Ok, Heres the scoop- I have been having issues, and I expect them from a 46k mile, 15 year old bike.
I know that these bikes (900rr) are noisy. they have that "knocky" sound, but this is a bit off- I had the bike tuned a few years ago at the local honda dealer, and the bike ran like a striped a$$ed ape, but had a pretty heavy duty knocking sound going on. I assumed that they would have let me know if it was something to bat an eye at, so I just went home rather than turning around and asking what was up.
At that point, it was several years since I had ridden it. (sold it, then bought it back but was all clogged up from sitting...)
I went out for a ride, and was trucking along when the light changed in front of me and I hit the brakes and blew the fork seals.
Here we go again. just got it back on the road, and it's parked again.
Couple months later I had the forks done, and went out on a memorial ride through the hills- well, never went all the way cause of that knocking sound.
I went back home pissed, and flogged the hell out of the bike. It ran great, just made the noise idle to mid. it cleared up on the top.

anyway, parked it, and 4 years later here I am.

I pulled the carbs.

I cleaned out emulsion tubes, and jets best I can tell, then let 91 sit in them for a week, and did it again.

Bike ran like crap

I synced the carbs, and it ran better, but like crap on the top, and a bad knock through the middle- Sounds like carbs starving/bad sync to me

Waited an couple more weeks, took it out, then re synced carbs.

I rode it for 15 miles, and no real problems to speak of, other than the noise.

Re- synced it again, and it was off slightly, but no improvement.

I pulled the plug wires- 1&4 made no difference, 2&3 stalled the engine.

Replaced the right coil, no difference.

Pulled the plugs, They looked PERFECT! WTH??? Tan to rosey.

The bike sounds like it's got a vacuum leak, or the carbs are out of sync, or the ignition is acting up, or it's starving for fuel-

The plugs show that everything appears to be pretty alright in the fuel dept-

I don't know how many times I have to sync those damn carbs, but I think I'm ok in this dept-

The adj ignition has never been moved since I know it ran well-



Anyone have any ideas??????? I know it has been quite a read, but I figure if you've made it this far, maybe you care enough to make a few suggestions?


Thanks guys!

 

have the valves been inspected? At 46k miles, thats the first place I would look.

Im not sure if Cam chain tensioners were ever noisy on the 900RR, but I imagine it would be worth looking into, again considering the mileage and age of the bike.

If pulling the plug wires on 1 and 4 made no difference, theres a good chance your only idling on two cylinders. When you cleaned the carbs, were able to clean out the pilot jets? I know you did the mains, but the pilot jets will control idle to about 1/8 throttle. you may have the two outboard cylinders lean at idle.

You sound mechanically inclined, but I might suggest taking the carb rack off and either doing an extreme clean and replace internal parts, or bring the rack to a dealership and have it profesionally rebuilt. You will still have to sync them, but if you know the internals are good, its much easier. Its also very easy to sync a carb set up out of sync if the carbs are not 100% correct. You'll end up getting them out of sync to compensate for the bad carb.

I think you have few different things. The noise is probably not even related to the running issue. Its more than likely due to being stored for so long. But the noise should be looked into.

 

Synchronizing the carbs is only going to effect the idle and low RPM. Nothing on mid or high, so I'm pretty sure it has nothing to do with that. When cleaning the carbs, did you also clean the idle air circuits (remove the A/F mixture screw) and fuel circuits ? Have any modifications to the intake been made ? Running stock jets, filter, those types of things ?

 

Thanks for taking the time to reply- You've got me thinking in a couple other directions as well-
also, the engine has approx 15k on it since I had to swap cases due to a crash- anything that needed replacing, got replaced. new rings, honed cylinders, new mains, tranny was gone thru, and all in all, I learned a TON!

One thing though- I know I can build it, I just have a very hard time tuning it!!

 

thanks for the reply as well!
as far as I know (or remember) this is what the bike is/has:

-96 900rrt says "rrt" under the seat on the subframe, have no idea what it means-
-it IS a california bike
-the smog stuff is gone- for the most part- I removed the PAIR smog device, charcoal canister and some excess lines that never effected the way it performed when I had it the first time..IDK what the past owner did to it at all, but it was running well when I sold it to him-
-for lack of a nicer way to put it, he's dead, so if he did anything froggy to it, I'll never know (don't think he would have done anything too harmful)
IT HAS:
-been re jetted (no idea how big, but if I go in there again, I'll make a list!)
-a Factory hon-008 adjustable ignition advancer (never moved since it ran well)
-two brothers full system
- no idea if the "brain" is the same

at 120 bucks for 4 carbs worth of o-rings and other wee goodies that I'll probably only need half of, I fear I'll have to purchase the rebuild kits if I go into the carbs again- unless there is a sweet source that someone knows about?? Hint Hint...

 

I've been reading a bunch on my issue, or at least looking through tons of issues trying to find similar ones with actual results. One thing that I have found, is that quite a few people are blaming the cam chain tensioner for the all too familiar "900rr knock"-

Now, I'm open to anything, and I'm thinking and thinking things through, but I just wonder if it's possible if the tensioner is not "tensioning" and allowed something to jump time a tooth possibly? I know it's a longshot, but maybe? I may just have to pull things apart once more, and check the cams, as well as replace anything that could produce a vacuum leak.

Another thing that is really irking me is the idle- it's sooooo sensitive! Like I said, it sounds like a vacuum leak to me, but I just can't locate it- the idle will be high at 2000 or 2500, but then come down to under 1000 and die. then you start it again, but you have to use the choke to enrich the bike, otherwise it will just crank and crank… once started, it goes back to 2k+ and then falls off again-
I have heard people talking about an "air needle" or "air adjuster screw", but don't quite see what they are talking about?? I know needles on two strokes, but not on these carbs. Here again, I'm no expert, and am thinking I may have just screwed all of the jets back in, but one was adjustable, and needed to be open two turns, and I just cut them off by screwing them all in during re-assy??

once again, and replies are welcome, and thanks in advance!

KM

 

Ok-
looks like the engine needs a fork put in it-
I actually checked all that was suggested, and it wasn't the cct- and the carbs were half of the problem. I have a spare rack that I swapped out the mains and all the good parts and that solved the problem. kinda… Now, I sync'd the carbs and all went well! the roughness went out the door and the idle was as it should be. but now that it's running good I hear a rattatat tat. like every third rpm there is this sound. if that makes sense.. So now I also am seeing an oil light flickering at lower rpms once up to temp. -not good. I thought the oil could be broken down from fuel because I had had so much trouble with the carbs and probably washed the cylinders down, but after an oil change it still had low press, and the damn knock. funny thing there wasn't anything big in the pan (bearing debris)????
That is until I pulled the engine apart.
I read in one of the threads on here that if you can hear it, it's a rod. and if you hear nothing, and then it fails BANG! then it's a main. I had been hoping and praying that it was just a #3 rod bearing, and that I'd just go ahead and replace the rod, and main bearings since I was in there. When I got into it, I did see small debris in the pan, not too bad actually- but in the strainer, WOW. then I went and split the cases…….. The mains were all spun! and the damn rod bearings looked great! how on earth??? but that's the deal here.
I'll ask on here, but I may start another thread and get better responses-

Has anyone had any experience with line boring a set of cases that has spun a bearing(s)? I'm not sure about the availability of different sizes. also, I mic'ed the crank and it doesn't appear to be galled or worn, but if there's a possibility of getting it fixed with machining, I'll let the shop tell me if it's good-