Hi! Low throttle low rpm issues - need sync?

Hi all, first I'd like to thank all the diehard contributors here, I've been reading for a while and I've learned a ton!

Sorry this is a long one. I have an 83 XJ1100 that i bought last year and have been fixing up bit by bit. The brakes were the biggest problem initially. Bunged right up. They worked but wouldn't release. Took a complete disassembly and cleaning to get them right. The little pinhole in the reservoir getting plugged has got to be the most common/underrated problem with hydraulic brakes, i had the exact same problem on another bike. The next problem was idle/low throttle/low rpm. And if you've read my embarassing first post, you know i messed up bad when i was cleaning the carbs last year. The mixture screws were like they were glued in. Anyway i finally found a set of carbs on ebay which i cleaned up and swapped jets with the original carbs (jets from ebay carbs were leaner) but the bike runs exactly the same as the old carbs! I should mention that i pulled the stock airbox and installed K&N pods however this problem existed before the pods. I should also mention that i've never actually synced the carbs. I did however "eyeball sync" them, that is i held the carbs up to a light and adjusted them until i saw the exact same sliver of light through each. I know, genius.

On to the symptoms. the bike idles "ok" but not great, every once in a while it bogs or blips all on it's own. Nothing crazy, pretty slight actually, but noticeable. I have the idle mixture screws set to 4 turns and it colortunes just on the edge of blue and yellow. The biggest problem when driving is getting into first from a stop. I have to ride at half-clutch for several seconds until i have enough momentum to fully engage the clutch. Otherwise the bike will stall or what i might call "surge" as if it can't decide to go or die. It evens out as the rpms increase and seems to run great on the freeway when rpms are higher - all throttle positions respond like they should. I've read "surging" can be a symptom of a lean mixture but before i start getting into a big rejetting project, i wonder if it's simply a matter of vacuum syncing the carbs. At least to rule that out. Another thing that crossed my mind was shimming the needles or throw in a dynojet kit to richen up the delivery system.

I've also looked at the wheel bearings and drive shaft to see if anything is adding resistance to the bike's "rollability". I've read (I've been doing a LOT of reading ) that these bikes are generally not easy rollers and mine seems to agree. My concern is that the resistance to rolling is contributing to the problem getting into first. I pulled the brake calipers to make sure they weren't dragging. Nope, they better not after i essentially rebuilt them. Front wheel was a little stiff turning. I checked the middle and final gear oil, both full and very clean. The final was a little high so i sucked some out to bring it between the marks on the dip stick. I pulled both wheels and the wheel bearings seemed to move fine but it was pretty dry in there so i cleaned and greased (mobil 1 synthetic). Front wheel improved, back wheel maybe improved a little too. It's hard to tell with the resistance the shaft drive adds. I haven't pulled the shaft apart yet but i'm sure it's due. That'll be next after the carbs.

Anyway, someone please tell me if my logic is flawed or if there is something i'm missing. I'm thinking i'll sync them and if that doesn't fix it, look at rejetting. I'm pretty confident in my "eyeball sync" job so i don't know how much difference it is going to make. Especially since i've done it on other bikes and never had this problem...

One more question, shouldn't i be able to pull WOT from idle? What could cause WOT from idle to bog or kill the engine? I have another bike that won't even take 1/2 throttle from idle, just bogs for a second and then "catches up". Both have the airbox removed and pods installed.

Any suggestions?

Trev

 

How many miles on the bike? Have you checked the valve clearences?
Get the bike on a slight downward incline & see if it gains momemtum.(engine off, out of gear)

 

Hi, there are 33,332 Canadian miles on it. I haven't checked valve clearance but that's a good idea I will be sure to do that when I have some time to spare.

Btw, I took it for a burn on the freeway around town and checked the plugs afterward. The outside 2 were grey/tan and the inside 2 were pretty white. I have the mixture on all 4 carbs set to 4 turns and the mains are all stock 112.5. Should a person bump the inside mains up a size or two more than the outsides? Could this be the reason for the low end flatness/surging?

 

Sounds like you need to open up the mixture screw a little on #2 & #3. Probably just a hair on #1 & #4. Hard to tell for sure without pics.

You can give the sync a go, but if your valves are off then it won't really solve the problem. If your idle is jumping around, I would guess a likely candidate is the throttle shaft seals. If you try to sync and you find the carbs are all over the place when you first hook them up, that is a potential indicator.

Sorry, it just registered you said you had pods. In the great words of Rosannarosadanna, never mind....

