Just Puzzled I Am

[petejw]

around 12 on the vac guage is pretty
normal for these bikes depending on the idle speed.

just a cpl of other things that come to mind,

are the three little holes near the butterflys (off idle ports)
not blocked?

no holes in the rubber diaphrams?

the enricher tube/jet in the float bowl isnt blocked?

are u sure u gapped the valves correctly, ive got a head on the
bench at the moment and setting the valves has been such a pain
i set the cam lobe where i think it should be, put the feeler guage in
and then rock the engine a little bit each way, the guage will either
feel a little tighter or looser depending on where i had the lobe set.

are the carbs definately off an 81 model, and not
off an xj? (the xj has different jetting)

i know im clutching at straws but just throwing out some ideas.

also at idle ur probably not going to get much colour on the plugs
till u take it out for a ride, id go by how its running more than the
plug colour but saying that u shouldnt be needing to screw the mixture
screws out by more than 3 - 3 1/2 turns.

[petejw]

lol
im a slow typer,

if its playing up while its cold, check the enricher
circuit and disregard my story earlier lol.

[Rasputin]

Ok I just sprayed carb cleaner thru all four carb bowls enricher. I then sprayed cleaner thru all four enricher circuits and it is all free and clear. The floats recheck at 23 mm and both sides of each float are the same. The air jets on the back side of the carbs seem to be 185, that is if I can trust my aged eyes.

[Rasputin]

All 4 intake boots seemed to have a good seal. Removed and re-installed them.

[bikerphil]

Does a known good set of carbs work on this motor, have you tried?

[Rickrod3]

I'm no expert just trying to help

Compression shows 150psi across the lot within 2-3 pounds. Have a leak down tester but have not done that yet. Next leak down test I do will be my first

Good compression thats a plus. I my mind to have good compression you have to have good vacuum.

Could the nipples to the gauges be clogged or gauges be bad?

I bought a set of motion pro with the blue fluid and I'm not too happy with them.

Rick

[TopCatGr58]

Hey Rasputin,

These bikes behave just like describe for cold starting, full choke/enrichener, then as warms up will rev higher, then push in enrichener to 1/2, then when revs higher again, push enrichener all the way in providing you are getting normal throttle response. Many/most folks don't wait for the bike to actually warm up before starting to ride, just start, finalize their gear/helmet and take off and then push the choke in once a little ways down the road.

I believe you're trying to read the plugs for the idle circuit, and as has been posted lots of times, that's where you don't want to rely on their color/ appearance. Reading the plugs is usually for THROTTLE CHOP UNDER LOAD conditions, to read the mains. Many folks have reported their plugs looking rich(falsely) when reading them from the idle running and not the throttle chop.

SO...I would suggest resetting them so that the engine/throttle responds properly when warm, then later check the plug color with the throttle chop method. You should experience the increasing revs when first starting cold with the enrichener as it warms up!

T.C.

[Rasputin]

Thanks for the input TC.
I am not very good at describing what I am hearing but it is not a normal start up at all. I have the 79SF and 78E both starting like they were brand new. I am familiar with how they act through the warm up and this just aint it.
I have set up my other bikes and have been able to achieve a nice color during idle as well. If it was not still snow covered here I would try riding it and seeing what a chop would do too.

[Rasputin]

if your not getting any vaccum or really low vaccum
at idle id be looking for things that would affect that,

did u check the cams for alignment, when u did ur valve check?
if the camshaft is out by a tooth it could give u the results ur getting.

.

Going back to this post from Pete gave me an idea that he may just be right.
Here are a few pics for your ponderings. First we have the Timing plate set to the T marks which were checked as well with a dial indicator.



Then we have a pic of the intake cam position



Next we look at the exhaust cam position



When I line up the exhaust cam position to look like this



Then the timing plate looks like this



I am thinking that I may have found why it has low vacuum and is not running right. May be why the carbs are so different in settings and other stuff that is happening.
I have never tried to adjust cams before so any input is appreciated. Do You think I am right or wrong? Is there anything I have to be specially careful of? I do have manuals but they only go so far and the experience of other members speaks volumes. Thanks

[DAVINCI]

Yup, looks like you're one tooth off on the exhaust cam.

