Intake Manifolds

Started the intake manifolds (Rick quickly corrected my use of "boots") and found it relatively easy to get the carbs out. However, only one of four manifolds are off as three bolts seem pretty seized. Am I better off cleaning and sealing them right where they are or should I risk snapping a bolt. Tried overnight penetrant, mild hammer taps, but with the aluminum material I am afraid to go too much further. And heat is not an option, given the rubber. Any thoughts out there?

 

After a cruise around the message boards and archives, it seems the best idea is putting the manifold that I did get off back on the bike and torque the already removed cap screws back into place. Then to fill in the cracks while they are on the bike. Cleaning the carbs while they are off seems like the right thing, then I'll button it back together to see if she'll run.

 

You could also consider heating the bolt with a soldering iron. Might swell up enough to break some of the crud.

 

If you're not replacing the manifolds don't remove them.

 

Good decision!
Snapping-off a Manifold Cap Screw or three ... would have put you so deep in so deep in (watch how I beat the auto censor) shidt* that you would be pullin'-out hair and cursing everything.

Clean the Carbs.
Thoroughly.
Bowls, Bowl Jets, Main Fuel, Pilot, Float Valve Pins and Seats*, EMULSION TUBES -- Outside, Inside and threw side-to-side (Nozzle), Main AIR Passage, Pilot AIR Passage, Diaphragm Assembly, DIAPHRAGM Assy. BORE*

*Clean, Scrub with ScotchBrite Pad (Gray), Polish until Mirror Finish.

*Bores ~> Search: "Clunk Test"

Enrichment Valves, Pilot Mixture Screws, both Passages.

Marine Corp, White-Glove Inspection ~~> CLEAN!

Put 'em back together.
Put 'em back on.
Sync them.

Tune 'em until there's no possible way that you can make it better.

Ride like you stole it!

 

Put the carbs back on.

Wait until the engine is completely cool (as in overnight cool).

Then run the engine until it's hot. REALLY hot. Like let it idle for 5-10 minutes (fan on front optional).

Now try to remove the bolts, using all your favorite tricks: Tap with a hammer (yes, it's a tight fit in there with the carbs in the way!). Torque the bolts slightly as if tightening them (clockwise) just a tiny scooch before loosening them. If those tricks fail, warm up the engine again and then squirt (a turkey baster works great) some cool/cold water onto the BOLT HEAD....squirt quite a bit.

The aluminum heads expand quite a bit faster than the steel bolts, and this differential expansion rate happens most significantly upon cold start (before the bolts start to get heat soaked). You want the threaded holes in the aluminum heads to expand as much as possible before the steel manifold bolts get into their expansion routine. This extra couple-of-thousandth's clearance can sometimes be the ticket to getting even the most stubborn of frozen fasteners to un-sieze.

You can also wrap a rag/shop towel/washcloth around the bolt heads and be squirting cold water on them while the engine is running. Sort of creating an extra heat-sink operation for the intake bolts. The cooler they remain while the hotter the aluminum gets is what you're shooting for......

 

Before we have him try any of this process ... I think it's fair to ask:

Have you done any of this?

What are the known Dangers?

 

Yes. All's fair in love and war and XJ motorsickle mechanic-ing.......

So:

Yes, I've done "it" (meaning the method, but not on the intake bolts, but on exhaust studs and other fasteners. The principle remains the same).

Known Dangers:

a) it may get you no where.
b) it may break a stud or bolt
c) you will probably burn your hands, unless you're really careful.
d) you'll have to spend more $$ to replace the bolts and, most probably, intake gaskets and, while you're at it, new manifolds, too, since although the "patch-them-with-RTV-or-an-old-inner-tube" trick may work for a while, it rarely lasts for long and, given what a chore it is to pull carbs on and off, you might as well do a professional (correct) job rather than a half-azz job---especially if you enjoy RIDING rather than GUESSING/DIAGNOSING what the cause of poor performance problems are......

;-)

 

Thanks for the info fellas. I fixed the manifolds on the bike (not as artsy as I need to be for this work) and they look OK. Just could not risk twisting the cap screws off. Cleaned the carbs and put it all back together, which was a lot easier than I thought it would be, and it still will not start. New battery, lots of crank, fuel in and on. Just doesn't seem to want to fire. Now where should I best direct my time?

 

Check spark at the plugs (make sure any and all plugs "out" of the engine are grounded to the engine block or you risk burningup a coil or TCI!).

Are you using the choke?

Out of curiosity, what model/year bike?

 

OK, OK, OK - - wait while I take a breath - - - I LOVE the easy stuff! I local pal suggested I pop the gas cap and it started right up!! And runs SWEET. Now the question remains - is the airlock done or do I need to do more to prevent a recurance?

 

There is a tiny fuel vent hole in the gas cap, under the sealing ring, and a check valve ball (looks like a tiny ball bearing) that allows the fuel tank to be vented while also preventing spills from the tank. You'll need to remove the cap from the tank and then start taking apart the innards of the cap. Not hard, BUT MAKE YOURSELF A DIAGRAM AS YOU GO! NOTE THE ORIENTATION OF THE ITEMS. Especially the "lock ears" mechanism as you take it apart (and you might as well lube it while you have it apart).

That vent ball is either stuck or the passage is crudded up.....

BTW, I have replacement cap-to-tank sealing ring/spring and the upper and lower inner cap mechanism rubber o-rings available if you decide to "rebuild" you gas cap while you have it apart...........

 

So if I take a hard turn or brake hard and gas spills out the cap...does that mean there is something wrong with my gas cap? Or just that I filled it too high?

 

Either, but........unless you REALLY overfilled the tank.....the check valve ball in the cap should prevent fuel leakage. The spring-cinched rubber sealing ring could also be worn out (a common problem) and it no longer seals properly to the metal filler neck. Or the 4 little metal springs that go under the sealing ring have siezed up and no longer exert the necessary pressure against the sealing ring to "push" it down against the filler neck.

Not to beat a dead horse, but did you know that there are over 20 individual springs just in the gas cap assembly itself?

 

ohhhhhh kay....

so perhaps I should give it a look. What would I buy?

I only fill it to the bottom of that insert in the opening. never higher.

 

PghXJ, I sent you a PM with all the info.........

 

Thanks Chacal...I will let you know what I need and if its needed. The forks need fixing first.

 

thanks chacal. I'll have a look over my cap and see if I see anything worn or needing replacement. It may just need a good cleaning.