1100 Maxim - first assessment

[turbopete]

Set to work on my new aquisition today. Looks like I have a fair bit of work, but things seem to be going well.

First job: Strip the brakes.

I've removed all 3 calipers, and although they looked like they were going to be hell to strip they came apart quite well. Pistons were well stuck in but all of them popped out with a blast of compressed air. Only casualty was one of the sliding-pin seals on the front nearside. The bike has one front caliper worked from the front M/C and the other linked with the rear. How well does this work? Has anyone here re-plumbed it so that the pair of front calipers work off the front M/Cylinder? What are the results?

Next job: Strip the carbs.

This is taxing even my almost limitless patience, but I've nearly got there. Evertything, inside was seized. The bowls came off fine but the floats were stuck solid, as were the needle valves, and the throttle sliders. I soaked the whole assembly in fresh petrol (ran out of carb cleaner). I drifted out the float pins and carefully worked the fine springs over the tangs to remove them from the stuck needles. The valve seat retaining screws came out ok and I managed to blow all 4 seats out with compressed air. The dome filters were spotless, I removed them and tried to blow the needles out of the seats - no chance of that. They are currently soaking in thinners overnight.
I managed to get the throttle sliders unstuck by dousing them in fresh petrol and then gently prising them up. They came free with a pop - the needles were gummed into the emultion tubes. I removed each carb top and cleaned the needles with thinners, but I'm looking for a way to clean the inside of the emultion tubes, as the needles still stick into them a bit. I'm thinking of using a fine dental "toothpick" brush. Are the tubes removable? If so how?

Apart from the gummed up bits the carbs internals are in perfect condition, with no signs of wear on the sliders or the needles. I think the float valves are going to give me a lot of trouble.

[Jerry]

A few people have re-plumbed the XJ brakes with good results. I find the stock system works fine for me, but you have to get into the habit of hitting the rear brake pedal first for every stop. I wouldn't worry about replumbing the system until after you get your bike on otherwise good runing condition.

For the carb question I'll defer to the carb gurus.....

[TopCatGr58]

Hey Pete,

Before you go any further, have you read the Carb FAQ's, tech tips? I'm concerned that you have soaked the bodies in cleaner, cause it will eat the butterfly seals! Next, don't worry about the float valve needles, they are tipped with VITON/rubber, will probably be creased, or deteriorated with cleaner, just pull them out. You can get replacement needle/seats fairly easily and not to expensive!

The emulsion tubes come out by unscrewing the MAIN jet underneath from the bowl side, then remove the washer, then you can press out the tubes from the bowl side, just be careful, there's a notch that keeps the tube aligned, and the tubes jet threads can be damaged. You said you've loosened the slides, hopefully you'll pulled the tops off and completely removed the slides/rubber diaphragms and inspected for pinholes in the rubber diaphragms while you've got them out?!

If they are gummed up as badly as you say, then the pilot jets are going to be seriously gummed as well, best to spray some P-B Blaster down there first, and make sure you have a good fitting screwdriver, cause the brass jet screwdriver slots are easily broken. They and that circuit will need some serious cleaning. Also, there are brass caps over the Pilot SCREWS on the top front edge of the carbs which will need to be drilled and pulled out so that you can remove them for thorough cleaning of the pilot circuit!

T.C.

[turbopete]

Originally posted by TopCatGr58
Hey Pete,

Before you go any further, have you read the Carb FAQ's, tech tips? I'm concerned that you have soaked the bodies in cleaner, cause it will eat the butterfly seals! Next, don't worry about the float valve needles, they are tipped with VITON/rubber, will probably be creased, or deteriorated with cleaner, just pull them out. You can get replacement needle/seats fairly easily and not to expensive!

Hey TopCat

Yes I have read the FAQ, and done some searches too. The carbs are in pretty good condition externally more dirty than anything, and I haven't cleaned them or soaked them in anything. Carb spares are notoriously expensive over here, last time I was quotes for GS850 needle valves and seats it was £80 per set.

