Gunson Colortune Issues

Can’t seem to edit the last post, but petcock is leaking approx 1/4oz an hr.

Starter jets and passages are clean.

I uploaded a pic of the wet set, can someone confirm that it’s the correct level? All 4 are at that level.

also there is a mesh screen under the float needle that was pretty gunky. How do I get it out to clean it? I spray it out with carb cleaner and got most of it, but what to make sure it’s good to go.

anything else I should be checking while I have it apart?

I’ll be checking the valves too since I’m already at this point.

 

Hmmmm

 

@hogfiddles Guess I’ll be checking the tank too

I know it has a little rust in it that I’ve tried to clean out before. Have any suggestions on how to clean out the dirt/grim/rust? Last time I took the petcock off and tried to get everything through that hole in the bottom but I had a problem with flash rusting after I washed the inside with water.

 

Water causes rust!!
Use phosphoric acid

 

Can you give me your process for cleaning it out and I’ll make sure I follow it to the T. I can send pics of the inside of the tank if you need to see what I’m dealing with.

And would it be better to get new internals for the petcock or just get a in-line fuel shutoff?

 

Do a search in the forums for “phosphoric acid” and you got all the reading you could ever want.

rebuilding the petcock give you a rebuilt petcock, but I have an snowmobile fuel line shutoff in my fuel line anyway. Fwiw

 

Chacal sent me a link to this (https://www.xjbikes.com/forums/threads/rebuilding-the-yamaha-vacuum-fuel-valve-w-pics.25058/) which I've read before. I got a replacement petcock internals through Chacal last year, but since I have a drip-drip-drip, do you think it's worth trying to bend the flat disc spring to get a better seal and see if that stops the leak?

 

There is, iirc, a little instruction that a lot of people miss.......something about hitting the piston, or disc, or washer....something...... in the PETCOCK to make it seat better. Otherwise it will continue to do that. Best have Len point that out to you, cuz I’m not finding it at the moment.

dave

 

@hogfiddles @chacal

Ya I saw it somewhere and just read back through the guide and I can't find it again. I might just throw an on/off in the fuel line and call it good, but since I'm cleaning the tank anyway, it's worth trying to bend it and get the o-ring to seat better.

I know the tall in-tank fuel filter is in rough shape, since I have an inline fuel filter, do I need to replace the in-tank one?

 

The in-tank one gets some stuff, but it’s more for knowing when to switch to reserve

 

those little screens should have come out with valve body . put an inline filter in your fuel hose and throw the caps away or get new ones and still do a fuel filter.

 

While I have them off the bike and apart, is there anything else that I should look at before I put them back together and on the bike?

I got the little screens out, just pressed on one side, they spun in the channel vertically and then you can grab them with needle nose pliers and pull them out.

I’m checking valves next. Is there a specific thread for checking them like there is for the wet set?

BTW: Jets are 36.5 and 107 with the float valve seat one at 2.0

 

Setting the fuel levels

also back flush the chamber back out the fuel tee to get any crud out of the chamber above the screens

valve shims
Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

 

Thanks for the links!

and I blasted those passages and clean hitting every passage so they keep getting soaked just in case anything is left.

Anyone have the link to that flat disc adjustment in the petcock? Or can I just add a washer behind the spring to give it some more force? I’m taking the petcock apart tomorrow and cleaning the tank too.

 

I might have bigger issues now...went to drain the oil and put some cheaper stuff in to flush out the gas and it didn’t come out which was weird because the gassy oil seemed to drain no problem. I put more in and still nothing. I’ve got 2.5 quarts in and it’s not coming out. I put it in 1st and 2nd and rocked it and the engine seems seized...any suggestions on how to fix this bugger without shelling out for a new engine...

When it died while I was Carbtuning it, it didn’t just die, the rpms just slowly came down like it was starved for fuel with no engine knocking or bad noises so hopefully that’s a good sign...

 

from the rebuild link just below photo with washer

In both pairs, the replacement springs are on the left. You can also use a washer as shown to increase spring tension and improve sealing; but if your seat is in good shape it should not be required.from catalog

HCP663 Aftermarket vacuum control module vacuum diaphram SPRING SHIM WASHER. This washer goes behind the vacuum diaphram plunger spring and acts as a tension shim to allow the spring to put more pressure on the replacement-style o-ringed plunger tip, and thus allowing it to seat and seal properly. Used on all XJ550, 1984-85 FJ600, 1986-88 FZ600, all XJ650 (except Turbo), all XJ700, XJ750RL, XJ750-X, XJ900RK, RL, N/FN, and F models, and all XS1100 Standard model petcocks,and the vacuum control unit on XJ1100, XS1100 Special, and XS1100 Midnight Special models. This washer goes under the spring and fits into the recessed well in the cover plate.

 

oil not coming out drain plug hole? maybe hole is plugged with chain guide gently push something into hole see if it clears and drains filter oil both batches through a screen look for bits of plastic

 

Not coming out drain plug hole or filter hole, I tilted the bike on it's side and center stand and nothing was coming out.

I put all of the plugs and bolts back in so hopefully as if my magic, it will fix itself

 

you mentioned a fuel leak into crank case. I picked up a 650 last year if it did not start on first try cylinders would fill with fuel and stop motor from turning over pulled out spark plug and fuel blew out the sparrk plug holes.

 

Ya the petcock was dripping around 1/4 oz an hour so it put a lot of fuel into the crank over the winter when it was parked and like an idiot I didn't change the oil before messing with it. I didn't know the oil was in the crank at that point, found out later.

So is there any way to assess the possible damage? I've never torn into the engine/piston/transmission portion of the engine before minus checking valve clearances so this is new territory for me.

I'm going to pour some Marvel Mystery Oil in the tops of the cylinder through the spark plug holes (saw it on YouTube and I don't have Acetone to mix with my ATF) and then tomorrow I'll see if the 19mm bolt turns on the crankshaft.