 

Just a quick update, I haven't got to the valves yet but i think you might be on to something with the throttle valve seals. I hadn't removed them when i cleaned the carbs but i just noticed that the seals are missing on both the outter carbs. The plastic washers are just kind of floating there loose under the circlip. I'm guessing they must have disintegrated and fell out. I'll try the dealer to see if i can order some new ones, otherwise is there another source for these little guys? Do you see any issues with throwing in some rubber 'O' rings for now until the new seals arrive? Also, is there a trick to replacing the seals between the inner carbs (assuming there are seals between)? Do i have to pull the carbs and linkage apart to get at them?

 

Correction, apparently the seals are in there. I pulled the circlips and washers off both sides and there is a rubber seal in each. It looks like an 'O' ring with a hollow side facing out. Does this sound right? I wonder why the washer would be so loose, i would think it should be snug against the seal... could someone provide some insight?

 

There are two seals on each carb and yes, you will have to split the rack to replace them. If you are already missing some seals for whatever reason, just replace all of them. My carbs are apart now doing just that job. It isn't what one would call a major operation but whilst you are in there, replace the fuel supply connector O-rings too.

It'll never run right with missing seals or with seals not designed for the job.

 

watching for updates!!!

 

not much of an update but i ordered the throttle shaft seals from chacal and picked up some silicone grease to install them (eze slide from napa). i probably should have ordered some fuel line o-rings as well. does anyone know if chacal carries them? are they made from any special kind of rubber to withstand exposure to fuel or can i use o-rings from a generic o-ring kit?

 

He has them and they are some special rubber. IIRC they are not exactly round either

 

Before looking at rejetting, see if you can richen the mixture by using the mixture screws.

And, by the way, are Canadian miles different than US miles? <grin>

 

Quick update, seals made no difference. But at least i can count them out. Chacal mentioned that the 1100s don't use o-rings on the fuel supply rail and he was right, the connectors are coated in rubber and have 2 ridges on each end. so no need for o-rings, they are built in! Breaking the carbs wasn't bad at all, i didn't disassemble the bowls or the hats because i've already done those a million times for cleaning and it didn't seem necessary for the seals.

While i had the carbs off, etc. i rebuilt the petcocks with a kit i picked up a while back to fix a leak in one side. Leak is gone and they work like new.

So i think by now i can rule out any mixture issues/vacuum leak on the carb side, correct? Mixture screws are at 5 turns out and colortune blue.

I'm going to check the valve clearances next.

Btw, canadian miles are great, they measure temperature as well.

 

Once you get your valves checked and the tight ones re-shimmed you'll need to sync and I'll bet it runs better. Check for vacuum leaks before you try to sync. use a propane tourch (unlit) and flood the carb boots with raw propane and see if the idle picks up. If it does check that area.


MN

 

More news, i cracked (not literally) the valve cover and measured the clearances. Guess what, they are all tight! The intake clearances from left to right are .08, .05, .08, and .08; exhaust clearances are .15, .15, .15, and .13. My feeler gauges start at .05 and go to .08 to .10, .13, .15 and so on so i'm hoping that is accurate enough. Based on the table in the service manual, i need to replace all of them! I should have guessed from the valve cover bolts, they looked like they had never been turned, i had to give the cover a few wacks with a rubber mallet to knock it loose and the gasket fell apart when i pulled the cover off.

Do you guys think this is definitely the cause of the erratic idle/low throttle, etc.?

Thanks for all the comments btw!

 

Well i ordered the valve bucket tool from chacal so i'll have to wait until that arrives so i can pull the shims and see which sizes i need to order. I'm guessing they are all stock but i would rather be sure. it'll likely be several weeks - mostly waiting for shipping - before i can provide any more updates on the progress. i'm hopeful the shims are the problem and there aren't any other issues...

 

The bucket tool arrived today so i pulled the shims right after work. The values on the intake side are 275, 280, 275 and 275. The exhaust side are 290, 295, 295 and 300. So i figure i'll order 4 270s for the intake and 280, 285, 285 and 290 for the exhaust, anyone care to double check my numbers?

I'll be ordering the new shims tonight and should have an update in a few more weeks!

 

I installed the new shims today (old rock hard gaskets that have been glued on really suck to take off!!) and threw it all back together. So the intake and exhaust valves are now up to spec.

However, it still runs exactly the same!

Any more ideas? Could the timing be off or something?

 

Spring update, I've started working on the bike again, itching to ride this thing! Went through the carbs again, everything is pristinely clean, jets are clear, passes clunk test, diaphragms are solid, no vacuum leaks, etc. so at this point I really can't believe the carbs are the problem.

After starting it up and running it for a few minutes it almost seems like it's missing now, like a cylinder isn't firing, especially on the left side, the muffler on that side sounds like sputtering.