The emulsion tubes come out by unscrewing the MAIN jet underneath from the bowl side, then remove the washer, then you can press out the tubes from the bowl side, just be careful, there's a notch that keeps the tube aligned, and the tubes jet threads can be damaged. You said you've loosened the slides, hopefully you'll pulled the tops off and completely removed the slides/rubber diaphragms and inspected for pinholes in the rubber diaphragms while you've got them out?!

Main jets came out easily enough, but the washers were stuck down very well, I shall make a small drift and try to press out the tubes, but I'm not too hopeful. Yes I have had the slides out and inspected the diaphragms, everything is like new, the diaphragms went back easily and without expanding out of shape.

If they are gummed up as badly as you say, then the pilot jets are going to be seriously gummed as well, best to spray some P-B Blaster down there first, and make sure you have a good fitting screwdriver, cause the brass jet screwdriver slots are easily broken. They and that circuit will need some serious cleaning. Also, there are brass caps over the Pilot SCREWS on the top front edge of the carbs which will need to be drilled and pulled out so that you can remove them for thorough cleaning of the pilot circuit!

T.C.

The pilot screw covers are already removed I noticed. I haven't touched the pilot system at all yet, not having any carb cleaner to hand. This is my biggest worry. With only 7000miles on the bike, these carbs are in great mechanical condition and I don't want to mess them up. Thank you for your advice

[prometheus578]

Yeah, you'll definately need new float needles. As for the seats... use chrome polish (mildly abrasive) and a lot of Q tips to polish the inside of the seat. This will straighten out the holes that the needles plug, plus clean and smooth out the sides of the seat so the needles won't stick.

[TopCatGr58]

Hey Pete,

The Main Jet washers will actually come out fairly easily with a small screwdriver down inside the center hole, and just angle pry them up, they are just being held in there with all of that fuel GUM. I used a nail, head side that was small enough to miss the emulsion tube notch, but large enough to mate and cover most of the tubes surface so that it didn't engage the threads, and then tapped it out, it will be stiff at first cause that GUM is like GLUE, but once you get it moving it'll just press the rest of the way out thru the top of the carb.

For the pilot jets(bottom of carb) AFTER you get some carb cleaner, either dribble some down inside the pilot jet hole if you get the big can/bucket of cleaner, or spray some down the hole if using the aerosol kind. Let it soak a while. Then get that rusty nut/bolt penetrating fluid and squirt that down there also. You might also want to try a blow dryer or heat gun, and run that on the outside of the tube a while, helps to expand the aluminum around the brass. I took a screwdriver and ground off the sides to a custom fit so that I could get the MOST tip to slot contact I could. Then once you're sure you have the screwdriver tip in contact and IN the slot, I used a small hammer to tap on it slightly to further wedge it into the slot....?pushes out more of the GUM, and also can help to "Shock" the parts loose. Then with a QUICK but firm twisting action CCW to snap the jet loose, going to slow can just cause the slot heads to break away!?

Hopefully the heavey GUM was limited to the lower parts of the bottom of the carb that was immersed in the fuel, so that not as much was up in the Pilot Jet hole??

The pilot screws are much easier, just be aware of the small rubber and metal washers on the bottom of the screw, they sometimes get stuck when you pull the screws out, then fall out at the most inopertune time.....like when you're not looking, and then they are lost!

MikesXS has branches in Europe:
Germany:MikesXS Germany
And in Netherlands:Netherlands
The parts for both seat and valve with US prices are following:

Carb Float Valve (Needle & Seat)

Carb Float Valve (Needle & Seat) - Push in type with O-Ring seal, needle & clip.
Fits: XS650G/H/SH/SJ/SK/SL (1980-84) stock Mikuni BS34 CV carbs.
Part #48-1445 $10.00US EA.


OR just:Float Needle with clip
Float Needle with clip - Fits: XS650G-K 1980-84 Stock 34mm. Mikuni CV Carbs
- Viton tipped Needle & clip Only!

