7moore7

Again, started my bike this morning, here's my events so far:

Fired up (yay!). Rear exhaust wrap smoking a bunch (IIRC it's supposed to do this as the silicon paint that I put on it is baked) Front exhaust wrap not smoking. Hmmmm...

Grab front exhaust. It's warm, but not hot. Rear exhaust header is just too warm to even touch. Ok, so something's not right.

Pull plugs- look decent. Rear one looks wet (it's the one that seems to be acting correctly). Maybe just because I shut off the motor so fast or something. Switch plugs. Same story- rear cylinder much warmer than the front at the exhaust. Switch coils. Same thing. So I'm pretty sure it's not the plugs or the coils. Didn't know where to go from here electronically, so...

Pull the airbox. Front slide has much less resistance than rear slide. Rear carb seems to be pulling much more suction when motor is running. Remove carbs and inspect diaphragm on front carb and it looks fine. Re-assemble. Front slide now has the same resistance as rear one. Ok, so maybe I just didn't assemble it correctly the first time... all original symptoms still exist other than the slides now opening at the same pressure if i push on them.

I suspect that it's a vacuum issue of some sort. Not positive, not quite sure where to check next. Manual is suggesting electrical, but I'm not sure where else to check on that one either. Perhaps it's associated with my other electrical problems? (Clocks and taillight don't work at the moment)

Suggestions would be great! I'll be back an forth playing doctor and playing student this evening...

lazn

Simple stuff first..

How are you feeding the carbs gas? You don't have the tank back yet right? And I think each carb has it's own gas line, so are you sure the front carb is getting gas?

7moore7

Haha, I'm just pouring gas into the fuel lines. So it runs for a couple of minutes at a time
But yeah, pouring into both lines...

lazn

And is it using the gas? (as in is the front empty after running it a bit?)

If so, I'd look at electrical.. check for spark by pulling the sparkplug and attaching it to the sparkplug wire then set it on the engine and briefly turn it over watching for spark. (don't leave it run like this with no plug)

7moore7

Ok I'll go try this part now. I do fill both hoses when it runs out, so it appears to be using gas...

7moore7

Spark confirmed... so either it's not sparking in the cylinder (I think I read about it doing this on someone else's) or it's carb related...

lazn

Yep, I am betting somehow carb related. Hmm, not my strong suit. Can you tell if gas is getting into the cylinder?

7moore7

Flashlight in the spark hole perhaps? I'll go look again. I suspect something simple like hoses assembled incorrectly. When I pulled the carbs to check the diaphragm, there was gas on the carb boot so I think gas is getting in...

At least I can pretty much rule out spark/electrical for the time being

mikstr

Let's see, if it's running like crap and lost all acceleration, perhaps someone stuck a HOG engine in your VTR.....

7moore7

Both cylinder heads seem to be slightly shiny/glisten a bit. I have just run the starter a couple of rounds to check for spark, so I'm assuming they should be this way. On another note, both heads are very covered in carbon- probably not good on this front, but since they're covered in the same amount I'm going to bury that one for later haha! I DO NOT feel like going in there and cleaning them up!

7moore7

Yeah, maybe it's been hangin' out next to my 600 Shadow for too long!

Not sure about acceleration haha, I only bop it up and down the driveway as I have no actual fuel source. Looks pretty funny driving around with no tank though!

8541Hawk

Well if you have fuel and spark that just leaves compression......
Did you by chance check the valve lash or replace the CCT's?

Also the problem with the front carb was the diaphragm was not seated correctly.

7moore7

I did both of these . Totally unfamiliar with compression, so probably why it wasn't in my list of things to look for. Sounds serious if it's an issue... off to figure this one out.


This was my somewhat embarrassing conclusion as well. Thought I had the carbs nailed haha.

8541Hawk

Well then it's time to double check your cam timing. You do need to be careful as the flywheel has 4 marks on it. F, FT, F, RT
The front cylinder can catch you out if you are not careful. What happens is as you come up on TDC you will first hit F (for fire) and around
10 degrees farther you hit FT (front timing). So if you timed your cams to the "F" mark they would be around 10 degrees advanced.

The rear cylinder is easier as it is F then RT, which is harder to get set incorrectly.

The "F" mark is for using a timing light as that is when the cylinder should fire at idle.




