or even 1200?

wobble - are your tires balanced?

 

Valves have been checked and corrected.

Carbs are clean with new rubber parts (minus diaphragms). Carb cleaner shoots through every passage and jet freely. Slides pass clunk test with flying colors.

Tires are balanced with DynaBeads.

I have something loose in the collector which buzzes and makes grinding sounds at certain RPM's. Could that make the engine sound generally noisier? The sounds seem to be coming from the engine specifically.

Related to the tach parallax issue, how likely is it that my electronic tach is completely wrong?

I've been wondering, I use hose clamps to tighten the intake boots to the carb bodies (the bike came that way). How tight should they be to not leak? I have them pretty tight right now, but after my test ride I was poking at some things with the engine running and (and this may be coincidence) when I squeezed the cylinder 1 intake boot where it meets the carb body the idle dropped a little.

I'm going to check for leaks again this afternoon.

 

DOH!

Sorry I did not see where it said which bike you have and it is not in your signature...
My XJ650 has a mechanical tach and there is a parallax issue when adjusting the idle control knob.

 

Sorry! I forgot to specify that.

My bike is an '82 XJ750J

 

Ok some observations .... first you will NOT get carbs fully clean with spray carb cleaner ...there are small passages (look at carb body you will see brass plugs ) that submerging in carb cleaner such as Berrymans 1 gallon carb cleaner is one product . To do this right a full carb tear down "break the rack" remove butterfly plates and the shaft seals (hint these will result in vacuum leaks if they have NEVER been replaced ) Soak carbs for up to 2 hrs EACH . This is covered in the church of clean . Another item DO NOT use plumbing hose clamps ..these can cut into the boots , xj4ever has the CORRECT clamps . These are just a few item that I see could cause problems. Cheers

 

Sorry, I should have been more specific.

I used spray carb cleaner as a final check of each passage. The rack was broken, each body soaked in cleaner, seals replaced, butterfly screws replaced, o rings replaced, etc.

I tried to be really thorough with cleaning the carbs.

I haven't tightened the clamps hard enough to cut into the boots. They are squeezing the rubber but not cutting at the edges.

 

if you squeezed the boots and rpm dropped you need different clamps there is a site that sells good ones. or buy oem clamps from someplace

you are talking about the motor to carbs boots correct?

 

Yes

I'll have a look at oem clamps.

Any advice on the steering issue?