So I decided to do a couple tests, going in a different direction. Compression test shows strong results (135,135,138,145). Spark test however revealed that 2 & 3 aren't sparking! Or extremely weak at best. 1 & 4 have strong spark so I tried swapping plugs, no difference. So it's looking like an ignition problem, could have sworn I had checked that before though... at any rate, what's the best plan of action to troubleshoot this "new" problem?

 

Well, 2 and 3 are on the same ignition coil. Sounds like that might be a "bad" coil. Take a look at it, test resistances.

Also, make sure the resistors in your spark plug caps aren't corroded, etc. (easiest way to check the cap is run a resistance straight across the cap; for my 650 the resistance in the cap is ~4k - don't pull the caps apart)

Spec should be in your manual, not sure for your 1100.

 

Ok I did a series of tests, here are the results:

Ignition coil test
1&4 primary 3.4 ohms
1&4 secondary (plug caps included) 30.6 Kohms
2&3 primary 3.2 ohms
2&3 secondary (plug caps included) 30.9 Kohms

Pickup coil test
left/front coil 118.4 ohms
right/rear coil 120.9 ohms

TCI power-on test (gleaned this from the XJCDs should send a single spark to each plug 2 seconds after turning ignition key on)
1&4 both pass (spark)
2&3 both fail (no spark)

So the coils are all very consistent in resistance which seems to point to the TCI unit and the power-on test seems to indicate that may be where the problem lies. However, when I do the power-on test for 2&3 there is no spark as indicated above but the lights dim slightly when the spark should occur and I think I hear a faint "tick" like the spark is happening, just not where it's supposed to... a short somewhere maybe?

During my electrical testing, I cleaned out some of the connectors along the way and it seemed to help a little - spark came back on 2&3 while running (however not for power-on test) but seems weak and intermittent.

I'll try swapping the ignition coils next and see if the spark follows the coil. If it does I'm thinking the 2&3 coil is arcing/shorting somewhere (either internally or externally), if it doesn't I guess it's the TCI. Sound reasonable?

 

I'm sure more experienced guys will chime in, but my 2 cents goes like this: these bikes are 25-30 yrs old. It's VERY likely that the electrical connections are dirty and/or loose. It's safe to assume that every connection has some extra resistance just from that. Therefore, I'd suggest you (or anyone with an old bike) go through the entire wiring harness and clean/grease every connection on the bike. Until you do that it's a bit of a crap shoot chasing down electrical gremlins.

 

Well I swapped the coils and the spark followed. So it seems the coil is the problem. I found a NOS set on ebay for a decent price (pretty well same price as the used ones actually!) so I grabbed them. I'll report back in a few weeks when they arrive.

skills4lou, that's a good idea, like I said I did clean the connectors that I figured might affect spark but I'll be sure to go through the rest of the connectors when I put the new coils in.

Trev

 

The new coils arrived today and I installed them and... still not working! I must have made a mistake when tested swapping the coils, or there was a freak good spark on the faulty coil wire. At any rate I now have 100% stock specifications from the TCI to the spark plugs (new coils, new caps, new plugs - the right ones this time, there were resistor plugs in there before).

I did some more testing and I think I've narrowed the real problem down to the TCI. I tested voltage on the ignition coil wires at the TCI plug and the gray wire (which leads to 2&3 coil) had significantly lower voltage during the power-on test cycle, like around 1 volt. After the power-on cycle both ignition coil wires were the same. So for some reason the TCI is not sending full voltage to that coil. Everything else seems to check out.

Can someone lend some advice on how to tackle the TCI based on my symptoms? Does it sound like a bad transistor, cap, what? I know my way around a circuit board and I've read the Ignition FAQ but would appreciate some insight from someone with TCI experience.

Cheers,

Trev

 

Hi Tibor,
I was having the same sort of issue and stripping the TCI down and de-soldering/re-soldering every joint was a little tedious but the problem was fixed... well okay I did a bunch of re-wiring and plug replacement also but I'm pretty sure it was the TCI causing the issue. Note the 'pretty sure' as I'm just glad doing the whole bit fixed it.
Hope this comment doesn't just add to the confusion!

 

pretty sure I just found one of a few ways to check the TCI, a Colortune plug. I was able to see the combustion in holes 1 & 4 but not 3 & 4, but I could see a week spark. reversed the low and high tension wires while leaving the coils in place and the problem reversed. TCI's on its way, everything's colortuned, hopefully it's a quick swap and i'm off. if you don't have one you'll be happy when you get it, It Is Cool

 

I just opened up the TCI and the big transistors test fine but one of the little ones is definitely bad. so my plan is to replace both of those transistors (not made anymore but found exact replacements super cheap on ebay ) and all the old electro caps just to be safe. wish me luck!

btw, the screws in the back/bottom came out easy, there was no glue like others have reported. there is a film of something on the component side of the circuit board though.