Part #48-5014 $4.00US EA.

Or...you'll probably need the gasket too, so get it all in one kit:
Carb Rebuild Kit
Carb Rebuild Kit - Fits: XS650SG-SL (1980-84) stock Mikuni 34mm. CV carbs
Kit Contains : Push-in Float Valve assembly with O-Ring, Carb rubber passage
Plug & Float bowl Gasket 3F7. Made in Japan - 1 kit required per carb.


Part #48-1408 $12.00US /Kit

I got the gasket alone, it's almost a perfect fit, just have to enlarge the small hole where the "fuel enrichener" pipe goes thru for proper alignment!! Hope this helps and you find decent prices from the German location?

T.C.

[turbopete]

Couple of pics of my poorly-lloking Maxim. I've already removed the brakes here and cleaned up the front forks and mudguard. See the damage to the seat unit and missing plug caps and indicators - the previous owners dogs ate them!





I've finally got the carbs stripped right down. I got all the jets out, and all of the emulsion tubes. I've un-blocked the enrichment circuit tubes in the float bowls. One of the pilot screws was stck in very well, so after soaking it a while in carb cleaner I filled the hole up with WD40 (release fluid) and then used a hot-air paint stripper to heat up the carb body until the WD40 started to boil then used a good-fitting screwdriver to carefully remove the pilot screw.

Can someone furnish me with the setup specs for the carbs (pilot screw turns and float height) please?

Pete

[turbopete]

Can anyone help me with these carb adjustments please. I need the float height (and where to measure it) ans the idle screw setting.

Cheers
Pete.

[DiverRay]

Pete;
Most of the riders set the floats to 24 mm. This is from the base of the carb body to the top of the float. You NEED to keep all 4 floats at the same level. you can adjust the level between about 24 (rich) to 26(lean)mm.
The carb thread should give the rest, but if I remember correctly, it is 1 1/2 turns out from LIGHTLY seated to start. make any other adjustments about 1/8 turn at a time.

[turbopete]

Cheers DiverRay.

I take it that I should remove the gasket and measure form the alloy face?

[lsippell]

Is this float measurement for the XJ or the XS? I ask this, because the manual gives no measurement on the floats for the XJ, just a measurement of the gas level relative to the surface the float bowl screw mates against. 3 mm below it +or- 1 mm.



Louis

[TopCatGr58]

Louis and TurboPete,

The fluid in the tube IS the manual's way, but it's such a P.I.T.A., so we just use the 24-26mm range. Mine is actually at 23, since the 80 series carbs stated that IF you didn't have the fluid tube to measure by, vs the 78-79 is slightly higher at ~25.
T.C.

[lsippell]

t.C.
Thats good to know since I'm going to pull my carbs to check a lean idle in one of them as soon as I finish reading all the new messages.

Louis

[turbopete]

Originally posted by prometheus578
Yeah, you'll definately need new float needles. As for the seats... use chrome polish (mildly abrasive) and a lot of Q tips to polish the inside of the seat. This will straighten out the holes that the needles plug, plus clean and smooth out the sides of the seat so the needles won't stick.

Seems you are right about needing new needles. I got them stripped down and polished out the seats, cleaned every speck off both seat and needles - absolutely spotless. I set the floats at 24.5mm, but the bike wouldn't run off choke and even on choke it was struggling. It's running lean. I stripped off the carbs again and re-checked everything for dirt/blockages, still all ok. I re-set the floats to 23mm, started the bike but still barely running, just about revs up but popping at part-throttle. Still lean.

I decided to check the float levels using the claer tube on the drain cocks. I cleaned out the tube with carb cleaner to reduce the fuel stiction in the tube. I checked the four carbs and they are all over the place. The highest is 9mm (should be 3) the lowest is 12mm. It does indeed look like I need new needles. I guess the rubber tips were deformed by soaking them in carb cleaner.