It happens a lot. That is why you always push the slide up when you reassemble a CV carb. If the slide just falls closed or doesn't make that "breathing" sound when the slide cycles, the diaphragm is nit seated correctly.

7moore7

Whoa one thing at a time! Just got a compression tester. I'm almost positive that timing is correct as I did it when I adjusted valve leash when the motor was out of the bike. I spent like 2 hours making sure the CCT's and timing were correct. I'll check again, though...

saige

just try running with tank and lines hooked up.maybe one cylinder is runnibg out of gas before the other or its just little air pockets that wont let it flow smoothly.

7moore7

Compression test results:

Front: 60psi
Rear 140-145psi

Spec: 164psi

oh man I shoulda known it wasn't something simple

Learning as I go here... it appears that I'm now supposed to narrow it down to bore/piston/rings or head gasket/valves.

Should I worry about the rear cylinder? Seems close, although not ideal. It'll probably depend on the results of the oil in the bore test...

7moore7

Tank is at paint- it's kinda a low priority/under the table job so might take awhile

7moore7

Ok, pending a compression noob's investigation, it appears that the problem lies in the head gasket/valves... (compression did not change with a squirt of oil in the cylinder)

Well, I suspect it was running like this before I tore into it. I wasn't as familiar with the Hawk back then, so can't say for sure- curious as to any performance that I was missing. Should have checked compression when I had the motor on the floor, but had no idea that this was something to do, really. I'm hoping I can fix whatever will be needed with the motor in the bike... I really don't feel like taring this thing apart again...

8541Hawk

Check the cam timing......

7moore7

haha ok ok i'll do that part next

7moore7

Dead on...




So do I replace the head gasket and inspect the valve seats? Right now I'm looking into the possibility of just taking the top end off and take it to a mechanic to It appears this may be an option (one that is super appealing at the moment)...

lazn

What are the actual cams doing at those marks? It is possible to install the cam gears incorrectly.

Also are the valves sealing properly when closed? (with the cam cover off you should be able to check for this but I forget how)

And yes you can pull the head and have that looked at if you determine that is the problem. But before you go pulling it do make sure first. (you like to pull things apart pretty quick based on your battery adventures..)

7moore7

Cam lobes are pointing up and out just like they're supposed to. Flywheel mark is right on the FT... so narrowing it down, heh.

Not that I would know how to tell, but the parting line between the top and the bottom of the motor looks fine (as in I don't visually see any gasket issues), so maybe valve seating issue? The more I look at this, the more I think I can pull it off without much effort. But like you said, I'll do some research on diagnosis before I rip it apart.

Still not fully confident in my tests to determine if it was top end or cylinder ring related- putting oil in the spark just seems weird haha.

Edit:
Maybe they're not pointing up enough. Should maybe try rotating them inwards one notch each?



Looking at the bolt pattern on the sprockets leads me to think that this would be a tough one to mess up though...

8541Hawk

Well the next set would be the wet compression test. Yes the one that you put some oil in the cylinder. What this does is help isolate the problem.

If the compression pressure rises the you have a problem with the rings.

If the compression pressure stays around the same, then you have a problem with the valves.

8541Hawk

The gears only go one one way so that shouldn't be the problem.

Was the bike running before you started to do all the work? Just asking to see if this is a new problem, which means you should recheck all you work.

With that have you rechecked your valve lash?

7moore7

Yes it was running, BUT, I suspect this problem was there before as I knew much less about the bike then, had never been into the carbs, no exhaust wrap telling me which cylinder was hot, etc...

In all actuality, it's running now, I putted around the driveway a bit. Re-checking valve lash as soon as I can find my danged ole feeler gauges! Theys seems to bees missings.

lazn

Hrmm, I thought I remember someone putting them in 180 degrees off. (or finding them installed wrong on a bike that was getting fixed) But this is all from memory so I could be wrong.

lazn

I thought the cams are supposed to look like this:


(image stolen from this thread: https://www.superhawkforum.com/forum...install-15184/ )

VTRsurfer

Did you say you'd been running a little rich? Another member had a low compression problem that turned out to be carbon deposits on the valve seats, if I recall correctly. That was about a year or so ago.

It might have been autoteach, but I'm not sure. You might want to search his thread history.