 

Btw, here is the parts list for my TCI repair/rebuild:

Transistors:
2 - 2SC945

Capacitors:
2 - 0.47uf 50V
1 - 2.2uf 50V
4 - 10uf 25V
1 - 100uf 6.3V

As I said the large transistors test good so they will not be replaced, electrolytic capacitors are being replaced because they degrade significantly over time (especially when not in use) and I think are likely responsible for the transistor failure. I'm considering bumping up the voltages for the replacements one step (i.e. 63V, 63V, 35V, 10V in the list above respectively). I haven't tested the voltages they are exposed to but I do know manufacturers commonly use caps rated too close to the operating voltage which can result in premature failure. The higher voltage provides headroom and hopefully results in more longevity. I think I just talked myself into it.

 

good luck, let us know!

 

Last night I replaced the transistors and caps but it made no difference. I also spent some time tracing wires and cleaning connectors and reheating solder joints. All the right wires are getting voltage until i plug in the TCI. Then only coils 1&4 get voltage/spark.

I'm at a loss. I'm beginning to think the TCI has a bad chip or something... does anyone have a spare TCI (10M variety) kicking around?

 

Hi tibor,
Looks like your onto something there with the tci box. Mine went out last spring for no apparent reason. Bike ran fine when I tore it apart but the tci didn't like being put in a box for the winter and decided to die on me.(mabey I should have put holes in the box so it could breath :lol: )

Did the bike have this problem before you installed the pods? You may want to invest in the stage3 dyno jet kit. I found on my 650 that it helped with the momentary blips. My bike had blips in the 3.5 to 4k and again from about 6 to 6.5-7k range it just felt like a slight slow down in the rpm climing at those ranges. After rejeting, needleclip adjustment, vacuum holes in slide pistons enlarged, and slide bore polishing you can go wot from like 2 or 3k in 3rd gear and it pulls smooth to 10k.
OK I'm not saying you have to do that when you run pods but every little bit helps.

 

Hey, yeah the bike has had this problem since I bought it (when it still had the original airbox), I originally thought it was a carb/intake issue (vacuum leak, etc) and only recently realized it's actually an ignition issue. I do have the dynojet kit for my bike but I'm waiting until I get this thing running (spark on all cylinders) first before I install it.

I'm considering picking up one of those Hyperpak modules, anyone have any experience? How reliable are they? The other option is wait for something on eBay and maybe it's not already fried. Or there's always the original that is apparently still available but costs a small fortune (don't ask me why it's available through a lawnmower site):

http://www.lawnmowerpros.com/detail.asp?id=10M-82305-10-00

 

I ordered the Hyperpak from New Zealand, not sure how long shipping takes but I would expect at least 2 weeks, probably longer.

The guy says it will plug into the existing harness connector, no rewiring required.

 

8O you didn't acctulay pay that price did you?!! 8O

 

I didn't get the OEM TCI from the link above, just couldn't bring myself to do it.

I got the Hyperpak which is an aftermarket TCI, $184 USD shipped off ebay. Not cheap but cheaper than 500 bucks!

 

Update: it's ALIVE! It took a couple tries to get a working TCI off ebay (I couldn't wait for the Hyperpak, see the story below) but I finally got one yesterday and it fired up on the first spin and literally roared to life (I just got a new Mac 4-2 exhaust and hadn't put the mufflers on yet). Open headers on this bike is the coolest sound I've ever heard! And loud as hell of course.

I think the TCI was the problem all along. I'm glad I did the other maintenance though, it will save me having to do it later. And the bench sync is almost bang on, I can only detect a very slight variation in the idle speed.

I still have the Hyperpak TCI on the way, it hasn't arrived yet because the seller got into a motorcycle accident the day I purchased! 8O But he had recovered enough to ship it on the 1st so it should be here soon. It's an expensive spare but I'm sure the day will come when I will need it.

 

I installed the stage 3 dynojet kit last night and took it for a boot, man it's running pretty good now! I swapped the original 47.5 pilot jets back in (had tried 50s but they are too big for the exhaust) and now idle is super smooth (still just bench sync) and WOT pulls very strong. There is just a slight hesitation in the mid range but i'm thinking a needle adjustment should solve it. I thought the 138 (stage 3) main jets would be way too huge but they are working out great!