Rebuilding old carbs you don't know the history to.

I've got a 2nd set of XJ1100 carbs that look to be in decent condition and am going to replace the old rubber parts/seals but I'm also going to attend to the jets and wonder about them.

I'm wondering how much you can trust the jets to be essentially normal if they have been cleaned earlier by an unknown repairman or PO? I'm wondering if someone cleaning the jet passages & uses something like a guitar string to get in there will likely create accidental enlargement of holes or maybe micro scratches to the inner surfaces which might affect efficient fuel flow?

Is it worthwhile to simply replace jets with new ones because there's an expected advantage to doing so? If so, which jets are the most frequent ones to need replacement? & how to tell if there's minimal damage that replacement is the best idea?

 

Read the Numbers Stamped on the Jets.

Use a Welders Tip Cleaning Set as a Gauge.
Buy two tip cleaning sets.

On one set, ... Snip the serrated parts clean-of the wire.
Using plain wire only, ... probe the Jets.
If they've been hacked-up ... you'll "Feel" it.

But, ... if you HAVE a decent set of BODY'S.
Everything nice-ee - nice-ee.

Just, get some brand NEW Jets.

chacal or Mikes XS // $3.00 ~ $5.00 ea.

 

Well, that's the thing I guess, these carbs look really nice from the outside (a bit of discoloration here & there) and by all appearances they are a 9 out of 10 for looks. I just don't know which of the jets would be good insurance to replace.

I'm happy with my present carbs but am looking forward to rebuilding these as well & am looking for the best gas mileage I can possibly wrangle. So the experiment is to have the touchy bits all be working at their best and see how that goes toward upping the mileage. I finally have the original exhaust looking really good. Getting closer to stock...

So if jets should be replaced as SOP, which ones? All of them?

 

If you wanna replace your jets go ahead. Stock #'s are in the book or around here somewhere. I personally don't think it's necessary unless you have reason to believe that they've been drilled, you can see scratches on the inside, or are otherwise boogered up.... Rick mentioned welder tip cleaning brushes, I use a .010 guitar string, either will work. As long as you're careful with the welder's brushes or whatever, you're not gonna damage the jets

Just as a heads up, I've heard of a few other people having trouble with dynajet... sizes not being accurate and/or good holes.... PM chacal and he'll hook you up with whatever you need.

 

Chances are ... all those jets will be OK.

If they are Bunged-up ... Replace.

Get a used Jewelers Loop or a LED Lighted Magnifying Glass and do a Visual Check of EVERY Jet.
::: Mikuni has AIR Jets at 3 & 9 O'clock in the Intake Horn :::

Make a Pilot Jet Power Flusher.
Take a section of Heat Shrink and shrink it on to a Carb Red Tube.
Leave the Outer-end "Un-shrink"

Place the Mikuni Pilot FUEL Jet into the Un-shrunk end.
Hole the Tubing tight too the Jet.
Blast away.

:: Aim it into a Bucket so you have a Minimum search area if it gets away on you. :::

 

I've tried removing the drain screws but they're frozen in solidly. I have a series of the Japanese "Philips Head" screwdrivers but these screws are hermaphrodite and it may be better to use a flat head on them. When I tried turning them, they didn't budge and I didn't want to torque further & damage them.

The pinkish glaze look is Kroil I've been applying for the last couple of days.



What's the best way to get these drain screws free? I don't want to use heat & melt the O-rings & leave a melted rubber area inside.

 

Impact driver! Never personally used one, but I know that is what you want; each hammer blow provides downward force AND torque simultaneously.

 

Impact Driver. If that doesn't get them, then you have to try heat. If that gets them replace the o-rings anyway. If it doesn't get them, just pull the bowls off.

Dave F

 

I"M NOT RECOMMENDING THIS---this is only what I did. I used a dremel tool & deepened the slot to use a large standard screwdriver & it worked. This is probably bad advice & I'm probably wrong, but it worked for me.

one more disclaimer *I'M NOT RECOMMENDING THIS* so.....

 

I used the sears extractor bit to drill out my stripped bowl screws and got hex screws from Chacal.

 

+1

 

+1 on the impact driver. The head on the screws in the pic look good enough for an impact driver to do the trick for you. I had 1 with a severely stripped head and had to drill it out and use an ease-out. I was very nervous doing it, but it came out. I replaced them with stainless ones from Chacal.

 

Those Drain Screws can be a nasty problem. Arm yourself for the chore.

Prep:
Dremel Tool w/ Flex-shaft Extension
Quick-Change Chuck & Collet Set
1/8" Diameter Collet

Diamond Tipped Cutting Set
• 1/8" Spherical Tipped Diamond Cutter

Perform some "Dentistry" on the Drain Screw. Cut a Slot for a Screwdriver Bit.
Shape a Screwdriver Bit to fit the Inside Diameter of the Drain Hole and get a good fit within the Slot you fabricate with the Diamond-tipped Cutter.

Craftsman Hand-held Impact Tool
1/2 -to- 3/8 Drive Adaptor
Universal Bit Holding Socket - (or 6-Point Socket that fits bit).

I lock the Ball-end of a Med. Ball-Peen Hammer in the Vice and use the Handle to steady the Fuel Bowl upon for the pending Impact-whack the Stuck Drain Screw needs to get.

Have a gloved assistant steady the Fuel Bowl on the Hammer Handle at an ANGLE where the IMPACT you supply to the SCREW will be rendered to the Screw and not lost in a torsional or non-anchored reaction to the blow.

Make the Impact "Count"
Strike the Tool a smart blow, ... then, regroup and reposition for any additional impact strikes necessary too dislodge the Drain Screw.

Apply "Downward" and "Twisting" torque to the Impact Tool just before striking the tool so that the Force of the Impact is translated to twisting force on the Drain screw each time you smack that some-bidge!

Diamond Burr Set:
http://www.garrettwade.com/diamond-burr ... /19T05.01/

Collet Kit:
http://www.all-spec.com/products/4485.html

 

Thank you all for the replies.

I gave in to the impact driver and going with a flat-head with tailored slots. After reading Ricks excellent review I used the bits I have on hand to enlarge the slot in the heads. I have a 25 pound rectangle of HY-80 steel that serves as an anvil. I was able to get the bits lined up and the force lined up linearly and they all broke free.

I just ordered a series of carb O-rings and will replace these among the others in the carb.

Nice price on the link for diamond burr set, Rick!

I now have another question but I'll start that in another thread to keep this one intact for the next person searching for the solution to stuck drain plugs.

Thanks again!

 

Replace the chewed-up Drain Screws.

Smear the Bowl Threads with Waterproof Synthetic Grease.
TIGHTLY double-wrap the Drain Plugs with PTFE Tape.
They'll never leak or seize again.

http://www.shop3m.com/70016054267.html? ... -PTFE-Tape