[DGXSER]

Yep I agree the exhaust is off. I sit stretch in the cam chain? Have you checked the tensioner to see how far out it is? It will take time (no pun intended) but obviously all three need to line up. Since the back of the chain stays tight I would get the T mark lined up, then pull the chain to get the intake cam set correctly, then finally set the exhaust cam. Then install the tensioner. I would also use a stick, your finger, something to keep tension on the chain as you set each cam. so you keep the chain correctly on the crank gear.

[Rasputin]

I have a couple of the Venture adjusters here that I plan to install on my bikes. Would I end up with enough slack by taking the stock tensioner out, to simply move the exhaust cam one tooth? Do I have to do the whole procedure as outlined in the manuals? I have not pulled the existing tensioner out, but it was set before I started running the bike. I was very careful to follow proper procedure when setting it. I am not sure how far out is is now.

[petejw]

glad i come in useful every now and then lol
and u found the problem,

as the others have said, its only out by a tooth,
its been a while since ive messed around with the cams
leave it at tdc with the intake cam already aligned,
remove the tensioner and adj the exhaust cam by lifting
the chain over the exhaust cog to align with the dots, do this
by not moving the crank and only moving the exhaust cam just enuff
for the chain to jump 1 tooth.
after uve put the tensioner back in and adjusted rotate the engine
a cpl of times to make sure its all set up corretly.

[DGXSER]

Looking at the current positions, the T mark seems quite a bit out now for the cams to be in line. (assuming both intake and exhaust line up with dots). But keep in mind the crank goes around twice for every one revolution of the cams.

I would be hesitant to turn the engine with them out of line like that myself. I think I would pull the tensioner, get a helper with you to keep the cam chain tight on the crank gear (or some process that keeps the cam chain on the crank gear and lets it slip the teeth required on the cams) and get the T lined up, makes sure you get the tension out of the back or carb/intake side of the chain when you line it up for the intake cam. Then work on the exhaust cam getting lined up with out the other two turning.

I guess in short, I'd go with the book procedure. Only because this is one of those things you as well as I and others have seen cause some valve damage when done incorrectly over the years.

Ohh, and make sure the bike is on the centerstand.

[TopCatGr58]

Well,

With the tensioner out, I still don't think you'll have enough slack to slip the chain 1 tooth with the sprocket still on the cam shoulder, unless the chain is really loose!? But that possibly could explain how it's gotten 1 tooth off??

To be able to pull the sprocket off the cam shoulder, you'll first need to rotate the engine and cam so that the OPPOSITE sprocket bolt is accessible, and REMOVE IT. Then rotate the engine like preparing for the cam chain tensioner adjustment, stop at the intake came dot. This should put the nearer cam sprocket bolt within access without having to rotate the engine/cams.

Get a stout piece of wire/rope, run it under the cam chain, and then attach it to a bungie chord or such to help keep tension on it. Then you can loosen the cam chain tensioner plunger. Then loosen the remaining sprocket bolt, so you can slide the sprocket off the cam shoulder, then you can rotate the sprocket 1 tooth along with realigning the dot to 12, then put the sprocket back on the shoulder, put the sprocket bolt back in, tighten.

Now, is where you could remove the old tensioner and put on a new one while you've got the chain under tension. Put new one or old one on, release the tensioner so that it's providing tension against the chain while you slowly release the chain bungie. IF old, lock the tensioner bolt. Then rotate the engine slowly to access the second sprocket bolt hole, put the remaining bolt in, tighten to spec. 14.5ft lbs, remember to torque first bolt as well.

Then perform cam chain tensioner adjustment per manual. Finally check your dot alignments again...or any where earlier in this process!

T.C.